multiple codes. idle issues... etc

[emothug1985]

1993 4.0 5 speed. Less then 60k original miles. Been having idle issues since I got it. On cold start it idles high for a second or two then drops flat and usually dies. If I feather the throttle for a minute or two I can get it to idle enough to stay running while it warms up. But while doing this the idle surges for awhile then usually levels off at really low idle. I had to adjust the bolt so it wouldn't die. And driving it when I come to a stop sign or light the idle stays high,between 2 or 3 k. Then will fall flat after half a minute or so. It has great power and good mpgs. I finally pulled the codes after checking all vacuum lines and doing full tune up and have 122,157,172,176,181 and 211. I did these all KOEO. I did however do a spray test with carb cleaner and it seems to surge rpms when sprayed close to the firewall side of the lower intake manifold. So I'm changing the gasket and will be cleaning the MAF tomorrow after work. I have changed a few sensors and cleaned the TB. It seems like all these codes could be related. I hope? Anyways any insight is appreciated.

 

[emothug1985]

Also the tps checks out. And I have changed the MAF for a new one. And I did the KOER test this morning and it only flashed 3 times?

 

[2stroke]

122- TP low

What was the voltage of the TPS at closed throttle?

157- MAF signal low or grounded

You say you have a new MAF

172- O2 sensor not switching; right or rear

Usually they indicate bank 1 or bank 2, so "right" depends on which side of the motor you are looking from. Simply change the O2 sensor.

176- O2 sensor not switching; left or front

Go ahead and replace both O2 sensors

181- Fuel system lean at part throttle

Bad O2's could cause this

211- Ignition PIP signal was erratic or missing

Through a little research, it looks like this could be caused by a bad camshaft position sensor. To test that, simply unplug it. It will be hard to start, but if it runs good un-plugged, the CPS is bad.

 

[the_don]

i believe the supply voltage the most of the sensors are 5.5vdc, and that voltage comes from to ECM.
under the alternator is two square harness connectors, pull them apart and clean all of the contact with a small brass wire brush then refill them with dielectric grease.

 

[emothug1985]

Voltage at tps closed was 1.4 iirc

 

[emothug1985]

And at WOT was at 4.7. Had smooth voltage gain throughout the cycle and tapping with a hammer produced no burps

 

[2stroke]

That's strange because closed throttle TPS signal is .8V-1V (might be wrong?). 1.4 is for sure out of spec. You would think it would give a high TP code. You have two options to cure that. Either turn out your throttle plate stop screw, or follow the procedure to make your TPS adjustable. Ideal is .94-.98V. The best way is to disconnect the IAC, adjust the throttle plate stop screw until you are at 500 RPM (Plugging the IAC in will bring idle back to normal), then adjust your TPS.

 

[emothug1985]

I figured It is set right because I have had to turn up the idle so it didn't flat out die when it dropped from high idle. Doing the intake manifold gaskets now. New O2 sensors only changed the weight in my wallet.

 

[2stroke]

because of 122 and 211, I think something else might be at play here as well. All of these parts don't just fail all of a sudden. Your TPS is still set to high though.

 

[emothug1985]

I can't attach a photo but the entire lower intake manifold gasket was done for. And the rear portion wasn't even there anymore. Which I think would correspond with all but the 211 code? I'll know tomorrow.. I jacked up the injector o rings pretty bad so I gotta get new ones.

 

[emothug1985]

Got the new gaskets and Orings installed last night. Runs perfect, all clear on the codes.

 

[FR-425]

That is the champ of vacuum leaks eh?