Progress Thread Nasty Ninety Notch

[joetrainer31]

Update: Blowhard 2.

I found my receipt from when the 2 CA legal cats were purchased. It clearly says that they have a 5yr/ 50k mile warranty. I'm only a year into that. So, I made an appointment with my old employer for Monday to have the cats in question replaced. However, I plan on watching them like a hawk to make sure the work is done right. I also found the O2 sensor receipt and they are still in warranty as well. Think I'll replace those too. They probably took a beating along with the cats.

The o/r H-pipe should be here Monday as well. The plan with that is to get the spun metallic cats and have them installed and switch out the mid pipe once we move to a non-emissions location. No fines and no smell is the desire!

 

[joetrainer31]

Update: H2O

Annnd I saw that the water pump (new) was leaking at the gasket (new) while I was under the car fixing the exhaust problem. This tells me, once again, that the tech who installed it did a poor job. Looks like it's time to rip the pump off and replace it.

Although this stinks I'm glad to find it now while in town and not while trying to move...

 

[hoopty5.0]

It wouldn't be a fox if they didn't have continual issues!

 

[joetrainer31]

It wouldn't be a fox if they didn't have continual issues!

It's crazy! I've put a total of 600 miles on the car in the last year and a half. That seems a bit excessive.

 

[joetrainer31]

Update: Poor work & poor parts = codes!

Okay, so we are going to battle again. Upon inspecting the water pump at the shop I saw that the prior "tech" smoked the job. He put an old water pump on my new engine. So, I R&R'd that pump with the quickness.

Next, I had my O2 sensors warrantied out. I made it exactly two miles before my CEL illuminated. One or both of the O2s is bad (code 91).

Lastly, when the tech was taking my car into the bay I heard a short pop/grind. I figured he just ground the gears for a second, but nope. It's not that easy. Now there is a code 67 for the NDS and/or A/C input high. I know there are 3 neutral safety switches on the car: 2 on the pedal and one on the top of the trans. Does anyone have a test path for these? This crap is killing me.

To clarify: there is a hard CEL. The codes were pulled KOEO. Code 67 was "O" = KOEO code. Code 91 was "C" = Continuous memory code.

Update: 7/20/16. Took the car a few miles to get gas. It seems that the more I work on it, the more money we pump into it, and the more I drive it; the more problems it has.

In hopes of eliminating a potential and/or actual problem I put vacuum caps on the lines that go to the smog pump assembly. The pump is bypassed and the line that goes to the h-pipe was connected with standard rubber hose (which is not good). The hose was dried out from the heat and I was concerned about a potential fire so I removed the rubber hose and blocked of the port in the stock h-pipe. I was concerned that this open hose under the car would mess with the TAB function, thus the vac caps mentioned above.

Anyhow, now the car has a HUGH whistling noise similar to a supercharger for the first couple of miles. Then, it goes away. It's too soon to tell if it's a dude water pump, the new (not reman) pump went on yesterday, or if it's related to the vac line cap off, or something else they messed up at the shop. All I know is that I went in with one issue and left with 3!

To recap the problems:
1) hard CEL
2) code 67 (KOEO)
3) code 91 (Continuous memory)
4) loud whistling noise when cold

* The idle seems rock steady, oddly enough.

Anyone? @jrichker , @hoopty5.0 , @FoxMustangLvr

 

[joetrainer31]

Update: More Trouble!

Between parking the car last night and this morning when I checked the codes again (post last night's test drive), there is ANOTHER code! Now, code 32 has popped. This car seems to be on a money sucking nose dive no matter what I do. Any ideas?

 

[hoopty5.0]

Uhhh... Not sure why you still have the 91. Unplug the + terminal for an hour and let the computer reset and dump codes again.

....At a certain point, I usually give up and say eff it, I'm driving it. This is also why my car is only marginally nice, haha

 

[joetrainer31]

Uhhh... Not sure why you still have the 91. Unplug the + terminal for an hour and let the computer reset and dump codes again.

....At a certain point, I usually give up and say eff it, I'm driving it. This is also why my car is only marginally nice, haha

Thanks for the input!

I think the problem has been resolved. I got it up on the rack at the shop and had the tech pull the driver side O2 (91). It was a Bosch unit from Autozone. The passenger side O2 (41) was a Denso from another parts house. Since I didn't have the code with the Denso I decided to have them put a Denso back in. I test drove it with the tech for 4 miles and the CEL didn't return. Before, it took 1.5-2 miles for the CEL to come on.

After 4 miles I scanned for codes again at the shop and none showed up; not the 91, 32, or 67. Now, the battery was disconnected and reconnected prior to the test drive in order to start from scratch, but I hope the problem was resolved. I did notice that the Denso O2 had 3 pigtail prongs whereas the Bosch had 4 prongs at the pigtail.

I put another mile on the car to get home and so far so good. I'll drive some more and update. This thing has me ready to cry! Once again, don't trust Autozone parts. I've had about a 70% failure/wrong part rate.

The whistle noise was because there was anti-freeze on the belt.

 

[jrichker]

Thanks for the input!

I think the problem has been resolved. I got it up on the rack at the shop and had the tech pull the driver side O2 (91). It was a Bosch unit from Autozone. The passenger side O2 (41) was a Denso from another parts house. Since I didn't have the code with the Denso I decided to have them put a Denso back in. I test drove it with the tech for 4 miles and the CEL didn't return. Before, it took 1.5-2 miles for the CEL to come on.

After 4 miles I scanned for codes again at the shop and none showed up; not the 91, 32, or 67. Now, the battery was disconnected and reconnected prior to the test drive in order to start from scratch, but I hope the problem was resolved. I did notice that the Denso O2 had 3 pigtail prongs whereas the Bosch had 4 prongs at the pigtail.

I put another mile on the car to get home and so far so good. I'll drive some more and update. This thing has me ready to cry! Once again, don't trust Autozone parts. I've had about a 70% failure/wrong part rate.

The whistle noise was because there was anti-freeze on the belt.

The 4 wire O2 sensor is for a 4 cylinder car....


It is probably a little late, but here is the test pat for code 41/91. You may want to save it for future reference...
Code 41 or 91. Or 43 Three digit code 172 or 176 - O2 sensor indicates system lean. Look for a vacuum leak or failing O2 sensor.

Revised 11-Jan-2015 to add check for fuel pressure out of range

Code 41 is the passenger side sensor, as viewed from the driver's seat.
Code 91 is the driver side sensor, as viewed from the driver's seat.

Code 172 is the passenger side sensor as viewed from the driver's seat.
Code 176 is the driver side sensor, as viewed from the driver's seat.

Code 43 is not side specific according to the Probst Ford Fuel injection book.

The computer sees a lean mixture signal coming from the O2 sensors and tries to compensate by adding more fuel. Many times the end result is an engine that runs pig rich and stinks of unburned fuel.

The following is a Quote from Charles O. Probst, Ford fuel Injection & Electronic Engine control:
"When the mixture is lean, the exhaust gas has oxygen, about the same amount as the ambient air. So the sensor will generate less than 400 Millivolts. Remember lean = less voltage.

When the mixture is rich, there's less oxygen in the exhaust than in the ambient air , so voltage is generated between the two sides of the tip. The voltage is greater than 600 millivolts. Remember rich = more voltage.

Here's a tip: the newer the sensor, the more the voltage changes, swinging from as low as 0.1 volt to as much as 0.9 volt. As an oxygen sensor ages, the voltage changes get smaller and slower - the voltage change lags behind the change in exhaust gas oxygen.

Because the oxygen sensor generates its own voltage, never apply voltage and never measure resistance of the sensor circuit. To measure voltage signals, use an analog voltmeter with a high input impedance, at least 10 megohms. Remember, a digital voltmeter will average a changing voltage." End Quote

Testing the O2 sensors 87-93 5.0 Mustangs
Measuring the O2 sensor voltage at the computer will give you a good idea of how well they are working. You'll have to pull the passenger side kick panel off to gain access to the computer connector. Remove the plastic wiring cover to get to the back side of the wiring. Use a safety pin or paper clip to probe the connections from the rear.

Disconnect the O2 sensor from the harness and use the body side O2 sensor harness as the starting point for testing. Do not measure the resistance of the O2 sensor , you may damage it. Resistance measurements for the O2 sensor harness are made with one meter lead on the O2 sensor harness and the other meter lead on the computer wire or pin for the O2 sensor.

Backside view of the computer wiring connector:

87-90 5.0 Mustangs:
Computer pin 43 Dark blue/Lt green – LH O2 sensor
Computer pin 29 Dark Green/Pink – RH O2 sensor
The computer pins are 29 (L\RH O2 with a dark green/pink wire) and 43 (LH O2 with a dark blue/pink wire). Use the ground next to the computer to ground the voltmeter. The O2 sensor voltage should switch between .2-.9 volt at idle.

91-93 5.0 Mustangs:
Computer pin 43 Red/Black – LH O2 sensor
Computer pin 29 Gray/Lt blue – RH O2 sensor
The computer pins are 29 (LH O2 with a Gray/Lt blue wire) and 43 (RH O2 with a Red/Black wire). Use the ground next to the computer to ground the voltmeter. The O2 sensor voltage should switch between .2-.9 volt at idle.


Testing the O2 sensors 94-95 5.0 Mustangs
Measuring the O2 sensor voltage at the computer will give you a good idea of how well they are working. You'll have to pull the passenger side kick panel off to gain access to the computer connector. Remove the plastic wiring cover to get to the back side of the wiring. Use a safety pin or paper clip to probe the connections from the rear. The computer pins are 29 (LH O2 with a red/black wire) and 27 (RH O2 with a gray/lt blue wire). Use pin 32 (gray/red wire) to ground the voltmeter. The O2 sensor voltage should switch between .2-.9 volt at idle.


Note that all resistance tests must be done with power off. Measuring resistance with a circuit powered on will give false readings and possibly damage the meter. Do not attempt to measure the resistance of the O2 sensors, it may damage them.

Testing the O2 sensor wiring harness
Most of the common multimeters have a resistance scale. Be sure the O2 sensors are disconnected and measure the resistance from the O2 sensor body harness to the pins on the computer. Using the Low Ohms range (usually 200 Ohms) you should see less than 1.5 Ohms.

87-90 5.0 Mustangs:
Computer pin 43 Dark blue/Lt green – LH O2 sensor
Computer pin 29 Dark Green/Pink – RH O2 sensor
Disconnect the connector from the O2 sensor and measure the resistance:
From the Dark blue/Lt green wire in the LH O2 sensor harness and the Dark blue/Lt green wire on the computer pin 43
From the Dark Green/Pink wire on the RH Os sensor harness and the Dark Green/Pink wire on the computer pin 29

91-93 5.0 Mustangs:
Computer pin 43 Red/Black – LH O2 sensor
Computer pin 29 Gray/Lt blue – RH O2 sensor
Disconnect the connector from the O2 sensor and measure the resistance:
From the Red/Black wire in the LH O2 sensor harness and the Red/Black wire on the computer pin 43
From the Dark Green/Pink Gray/Lt blue wire on the RH Os sensor harness and the Gray/Lt blue wire on the computer pin 29

94-95 5.0 Mustangs:
Computer pin 29 Red/Black – LH O2 sensor
Computer pin 27 Gray/Lt blue – RH O2 sensor
From the Red/Black wire in the LH O2 sensor harness and the Red/Black wire on the computer pin 29
From the Dark Green/Pink Gray/Lt blue wire on the RH Os sensor harness and the Gray/Lt blue wire on the computer pin 27

There is a connector between the body harness and the O2 sensor harness. Make sure the connectors are mated together, the contacts and wiring are not damaged and the contacts are clean and not coated with oil.

The O2 sensor ground (orange wire with a ring terminal on it) is in the wiring harness for the fuel injection wiring. I grounded mine to one of the intake manifold bolts

Check the fuel pressure – the fuel pressure is 37-41 PSI with the vacuum disconnected and the engine idling. Fuel pressure out of range can cause the 41 & 91 codes together. It will not cause a single code, only both codes together.

Make sure you have the proper 3 wire O2 sensors. Only the 4 cylinder cars used a 4 wire sensor, which is not compatible with the V8 wiring harness.

Replace the O2 sensors in pairs if replacement is indicated. If one is weak or bad, the other one probably isn't far behind.

Code 41 can also be due to carbon plugging the driver’s side Thermactor air crossover tube on the back of the engine. The tube fills up with carbon and does not pass air to the driver’s side head ports. This puts an excess amount of air in the passenger side exhaust and can set the code 41. Remove the tube and clean it out so that both sides get good airflow: this may be more difficult than it sounds. You need something like a mini rotor-rooter to do the job because of the curves in the tube. Something like the outer spiral jacket of a flexible push-pull cable may be the thing that does the trick.

If you get only code 41 and have changed the sensor, look for vacuum leaks. This is especially true if you are having idle problems. The small plastic tubing is very brittle after many years of the heating it receives. Replace the tubing and check the PVC and the hoses connected to it.

 

[joetrainer31]

The 4 wire O2 sensor is for a 4 cylinder car....


It is probably a little late, but here is the test pat for code 41/91. You may want to save it for future reference...
Code 41 or 91. Or 43 Three digit code 172 or 176 - O2 sensor indicates system lean. Look for a vacuum leak or failing O2 sensor.

Revised 11-Jan-2015 to add check for fuel pressure out of range

Code 41 is the passenger side sensor, as viewed from the driver's seat.
Code 91 is the driver side sensor, as viewed from the driver's seat.

Code 172 is the passenger side sensor as viewed from the driver's seat.
Code 176 is the driver side sensor, as viewed from the driver's seat.

Code 43 is not side specific according to the Probst Ford Fuel injection book.

The computer sees a lean mixture signal coming from the O2 sensors and tries to compensate by adding more fuel. Many times the end result is an engine that runs pig rich and stinks of unburned fuel.

The following is a Quote from Charles O. Probst, Ford fuel Injection & Electronic Engine control:
"When the mixture is lean, the exhaust gas has oxygen, about the same amount as the ambient air. So the sensor will generate less than 400 Millivolts. Remember lean = less voltage.

When the mixture is rich, there's less oxygen in the exhaust than in the ambient air , so voltage is generated between the two sides of the tip. The voltage is greater than 600 millivolts. Remember rich = more voltage.

Here's a tip: the newer the sensor, the more the voltage changes, swinging from as low as 0.1 volt to as much as 0.9 volt. As an oxygen sensor ages, the voltage changes get smaller and slower - the voltage change lags behind the change in exhaust gas oxygen.

Because the oxygen sensor generates its own voltage, never apply voltage and never measure resistance of the sensor circuit. To measure voltage signals, use an analog voltmeter with a high input impedance, at least 10 megohms. Remember, a digital voltmeter will average a changing voltage." End Quote

Testing the O2 sensors 87-93 5.0 Mustangs
Measuring the O2 sensor voltage at the computer will give you a good idea of how well they are working. You'll have to pull the passenger side kick panel off to gain access to the computer connector. Remove the plastic wiring cover to get to the back side of the wiring. Use a safety pin or paper clip to probe the connections from the rear.

Disconnect the O2 sensor from the harness and use the body side O2 sensor harness as the starting point for testing. Do not measure the resistance of the O2 sensor , you may damage it. Resistance measurements for the O2 sensor harness are made with one meter lead on the O2 sensor harness and the other meter lead on the computer wire or pin for the O2 sensor.

Backside view of the computer wiring connector:

87-90 5.0 Mustangs:
Computer pin 43 Dark blue/Lt green – LH O2 sensor
Computer pin 29 Dark Green/Pink – RH O2 sensor
The computer pins are 29 (L\RH O2 with a dark green/pink wire) and 43 (LH O2 with a dark blue/pink wire). Use the ground next to the computer to ground the voltmeter. The O2 sensor voltage should switch between .2-.9 volt at idle.

91-93 5.0 Mustangs:
Computer pin 43 Red/Black – LH O2 sensor
Computer pin 29 Gray/Lt blue – RH O2 sensor
The computer pins are 29 (LH O2 with a Gray/Lt blue wire) and 43 (RH O2 with a Red/Black wire). Use the ground next to the computer to ground the voltmeter. The O2 sensor voltage should switch between .2-.9 volt at idle.


Testing the O2 sensors 94-95 5.0 Mustangs
Measuring the O2 sensor voltage at the computer will give you a good idea of how well they are working. You'll have to pull the passenger side kick panel off to gain access to the computer connector. Remove the plastic wiring cover to get to the back side of the wiring. Use a safety pin or paper clip to probe the connections from the rear. The computer pins are 29 (LH O2 with a red/black wire) and 27 (RH O2 with a gray/lt blue wire). Use pin 32 (gray/red wire) to ground the voltmeter. The O2 sensor voltage should switch between .2-.9 volt at idle.


Note that all resistance tests must be done with power off. Measuring resistance with a circuit powered on will give false readings and possibly damage the meter. Do not attempt to measure the resistance of the O2 sensors, it may damage them.

Testing the O2 sensor wiring harness
Most of the common multimeters have a resistance scale. Be sure the O2 sensors are disconnected and measure the resistance from the O2 sensor body harness to the pins on the computer. Using the Low Ohms range (usually 200 Ohms) you should see less than 1.5 Ohms.

87-90 5.0 Mustangs:
Computer pin 43 Dark blue/Lt green – LH O2 sensor
Computer pin 29 Dark Green/Pink – RH O2 sensor
Disconnect the connector from the O2 sensor and measure the resistance:
From the Dark blue/Lt green wire in the LH O2 sensor harness and the Dark blue/Lt green wire on the computer pin 43
From the Dark Green/Pink wire on the RH Os sensor harness and the Dark Green/Pink wire on the computer pin 29

91-93 5.0 Mustangs:
Computer pin 43 Red/Black – LH O2 sensor
Computer pin 29 Gray/Lt blue – RH O2 sensor
Disconnect the connector from the O2 sensor and measure the resistance:
From the Red/Black wire in the LH O2 sensor harness and the Red/Black wire on the computer pin 43
From the Dark Green/Pink Gray/Lt blue wire on the RH Os sensor harness and the Gray/Lt blue wire on the computer pin 29

94-95 5.0 Mustangs:
Computer pin 29 Red/Black – LH O2 sensor
Computer pin 27 Gray/Lt blue – RH O2 sensor
From the Red/Black wire in the LH O2 sensor harness and the Red/Black wire on the computer pin 29
From the Dark Green/Pink Gray/Lt blue wire on the RH Os sensor harness and the Gray/Lt blue wire on the computer pin 27

There is a connector between the body harness and the O2 sensor harness. Make sure the connectors are mated together, the contacts and wiring are not damaged and the contacts are clean and not coated with oil.

The O2 sensor ground (orange wire with a ring terminal on it) is in the wiring harness for the fuel injection wiring. I grounded mine to one of the intake manifold bolts

Check the fuel pressure – the fuel pressure is 37-41 PSI with the vacuum disconnected and the engine idling. Fuel pressure out of range can cause the 41 & 91 codes together. It will not cause a single code, only both codes together.

Make sure you have the proper 3 wire O2 sensors. Only the 4 cylinder cars used a 4 wire sensor, which is not compatible with the V8 wiring harness.

Replace the O2 sensors in pairs if replacement is indicated. If one is weak or bad, the other one probably isn't far behind.

Code 41 can also be due to carbon plugging the driver’s side Thermactor air crossover tube on the back of the engine. The tube fills up with carbon and does not pass air to the driver’s side head ports. This puts an excess amount of air in the passenger side exhaust and can set the code 41. Remove the tube and clean it out so that both sides get good airflow: this may be more difficult than it sounds. You need something like a mini rotor-rooter to do the job because of the curves in the tube. Something like the outer spiral jacket of a flexible push-pull cable may be the thing that does the trick.

If you get only code 41 and have changed the sensor, look for vacuum leaks. This is especially true if you are having idle problems. The small plastic tubing is very brittle after many years of the heating it receives. Replace the tubing and check the PVC and the hoses connected to it.

Thank you very much for the helpful information! Yes, I've already R&R'd the O2 sensor, but this info is golden! Thank you again.

 

[joetrainer31]

Update: Just When You Thought it was Safe to Drive Again...

Double checked the car for codes this morning before driving. There were no codes last night, only 10 and 11, which is a pass, but after a year and a half I was skeptical. So this morning I did a KOEO test only to find that...that's right...some of the same codes were back and they brought a new friend with them. This never ending situation is so frustrating. I'm not really sure what to do at this point.

The current codes are:

1) 67 (KOEO), fixed before and was fine for several months, now back again.

2) 32 (Continuous memory). This is a new one. Although, the EGR is new, the EGR sensor is new, and the vac lines are new. Yet, in the world of parts this can mean nothing.

3) 96 (Continuous memory). I fixed this one myself a couple of months ago by R&Ring a new pigtail for the fuel pump relay and putting in a new relay just cause. The code was resolved afterward for months, now no-go.

Any ideas? Could the Stinger Roadkill insulation on the floor pan be causing a short (aluminum side up)? I'm really at a loss. I've never had codes return 2 or 3 times after months of being gone.

@jrichker, @hoopty5.0, @A5literMan, @FoxMustangLvr

Note: I'm not sure if this would cause the 96 code, but the fuel level sender (which is new), is sluggish, as viewed by the cluster fuel gauge, in registering fuel level changes about half way on the gauge. Sometimes, it will go back up after I've driven and know it should have gone down. It always seems to straighten out after a bit of non-sense. I vaguely remember the fuel level sender having something to do (possibly) with voltage and code 96. However, I hold that with an open hand.

 

[jrichker]

First step for all the codes you posted; check and clean the connections.


Code 32 - EGR voltage below closed limit
Missing VREF (5v), 10 pin connector problems, EGR wiring connector problems

Let’s put on our Inspector Gadget propeller head beanies and think about how this works:
The EGR sensor is a variable resistor with ground on one leg and Vref (5 volts) on the other. Its’ resistance ranges from 4000 to 5500 Ohms measured between Vref & ground, depending on the sensor. The center connection of the variable resistor is the slider that moves in response to the amount of vacuum applied. The slider has some minimum value of resistance greater than 100 ohms so that the computer always sees a voltage present at its’ input. If the value was 0 ohms, there would be no voltage output. Then the computer would not be able to distinguish between a properly functioning sensor and one that had a broken wire or bad connection. The EGR I have in hand reads 700 Ohms between the slider (EPV) and ground (SIG RTN) at rest with no vacuum applied.

As vacuum is applied, the voltage on the slider increases (EVP). As the voltage increases, the computer knows the how much the EGR valve is opened and how much exhaust gas is being recirculated. It uses the load table to calculate the amount of exhaust gas required depending on RPM, Mass Air Flow, ACT, ECT & TPS. It then sends a signal to the Electronic Vacuum Regulator to hold, increase or decrease the vacuum being applied to the EGR valve.

Theory class is over now, let’s spin up our propeller head beanies and get with it… Go Gadget, Go…

Measure the resistance of the EGR sensor between the two end pins. You should see between 3500 to 5500 Ohms. With the sensor removed, measure the resistance again while pressing on the plunger. You should see the resistance drop from its high value to a low reading of 200-700 ohms depending on the sensor. No resistance readings, or values way out of range, the sensor is bad.
If the Orange white wire has Vref, (5 volts =/-.25 volt) then you have some wiring problems because the computer isn’t seeing the minimum voltage on the EVR pin. Ohm the wiring back to the computer. Check for resistance between the brown/lt green wire on the EGR sensor and pin 27 on the computer: you should have less than 1 ohm. Repeat the process for the orange/white wire and pin 26. Do it again between the black/white wire and pin 46. In no case should you have more than 1 ohm. Remember that resistance checks are always done with the power off the circuit.

See the graphic for the 10 pin connector circuit layout.

Voltage and resistance checks are good: Here’s an EGR test procedure I copied from cjones

to check the EGR valve:
bring the engine to normal temp.
connect a vacuum pump to the EGR Valve
apply 5 in vacuum to the valve.
if engine stumbled or died then EGR Valve and passage(there is a passageway through the heads and intake) are good.
if engine did NOT stumble or die then either the EGR Valve is bad and/or the passage is blocked.
if engine stumbled, connect vacuum gauge to the hose coming off of the EGR Valve
snap throttle to 2500 RPM’s (remember snap the throttle don't hold it there).
did the vacuum gauge show about 5 in vacuum?

if not, check for manifold vacuum at the EGR vacuum valve.
if you have manifold vacuum then connect vacuum gauge to the EGR valve side of the vacuum valve and snap throttle to 2500 RPM’s.
should read about 5 in vacuum
End of cjones's test.

If the test procedure fails to provide proper vacuum, check vacuum feed lines for cracks & damage. If the vacuum lines are good, check the electrical wiring to the EVR. If the EVR electrical wiring is good, look for 12 volts on the red wire for the EVR. If the 12 volts is good, look for a varying voltage on the dark green wire on the EVR. Case of last resort, replace the EVR and then the computer


Code 67 –
Revised 2 Nov 2012 to add definition of the NSS functions for both 5 speed and auto transmissions

Cause of problem:
clutch not depressed (5 speed) or car not in neutral or park (auto) or A/C in On position when codes where dumped. Possible neutral safety switch or wiring problem. This code may prevent you from running the Key On Engine On tests.

External evidence from other sources claims that a code 67 can cause an idle surge condition. Do try to find and fix any issues with the switch and wiring if you get a code 67.

What the NSS (Neutral Safety Switch) does:
5 speed transmission: It has no connection with the starter, and the engine can be cranked without it being connected.
Auto transmission: It is the safety interlock that prevents the starter from cranking the engine with the transmission in gear.
What it does for both 5 speed and auto transmission cars:
The computer wants to make sure the A/C is off due to the added load on the engine for the engine running computer diagnostic tests. It also checks to see that the transmission is in Neutral (5 speed and auto transmission) and the clutch depressed (T5, T56, Tremec 3550 & TKO)). This prevents the diagnostics from being run when the car is driven. Key On Engine Running test mode takes the throttle control away from the driver for several tests. This could prove hazardous if the computer was jumpered into test mode and then driven.

The following is for 5 speed cars only.
The NSS code 67 can be bypassed for testing. You will need to temporarily ground computer pin 30 to the chassis. Computer pin 30 uses a Lt blue/yellow wire. Remove the passenger side kick panel and then remove the plastic cover from the computer wiring connector. Use a safety pin to probe the connector from the rear. Jumper the safety pin to the ground near the computer.
Be sure to remove the jumper BEFORE attempting to drive the car!!!

Code 96 for 86-90 model 5.0 Mustang – KOEO- Fuel pump monitor circuit shows no power - Fuel pump relay or battery power feed was open - Power / Fuel Pump Circuits. The fuel pump lost power at some time while the ignition switch was in the run position. The main power feed to the pump is what is losing power.

Look for a failing fuel pump relay, bad connections or broken wiring. The fuel pump relay is located under the passenger seat. On Mass Air Conversions, the signal lead that tells the computer that the fuel pump has power may not have been wired correctly.
See http://www.stangnet.com/tech/maf/massairconversion.html

Look for power at the fuel pump - the fuel pump has a connector at the rear of the car with a pink/black wire and a black wire that goes to the fuel pump. The pink/black wire should be hot when the test connector is jumpered to the test position. . To trick the fuel pump into running, find the ECC test connector and jump the connector in the lower RH corner to ground.

86-90 Models:
Using the diagram, check the red/black wire from the fuel pump relay: you should see 12 volts or so. If not, check the inertia switch: on a hatch it is on the drivers side by the taillight. Look for a black rubber plug that pops out: if you don't find it, then loosen up the plastic trim. Check for voltage on both sides of the switch. If there is voltage on both sides, then check the Pink/black wire on the fuel pump relay: it is the power feed to the fuel pump. Good voltage there, then the fuel pump body to tank wiring harness connector is the likely culprit since it is getting power. No voltage there, check the Orange/Lt blue wire, it is the power feed to the fuel pump relay & has a fuse link in it. Good voltage there & at the Pink/black wire, swap the relay.

Keep in mind that the relay wiring and socket can also cause intermittent problems. Clean the relay socket with non-flammable brake parts cleaner or electrical contact cleaner. If you find damaged wiring at the relay socket, replacement pigtail socket assemblies are available at the auto parts stores. Be sure to solder the wires and cover the solder joints with heat shrink tubing if you replace the relay socket.

Check for 12 volts at pin #19 on the computer with the engine running

 

[joetrainer31]

First step for all the codes you posted; check and clean the connections.


Code 32 - EGR voltage below closed limit
Missing VREF (5v), 10 pin connector problems, EGR wiring connector problems

Let’s put on our Inspector Gadget propeller head beanies and think about how this works:
The EGR sensor is a variable resistor with ground on one leg and Vref (5 volts) on the other. Its’ resistance ranges from 4000 to 5500 Ohms measured between Vref & ground, depending on the sensor. The center connection of the variable resistor is the slider that moves in response to the amount of vacuum applied. The slider has some minimum value of resistance greater than 100 ohms so that the computer always sees a voltage present at its’ input. If the value was 0 ohms, there would be no voltage output. Then the computer would not be able to distinguish between a properly functioning sensor and one that had a broken wire or bad connection. The EGR I have in hand reads 700 Ohms between the slider (EPV) and ground (SIG RTN) at rest with no vacuum applied.

As vacuum is applied, the voltage on the slider increases (EVP). As the voltage increases, the computer knows the how much the EGR valve is opened and how much exhaust gas is being recirculated. It uses the load table to calculate the amount of exhaust gas required depending on RPM, Mass Air Flow, ACT, ECT & TPS. It then sends a signal to the Electronic Vacuum Regulator to hold, increase or decrease the vacuum being applied to the EGR valve.

Theory class is over now, let’s spin up our propeller head beanies and get with it… Go Gadget, Go…

Measure the resistance of the EGR sensor between the two end pins. You should see between 3500 to 5500 Ohms. With the sensor removed, measure the resistance again while pressing on the plunger. You should see the resistance drop from its high value to a low reading of 200-700 ohms depending on the sensor. No resistance readings, or values way out of range, the sensor is bad.
If the Orange white wire has Vref, (5 volts =/-.25 volt) then you have some wiring problems because the computer isn’t seeing the minimum voltage on the EVR pin. Ohm the wiring back to the computer. Check for resistance between the brown/lt green wire on the EGR sensor and pin 27 on the computer: you should have less than 1 ohm. Repeat the process for the orange/white wire and pin 26. Do it again between the black/white wire and pin 46. In no case should you have more than 1 ohm. Remember that resistance checks are always done with the power off the circuit.

See the graphic for the 10 pin connector circuit layout.

Voltage and resistance checks are good: Here’s an EGR test procedure I copied from cjones

to check the EGR valve:
bring the engine to normal temp.
connect a vacuum pump to the EGR Valve
apply 5 in vacuum to the valve.
if engine stumbled or died then EGR Valve and passage(there is a passageway through the heads and intake) are good.
if engine did NOT stumble or die then either the EGR Valve is bad and/or the passage is blocked.
if engine stumbled, connect vacuum gauge to the hose coming off of the EGR Valve
snap throttle to 2500 RPM’s (remember snap the throttle don't hold it there).
did the vacuum gauge show about 5 in vacuum?

if not, check for manifold vacuum at the EGR vacuum valve.
if you have manifold vacuum then connect vacuum gauge to the EGR valve side of the vacuum valve and snap throttle to 2500 RPM’s.
should read about 5 in vacuum
End of cjones's test.

If the test procedure fails to provide proper vacuum, check vacuum feed lines for cracks & damage. If the vacuum lines are good, check the electrical wiring to the EVR. If the EVR electrical wiring is good, look for 12 volts on the red wire for the EVR. If the 12 volts is good, look for a varying voltage on the dark green wire on the EVR. Case of last resort, replace the EVR and then the computer


Code 67 –
Revised 2 Nov 2012 to add definition of the NSS functions for both 5 speed and auto transmissions

Cause of problem:
clutch not depressed (5 speed) or car not in neutral or park (auto) or A/C in On position when codes where dumped. Possible neutral safety switch or wiring problem. This code may prevent you from running the Key On Engine On tests.

External evidence from other sources claims that a code 67 can cause an idle surge condition. Do try to find and fix any issues with the switch and wiring if you get a code 67.

What the NSS (Neutral Safety Switch) does:
5 speed transmission: It has no connection with the starter, and the engine can be cranked without it being connected.
Auto transmission: It is the safety interlock that prevents the starter from cranking the engine with the transmission in gear.
What it does for both 5 speed and auto transmission cars:
The computer wants to make sure the A/C is off due to the added load on the engine for the engine running computer diagnostic tests. It also checks to see that the transmission is in Neutral (5 speed and auto transmission) and the clutch depressed (T5, T56, Tremec 3550 & TKO)). This prevents the diagnostics from being run when the car is driven. Key On Engine Running test mode takes the throttle control away from the driver for several tests. This could prove hazardous if the computer was jumpered into test mode and then driven.

The following is for 5 speed cars only.
The NSS code 67 can be bypassed for testing. You will need to temporarily ground computer pin 30 to the chassis. Computer pin 30 uses a Lt blue/yellow wire. Remove the passenger side kick panel and then remove the plastic cover from the computer wiring connector. Use a safety pin to probe the connector from the rear. Jumper the safety pin to the ground near the computer.
Be sure to remove the jumper BEFORE attempting to drive the car!!!

Code 96 for 86-90 model 5.0 Mustang – KOEO- Fuel pump monitor circuit shows no power - Fuel pump relay or battery power feed was open - Power / Fuel Pump Circuits. The fuel pump lost power at some time while the ignition switch was in the run position. The main power feed to the pump is what is losing power.

Look for a failing fuel pump relay, bad connections or broken wiring. The fuel pump relay is located under the passenger seat. On Mass Air Conversions, the signal lead that tells the computer that the fuel pump has power may not have been wired correctly.
See http://www.stangnet.com/tech/maf/massairconversion.html

Look for power at the fuel pump - the fuel pump has a connector at the rear of the car with a pink/black wire and a black wire that goes to the fuel pump. The pink/black wire should be hot when the test connector is jumpered to the test position. . To trick the fuel pump into running, find the ECC test connector and jump the connector in the lower RH corner to ground.

86-90 Models:
Using the diagram, check the red/black wire from the fuel pump relay: you should see 12 volts or so. If not, check the inertia switch: on a hatch it is on the drivers side by the taillight. Look for a black rubber plug that pops out: if you don't find it, then loosen up the plastic trim. Check for voltage on both sides of the switch. If there is voltage on both sides, then check the Pink/black wire on the fuel pump relay: it is the power feed to the fuel pump. Good voltage there, then the fuel pump body to tank wiring harness connector is the likely culprit since it is getting power. No voltage there, check the Orange/Lt blue wire, it is the power feed to the fuel pump relay & has a fuse link in it. Good voltage there & at the Pink/black wire, swap the relay.

Keep in mind that the relay wiring and socket can also cause intermittent problems. Clean the relay socket with non-flammable brake parts cleaner or electrical contact cleaner. If you find damaged wiring at the relay socket, replacement pigtail socket assemblies are available at the auto parts stores. Be sure to solder the wires and cover the solder joints with heat shrink tubing if you replace the relay socket.

Check for 12 volts at pin #19 on the computer with the engine running

This is great! I'm going to have to work my way through this. I will probably have questions.

One observation and question: It seems that you are saying that the clutch pedal needs to be held down while getting the KOEO codes in order to avoid code 67. Is that correct? Because I was not doing that when I dumped the codes.

 

[hoopty5.0]

This is great! I'm going to have to work my way through this. I will probably have questions.

One observation and question: It seems that you are saying that the clutch pedal needs to be held down while getting the KOEO codes in order to avoid code 67. Is that correct? Because I was not doing that when I dumped the codes.

Correct. And it's not fun with a heavy fox clutch.

 

[joetrainer31]

Correct. And it's not fun with a heavy fox clutch.

Well, there's one correction I can make asap. I was never holding it down -that I can remember.

 

[joetrainer31]

Update: The seemingly Impossible Keeps Happening

Been sick again so in depth diagnostic out in the heat has been out of the question. However, I did R&R the EGR Solenoid and associate vac tubes since they were 26 years old. I thought it was worth a shot for code 32. I also R&R'd the fuel pump relay just incase. I cleared the computer with the battery unhooked over night, test drove the car 11 miles and it ran PERFECT.

After the 11 mile test drive I parked it in the parking spot and went inside for several hours. Just a few minutes ago I decided to test drive it another 10 miles or so. However, I only got about 1.5 miles and the stinking car started bucking, stalling, and had a CEL. What in the world?!?!?!? It's never acted like that before. Sure, I had the codes, but it was basically impossible to tell that there was trouble w/o scanning for codes.

To sum up: R&R'd EGR solenoid and vac lines, R&R'd fuel pump relay, car drove PERFECT, car sat for 6 hours, car ran like CRAP and almost needed a tow truck.

Update 10 minutes later: Just scanned for codes. Code 67 is gone now that I'm holding in the clutch. Code 32 is gone after the EGR solenoid and vac line R&R. However, new codes have manifested. They are:

1) 31 Continuous.
2) 63 Continuous.
3) 96 Continuous, this one is still hanging around.


Off topic, but I also R&R'd my drive belt. If anyone wants to know, an 84.5" belt will not fit your car if you plan on bypassing the smog pump, have stock pullies, and have a 3G alternator. You will need a Gates K060849.

 

[hoopty5.0]

Wow. You need to go to New Orleans and see the lady in the back building. There's a hoodoo crux on your car, man.

 

[A5literMan]

I'm starting to wonder if you don't just have a bad computer. I hate wiring/electronic issues. Good luck.

 

[stykthyn]

I'm starting to wonder if you don't just have a bad computer. I hate wiring/electronic issues. Good luck.

It does start to sound like maybe there's a bad capacitor in the ecu. I was chasing all sorts of similar recurring issues. Final priest to the exorcism was a new ecu.

 

[joetrainer31]

Wow. You need to go to New Orleans and see the lady in the back building. There's a hoodoo crux on your car, man.

Its ridiculous.