My 88 runs crappy closed loop

[sln583]

My 88 california 5.0 runs terrible in closed loop. it hesitates, bucks and pops the higher the RPMs go and it gets worse with a load on it. I detirmined it only does this in closed loop because the car runs great at wide open throttle and when I first start it. I have evan turned the car off while coasting, cranked it up and it ran fine for about 30 seconds until it goes into closed loop again. The only code I am getting is a 44 during KOER, which is Thermactor and I dont think its causing this.

Im not sure where to start. Not evan sure if its an ignition or fuel system problem?

I had the engine out about 3 years ago and most of the parts have less than 10000 miles on them. I replaced the distributor and o2 sensors at that time. This problem has been happening since I redid the engine but seems to be getting worse.
Makes the car very unpleasant to drive.
Thanks for the help in advance, Any suggestions are appreciated.

Edit
I just checked the timing, its at 12 deg with the SPOUT removed, about 22-26 with the SPOUT in, should it be jumping around that much

 

[HISSIN50]

Do you have your old dizzy and O2's anymore?

 

[sln583]

Unfortunatly I do not. have them.

The timing was retarded a bit when I first checked it, maybe 6-8 deg. seems to be running better know that I advanced it. I will take it for a test drive after the kids are in bed.

 

[sln583]

I tried it with the timing at 6 deg and 16 deg, no difference.
What could cause hesitation and bucking in closed loop but run fine in open loop, and not throw any codes? Could the TFI module be "a little bit" bad?
Or the O2 sensors be defective, but not enough to throw a code?
This is very frustrating.

 

[strtrcr50]

Just out of curiosity, do you have a k&n type filter that you recently cleaned and oiled?

 

[sln583]

Yes I do, and I cleaned and lubricated it 3 years ago when I had the engine out. Right before this problem started.
Could it have crudded up my MAF sensor?

 

[strtrcr50]

Yes I do, and I cleaned and lubricated it 3 years ago when I had the engine out. Right before this problem started.
Could it have crudded up my MAF sensor?

Yes. When the filter is over oiled, it gets on the maf element. Try cleaning it with electrical contact cleaner.

 

[strtrcr50]

Did that help?

 

[aar0s]

mine was doing someting similar, turned out to be the map sensor. i know that mass air cars dont have map's but they have something like it. i took mine off and they were able to test it at the 'zone. 80 bucks later i have no problems.

 

[sln583]

Did that help?

Cleaning tha MAF wire did not make a difference unfortunatly.
I took the entire air inlet track apart. From the Airfilter to the throttlebody, thinking I had some unmetered air getting in somewhere, It seems to be running better, but its still doing it. I erased the adaptive memory so its hard to tell if the problem changed, its definatly still there.

The MAF cars have a BP sensor, instead of a MAP Sensor I think.
Can they test those at autozone?
Can they test My MAF sensor, or any other sensors?
Im kinda broke and really cant afford to throw parts at this problem.

 

[jrichker]

A failing MAP sensor would set code 22.

Code 22 or 126 MAP (vacuum) or BARO signal out of range. The MAP or BARO sensor is pretty much the same sensor for both Mass Air & Speed Density cars. The main difference is where it is connected. Mass Air cars vent it to the atmosphere, while Speed Density cars connect it to the intake manifold vacuum. Its purpose is to help set a baseline for the air/fuel mixture by sensing changes in barometric pressure. The MAP or BAP sensor puts out a 5 volt square wave that changes frequency with variations in atmospheric pressure. The base is 154 HZ at 29.92" of mercury - dry sunny day at sea level, about 68-72 degrees. You need an oscilloscope or frequency meter to measure it. There a very few DVM with a price tag under $40 that will measure frequency, but there are some out there.

The MAP/BARO sensor is mounted on the firewall behind the upper manifold on 86-93 Mustangs.

Baro or MAP test using frequency meter - run the test key on engine off. The noise from the ignition system will likely upset the frequency meter. I used a 10 x oscilloscope probe connected from the frequency meter to the MAP/BAP to reduce the jitter in the meter's readout.

If it is defective, your air/fuel ratio will be off and the car’s performance & emissions will suffer

Some basic checks you can make to be sure that the sensor is getting power & ground:
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.
Check the resistance between the black/white wire on the MAP/BARO sensor and then the black/white wire on the EGR and the same wire on the TPS. It should be less than 1 ohm. Next check the resistance between the black/white wire and the negative battery cable. It should be less than 1.5 ohm.

The following power on check requires you to turn the ignition switch to the Run position.
Use a DVM to check for 5 volts on the orange/white wire. If it is missing, look for +5 volts at the orange/white wire on the TPS or EGR sensors. Use the black/white wire for the ground for the DVM.

 

[sln583]

I think I made some progress

Lacking the scratch to throw parts at the problem, I decided to test every Vacuum line on the car. I found one leak (oddly enough it was in the T to my Vacum guage ) Fixed it and Took it for a drive, its still doing it. I checked the vacuum line going to the HVAC stuff under the dash, it will only hold about 5 inches of vacuum. Then I checked it with the engine running and it held 25 inches.
I tested the Vacuum line going over to the EGR Solenoid on the rear of the passenger fender and it wont hold Vacuum whether the engine is running or not. I tested the Vacum at the EGR valve, and it is getting the 5 inches it is supposed to get when the commputer tells the valve to open, so I know the EVP is working.
My question is, should it hold vacuum? if it doesent, isnt that a vacuum leak?.

This is the part I am talking about

That round looking thing at the back of the shock tower with the red and green vacuum lines coming out of it.

When I put my vacuum pump on the lower nipple, it wont hold Vacuum.

Is that right, should I replace it.
Thanks for your help guys

 

[aar0s]

seems like someone else was having problems with that part lately...
I think there is a way to test it, jrichker i think posted something a little while back about how to test it. Autozone has them listed on their website for 40 bucks, couldnt find it on LMR.
edit: see if this helpshttp://forums.stangnet.com/765133-egr-vacuum-idle.html

 

[sln583]

Thanks for the link.
I verified the EGR system is working properly in every way, I think the EVP is just leaking Vacuum. I was hoping some one could tell me if it was supposed to do that or not before I dropped $40 on another part that didnt need to be replaced.
I will go down to auto zone with my vacuum pump and check to see if the new one holds vacuum before I buy it. Hopefully they have one in stock.
I will let you guys know.

 

[jrichker]

The EVR is basically a controlled vacuum leak. It uses applied vacuum on the manifold side and allows a variable amount of atmospheric air to be sucked into the regulator. You'll find a sponge foam rubber filter around the EVR that filters the air that it sucks in. The computer uses the feedback it gets from the EGR sensor to vary the pulse sent to the EVR. The longer the pulse, the more air the EVR lets into the vacuum line that feeds the EGR valve. The long pulse reduces the vacuum applied to the EGR valve diaphragm. A shorter pulse increases the vacuum applied to the EGR valve diaphragm.

For the reasons above, the EVR probably won’t hold vacuum when it is applied.

You may have already seen this EGR tech note, but just in case you haven't here it is...

Some basic theory to clarify how things work is in order…

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, 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.

Late Model Restoration has the Ford Racing M-12071-N302 kit with the EGR valve & sensor along with the ACT & ECT sensors for $45. See * * * N/A * * * 86-93 SENSOR KIT, 5.0L EFI, INCLUDES EGR VALVE & SENSOR, COOLANT TEMP SENSOR, & AIR CHARGE TEMP SENSOR MUSTANG for more details

 

[aar0s]

just out of curiosity i took the cap off of my evr and lo and behold there was a nasty piece of foam and alot of corrosion and crud. I wonder if thats why my car sometimes runs like crap, pings and is a slug under part throttle. I need to come up with a vac pump.

 

[sln583]

Thanks Jrichker, You saved me $40.
A controled vacuum leak. You would think that would realy screw up a MAF system. The EEC IV never ceases to amaze me.
I Think I had a loose clamp after my Mass air meter that was letting unmetered air in and was causing most of my problem. There was also the vacuum leak I found that was contributing.
The car is running better than it has in years. Thanks for the help guys.
There is still a slight hesitation at 1500-2000 RPM under load, and I will continue to tinker with things till the car runs perfect.

 

[sln583]

For the record, I checked the EVR on a 1995 Bronco I use at work.
It did not hold Vacuum when it was running or when it is off.
This definatly confirms what jrichker said about a controlled Vacuum leak

just out of curiosity i took the cap off of my evr and lo and behold there was a nasty piece of foam and alot of corrosion and crud. I wonder if thats why my car sometimes runs like crap, pings and is a slug under part throttle. I need to come up with a vac pump.

I would definatly pick up a Vacuum pump and check for leaks.
I use a vacuum pump with a bunch of different fittings and some junkyard vacuum connections. If you want to test if something will hold vacuum, you pump it up and watch the vacuum build on the guage. If no vacuum is showing on the guage after pumping a few times, there is a leak. This is for things going away from the engine. Any lines going to the engine will not hold vacuum with the engine off, because you are just sucking around the rings. You can also use this tool to measure engine Vacuum. Plug it into something coming from the engine while it is running and you will see vacuum on the guage, if it is present. One thing I found surprising is that engine vacuum is powerful enough that if you have a small leak in a vacuum line, you will probably still see plenty of engine vacuum at the other end of the line, in spite of the leak. If you want to test a line for a leak, put the pump in one end and plug the other end and it should hold vacuum. if not, there is a leak

This is the line going under the dash and out to the passenger fender, it will only hold 5 inches of vacuum, unless the engine is on, then it holds 25 inches all day, there must be some solenoids under there that close when the engine starts.

This is the line going to my boost guage, FMU and and blow off valve, Holds 25inches when the engine is off.
It wouldnt hold at first, so I checked the accessories (FMU, Bypass valve, guage) at the other end of the line, they all held Vacuum. I disconected the long line itself, it held vacuum, I checked the Plastic T, it leaked. Mission accomplished. Replaced Plastic T. (need to get a brass T)

That round looking thing at the back of the shock tower with the red and green vacuum lines coming out of it is the EVR . It wont hold Vacuum though, when the engine is on or off.

Its really incredible how well the EEC IV can cover up a vacuum leak. I unplug a major line and the engine sputters, and then the computer compensates and it revs up, then smothes out. I remember being stuck on the side of the road when my carberator got a vacuum leak.

The Mity Vac is about $30, and you can bleed your brakes with it as well.
Mity Vac Automotive Tune-up and Brake Bleeding Kit

Hope this helps someone.

 

[aar0s]

my father in law and I checked the Evr's electrical connections tonight. every thing was crudded bad. he pulled some kind of goo out of the plug while i sanded the green crap off the connection. Is there a diagram in there that adds vacuum or does it get the vac from the manifold?
Im putting that vac pump on my xmas list.

 

[sln583]

Im not sure what your asking.
the bottom vacuum line (Red)goes through a connector and to the manifold, where it sources vacuum.
The top Vacuum connector (green) goes through the same connector and to the EGR valve.
I assume there is a diphram of some sort between them that closes off the leak so the EGR sees the required vacuum it needs to open the egr valve.
I connected my Vac/boost guage to the EGR end of the Vacuum line and drove around to see when it opens, it sees vacuum at cruise, about 5 inches.

Hope this helps