QuestionQUESTION: Hi. My girlfriend has a 1996 Dodge Intrepid (3.3 V6, 120,000 miles) and it intermittently stalls out on her. It is not a consistent problem and has yet to do it for me on the occasions I've driven the car, but so far I've been able to narrow down a few symptoms. First, it does not appear to set a code, as the check engine light does not remain on after restarting. It usually will restart. It seems to happen hot, not cold, such as after 15 minutes or more of driving. It seems to occur when coming to a stop or slowing for a turn. I maintain the car fairly well and do most repairs myself, so I am somewhat familiar with the car and I own a 1994 5th Ave w/3.3. I have not yet tried to read a code either by the key method or borrowing a scan tool (which I can do if necessary) but I haven't done that yet since the light hasn't come on. I suggested once that when it seems to want to stall, that she lightly keep the throttle on, and that seems to stop it from stalling out. Could the TPS be going bad and not setting a code? Where can I start to track this ghost down? Any ideas would be great! Thanks! John
ANSWER: Hi John,
Only codes that cause pollution increase will turn the light on continuously, there are many others that store in the memory nonetheless. So use the key to see what you get. I doubt it is the TPS. The stalling when slowing and stopping is characteristic too of another issue:
I have idea, one of my favorites when bad idle rears its ugly head. I would take a look at the exhaust gas recirculation valve which is located behind the engine near the air intake throttle valve. It is mounted in a pipe that runs between passenger side exhaust manifold and the air intake manifold. The valve is mounted horizontally and has a valve stem between its round vacuum actuator top and the body of the valve attached to the pipe, inside the flange that connects the two parts. The stem has a slot into which you can insert the tip of a flat-bladed screwdriver so as to lever the stem back and forth against spring action which should move freely and close tightly. If the stem seems to be sticky so that stem doesn't close all the way by spring action, then you can try spraying some penetrating solvent like WD-40 on the valve stem to freeup its motion.
If the valve is sticking slightly ajar it will make for a rough idle and poor acceleration such as you describe because the mixture is too dilute. It is one of the most common causes of this symptom. So see if you can find the valve and check/lubricate the stem. To check it in motion you can rev the engine from idle to 2500 rpm and back to idle and watch to see if the valve stem moves freely in both directions to the extreme open and closed positions. It may be that the interior of the valve is cruddy so that might require that it be unbolted from the pipe where it it attached and cleaned. But chances are good it will only be a sticky stem. Feel free to write back with the results and other questions you might have.
Roland
PS Use the 'thank/rate' tab to get back to me without having to wait for me to be 'available' to take a question.
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QUESTION: Hi Roland! Thanks for the quick reply! I will check out the EGR tomorrow when I see her. As for the codes, I had her go read them. We got a 12 and a 33, both of which I know the reasons for. According to the codes list 12 means the battery was recently disconnected, and yep, it was. The 33 means A/C clutch relay circuit open, which is true. We disconnected the clutch because it went bad and we haven't been able to afford to repair it. In the meantime, just to clarify, the car runs well and does not have a rough idle/poor acceleration issue. Only at times when she slows to turn or comes to a stop for a light or in traffic will it just shut down or shudder and want to shut down. Don't know if that makes a difference in your evaluation. Sorry I can't be more specific, but I am trying to get clues from her since it does the typical thing of not doing it when someone who works on cars gets near it! Thanks again! John
ANSWER: Hi John,
Yes, the valve has to be shut tightly when slowing down or idling as when it is ajar the exhaust gas will, if admitted into the intake manifold, lean out the mixture. Thus the poor idle or die of the engine. The problem usually also causes hard restart, but it might restart but idle poorly. Another possibility is that the coolant temp sensor is off-value. Its resistance should drop to about 1000 ohm when the engine is warm so check that out as well. It is located next to the thermostat housing and has a tan/black and black/light blue wire. There is also an air intake sensor at the back of the manifold with black/red and black/light blue wires that should also decrease its resistance similarly as the engine warms. Those are possibilites of the egr doesn't prove out. Finally, cleaning the throat, butterfly valve plate on both sides, and idle air passage way at the throttle body is another possible correction.
Roland
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QUESTION: Hi Roland. Well, I pulled the EGR valve, thoroughly cleaned it with carb cleaner and lubricated it with WD-40. I moved the plunger with a screwdriver and also applied vacuum while off the car and noted that the plunger appeared to operate. I then reinstalled it and drove the car. The problem still existed. I also tested the coolant temp and air intake sensors. Both started out around 20 k-ohms cold and measured 989 ohms and 3.4 k-ohms respectively when the engine was hot. Thus I believe they are operating correctly.
Do you have any other suggestions? Is there a chance that the EGR could still be the problem and simply needs replaced? Are there any other tests I could perform to verify the EGR is good or not? I was reading about other possible causes of stalling and poor idling and found several other suspect areas. One is the AIS motor on the throttle-body. The other is the control for the EGR valve. Could either of those cause problems and how would I test them?
I would like to add that I finally experienced the stalls myself. They are very unpredictable and hard to define. Usually there is no warning. However, a few consistent symptoms are: mostly stalls after warmed up; usually occurs during deceleration to turn, stopping or parking maneuvers. It either just shuts down or it seems like it loads up, like an older car with a carb when the choke sticks closed. After a quick shut down, it will restart with no problem. But if you try to catch it before it stalls by giving it gas, then it stalls, it is very hard to start for a few minutes.
Again, many thanks for your guidance and support. I think this is going to be stubborn one to track down, but as I told my girlfriend, I'm more stubborn than the car! Take care. John
AnswerHi John,
I don't see how the egr could remain open if the spring is returning it to the closed condition, without it setting a fault code 32. Similarly with the AIS not responding (code 25). You might do well to check all the vacuum hoses that are attached to the intake manifold to try and find one that is cracked such as to cause an intermittent vacuum leak when the engine shifts on it mounts, for example. Another possible intake manifold leak cause would be the PCV valve that connects the intake manifold to one of the valve covers. Those are very inexpensive and probably should be replaced if you haven'd done that yet. If that stuck open that could cause a stall. Other than a recheck for codes I can't think of anything else at this time. But try all those and see if you strike pay dirt!
Roland
PS Thanks for the previous evaluation and nomination. Feel free to use the 'thank/rate' to get back to me with further questions/progress, avoiding waiting for me to be 'available' to take a question.
FYI, I removed the AIS motor and cleaned out the passageways in the throttle-body and pintel. They were a bit carboned up. I took the car for a 20 minute run through the neighborhood and it did not stall as it did before. I'm not convinced that the problem is resolved and the real test will be my drive to work tomorrow. FYI, I did check a number of the vacuum lines and they seemed OK. I did not check every one under the hood, just the ones around the EGR, the intake and ones generally connected to those. I removed them and inspected for cracks, checked the ends that they connected to, etc. Again, many thanks, and if I come up with any new information I'll send a new question. Take care & have a great holiday! John
Hi John,
Many thanks for the kind remarks, and my best wishes to you and yours as well.
I agree fully with the throttle body cleaning (including both sides of the throttle plate); that had slipped my mind as a possible remedy. I suspect that will solve this car problem for your girlfriend.
