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Another rough idle thread

15K views 44 replies 12 participants last post by  Kscha41 
#1 ·
First off I searched threw a few threads on rough idle with no answer to my problem. It a Gc sport 3.3 with 81,000 miles. When its is in park or nuetrel it idles pretty well, still not as it sould, but as soon as you put it in drive or reverse the idle drops down. The tach jumps all over the place to keep the engine running. I can drive it down the road(engine seems to be hesitent) and as soon as I come to a stop the idle will drop down to 400 rpm back to 700 rpm back to 500 rpm and so on. It has not yet stalled but has come close. Sometimes when I come to stop it will idle fine. I have replaced wires, plugs(replaced with factory ones), I tried a new coil, the plugs a set at the right gap. I also have tried dry gas, fuel injector cleaner. The check engine light is on but only for radiator fan relay, which I already replaced and I now think it is the pcm. Can a bad pcm which is not making the fans run cause a rough idle. When the van is idling and you are near the exhaust the noise of the exhaust is more of a bla,bla,bla vs a blaaaaaaaaaaaaaaaa. I have read in other thread maybe a bad egr, and I will try to clean it tomarrow, but what makes me think it is not the egr is that the engine seems to have a miss while acceratings. I can't find any vacume leaks. Can this problem be bad injecters. Please help because it seems to be getting worse and I'm afaird it is going to start to stall.
 
#2 ·
dirty throttle-body/IAC valve

You will need to open up inspect and clean your throttle-body/IAC valve>>>soot/dirt accumulation there from EGR becomes sticky/clogs air inlet ports for the IAC valve solenoid to function.

If your problem still persist after thoroughly cleaning up your throttle-body, then check if your vacuum sensor is still okay. Replacement is readily available at mopar.

hope this helps,
Bulldog Van
 
#3 ·
I also forgot to add that I cleaned the throttle body already and yesterday when I turned the key to the on position I can hear the egr make a humming sound. Is that normal? I will try to clean the IAC valve next. Thanks
 
#4 ·
also check for mil codes/key dance, check all hose to throttle body

You can check for EGR problem by doing the key dance>>>check for stored codes in your van's computer, if any.

Some members fixed their idling problem by just cleaning the throttle-body and checking all the hoses going into it for air/vacuum leaks. Any air/vacuum leak that is not metered/measured through the throttle-plate and IAC valve within the throttle-body will throw-off the measurement of the vacuum sensor, one of the key input for fuel/air mixture setting for your ignition and fuel injectors.

Bulldog Van
 
#5 ·
Its seems to be better when cold but shorty after it will go all over the place. And also today at the stop light it stalled. So from then on I threw it in nurtral when I came to a stop. It then idles fine. It seems to be getting worse. I tried to clean the IAC today but didn't do much. I am going to take it apart tomarrow and try to clean it better. I am also going to try and disconnect the egr. How do I do the key dance?
 
#6 ·
Well I also forgot to add earier is that I also replaced the pcv valve. I also cleaned the thottle body again. It did not run any better. I found out how to do the key dance, I got 4 codes. 1. p1684, I don't know what that is, it dosen't tell me in my manual. 2.p1491 Rad fan control relay circut. I've been trying to fix that one. 3. p0403 EGR solenoid circuit. 4. p0206 Injector #6 control circuit. Thats maybe my problem to my rough idling. Its says in my manual to disconnect the plug at the injector to see if it changes anything. I disconnected it and the engine did not change one bit. Theres my problem, but how do I fix it? Is it a bad injector or something else. A couple of months ago Auto Zone told me to stick a paper clip in the plug that connects the harness to the injector to see if that will make the code go away. Did that screw things up to the wiring or the pcm by sticking a paper clip in the plug on the wire of the harness.
 
#8 ·
A couple of months ago Auto Zone told me to stick a paper clip in the plug that connects the harness to the injector to see if that will make the code go away. Did that screw things up to the wiring or the pcm by sticking a paper clip in the plug on the wire of the harness.
After you tried the paper clip mojo thing, did it make the problem worse immediately? If not, then you probably didn't do anything too bad.

What was the A.Z. guy's rationale for doing that? Codes usually mean something (other than "please stick me with a paper clip" :biggrin:)
 
#10 ·
P1684 means the power to the PCM/TCM has been interrupted within last 50 restarts, such as when you disconnect the battery or have a loose battery connection.
 
#12 ·
Actually the more I think about it, the guy told me to poke the plug for the temp sensor and I could not find it on the engine and I thought that was it. I guess I was wrong:smashfrea It is hard to tell it it changed anything because the engine had warped head( cyclinders 1,3,5 only were at 40 psi) so the engine was messed up already. Can I test anything to fiqure out if I screwed things up to the wireing on #6, or does it just happen to be a bad injector. As someone said before, I would hope there would be a protection thingy on it. I guess I just wasn't thinking. But still auto zone told me to paper clip the temp sensor one( which I know where it is now) wouldn't that short circuit that. I guess I could swap injectors with another one and see if the code changes to a different injecter.
 
#13 ·
When I took the paper clip to the plug, the clip did not get hot at all. I have sorted a few things out before and the wire tends to get hot or melt. Is there some type of fuse? They are the same guys that were trying to sell me the rad fan relay for the gen 3 van and they swore they gave me the right one. I was looking all over under the hood for the relay they gave me and someone told me it was behind the bumper. I took it off and brought it back to az and told them this is the one I need. They told me that was my a/c relay. I returned the one they gave me and went to the dealer and got it for the same price as az but this time the right one. Still didn't take car of my problem.
 
#14 ·
Well today I swaped injector 6 to injector 4 and 4 to 6, hoping that if it was a bad injector that it would show a code for injector 4 now. I put everything back together and got the same codes:angrya::angrya::angrya:. So it is still showing that injector 6 isn't working. So it now sounds like something with the wiring or pcm. Can somebody :help_wsig me. Can I test the harness somehow to see if I am getting power to it? This dodge is kicking my butt. It would make a good boat ancor for my boat.
 
#15 ·
My '97 T&C had a sort of rough idle. These vans, along with other chysler/dodges, have a returnless fuel system so, if by any chance, dirt gets past the filter, it builds up in the fuel rail/injectors with no where to go and only reduces injector efficiency and spray pattern. I had the fuel injectors cleaned(with an OTC on vehicle fuel injector cleaner) and the idle is perfectly smooth now, along with better acceleration, throttle response, and gas mileage increased slightly. It was interesting to watch. While the van was running the fuel pump relay is removed and it runs til there is no more gas in the fuel rail and dies, the OTC is installed onto the fuel rail via the service port and seafoam or something of the sort is run through the injectors. The van ran off the seafoam. Just a thought.
 
#16 ·
Well I know its not a bad injector because I swapped the injector 6 to # 4 and #4 to #6. If it was a bad injector the code would of changed to injector 4 but the code is still for injector 6. I would like to bring it to the dealer because for 89 dollars he says they run all the test and will find out what is wrong with the system along with the other codes. But the guy who owns the van isn't working right now and doesn't have money to waste. I guess it is more fuel afficent now that only 5 injectors are working.
 
#18 ·
Does anybody else happen to maybe have a answer. It stalled again on me and it would not start back up right again. Actually it started up right away but only ran at 200 rpm and when I hit the gas it did nothing. Then it stalled again and would not start until about a minute later. It is kinda of embarising with thirty day tags on it and I 'm at an intersection with my flashers on.:eek:
 
#22 ·
What's the year of that vehicle? If it has the older type EGR assembly, you should be able to make it work by putting a vacuum line directly to the valve itself and put a golf tee in the hose you disconnect. The problem occurs when the EGR valve allows too much exhaust gas into the intake. By putting a vacuum line directly to the valve, this should keep it closed so that no exhaust gas enters the intake. You may find the engine pinging at highway speeds though. I didn't when I did it on a 1995 that wanted to stumble and die. At least by doing this you can find out if it is the problem.
The idea of allowing exhaust gas into the intake is to cool down combustion so less pollutants are emitted.
If the Van is 2001 or newer, the EGR valve assembly is different. Apparently you can take these ones apart and clean them up. My 2002 was built without one, many were.
 
#23 ·
The van is a 2001 and it is a 3.3 if that matters. So you can clean these? The code I am getting is for the solenoid not the egr so I think the actual egr is good.
 
#25 · (Edited)
Well I finally took it to the local 5 star to have the problems diagnosed. They gave me five codes P0403, p1491, p0206, p0442, p0455. Now when I did the key dance I got p1491, p0403, p0206 and p1193. Now I can not find what p1193 means. I found a couple small cracks in a few hoses I am going to fix and the egr vacume hose is melted. Dodge told me that I need a new pcm, egr, radiator fan relay, vacume hoses and gave me a total of 1400 dollars:help_wsig They said the pcm will fix injector 6 and part of the radiator fan problem. The relay will fix the other. Oh they did some kind of recall while it was in and he said it was just a piece of tape. Well when I got home I noticed that the plastic peice that going around the radio and climate control was not in right. So I got home and took it apart and I noticed that they put some kind of tape on top of the radio:ask_wsign. Well I put it together right. We should just part out the van. We went to a junk yard the other day looking for parts but no luck. They also told me that the egr was bad. If that was bad, wouldn't I get a code for this? Also why am I getting slighty different codes than the dealer?
 
#31 ·
Well I disconnected the neg cable on the battery and the p1193 code went away.:biggrin: Now I just have to get rid of the 50 codes. I was talking to the service dept. today and I asked him if I got a pcm out of a junk yard car with a 3.3 grand caravan 2001 if I would have to get it reprogramed. He said yes. It is a shame because the warrenty for the pcm is 8 year,80,000 mile and it is a 2001 with 81,333 miles.:(
 
#32 · (Edited)
Well we finally got the radiator fans working. We brought it to a shop and it was a broken wire. Now we are leaking ps fluid. We fix one problem and we get another one. Now we just need to replace the egr valve and replace a few dried evap lines. And try to find the ps leak. The guy brings the van around front to us and I poped the hood to see if they put the ps container screws back in(they left them out last time) and I hear the pump sqealing. There was no fluid left in it. They toped it off and another guy came out and said oh I think the noise is there because it sat for a couple of days. I said no, there was no fluid in it. And on top of that the van sat for three years and when I started it up, it didn't sqeal. You can't when with sowm of these mechcanics. They think just because they have a mechanics license that they know it all. Also forgot to add, when you turn your ac on, is your fans surpose to kick on right away or does it take a minute? Thanks
 
#33 ·
That's discouraging for sure, but I'm convinced you're determined to overcome the problems and get the van working properly again. Wise to profile your mechanic as to work ethic and BS capability.
I believe one of the worst things for a vehicle is to leave it unused for extended periods of time or mothballing it. Vehicles work best when used daily.
 
#37 ·
Well after a year of messing around with the van, the check engine light is NOW OFF. We finally replace the egr valve and disconnected the battery and then reconnected and started. No more light:headbange. The light before would come on right away if you disconnected the battery. I haven't realy driven it much since I replaced it so I don't know if it is any better, but no more stupid light.
 
#38 ·
If I am not mistaken, if the EGR is stuck open, it will barely idle, or be quite rough. But at highway speeds it should even out. It would not seem to be related to the position of the transmission, which is where I think this started. Nor would just one injector cause overall bad performance, it should be a noticeable rythmic miss. It sounds like your sensor problems (which affect everything) might be a more likely cause of your problems, although you would likely have a lot of extraneous problems first time you check out an older car. But they wouldn't necessarily cause the problems you are describing.
 
#39 ·
The van is wierd. Sometimes it idles great know and other times not so much. I going to give it time because I disconnected the battery and I figures maybe the pcm needs to relearn.
 
#42 ·
Check for vacuum leaks near the missing cylinder. Even a small leak can lean out just that one cylinder to cause that problem. I had this happen on a Toyota that I used to own. Drove me crazy for a while trying to find it.
Hank
 
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