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Discussion Starter #1
I have a 2007 Chrysler Voyager (European model) with a 2.8 liter CRD diesel engine and the 4-speed automatic transmission. 135k miles. 70k miles driven since transmission rebuild and 20k since last fluid change. No fault codes in the computer. In the two months that I've owned it it has developed a somewhat regular jerking symptom at speed. It's very close to what a misfire in a gasoline car would feel. Holding a steady throttle with the converter locked the jerking is felt at a regular rate of about once a second. Sometimes two jerks in a row. During the jerks there is no change in the engine sound and the tachometer needle holds steady. When I accelerate just enough not to unlock the converter it jerks a lot less. If I press hard enough on the accelerator so that the converter unlocks the jerking is gone. Same thing if I let off the gas it feels smooth.
A transmission repair specialist test drove it and said he doesn't think it's transmission related, but I once drove a Mercedes with a jerk under acceleration which was cured with a fluid change.
I'm suspecting it could have something to do with the EGR system, and I may have to head for the Jeep forums for diesel knowledge, but first I want to rule out the transmission as the cause.
Any insights to this problem are appreciated.
 

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Codes, pending or otherwise? Chryslerforum. com centers on Euro Chrysler minivans. Might try there.
 

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Have no knowledge of diesels, but the trans should have CVI values stored (clutch volume indexes) - if the TCC is just starting to fail you could conceivably experience what you're describing...

Do you know what fluid was poured into the trans at last change?
 

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@Baron: It's not really a vibration. It's more intermittent although it occurs continuosly. Just a light shake that doesn't last longer than driving over a bump.
But for your question, do you mean pressing the brakes while holding the throttle?

@RIP: Generic bluetooth reader doesn't find any codes. Thanks for the website tip.

@atoman: How can I find out the CVI values? The garage's receipt says ATF+4.

Oh, one detail I forgot to mention is there are a lot of air bubbles on the trans dipstick after driving. That's what to led me to suspect transmission trouble in the first place.
I can't tell if the whole fluid is foamed up or if there are just some bubbles on the top because they disappear very quickly after stopping.
If there's a lot of air mixed with the fluid it might cause loss of hydraulic pressure for the clutches. No idea what's causing the bubbles.
As a first aid I added a bottle of Lubegard Platinum today. It's supposed to prevent foaming among other things. I'm still going to change the fluid at the earliest opportunity.
I hope it's not the transmission because having rebuilt one transmission (CD4E) on my Ford Mondeo (=Contour) I really don't feel like going through all that again.
 

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mine has bubbles too sometimes, it shouldn't be too much to worry about

what you're describing sounds a lot like torque converter shutter

it happens sometimes on the A604 transmissions, i believe the 2.8 uses a different transmission

press the brakes while at that speed just enough to engage them and the torque converter should instantly unlock, you can be on the throttle if you'd like during the process

if the shaking stops, the torque converter is very likely the trouble
 

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On our petrol vans, CVI values can be accessed via DRB-III scan tool (or equivalent). They won't mean anything if fluid is aerated...

Have you checked the fluid level after driving - while the trans is hot?
Aerated fluid could be the cause of TC clutch slip...
As ATF+4 expands with temp, it could be becoming overfilled - check it when it's hot and adjust accordingly (the garage filled it cold and may have checked level on warm trans, probably never got it fully hot)
There should be a temp / trans dipstick level pic for the trans under "quick fixes" thread.
 

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It sounds like you are on the right track by examining the torque converter and transmission fluid, etc.

Some thoughts regarding determining engine versus transmission related based upon the engine RPMs:
  • My 2001 Jeep Grand Cherokee 4.0L will log a P0740 for a Torque Converter Clutch issue (Torque Converter Clutch lockup, No RPM Drop at Lockup) and my 05 DGCV should also (I have not had the issue w/ the 05 DGCV)
  • I'd recommend that you utilize a scan tool with live data capture capabilities to verify that your engine's RPM is indeed consistent w/ the readings from the throttle position and torque converter lockup throughout the jerking
    • With my Bluedriver scan tool, the minimal set of live data logging data sources setup would consist of the following data sources:
      1. Engine RPM
      2. Vehicle speed
      3. Throttle position sensor
  • Here is a sample excerpt of data captured from my Bluedriver's export to a CSV file for a normal drive in a 2001 Jeep Grand Cherokee 4.0L:
    • First 2 data rows are at 0 mph/idle; next 15 rows are while excelerating 9 -20 mph; transmission shift at row 20 (lower RPM)
    • I am including just enough data so that you have an idea of the data content/format
    • BDDataLog 2001 Jeep 91319 1227 PM.Excerpt.IncreasingSpeed.jpg
  • Road test, capture, analyze:
    • Drive the vehicle to a testing location where you know the issue is reproducible
    • Ideally you do NOT want your location to be a factor in terms of varying the engine RPMs or vehicle speed due to hills, pedal position, etc, but as long as the test's variables are consistent you will be able to analyze and compare the results
    • Start the data logging capture
    • Review the captured data and make a diagnosis of engine versus transmission related
    • Repeat the 'road test & capture' step multiple times in order to help you verify that your diagnosis is accurate
  • Analysis:
    • My version of the Bluedriver app supports the capture, save and share of the report in a CSV format, in my case via an email
    • Download the file, open a spreadsheet application and review the data
 

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Question. When this jerk/shutter started, by chance did you install in the vehicle an aftermarket power inverter? On my 2005, I had installed a 400W power inverter. When I got the van up to 40mph/65kph, the jerk/shutter would happen in a perfect rhythm and like you had stated, sometimes 2X. I too thought it was the TCC or a solenoid. In that week of time, I had to disconnect power to the inverter for some odd reason. Drove for a few days and realized the problem was gone.

Some time ago, I did read in the forums of wire harness chaffing to the transmission that produces the same troubles. Your mechanic could be correct. Before dropping much money into this, please examine each and every electrical item to the transmission.
 

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@Baron: It's not really a vibration. It's more intermittent although it occurs continuosly. Just a light shake that doesn't last longer than driving over a bump.
But for your question, do you mean pressing the brakes while holding the throttle?

@RIP: Generic bluetooth reader doesn't find any codes. Thanks for the website tip.

@atoman: How can I find out the CVI values? The garage's receipt says ATF+4.

Oh, one detail I forgot to mention is there are a lot of air bubbles on the trans dipstick after driving. That's what to led me to suspect transmission trouble in the first place.
I can't tell if the whole fluid is foamed up or if there are just some bubbles on the top because they disappear very quickly after stopping.
If there's a lot of air mixed with the fluid it might cause loss of hydraulic pressure for the clutches. No idea what's causing the bubbles.
As a first aid I added a bottle of Lubegard Platinum today. It's supposed to prevent foaming among other things. I'm still going to change the fluid at the earliest opportunity.
I hope it's not the transmission because having rebuilt one transmission (CD4E) on my Ford Mondeo (=Contour) I really don't feel like going through all that again.
The Lubegard was a good addition. A good product.
 

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Discussion Starter #12
Took me some time to follow all the good advice given here. Thanks. The van drives a lot smoother now. In fact I couldn't reproduce the problem at all on a 30-minute test drive.
I'm not sure why it got better though. There are too many variables. Besides adding the Lubegard I also wiggled the wire harnesses at the connectors in case of corrosion and the outside temperature had dropped by 10 degrees since my last drive. If it's an EGR fault the ambient temperature might play a part in its operation.

It's not foaming so much anymore either..

56530


Live data capture shows slight fluctuation in engine speed. I could not read transmission input shaft speed to see if it varied accordingly. The fuel pressure is quite constant.

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56531


The transmission fluid and filter still need changing. Is it ok to suck it through the dipstick tube before removing the pan? How much of it can be removed this way?
 

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In would think that the Lubegard probably helped. I've used their products for quite some time now and they work as advertised. Good company, right across the lake from me. I have sucked the fluid out through the trans dipstick but I had replaced the filter at the service prior ( I cleaned out the pan, cleaned off the magnet and put in a new good quality filter) so I felt it was probably OK. If you haven't ever done the filter, now is the time and then at the next service do the dipstick removal deal if you want.
 

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I've not used lubegard on the Caravan 4th gen. ATF+4 should already cover that. Now, I've used it in the 2nd gen and a full RAM 5.2L magnum truck that did a bunch of towing. It's good stuff for that.

Chances are, the lubegard fix the foaming issues. Did you remove trans fluid first and then added the lubegard to replace it? That typically what I've done in the past.
 

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Yes, I took out the a bit of fluid so that when the Lubegard was added it was not over full. I had overfilled my 3rd Gen one time and on a long pull it would kick fluid out of the top of dipstick tube. I first used Lubegard on a Ford Probe that was having hard shift issues and it cured that right up. I was also having foaming issues in the power steering and their additive fixed that. It's good stuff.
 

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the outside temperature had dropped by 10 degrees since my last drive.
It could simply be that lower temps are resulting in lower trans temp - less fluid expansion thus avoiding the overfill condition... If the problem reappears when temps rise, check that fluid level when hot (you won't see how high it gets now)
 

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Discussion Starter #17
The problem has returned if it ever really went away. I'm starting to think the transmission is not the cause. Even when I take my foot of the gas pedal the twitching is still sometimes there for as long as the converter clutch is engaged. When the torque converter is unlocked any rough running of the engine would be smoothed out by the converter.
I have driven a lot of cars with a manual transmission and a misfire in one feels about the same. That leads me to believe there's something wrong with the engine.
I can't test the tc clutch release by applying the brakes while holding the throttle because the engine cuts off the power as soon as I touch the brakes.
The fluid level is pretty close to the cold mark before driving and a bit over the hot mark afterwards. In the picture I posted I had shut off the engine before removing the dipstick to get a better view of the bubbles.
The fluid change is still on my to do list because I haven't been able to source a good quality filter. Any recommended brands?
If it was the torque converter or the transmission at fault how would it perform under heavy acceleration? The van goes very well when I floor it. It shifts very predictably and the power delivery is smooth. Only at light throttle it does that jerking and twitching. It's not a very strong effect, though. Just enough to make someone who likes to keep his gear in 100% running order concerned.
 

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OP, you've got to monitor fuel pressure when the van is jerking. Also, the pressure readings you posted don't make sense, as fuel pressure should be 50 to 60 psi. When I convert the kpa to psi, it don't make sense.
 

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If the problem only appears when trans is hot, siphon out a pint of fluid and see if the aeration is eliminated... (the fluid level should stay at or below the full mark)

As for filter, I'd try to source an OE Mopar - it's not a part you'll change often so the price difference is not significant.
 

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If the problem only appears when trans is hot, siphon out a pint of fluid and see if the aeration is eliminated... (the fluid level should stay at or below the full mark)

As for filter, I'd try to source an OE Mopar - it's not a part you'll change often so the price difference is not significant.
I don't believe overfilling will cause any problems, not at all (other than fire hazard).

Aeration doesn't happen in transmissions (doesn't matter what you heard). Not for over filling, that is.
 
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