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Discussion Starter #1
Hey guys, I'm new around here, but from what I've seen it looks like there are a lot of good people with great suggestions floating around. Already searched existing threads and, though people had rough idle problems, none helped me out. So here's whats up:

I have a 2001 Chrysler T&C 3.8L engine that has an extremely rough idle. Like really bad shaking. It happens whenever the car is stopped in any gear. Used to be smooth in park, neutral, and reverse, but it shakes in even those now. I've checked the engine mounts and replaced the center one along with the driver side/transmission mount. The passenger one wasn't shot. It seems like the shaking is more toward the driver side than the passenger side, but the entire front still shakes. I know the power steering pump and reservoir need changing, but I really doubt those can cause such movement. The RMP hovers around 650-750 while in Park and around 500-600 while in Drive. The shaking seems to stop when I gas it to around 1,000 RMP. The engine light isn't on (no, the light bulb isn't burnt. I've checked). And the weather here in South Florida doesn't do much damage to cars. Oh, and the ABS light comes on very rarely then turns off by itself. Another thing: I lifted the entire front of the car using jacks to see if it was the tires/suspension causing the shaking, but the front still shook. All fluids are good right now. I recently changed the engine oil and replaced it's filter.

That's all that comes to mind right now, but if any more info is needed, I'll happily provide. My dad and I work on this car together, and it's the first time that we've hit a brick wall. Whatever we think of eventually gets ruled out. Thank you guys in advance!

Kaan
 

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Very unusual for an engine to idle roughly and not throw a code if there's something electrically wrong - which is generally the case, but even a mechanical fault will throw a code eventually because of the engine performance monitoring functions the electronics do. The ABS light may be unrelated to the idle issue.

Have you run through the basics like making sure that the plugs are in good condition and gapped properly?
Plug wires are in the correct order and in good condition?
Traced vacuum lines, breather and PCV lines to make sure those are in good shape?
Checked for codes that may not trigger the MIL, using the "key dance"?
EGR valve operation?
Checked for the melted injector harness problem?
 

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I had an issue with my 2002 3.8L running bad at idle. It was throwing mis-fire codes and you could smell the exhaust. My problem turned out to be bad plug wires...doing plugs and wires fixed the problem. Is it a mis-fire or an engine mount/balance problem?
 

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Sounds to me like engine mounts, but on second re-read, you said you replaced them. did you do the front center one as well as that one stops the engine from rocking quite a bit too. Best to do all 4 at the same time. Are all your spark leads in the correct order? Maybe two are accidentally swapped? If you had a vaccum leak, your rpm would be floating and potentially a loud hiss. Also, it would be idling much higher, close to 1000 to 1100 rpm in park-neutral.

I would start with the spark leads, violent shaking is usually reversed leads and it happens.
 

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Drivin' Maniac
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As Douggro mentioned, I don't read anything about replacing the ignition components: Plugs, wires, then check the injector harness.

After about 60K miles, the waste-spark system on these engines makes the plug gaps really, really W-I-D-E. This causes idle misfires but it doesn't seem to set a CEL. As the OP stated, otherwise (off-idle) the engine runs fine.
 

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When was the last time the throttle body & IAC were cleaned (by taking the entire assy off and cleaning both sides and all edges on a bench)?
This is especially critical if you've not replaced the PCV valve in a while and the motor seems to be "eating" oil...
 

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Discussion Starter #7
Quick thanks to all of you. I hoped to get back to some of you yesterday but never had the time. Now back to the topic: I'll definitely check my plugs and cables since almost everyone mentioned that. The only reason I didn't suspect them is cause there's no misfiring on the car. It runs perfectly once you press on the gas. Right before I replaced the plugs a while back, I could feel that the engine wasn't running properly. I'll go through all the suggestions and try em one by one over the weekend and let you guys know how it goes. Hopefully something will work. Again, thanks to all of you.

Crapavan - I did replace the front center mount but forgot to mention it. You said replace all 4, which one's the fourth?

Douggro and Carbuff2 - The cables have to be in the correct order since the problem is recent but the cables aren't but I'll check the gauges on the plugs this weekend

Spacecoast - No misfire problems at all. I've felt those before, so I know for a fact it isn't misfiring

Atoman - it's never been cleaned since I've owned the van. I was planning on taking it apart this weekend as well.
 

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My 2002 has about 90K miles, and about 5K miles ago is when I had an idle misfire. Just happened one morning when my wife cranked up the van. Prior to that I had never touched the plugs or wires...when I pulled the plugs the gaps were quite large and in poor shape, and I found two places where voltage had arched out of the wires into ground. If your wires are old, it's suspect...and so are the plugs. Make sure each wire is fully seated on plug and coil.
 

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There are 4 mounts:
1) front lower radiator cross member to the trans case
2) upper passenger side - above accessory belt drive
3) upper driver's side - just under/behind battery
4) rear of trans case adjacent to exhaust pipe, covered by a heat shield

When you clean the TB, make sure all connectors are clean and secure and take the time to check for any leaks / split or cracking hoses. Also, be patient and clean the Idle Air Control passages and parts - if it's covered in thick layer of crud it's best to take it apart rather than soak in cleaner (in fact keep that cleaner away from all sensors as much as possible)
 

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Discussion Starter #10
I took out that rear transmission mount yesterday and it's a goner. Couldn't put the new one in tho because the damn engine wouldn't find its place so the bolt doesn't go straight through the mount. It's gon learn today (Kevin Hart fans?). I'll update when it's done.
 

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Use a hyd jack so you can make minute changes.

I always leave all bolts loose until all bolts are in place, makes it much easier.
 

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Discussion Starter #13
It worked!!!! No more rough idle. Now I just gotta replace the power steering pump so the steering wheel stops shaking. Thanks for all the help guys. For anyone who needs to replace their own rear mount: there's a small bent piece of metal right next to the oil pan, use that to lift the engine so that the mount can find its place. Had to play around with the angle I lifted it at, but it eventually worked. And gusc is right, my hydraulic jack saved me a lot of time. Thank you all by the way!
 

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A clogged PS filter in the reservoir will cause the front wheels to shake when not moving.

On my '03 it gets worse with cold temp, I'll be changing mine soon.
 

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Discussion Starter #16
@giant96, do you have pictures of your bad rear mount ?
It took a while, but here's what mine looked like. One's a side view and the other is a top view. On the top view one, the part with two holes faces the back of the car.
First time uploading pictures so hopefully it worked.

IMG_5719.JPG IMG_5721.JPG
 

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Drivin' Maniac
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You picture upload worked . :thumb:


Funny thing, I was purchasing tires for another of my cars yesterday, and one of those motor mounts was sitting on the counter at the tire store! HMMM :biggrin:
 

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Discussion Starter #19
You picture upload worked . :thumb:


Funny thing, I was purchasing tires for another of my cars yesterday, and one of those motor mounts was sitting on the counter at the tire store! HMMM :biggrin:
God bless the man who has/had to replace it haha
 
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