Idling and Stalling

[Sly_Jeeper]

Have you fixed the O2 connection?


1989 4.0
Renix
Scratchy Ba/10
2wd
Stock
Short bed base

[Dammerung]

Okay, back again. Replaced the oxygen sensor, but I haven’t started it because I pulled the egr to look at the carbon build up and it. Was. FULL. Less than a quarter of the diameter of the original hole in the intake due to the big ring of carbon. So I waited to get the new egr, but the one I got does not look the same as the old one. Is it useable? Got it off RA for anyone wondering.



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[Dammerung]

New update. Just put the old EGR back on and it idles even WORSE now! I’m stumped because I can’t find another EGR valve and transducer if that even is the problem anymore. If I can’t figure this out, it might just be time to sell it and wait for another to come along .


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[Sly_Jeeper]

Dang


1989 4.0
Renix
Scratchy Ba/10
2wd
Stock
Short bed base

[Dammerung]

I can’t keep something like this if it’s got a big chance to stall at idle and could get me in an accident if it decides to buck under throttle while in traffic. I can’t really do much else with it and it’s supposed to be my daily. Really sucks that there’s no part availability.


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[MiNi Beast]

are you emission control state? if not just eliminate it. 

[MiNi Beast]

don't give up so easily. little at a time. read and learn and fix and repeat. you will grow as your truck gets better. you shall smile in the sunshine without stalling. keep at it. 

[Dammerung]

are you emission control state? if not just eliminate it. 

I wish I wasn’t. Stuck in Cali...


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[MiNi Beast]

bummer. go to work. 

[SVPete]

WahooSteeler posted some photos of the EGR transducer and a writeup that may be helpful in the below thread:

 

 

 

An EGR problem isn't likely caused by the EGR itself (although cleaning out the carbon buildup is a good thing to do), but by the transducer. Either by the vacuum bleed hole being plugged or the spring rusted away.

 

I don't think there is a magic bullet answer and I understand your frustration...been there.

 

I experienced bucking (although I never heard a backfire explosion noise) and dying issues (driving along and the engine just stopped running, no rhyme or reason, injectors would fire a few more times flooding the engine and having to crank forever to restart). The problem for me was between the EGR and transducer, coil (original at the time), distributor cap and rotor, plug wires, and plugs. I say between because:

 

The spring in the EGR transducer was rusted to dust. The only way to get a new transducer is with a new EGR (which seems to be no longer available).

 

While waiting for the EGR valve to come it, I broke a plug wire. So I had to wait for everything to come in and replaced all those items at one time. Problem was solved, although I really would have liked to know which was the culprit (it is possible I had a more than one issue). Upon visual inspection, I was pretty sure one of my plug wires was making poor contact with the plug.

 

I checked, cleaned, tested as many things as I could according to Cruisers tips first. So that would be a good place to start if you haven't done so already.

 

I had been thinking that maybe the catalytic converter was clogged causing it, but I cured it as mentioned above. Funnily, when I replaced the exhaust system later, the entire matrix in the cat was gone, it had turned into a straight pipe. Not saying that a clogged cat couldn't be a problem, just thinking that the backfiring/explosions/bucking would destroy the cat matrix (would that push it into the muffler then?). So a clogged cat was not part of my problem.

 

Another thread to check out is:

 

 

 

 

 

[Dammerung]

WahooSteeler posted some photos of the EGR transducer and a writeup that may be helpful in the below thread:
 
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An EGR problem isn't likely caused by the EGR itself (although cleaning out the carbon buildup is a good thing to do), but by the transducer. Either by the vacuum bleed hole being plugged or the spring rusted away.
 
I don't think there is a magic bullet answer and I understand your frustration...been there.
 
I experienced bucking (although I never heard a backfire explosion noise) and dying issues (driving along and the engine just stopped running, no rhyme or reason, injectors would fire a few more times flooding the engine and having to crank forever to restart). The problem for me was between the EGR and transducer, coil (original at the time), distributor cap and rotor, plug wires, and plugs. I say between because:
 
The spring in the EGR transducer was rusted to dust. The only way to get a new transducer is with a new EGR (which seems to be no longer available).
 
While waiting for the EGR valve to come it, I broke a plug wire. So I had to wait for everything to come in and replaced all those items at one time. Problem was solved, although I really would have liked to know which was the culprit (it is possible I had a more than one issue). Upon visual inspection, I was pretty sure one of my plug wires was making poor contact with the plug.
 
I checked, cleaned, tested as many things as I could according to Cruisers tips first. So that would be a good place to start if you haven't done so already.
 
I had been thinking that maybe the catalytic converter was clogged causing it, but I cured it as mentioned above. Funnily, when I replaced the exhaust system later, the entire matrix in the cat was gone, it had turned into a straight pipe. Not saying that a clogged cat couldn't be a problem, just thinking that the backfiring/explosions/bucking would destroy the cat matrix (would that push it into the muffler then?). So a clogged cat was not part of my problem.
 
Another thread to check out is:
 
 
 
 
 

Thanks! When I was looking for ways to clean the EGR I heard something about the transducer spring rusting away into dust, so I pulled mine apart and it looked okay, but it still looks like the factory piece, so it’s probably not in the best of shape anyways.


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[Jaime]

I had a similar problem on my 88 a few years ago. It would buck and back fire like crazy then settle down. After replacing a lot of parts and taking it to a mechanic with no luck, it ended up being the ignition control module. 
I can’t tell how to test it. Never found out how. It’s about a $100 part. I went to the local pick a part and got one for 3 bucks. If nothing else is fixing the problem maybe give that a shot.

[Andy in Pa]

I have not seen anyone mention vacuum lines yet.  Please make sure all of your vacuum lines are in good shape.  Having a leak will cause it to stumble and shut off like this as well.  This also includes around the throttle body and the fittings on the intake manifold.  The line to the MAP sensor.  Those rubber 90's and such on the vacuum lines tend to dry-rot and don't seal as well as they need to sometimes.  Don't forget the lines and the vacuum ball underneath the front fender.

 

Then follow Cruisers recommendations for setting the voltage on the TPS.  Leave the meter on it and make sure the voltage changes linearly as the throttle opens/closes.

 

Something in the ignition system could cause this too.  The ignition control module is potted from the bottom, and that potting gets dried out and starts to crack.  Moisture can get in there and cause these problems.  Are the cap/rotor, plugs and wires new?  Were the plugs gapped correctly before install? 

 

[Dammerung]

I plugged off the EGR and now it’s back to how it was originally, so we’re still at square one. I’m gonna try to get a new distributor and go up to Sacramento or Stockton to their pick n pulls to get an EGR and that Ignition module. Any brand recommendations for the distributor?


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[Big_Mark]

My MJ has started doing the same things, can't wait to see how this plays out!

Fingers crossed one of those two items fixes your issue.

[Dammerung]

My MJ has started doing the same things, can't wait to see how this plays out!
Fingers crossed one of those two items fixes your issue.

Have you plugged off your EGR like the others were talking about? If you’re looking at the EGR solenoid from the driver’s side fender, you have to plug off the elbow on the LEFT side of the solenoid, near the electrical connector. Since I screwed up my egr, I haven’t been driving mine until yesterday where I drove it without any bucking happening. I’ve replaced the spark plug wires, CPS, and O2 sensor, if you want to know.


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[SVPete]

4 hours ago, Dammerung said:

Have you plugged off your EGR like the others were talking about? If you’re looking at the EGR solenoid from the driver’s side fender, you have to plug off the elbow on the LEFT side of the solenoid, near the electrical connector. Since I screwed up my egr, I haven’t been driving mine until yesterday where I drove it without any bucking happening. I’ve replaced the spark plug wires, CPS, and O2 sensor, if you want to know.


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So the bucking is gone with the EGR plugged?

 

Still stalling? Assume you have checked/adjusted the TPS?

[Dammerung]

So the bucking is gone with the EGR plugged?
 
Still stalling? Assume you have checked/adjusted the TPS?

I adjusted the tps a while back along with doing the sensor grounds and cutting the grounds that went through the c101 connector together. I honestly haven’t driven it enough recently to actually determine if the egr was the main issue. Death wobble, potential to stall, and the potential to not accelerate really don’t make me comfortable to drive it. But, it hasn’t bucked on me yet and neither has it stalled, so perhaps?


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[Big_Mark]

8 hours ago, Dammerung said:

Have you plugged off your EGR like the others were talking about? If you’re looking at the EGR solenoid from the driver’s side fender, you have to plug off the elbow on the LEFT side of the solenoid, near the electrical connector. Since I screwed up my egr, I haven’t been driving mine until yesterday where I drove it without any bucking happening. I’ve replaced the spark plug wires, CPS, and O2 sensor, if you want to know.


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Not yet, I guess I'll give it a go and see what happens. Will post up here and in my thread with results. thanks man I feel you pain.

[Dammerung]

Finally back after so long! I’ve done quite a bit with this truck since I’ve last posted. I managed to find an EGR solenoid and valve as well as replaced the fuel injectors. While I was putting the rail back on, I snapped the MAP vacuum line and just managed to get through Cruiser54’s fix. After all of that, I tried the truck again and it still has a “Lean Loop Fault” code from the Engine monitor. The only other things I could think of now which can be causing it to stumble are the block coolant sensor (because apparently it helps manage fuel/air mixture I guess?) a vacuum leak of some kind, or something in the ignition. Keep in mind, I’ve replaced the CPS and it reads around .3 volts, but I’m not too sure that it controls fuel/air mix, so that one is up in the air. I know there’s potentially a vacuum leak as under acceleration, the AC gets really weak. But I don’t know if the AC and engine vac are heavily linked.


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[MiNi Beast]

cps should be 5-6 range bad cps or wire connection. check harness and tight on block for solid reading of drive plate. 

[Dammerung]

After driving for a couple days, I’ve got some more news. I now get the lean loop fault and rich loop fault on startup, so I guess some sensor can’t handle me running nicer injectors. On the second startup, I got an O2 voltage code, which I’m not sure about. I don’t really think the 02 sensor is bad, considering I just replaced it with the NGK model. I’m not too sure what to do about this anymore.


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[fiatslug87]

I've had problems with new O2 sensors and found NOS Mopar that fixed my problem. Read this thread 

 

[Ωhm]

When LOGGED-IN. Go to upper right hand corner of screen. Click on Username. Click on Account Settings. Find and click on Signature. Add your vehicle information here (YR, ENG, TRANS, etc, etc) then click on SAVE. This helps everyone. This information will be available every time you post.

[Dammerung]

I've had problems with new O2 sensors and found NOS Mopar that fixed my problem. Read this thread 
 

That’s interesting! I know of a 90 Cherokee in a pick n pull yard near me. I’ll pull the sensor off of it and see if that works. The only thing is that my O2 sensor hasn’t been wacky until after these injectors were swapped in. I’ll still try it though, it’s better than doing nothing.


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