Is this happening at light throttle, but seems fine at heavier throttle applications?

 

andyg, Please say more about why light throttle matters...

My 2003 T&C 3.8 AWD with 130K miles sometimes hesitates and bucks on the 1st to 2nd shift. Only ever happens on light acceleration - never on hard acceleration.

 

The hesitation seems to happen most when you are stopped at a light and give it gas to go. Or have just backed out of the driveway and have just put into drive.

Doesn't seem to happen otherwise. Does that make sense?

 

Still having this issue - anyone have any thoughts on what it might be?

 

I've had the same condition for a couple years now. Mine only happens under light acceleration and only from 1st to 2nd. Replaced solenoid pack, input and output sensors and fluid and filter(atf+4) and no change. Any other ideas?

 

Before you spend a lot of money, you might want to have the transmission's computer read.

You're stumble is probably an engine issue, on my '92 it was a spark plug wire. On my 2003, it was a spark plug. Be aware that until it gets worse and can be duplicated all the time, it will be hard to find.

 

Try replacing the TPS sensor first.
It is under $20.00 and they are known to cause those issues.
BWD/SMP & Airtex/Wells re-designed theirs using hall-sensors and they are more reliable now.
(The older ones had solder joints which were prone to failure)

http://www.wellsve.com/advantage_throttle.html

 

if you haven't done so already, start by cleaning the throttle body.. and while at it, leave the battery disconnected for at least 10-15 min. (you'll have to reprogram you radio presets, clock etc)

 

Mine does the same thing, just as described. Other than this, which happens every once and a while and usually under light acceleration / light throttle, everything runs great. Trans shifts nice and firmly from Reverse to Forward and vice versa. I have noticed a very slight leak, that appears to be coming from the solenoid pack from what I can tell. I just had surgery a few weeks ago so I can't really get under there and take a look at everything yet. Mine has about 71K miles on it.

 

Ok, wanted to follow up on this.

We finally decided to bring it up to the dealer. They hooked it up for diagnostics and also said the that the transmission looked good and didn't seem to be the issue.

Recommendation came back for two things - 1) replacing the spark plugs and wires (they were original and most likely were never done by the original owner and 2) there was a code update / firmware update for the computer. They said it didn't specifically address that issue but did have something to do with shifting.

Anyway, got it back and the shifting problem is gone. Also noticed that shifts now take place at about 15-17 mph and before they were taking place at 10-12mph.

Today also did a fuel injector cleaning as well.

Car is running like new.

 

levelbest, How much did the dealership charge for the transmission firmware upgrade? Also, did they happen to list the firmware version number?

(I just put in plugs and wires and am interested in just the firmware)

 

Light throttle usually points to the tps as it wears down in the light throttle areas first. Heavy throttle fixes it as that area is much less used.

 

Wow - this has been bugging me for years. At less than $30 a new TPS seems well worth a shot.
I'm about to do plugs and wires and I guess the rear plugs are a little easier with the TB out.

 

OK - so I've replaced the TSP and gotten a $99 reflash from the dealership but my 1st to 2nd light throttle stumble, bucking, miss, hesitation is just as annoying as ever... All advice appreciated!

 

For what its worth... My 1st to 2nd gear stumble feels a bit like missed shift in a manual transmission car. It will buck harshly 3 or 4 times then smooth out. If I left off the gas for about a half second slightly when I feel it starting to happen I can avoid the worst of it. My van has all wheel drive and a neighbor had a 2002 AWD GC with the exact same issue (for all 100K miles of ownership - never solved by dealer) so I've always thought it had to do with AWD. Really would like to solve as it affects driveability - and I have a new teen driver coming on soon.

 

Did you ever figure out the issue to correct the buck when going from first to second?

 

where have you seen a teen driver low throttle 1-2?
Most of these vans have a 'stumble' given the right conditions and it usually gets worse as the fluid wears. Things that seem to diminish this 'condition' are 1) consistent driving (helps the computer predict what's about to happen) and 2) good electrical connections (grounds and power) + good/stable power supply (no spikes/drops in voltage).

 

Following Up

Hey LEVELBEST, what did the issue turn out to be? I have the exact same issue with my 2003 Grand Caravan. Under light acceleration it does what I call a quick 1st-2nd-1st-2nd-1st-2nd and then off it goes. All in about 1 second. I'm thinking about replacing my transmission control module. Did they just reprogram the shift point?

 

I have had this problem since I bought my 2003 AWD Grand Caravan five years ago with only 38,000 miles on the vehicle. I replaced the input and output sensors three years ago, which did not solve the problem. I read this thread two days ago, replaced the throttle position sensor yesterday, and the problem is gone! What a simple fix - a 24 dollar part and less than a half hour to install it. Any backyard mechanic could do it.

 

I guess I never saw this Topic. Have contributed to other similar ones.



Our 2002 3.8L van has exhibited this 1>2 'buck' or stutter under light throttle for many years and 1000s of miles. It never happens with a cold engine or with increased throttle pressure.

Supposedly it is a result of engine control providing too lean of a mixture at light throttle.

It will become a non-issue once you develop the muscle memory to depress the accelerator a bit, just before the shift occurs. Not enough gas to increase acceleration, but just enough to inject more fuel.



Interesting sidebar: About 4 years ago, I had the wiper cowl off so I removed the spark plugs, cleaned and gapped them. The stutter went away for 2 months!

 

This is good to know but unfortunately for me I replaced the plugs, wires and coil pack but still have the issue. I changed the tps and did a transmission relearn this past weekend but still notice it regardless of a cold or hot engine.

After reading over several post here and on other forums people have had good success after changing the shift controller and input/output speed sensors. I plan to do that next along with changing the fluid/filter and doing another relearn. After doing that I’ll report back here with the results.

 

I had this issue with my 2004 GC SXT. I had the transmission fluid changed with new filter, no change.
After reading a post somewhere I did it again except this time I did it in my shop.
The transmission oil pan was sealed with liquid sealant (likely factory).
Filled the transmission up and checked the level while engine was idling.
The problem is gone.

 

I want to give an update on my situation. Last weekend I had my tps sensor replaced with a NGK/NTK model and had the throttle body cleaned up. The mechanic also reset the idle and then performed a transmission quick relearn with a programmer. After doing this the van drives and shifts like new. If anyone else is having the 1-2 shift issue I suggest doing this.

I had this issue with my 2004 GC SXT. I had the transmission fluid changed with new filter, no change.
After reading a post somewhere I did it again except this time I did it in my shop.
The transmission oil pan was sealed with liquid sealant (likely factory).
Filled the transmission up and checked the level while engine was idling.
The problem is gone.

From what I’ve read on here after changing the fluid and filter you should do a transmission relearn or a quick relearn with a scanner before driving very much. I’m glad to read changing fluid and filter fixed your issue though, that’s what I was going to try next if the tps sensor didn’t correct the issue.

 

How is a quick relearn preformed? What tool do I need? Thanks!

 

You will need a scan tool that has the function to do it. I think there’s a manual way too but it’s pretty involved if I remember correctly.

 

Just reposting same info with out the strike through. lObviously hit an extra keys somehow.
Fitler won't hurt, but remember 2 different operating conditions, the stumble is lower fuel flow, therefore can be injectors, fuel filter would mostly restrict at high flow rates therefore the engine needs to be say 4000 RPM + before that would show as a problem So don't expect filter to be a fix.
Spark can also show up under high load & low RPM and unless you can feel the difference between a fuel problem and an ignition problem, and (usually I find fuel to be not as sharp a discontinuity as spark but been fooled also and it was the other to fix it.) Ive had bad coils and sometimes the plug or spark plug wire So some additional thoughts for you if the current path doesn't fix it for you.

 

Sorry for last post, I see the TPS fixed problem, so great unless youve gotten a bad batch of fuel, or have really high mileage the fuel filter is probably ok. Just remember fuel filter issue should be constant, not intermittent, and worse under high fuel deliver rates operating conditions

 

My problem returned tonight unfortunately

The van was driven close to 200 miles and everything worked absolutely excellent. The first to second shift was as smooth as butter and around 1800-2000 rpm every time.

Today while on the highway a truck pulled out in front of us and my wife had to slam on the brakes, almost locking them up, and go to the side of the road. She didn’t come to a stop just slowed way down really fast and then continued on the highway.

After that during the next stop and acceleration the problem returned and has continued all day. The van now shifts from first to second at 1300-1500 rpm and bucks 1-3 times. Before the slowdown the van shifted correctly.

Why would a very abrupt slow down cause this problem to return and the shift to change to a lower rpm? The only thing I can think of is either the input or output speed sensor is going out and the quick relearn corrected it and after the hard slowdown it got out of wack again.