1996 Grand Voyager bucks at idle in gear, but not in neutral or Park

The subject pretty well describes the problem. My 1996 Grand Voyager with the 3.3L/4 speed drive train began to act up on me today. The van has 175,000 miles on it and I was nearing the end of a long road trip and stopped for gas. The van had been cruising the previous 3 hours at

65 MPH. As I was pulling out of the gas station, the van bucked pretty violently shaking the van smartly. The tach jumped around between 1,000 and probably less than 400 RPM. The van didn't completely stall, but came very close. Once I got some throttle in and got above 15 MPH or so, the van smoothed out.

The van ran fine at speed, but when I got near home and had to go through town, it would this at every stoplight, ocassionally stalling. It would restart instantly and idle great in park or neutral, but as soon as I shifted into D or R, it would buck like a bronco until I got it moving a little.

Some time back, I had similar symptoms when my fuel pump was failing, however, there was one major difference and that is that before shifting into neutral didn't help. The service manager at that time thought it might be the torque converter locking up inadvertantly, but he changed his mind once he heard that shifting into neutral didn't help the problem. Since shifting out of gear now does help, is this possibly an indication that this is the torque converter clutch intermittently locking up? Are there other failure modes consistent with these symptoms? Which sensors does the transmission controller use to decide when to engage the clutch?

Matt

Reply to
Matt Whiting
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When was the throttle body last cleaned thoroughly? How old are the plugs and wires? Are the fuel injectors working properly or could they be partially blocked?

I'm not as quick to blame the transmission. I just think you are seeing this because of the load when at idle.

Bob

Reply to
Bob Shuman

Throttle body was cleaned about two months ago. Plugs and wires were replaced 25,000 miles ago along with the coil pack. I can't say for sure on the fuel injectors as I don't know how to determine if one is partially blocked, but it seems like that would cause problems other than just at idle in gear.

Could well be. That is why I'm asking what other failure modes would be consistent with these symptoms.

Matt

Reply to
Matt Whiting

My thoughts: I'd start by looking at the three front plugs to see how they look and if they provide any indication of being fouled. I'd then clean the TB again making sure to disassemble and clean the AIS using throttle body cleaner, a toothbrush, and some clean rags. I'd use new gasket to reassemble and see if this eliminated the problem. If not, then it still could be an AIS problem, a stuck EGR (but you did not indicate any error codes), or a bad spark plug or wire though they were replaced 24K ago, or even a tank of bad gas. I'd probably also throw a large bottle of Techron injector cleaner into a full tank as well. As a last resort if none of this helped and before taking it in for service, I'd probably change all 6 plugs.

Good luck. Let us know what you determine is the cause.

Bob

Reply to
Bob Shuman

If the transmission is original I would be rather suspicious of it. Here's some things to try:

Try starting out in 1 gear instead of in D and see if the problem goes away.

If your going at 15Mph and you stop on the gas, does it buck again?

Does it buck when your at high speed and your going up a hill with the pedal to the floor?

Ted

Reply to
Ted Mittelstaedt

It acted up in D, 1 and R.

Didn't try that and the problem hasn't recurred since the day it orginally happened.

Didn't try that either. I will if/when it acts up again.

Matt

Reply to
Matt Whiting

Sounds like a major vacuum leak...like a PCV valve hose. If so, it will eventually "teach" itself to run with it. Then it will repeat the episode when you fix the problem.

Reply to
Steve

Matt, I had the same problem on my 96. Mine stalled when I came to a traffic light. I had to start it in neutral, drop it in to drive and back to neutral to get it moving so it wouldn't stall. Parked it overnight and the next day no problem. The problem came back about a week later, only this time you could hear metal grinding. I put in a Chrysler rebuild.(under warranty thank you) This was at 53K!!, and I changed the fluid and filter regularly with ATF#3 I now have 110k and no problems. Good luck.

Reply to
Dave

Well, hopefully, I'll have better luck than you, but even so if it dies tomorrow, I won't feel too badly given that this is the original tranny at nearly 176,000 miles now.

I had a similar problem once nearly a year ago, but it coincided with a failing fuel pump so I thought it was related, but I'm guessing now it was merely coincidental. It hasn't happened all week driving to work, so maybe it was water in the gas I bought or something. It just happened so fast after filling up that I couldn't believe the gas could have gotten circulated through the system that quickly.

Who knows? I'll just keep driving it until it acts up consistently enough to troubleshoot it reasonably.

Matt

Reply to
Matt Whiting

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