Hi...

I have been fighting a drivability problem with this van since we got it eight months ago.

I'm unemployed with a handicapped child and just can not seem to get it into the shop, so I am (over time) trying to figure it out on my own.

I did not purchase the parts listed below, I know someone from our church that lets me go to his junk yard and get whatever parts I need. So even though they are used, multiple used OEM parts were tried and bad used parts were ruled out when vehicle continued to exhibit the same issues with multiple parts.

1999 Grand Caravan Sport. 3.3 Flex with the 604.

Found a plenum leak and fixed with new gasket. That problem gone. No more vacuum leaks.

Still has very erratic driving behavior. RPM gauge jumping up and down, If you pat the gas and then hit the brakes, van will stall and motor will die. Will start right back up.
I've tried multiple IAC's and still do not seem to be able to control engine idle. Dips all the time to below 500-400 RPM. Sometimes dies.

I don't know anything about tranny lock-up issues but have some suspicions about that being the cause. Van jerks throughout the full driving range. And a bit more than a mild jerking. This vehicle has no tranny leak and we have not had to put any tranny fluid in it since we have had it.

I can tell you that it came from a person that ONLY took it to the Dodge dealer for anything it needed.

Replaced many, many parts on motor. Including but not limited to, TPS, IAC, Crank sensor, EGR, tranny up speed switch, down sensor switch, downstream 02 sensor, PCM, TCM, new wires, new plugs and whatever else I am forgetting.

Most of the time when cold, runs smooth at idle, just like new. Sounds odd but seems to run better when AC is on. What the heck is up with that? Sometimes power breaking will stall it out and sometimes not.

Van also is a bit hard to start and has a ka-put cluck type of behavior when shut off. (If you can figure that one out) hehe...

I've been told that the cat is ok but I do not know that for sure. There is a black smutty coating at the end around the tail pipe, like maybe some kind of lean condition.

Not tested:

Fuel pump, filter or injectors.
Cam sensor.
Compression.
Wiring faults.

Any ideas guy/gals?

Any help would be greatly appreciated,
John

PS - I have one of those cheap OBD2 cables and ScanXL software. Not many readings and no graphs but SOME data anyway. I have taken some snaps of various readings at a few different speeds. I do not know if they will divulge anything significant but below is the link for everyone to look at them.

Here is the link with some PC Scanner pics: http://eliteipodman.com/van-pics/

 

Have you changed tranny fluid and filter? That would give you a look at the pan for debris. Have you seen the check engine light and checked for codes along the way? It sure sounds like a vacuum leak. Might triple check all sources. How about a MAP sensor?

May run better with a/c because the PCM opens the IAC further to compensate for the added load of the compressor.

BTW - The A604 was replaced by the 41TE in early 90s. Essentially a 604 with improvements.

 

Thanks for the reply Cougar...

Thanks for the tip on the tranny ID.

I think two cans of brake parts cleaner should have picked up any additional vacuum leaks. So I am pretty sure about that.

No... we have not done anything to the tranny. As the +4 fluid is very expensive and it has had no leak, I have not messed with it.

Can you tell me what type of symptoms I would see if there was a lock-up problem? Two different people told me there was a lockup problem. I've never has or experienced one so I am not sure.

This has driven me crazy and we have to drive that van 80 miles to take my kid to the doctor at least twice a month.

Really need to figure this out...

Thank you again,
John

PS - No light now. MIL used to come on throwing a cat code. But later went away when I replaced the Plenum gasket. There is no Freeze Frame data and no stored codes.

PSS - I have one of those cheap OBD2 cables and ScanXL software. Not many readings and no graphs but SOME data anyway. I have taken some snaps of various readings at a few different speeds. I do not know if they will divulge anything significant but below is the link for everyone to look at them.

Here is the link with some PC Scanner pics: http://eliteipodman.com/van-pics/

 

Sounds like a cracked flex plate.

 

Um...

 

I'll be sure to pour a bucket on steam on it to fix it...

 

If you replaced the crank sensor with an aftermarket unit; I have not had any success with anything but dealer parts for both the crank and cam sensors. Crank sensor controls the spark, cam sensor controls the fuel. Start with these.

 

The flex plate is the flywheel and what the crank sensor reads off of. It will crack around where it is bolted on and cause the issues you are describing.

 

Ah...

Thank you Tizzy. I'll check that out.

Problem is, sometimes, when cold, van runs great.

Thanks again,
John

 

metal swells when it gets hot, that's when they loosen up. When it cools down, it kinda clamps back together. Most likely have to pull the transmission to check it, that's the down side.