FAILED SMOG!! High No High Hc... Ideas?

[88gt373]

So i failed STUPID Cali Smog sniffer..... My visual is good heres what i went over before i smogged......

1988 mustang gt, flow master super 40's, all stock

Good vacume (16lbs @ Idle)
NEW IAC/IAB
NEW EGR/EGR solenoid
timing @ 12* (im running 91 premium gas)
cats are stock
all new msd cap/rotor/accel wires/crane lx91 coil/plugs etc
TPS is correct/IAC is correct



i have read that if you have a bad/stuck t stat that it could make you run rich... my temp never gets past the "n-o" in NORMAL on the temp guage... actually i can run the car all day and open the radiator cap with no steam or spilling... could that be it? my O2 sensors i think are pretty old.. they look ok could that be it? im sure they dont have 60k on them
what about that sea-foam stuff.... never tried it... tips?

help would be great i need to smog to title my car... thanks

 

[88gt373]

BTW here are the numbers on my paper

pass HC @ 15mph 85.........mine 177 (avg 40
pass HC @ 25mph 67.........mine 149 (avg 31

pass NO @ 15mph 565........mine 869 (avg 307
pass NO @ 25mph 522........mine 778 (avg 278

CO% to pass @ 15mph .54%....mine .52% (avg .05% both
CO% to pass @ 25mph .45%....mine .34%

Hope these numbers can help

 

[90mustangGT]

How does it run? Check for Vacuum leaks.

Do a tune up, make sure your timing is lower, 10* but if you can get away with it, set it at 4*. Put about 50psi in the rear tires (lower rolling resistance). Make sure your EGR is working properly. Do a full tune up, plugs, and check condition of the cap and rotor as well as the wires. Set the gap on the plugs to minimum spec. Yes, 02's are cheap so if they are old, then change them.

NOx is caused by high combustion chamber temps. This can actually be caused by a lean condition. The HC's are unburnt fuel, also can be caused by a lean condition, or a very rich condition. How's compression on the cylinders?

The only other options I see, which very well might fix it, but will be costly, and you need to make sure everything else is right, is the cats. If you have stock cats on there, they probably aren't working too well, and not to mention that the cats of those years were not near as effecient as the newer style. The new one's will clean up the exhaust better, and they flow better. Lots has happened in over the past 20 years to say the least.

My ultimate soution, move out of CA. CA hates your car and wants you to buy a prius or leaf. Those standards are stricter than when the car was new. F that. TX is where it's happening, just leave any liberal leftist ideas in CA.

 

[jrichker]

How to pass emissions testing:

High NO - high combustion temps - retard timing, check EGR for operation.
High CO – Rich condition - fuel pressure too high, check O2 sensors, replace air filter, Clean MAF element.
High HC – Lean misfire, vacuum leak, common misfire due to worn or weak ignition system components. On rare occasions, an overly rich mixture may be the cause. Do the ethanol/E85 fill up as suggested.
High CO & HC - Cat converters, smog pump, and smog pump controls.

How to pass emissions testing:

1.) Make sure all the emissions gear the car was made with is present and connected up properly. That includes a working smog pump and cats. The smog tech will do a visual check to make sure that all the original equipment is present and connected up.

2.) Make sure that you have fresh tune up with spark plugs, plug wires, cap, rotor, fuel & air filters. An oil & filter change is a good idea while you are at it.

3.) Dumping The computer diagnostic codes on 86-95 Mustangs

Revised 3-Jun-2011. Removed the link to BATAuto.com and troublecodes.net instructions on codes and how to dump them. Post the codes you get and I will post 5.0 Mustang specific code definitions and fixes.

Dump the codes and see what the computer says is wrong…Codes may be present in the computer even if the Check Engine light isn’t on.

Here's the way to dump the computer codes with only a jumper wire or paper clip and the check engine light, or test light or voltmeter. I’ve used it for years, and it works great. You watch the flashing test lamp or Check Engine Light and count the flashes.

Be sure to turn off the A/C, and put the transmission in neutral when dumping the codes. Fail to do this and you will generate a code 67 and not be able to dump the Engine Running codes.

Dumping the Engine Running codes: The procedure is the same, you start the engine with the test jumper in place. Be sure the A/C is off and the transmission is in neutral. You'll get an 11, then a 4 and the engine will speed up to do the EGR test. After the engine speed decreases back to idle, it will dump the engine running codes.

Here's the link to dump the computer codes with only a jumper wire or paper clip and the check engine light, or test light or voltmeter. I’ve used it for years, and it works great. You watch the flashing test lamp or Check Engine Light and count the flashes.

If your car is an 86-88 stang, you'll have to use the test lamp or voltmeter method. There is no functional check engine light on the 86-88's except possibly the Cali Mass Air cars.

The STI has a gray connector shell and a white/red wire. It comes from the same bundle of wires as the self test connector.

89 through 95 cars have a working Check Engine light. Watch it instead of using a test lamp.

The STI has a gray connector shell and a white/red wire. It comes from the same bundle of wires as the self test connector.


WARNING!!! There is a single dark brown connector with a black/orange wire. It is the 12 volt power to the under the hood light. Do not jumper it to the computer test connector. If you do, you will damage the computer.

What to expect:
You should get a code 11 (two single flashes in succession). This says that the computer's internal workings are OK, and that the wiring to put the computer into diagnostic mode is good. No code 11 and you have some wiring problems.

Codes have different answers if the engine is running from the answers that it has when the engine isn't running. It helps a lot to know if you had the engine running when you ran the test.

Trouble codes are either 2 digit or 3 digit, there are no cars that use both 2 digit codes and 3 digit codes.

Alternate methods:
For those who are intimidated by all the wires & connections, see Actron® for what a typical hand scanner looks like. Normal retail price is about $30 or so at AutoZone or Wal-Mart.

Or for a nicer scanner see Equus - Digital Ford Code Reader (3145) – It has a 3 digit LCD display so that you don’t have to count flashes or beeps.. Cost is $30.
Or for a nicer scanner see http://www.midwayautosupply.com/p-7208-equus-digital-ford-code-reader-3145.aspx– It has a 3 digit LCD display so that you don’t have to count flashes or beeps.. Cost is $30.


4.) Post the codes and get help to fix them. Don’t try to pass with codes not fixed. Clearing the computer just temporarily removes them from memory, it doesn’t fix the problem that caused the code to be set.

5.) Be sure to do the testing on a hot engine. Drive for 15-20 minutes prior to taking the test to get operating temps up into the normal range. Do not shut off the engine while waiting for your turn on the test machine. An engine up to full operating temperature puts out fewer emissions.

 

[chrisboss429]

Well said GT.....I'm in cali, had same issues and am moving before they take my car....Americans don't surrender nothing....and no lefty here!

 

[88gt373]

Well said GT.....I'm in cali, had same issues and am moving before they take my car....Americans don't surrender nothing....and no lefty here!

i agree. moving would be ideal in many ways... but in dont think the wife and kids would move to fancy my car fetish. lol.. but any how.... as far a 90GT says, my timing is set at 10* base and i can only go two degrees either way from 10* base without an automatic fail (they check with a timing gun).. i also have no codes, my ignition system is BRAND NEW.... and i get great vacuum and have no codes... egr is new.. i did a rebuild and the whole engine is pretty new along with sensors and acc...

what about the aftermarket underdrive crank pulley i have... could that be enough to underdrive my smog pump to help me fail??

 

[88gt373]

Well said GT.....I'm in cali, had same issues and am moving before they take my car....Americans don't surrender nothing....and no lefty here!

i agree. moving would be ideal in many ways... but in dont think the wife and kids would move to fancy my car fetish. lol.. but any how.... as far a 90GT says, my timing is set at 10* base and i can only go two degrees either way from 10* base without an automatic fail (they check with a timing gun).. i also have no codes, my ignition system is BRAND NEW.... and i get great vacuum and have no codes... egr is new.. i did a rebuild and the whole engine is pretty new along with sensors and acc...

what about the aftermarket underdrive crank pulley i have... could that be enough to underdrive my smog pump to help me fail??

 

[jrichker]

High NO - high combustion temps - retard timing, check EGR for operation.


EGR System theory and testing

The EGR shuts off at Wide Open Throttle (WOT), so it has minimal effect on performance. The addition of exhaust gas drops combustion temperature, increases gas mileage and reduces the tendency of the engine to ping. It can also reduce HC emissions by reducing fuel consumption. The primary result of EGR usage is a reduction in NOx emissions.

The EGR system has a vacuum source (line from the intake manifold) that goes to the EVR, computer operated electronic vacuum regulator. The EVR is located on the back of the passenger side shock strut tower. The computer uses RPM, Load. and some other factors to tell the EVR to pass vacuum to open the EGR valve. The EGR valve and the passages in the heads and intake manifold route exhaust gas to the EGR spacer (throttle body spacer). The EGR sensor tells the computer how far the EGR valve is open. Then computer adjusts the signal sent to the EVR to hold, increase or decrease the vacuum. The computer adds spark advance to compensate for the recirculated gases and the slower rate they burn at.

Troubleshooting:
There should be no vacuum at the EGR valve when at idle. If there is, the EVR (electronic vacuum regulator) mounted on the backside of the passenger side wheelwell is suspect. Check the vacuum line plumbing to make sure the previous owner didn’t cross the vacuum lines.

Diagram courtesy of Tmoss & Stang&2birds. (the diagram says 88 GT, but the EGR part is the same for 86-93 Mustangs)

The EGR sensor is basically a variable resistor, like the volume control on a radio. One end is 5 volt VREF power from the computer (red/orange wire). One end is computer signal ground (black/white), and the middle wire (brown/lt green) is the signal output from the EGR sensor. It is designed to always have some small voltage output from it anytime the ignition switch is the Run position. That way the computer knows the sensor & the wiring is OK. No voltage on computer pin 27 (brown/lt green wire) and the computer thinks the sensor is bad or the wire is broken and sets code 31. The voltage output can range from approximately .6-.85 volt.

The EVR regulates vacuum to the EGR valve to maintain the correct amount of vacuum. The solenoid coil should measure 20-70 Ohms resistance. The regulator has a vacuum feed on the bottom which draws from the intake manifold. The other vacuum line is regulated vacuum going to the EGR valve. One side of the EVR electrical circuit is +12 volts anytime the ignition switch is in the run position. The other side of the electrical circuit is the ground path and is controlled by the computer. The computer switches the ground on and off to control the regulator solenoid.



EGR test procedure courtesy of cjones

EGR test procedure courtesy of cjones

to check the EGR valve:
bring the engine to normal temp.

connect a vacuum pump to the EGR Valve or see the EGR test jig drawing below. Connnect the test jig or to directly to manifold vacuum.

Do not connect the EGR test jig to the EVR (Electronic Vacuum Regulator).

apply 5in vacuum to the valve. Using the test jig, use your finger to vary the vacuum

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 EGR test jig to the hose coming off of the EGR Valve.
Use your finger to cap the open port on the vacuum tee.
snap throttle to 2500 RPM (remember snap the throttle don't hold it there).
did the vacuum gauge show about 2-5 in vacuum?
if not the EVR has failed

EGR test jig

To test the computer and wiring to the computer, you can use a test light across the EVR wiring connectors and dump the codes. When you dump the codes, the computer does a self test that toggles every relay/actuator/solenoid on and off. When this happens, the test light will flicker. If the test light remains on the computer or the wiring is suspect.

To check the EVR to computer wiring, disconnect the EVR connector and connect one end of the Ohmmeter to the dark green wire EVR wiring. Remove the passenger side kick panel and use a 10 MM socket to remove the computer connector from the computer. Set the Ohmmeter to high range and connect the other ohmmeter lead to ground. You should see an infinite open circuit indication or a reading greater than 1 Meg Ohm. If you see less than 200 Ohms, the dark green wire has shorted to ground somewhere.

Late Model Restoration may still have the Ford Racing M-12071-N302 kit with the EGR valve & sensor along with the ACT & ECT sensors for $45. See http://www.latemodelrestoration.com/iwwida.pvx?;item?item_no=M12071N302 1&comp=LRS for more details


High HC – Lean misfire, vacuum leak, common misfire due to worn or weak ignition system components. On rare occasions, an overly rich mixture may be the cause. Do the ethanol/E85 fill up as suggested.

Check spark plugs, spark plug wires & distributor cap for damage or loose connections.

Do a cylinder balance test to spot weak or misfiring cylinders. Replace PVC valve, grommet & clean screen that is below the PVC grommet.

Inspect all the vacuum lines, looking for small cracks and damage. Be prepared to replace any broken or damaged line you find.

b]Diagram courtesy of Tmoss & Stang&2birds[/b]

Check fuel pressure:
The local auto parts store may rent or loan a fuel pressure test gauge if you don't have one.
Disconnect vacuum line and check it for evidence of fuel present on the line. If you find fuel, the fuel pressure regulator has failed. Cap the vacuum line and stow it out of the way.
Connect fuel pressure test gauge to Schrader port located just behind the alternator.
Turn the ignition switch on & start the engine. Observe the pressure : you should see 37-41 PSI at idle.
Turn the ignition off, reconnect the vacuum line and disconnect the fuel pressure test gauge. Watch out for squirting gas when you do this.


Cylinder balance test:
The computer has a cylinder balance test that helps locate cylinder with low power output. You’ll need to dump the codes out of the computer and make sure that you have the A/C off, and the transmission in neutral. Fail to do this and you can’t do the engine running dump codes test that allows you to do the cylinder balance test.

Here's the way to dump the computer codes with only a jumper wire or paper clip and the check engine light, or test light or voltmeter. I’ve used it for years, and it works great. You watch the flashing test lamp or Check Engine Light and count the flashes.

Be sure to turn off the A/C, and put the transmission in neutral when dumping the codes. Fail to do this and you will generate a code 67 and not be able to dump the Engine Running codes.


Here's the link to dump the computer codes with only a jumper wire or paper clip and the check engine light, or test light or voltmeter. I’ve used it for years, and it works great. You watch the flashing test lamp or Check Engine Light and count the flashes.

See Troublcodes.net Trouble Codes OBD & OBD2 Trouble Codes and Technical info & Tool Store. By BAT Auto Technical

If your car is an 86-88 stang, you'll have to use the test lamp or voltmeter method. There is no functional check engine light on the 86-88's except possibly the Cali Mass Air cars.

The STI has a gray connector shell and a white/red wire. It comes from the same bundle of wires as the self test connector.

89 through 95 cars have a working Check Engine light. Watch it instead of using a test lamp.

The STI has a gray connector shell and a white/red wire. It comes from the same bundle of wires as the self test connector.


WARNING!!! There is a single dark brown connector with a black/orange wire. It is the 12 volt power to the under the hood light. Do not jumper it to the computer test connector. If you do, you will damage the computer.

What to expect:
You should get a code 11 (two single flashes in succession). This says that the computer's internal workings are OK, and that the wiring to put the computer into diagnostic mode is good. No code 11 and you have some wiring problems. This is crucial: the same wire that provides the ground to dump the codes provides signal ground for the TPS, EGR, ACT and Map/Baro sensors. If it fails, you will have poor performance, economy and driveablity problems

Some codes have different answers if the engine is running from the answers that it has when the engine isn't running. It helps a lot to know if you had the engine running when you ran the test.

Dumping the Engine Running codes: The procedure is the same, you start the engine with the test jumper in place. Be sure the A/C is off and the transmission is in neutral. You'll get an 11, then a 4 and the engine will speed up to do the EGR test. After the engine speed decreases back to idle, it will dump the engine running codes.

Trouble codes are either 2 digit or 3 digit, there are no cars that use both 2 digit codes and 3 digit codes.

Cylinder balance test
Warm the car's engine up to normal operating temperature. Use a jumper wire or paper clip to put the computer into test mode. Start the engine and let it go through the normal diagnostic tests, then quickly press the throttle to the floor. The engine RPM should exceed 2500 RPM's for a brief second. The engine RPM's will increase to about 1450-1600 RPM and hold steady. The engine will shut off power to each injector, one at a time. When it has sequenced through all 8 injectors, it will flash 9 for everything OK, or the number of the failing cylinder such as 2 for cylinder #2. Quickly pressing the throttle again up to 2500 RPM’s will cause the test to re-run with smaller qualifying figures.
Do it a third time, and if the same cylinder shows up, the cylinder is weak and isn’t putting out power like it should. See the Chilton’s Shop manual for the complete test procedure


Do a compression test on all the cylinders.
Take special note of any cylinder that shows up as weak in the cylinder balance test. Low compression on one of these cylinders rules out the injectors as being the most likely cause of the problem. Look at cylinders that fail the cylinder balance test but have good compression. These cylinders either have a bad injector, bad spark plug or spark plug wire. Move the wire and then the spark plug to another cylinder and run the cylinder balance test again. If it follows the moved wire or spark plug, you have found the problem. If the same cylinder fails the test again, the injector is bad. If different cylinders fail the cylinder balance test, you have ignition problems or wiring problems in the 10 pin black & white electrical connectors located by the EGR.

How to do a compression test:
Only use a compression tester with a screw in adapter for the spark plug hole. The other type leaks too much to get an accurate reading. Your local auto parts store may have a compression tester to rent. If you do mechanic work on your own car on a regular basis, it would be a good tool to add to your collection.

With the engine warmed up, remove all spark plugs and prop the throttle wide open, crank the engine until it the gage reading stops increasing. On a cold engine, it will be hard to tell what's good & what's not. Some of the recent posts have numbers ranging from 140-170 psi. If the compression is low, squirt some oil in the cylinder and do it again – if it comes up, the rings are worn. There should be no more than 10% difference between cylinders. Use a blow down leak test (puts compressed air inside cylinders) on cylinders that have more than 10% difference.

See the link to my site for details on how to build your own blow down type compression tester.

See the following website for some help from Tmoss (diagram designer) & Stang&2Birds (website host) for help on 88-95 wiring Mustang FAQ - Wiring & Engine Info Everyone should bookmark this site.

Ignition switch wiring
http://www.veryuseful.com/mustang/tech/engine/images/IgnitionSwitchWiring.gif

Fuel, alternator, A/C and ignition wiring
http://www.veryuseful.com/mustang/tech/engine/images/fuel-alt-links-ign-ac.gif

Complete computer, actuator & sensor wiring diagram for 88-91 Mass Air Mustangs
http://www.veryuseful.com/mustang/tech/engine/images/88-91_5.0_EEC_Wiring_Diagram.gif

Complete computer, actuator & sensor wiring diagram for 91-93 Mass Air Mustangs
http://www.veryuseful.com/mustang/tech/engine/images/91-93_5.0_EEC_Wiring_Diagram.gif

Vacuum diagram 89-93 Mustangs
http://www.veryuseful.com/mustang/tech/engine/images/mustangFoxFordVacuumDiagram.jpg

HVAC vacuum diagram
http://www.veryuseful.com/mustang/tech/engine/images/Mustang_AC_heat_vacuum_controls.gif

TFI module differences & pinout
http://www.veryuseful.com/mustang/tech/engine/images/TFI_5.0_comparison.gif

Fuse box layout
http://www.veryuseful.com/mustang/tech/engine/images/MustangFuseBox.gif

 

[88gt373]

so i checked and read through your diagram you posted twice, JRICHKER, lol. i actually found those on this site by searching, its a good write up BTW.

I checked all my vacuum lines and found that my MAIN vacuum line going from the manifold to the main vacuum split (the one going to the evap w/ the check valve) and the line was a REALLY thin one with a tiny bore.. so i blew air through it using my mouth and it was pretty tough to blow thru.... so replaced it with a better flowing tube...then checked the rest of the vac lines and all was ok...hopefully that helps.

next, i replaced the EGR valve gasket after cleaning the egr...

now the car idles a little bit better and puuuurrss like a kitten...or a tiger...grrrrr

next im goin to put the stock crank pulley.... any theories on the under drive HELPING me FAIL???? should i swap the pulley to be safe? thoughts?......

also did sea foam in the tank, thru the vac, and in the oil... doesnt smell as rich but still smells a lil rich tho..... hope its not the cats....

 

[BlownFiveLiter]

You don't need any more than 87 octane, so you're sending unburned fuel down the tailpipe with the 91. Run your tank pretty low on the 91, turn your timing back down to 10°, and fill up with 87. Give the emissions another shot after that. You could also buy some of the CRC Guaranteed to Pass stuff and see if it helps. I've seen, on several occasions, that people have used it with success.

 

[88gt373]

You don't need any more than 87 octane, so you're sending unburned fuel down the tailpipe with the 91. Run your tank pretty low on the 91, turn your timing back down to 10°, and fill up with 87. Give the emissions another shot after that. You could also buy some of the CRC Guaranteed to Pass stuff and see if it helps. I've seen, on several occasions, that people have used it with success.

I'll try the G2P ive heard good things and read good things too... no one has answered this, but what about putting my stock crank pulley back on there? you think that will help my pumping more air in the system

 

[BYRDPE]

i took my timing down to 0* and i added a quart and 1/2 of denatured alcohol to a 1/4 tank of gas and i passed after 3 tries. i was at 340 and needed to get to 220...got it to 86.

 

[88gt373]

i took my timing down to 0* and i added a quart and 1/2 of denatured alcohol to a 1/4 tank of gas and i passed after 3 tries. i was at 340 and needed to get to 220...got it to 86.

ok guys.... heres the deal.. i finally had a second smog test done and it failed again... the numbers were a little but better but not by much.. i put 2 quarts of denatured alcohol but i had like 15 bucks of gas in there ( my gauge is broken btw ).. heres what i did after:

new gauge temp sensor
new air charge sensor
new computer temp sensor
and new o2 sensors...

im thinking about adding a gallon of denatured alcohol this time... could gummed up valves cause high nox and co2? theres a guy i know selling reman/new e7 heads for 175 w/ 0 miles.... what do you guys think? new heads too much? i got a set of newer 19lb injectors too? im about all out of solutions

 

[FoMoCo17]

HC's are parts of unburned gasoline passing through to the exhaust
CO's are products of incomplete combustion
NO's are produced when higher than normal combustion temperatures occur.

From what you posted, you have a good combustion process taking place which is good. You also have a little bit of unburned gasoline getting through possibly due to timing, MAF, TPS, ECT or another sensor that has a reading which is off a bit causing it to richen just a hair too much .... or, wrong size injectors or incorrect fuel pressure settings if these have been altered. Also, check for vacuum leaks.

Additionally, your combustion temperatures are too high causing the high NO readings. Three things that come to mind immediately would be EGR system operation, Air injection system, and cooling system operation. With the cooling system, it could be the fan clutch to a slow thermostat to belt slippage etc..

These areas should reveal something and or adjustments should be made to get it within specs.

 

[88gt373]

HC's are parts of unburned gasoline passing through to the exhaust
CO's are products of incomplete combustion
NO's are produced when higher than normal combustion temperatures occur.

From what you posted, you have a good combustion process taking place which is good. You also have a little bit of unburned gasoline getting through possibly due to timing, MAF, TPS, ECT or another sensor that has a reading which is off a bit causing it to richen just a hair too much .... or, wrong size injectors or incorrect fuel pressure settings if these have been altered. Also, check for vacuum leaks.

Additionally, your combustion temperatures are too high causing the high NO readings. Three things that come to mind immediately would be EGR system operation, Air injection system, and cooling system operation. With the cooling system, it could be the fan clutch to a slow thermostat to belt slippage etc..

These areas should reveal something and or adjustments should be made to get it within specs.

thanks for helping me narrow it down..... i am having a little bit of an issue with the cooling system: all is new (both temp sensors, fan clutch, rad, t stat) BUT.... it seems like the system never builds up pressure. i can run the car all day and then right after take the rad cap off and nothing crazy... any ideas?

#2 if my egr system/air injection system if not up to snuff, will an engine code come up? i have no codes currently and have great vacuum (16-17lbs idle)

i will check my tps tomorrow...... you mentioned about fuel pressure: i think my injectors or at least acouple of them arent running great so i have another set of 19#ers and maybe out a new FPR since im there....

 

[BYRDPE]

whats your timing set at?

 

[88gt373]

my timing was set to 12* when i had smog done the first time (fail) then set it to 8* the second time (fail but a tad bit better on Hc No).

 

[7991LXnSHO]

How to pass emissions testing:

High NO - high combustion temps - retard timing, check EGR for operation.
High CO – Rich condition - fuel pressure too high, check O2 sensors, replace air filter, Clean MAF element.
High HC – Lean misfire, vacuum leak, common misfire due to worn or weak ignition system components. On rare occasions, an overly rich mixture may be the cause. Do the ethanol/E85 fill up as suggested.
High CO & HC - Cat converters, smog pump, and smog pump controls.

How to pass emissions testing:

1.) Make sure all the emissions gear the car was made with is present and connected up properly. That includes a working smog pump and cats. The smog tech will do a visual check to make sure that all the original equipment is present and connected up.

2.) Make sure that you have fresh tune up with spark plugs, plug wires, cap, rotor, fuel & air filters. An oil & filter change is a good idea while you are at it.

3.) Dumping The computer diagnostic codes on 86-95 Mustangs

Revised 3-Jun-2011. Removed the link to BATAuto.com and troublecodes.net instructions on codes and how to dump them. Post the codes you get and I will post 5.0 Mustang specific code definitions and fixes.

Dump the codes and see what the computer says is wrong…Codes may be present in the computer even if the Check Engine light isn’t on.

Here's the way to dump the computer codes with only a jumper wire or paper clip and the check engine light, or test light or voltmeter. I’ve used it for years, and it works great. You watch the flashing test lamp or Check Engine Light and count the flashes.

Be sure to turn off the A/C, and put the transmission in neutral when dumping the codes. Fail to do this and you will generate a code 67 and not be able to dump the Engine Running codes.

Dumping the Engine Running codes: The procedure is the same, you start the engine with the test jumper in place. Be sure the A/C is off and the transmission is in neutral. You'll get an 11, then a 4 and the engine will speed up to do the EGR test. After the engine speed decreases back to idle, it will dump the engine running codes.

Here's the link to dump the computer codes with only a jumper wire or paper clip and the check engine light, or test light or voltmeter. I’ve used it for years, and it works great. You watch the flashing test lamp or Check Engine Light and count the flashes.

If your car is an 86-88 stang, you'll have to use the test lamp or voltmeter method. There is no functional check engine light on the 86-88's except possibly the Cali Mass Air cars.

The STI has a gray connector shell and a white/red wire. It comes from the same bundle of wires as the self test connector.

89 through 95 cars have a working Check Engine light. Watch it instead of using a test lamp.

The STI has a gray connector shell and a white/red wire. It comes from the same bundle of wires as the self test connector.


WARNING!!! There is a single dark brown connector with a black/orange wire. It is the 12 volt power to the under the hood light. Do not jumper it to the computer test connector. If you do, you will damage the computer.

What to expect:
You should get a code 11 (two single flashes in succession). This says that the computer's internal workings are OK, and that the wiring to put the computer into diagnostic mode is good. No code 11 and you have some wiring problems.

Codes have different answers if the engine is running from the answers that it has when the engine isn't running. It helps a lot to know if you had the engine running when you ran the test.

Trouble codes are either 2 digit or 3 digit, there are no cars that use both 2 digit codes and 3 digit codes.

Alternate methods:
For those who are intimidated by all the wires & connections, see Actron® for what a typical hand scanner looks like. Normal retail price is about $30 or so at AutoZone or Wal-Mart.

Or for a nicer scanner see Equus - Digital Ford Code Reader (3145) – It has a 3 digit LCD display so that you don’t have to count flashes or beeps.. Cost is $30.
Or for a nicer scanner see http://www.midwayautosupply.com/p-7208-equus-digital-ford-code-reader-3145.aspx– It has a 3 digit LCD display so that you don’t have to count flashes or beeps.. Cost is $30.


4.) Post the codes and get help to fix them. Don’t try to pass with codes not fixed. Clearing the computer just temporarily removes them from memory, it doesn’t fix the problem that caused the code to be set.

5.) Be sure to do the testing on a hot engine. Drive for 15-20 minutes prior to taking the test to get operating temps up into the normal range. Do not shut off the engine while waiting for your turn on the test machine. An engine up to full operating temperature puts out fewer emissions.

Does anyone have an REAL PICTURE marked with where the vacuum controlled items are supposed to be and look like???? The digrams are nice, but if the lines are not there, it is hard to see if they are running to the right device. Also, it would really help figure out what the last owner got rid of before I go to the salvage yard. I'd know what the missing stuff looks like and where to find it it under the salvage car's hood.

For example, where are the vacuum res. and check valve supposed to be? I can figure out where the missing air pump was, but the smaller stuff was not something I dealt with on any older carb car. And the computer is missing some of the items.