auto tranny: forceful downshifting, wont shift up

Car started acting up, seems to be more in stop and go traffic. When the car downshifts from second into first there's a noticeable lurch. Seems to be doing this fairly consistently.

Yesterday I was noticing the lurching downshift as I was driving downtown Toronto. When I went to pull away from a set of lights the car refused to shift out of first (5000 rpm doing 40kph sucks) I went through two lights like this and pulled over. Disconnected the battery to reset the computer and tried again, and it was shifting fine.

So I'm torn, is a Tranny issue or is it more likely to be my ECM? Or the Tranny computer perhaps?

Have you flushed the tranny fluid?

I have not. I checked the fluid levels (of course) to make sure I wasn't low or anything, and they're at acceptable levels. I did already have to replace the ECM in the car when I bought it, I'm thinking perhaps the tranny computer (TCM?) is the issue.

Fluid looks clean otherwise?

Doesn't seem to be any oil/dirt in the tranny fluid. looks fairly clean.

I'm fresh out of ideas lol

How many kms on the car ?

212,000

When checking the tranny fluid, you have the car running and in Neutral right?

Check and make sure your TPS is adjusted correctly and all connectors under the hood are tight. Does it do this when cold and warm? How is your idle otherwise?

When was the last time your tranny fluid filter was changed? Just because you have lots of fluid doesn't mean that the filter isn't clogged. This will cause issues as well.

First step is to pull codes from the TCU. Go to http://www.plymouthlaser.com/tcucodes.htm if you haven't already. Then let us know what you got and maybe we can help interpret the readings.

I had to drive it home today from my girlfriends place, it was only temporarily parked there overnight. It made the ride home without issue, but I was a little less aggressive and keeping an eye on the tachometer. Some of the downshifts into first had a bit of the lurching action but I was slowing down in a slower fashion, giving the transmission more time to downshift, it wasn't as bad as yesterday. It shifted up through the gears without issue.

Can I still run the codes from the TCU? or will the short term memory of yesterdays issue be erased by my drive home today?

Codes will stay there until you disconnect the battery.

So I can't go about doing this until the issue re-occurs it seems like.

I'm considering changing the trans filter, cleaning the magnet and changing the trans fluid as a starting point. Then examining the TCU/M and sensors. Does this seem like the logical course of action to others?

Yes, I would start there. Fluid has everything to do with the Auto Trannies and is the most critical part of the whole thing.

I use Mobil 1 ATF +4 and get an OEM Tranny Filter.

Perhaps for the issue of not shifting out of 1st, but there could be codes for the lurching action which you said was happening on the way back from your girl friend's.

If the no shift issue does happen again you do not need to disconnect the battery to cancel limp mode. You just need to turn the key to the off position. For an intermittent problem you could be able to drive away just fine and the code will still be stored in the TCU.

If resetting the ECM/TCU solved the issue the first time does the negate the idea that trans fluid could be to blame?

It's your tps. RTM sells non oem ones at a fraction of oem cost. Changing your tranny fluid is never a bad idea but don't delude yourself into thinking that your problem is going to go away with that alone.

What makes you think it's the TPS over the tranny computer Paul?

The TPS is a major player in shift points and up/down shift pressures/applications in the Auto tranny. The TPS is sending a faulty signal to the TCU causing your shift points to be all messed up.

I agree with Paul as I've had this issue before.

A Filter/Flush wouldn't hurt either if you've never done it.

I haven't yet changed the timing belt, oil, oil filter, trans fluid, trans filter...yadda yadda yadda. It's my intention to do all of these things, I suppose I'll add the tps to the list. I've got all kinds of little things that need doing, but I've only had the car roughly a month and have yet to do any of these things. Time to get on it while I still have some sunshine this week I guess.

Here's a thought. A problem I see all the time in fwd Chrysler transmissions, causes erratic and violent shifts. The TV actuator (or Kickdown cable, as its known to the older boys) often ceases up. Since the Throttle Valve controls the line pressure, all kinds of harsh/prolonged shifting problems come to light. All you have to do to fix it is free up this linkage. In order to find this linkage of which I speak of, look at your throttle body. There should be a cable that goes to the accelerator pedal, and then a second cable that goes down to the transmission. Follow the second cable down, you will see it end at a perch that is combined with your gear selector. You should be able to move this perch freely with your hand, if not, there's your problem.

As I said, this is common with Chrysler products, I dont know whether your driving a TSi or an ESi but it's worth checking out, and the check is relatively simple to preform. Good luck.

I'm driving the ESi, but I'll certainly take a look Eric, thanks for the tip!

On all DSM cars, the only auto cable going to the transmission is the shift cable. Everything else is done electronically.

Well, I'd cleaned the contacts on the TPS, done a couples days driving without issue. I was going to post a wanted ad for one before resorting to RTM, but hadn't gotten around to it.

Sadly, disaster today.

It surprised me by suddenly downshifting when I was at speed in 4th or 5th. It's never done this before, only had issues shifting out of first.

Car downshifted, RPMS went through the roof, had to shut the car off and hit the flashers. Just paid of the tow driver who brought me back.

Second tow inside of a month... pretty disheartened

Well at least you should be able to pull codes from the TCU now.

I'm not sure if you are implying you suffered engine problems but if the car just went into limp mode then you don't really need to get a tow. One of the reasons the tranny goes into limp mode is so that you don't damage anything if you continue driving, ie, to "limp" home. Usually the only thing you hurt by driving in limp mode is your gas mileage.

It was acting up a bit previous today. I'd actually forgotten in light of what happened. In stop and go traffic (headed east on Queen st.) when pulling away from the lights it would not shift out of first. I tried killing the engine at a few red lights to enter limp mode and hopefully "reset" the issue. But it did nothing of the sort. Eventually after...six lights? (was in heavy traffic and didn't have to go faster than 40K, didn't go over 3.5k rpm) it shifted smoothly into second and third and so on. I got to where I was going and let it sit for a couple hours.

I was worried it might act up on the way home from downtown, but once I got onto the DVP I assumed that it would remain in gear because it's never had issues doing that before. The rest you guys know.

I'm thinking now, I didn't have these issues before I installed my Short Ram Intake. Could I have somehow effected the throttle body? Could the intake itself be effecting things?

I don't believe I damaged the engine, I was concerned that if the transmission downshifted yet ANOTHER gear, that the RPMS would redline and damage the engine. The needle was all over the tachometer, and the engine went from normal to working VERY hard in a flash. I got spooked and killed the engine. That's where it stands

Upon doing some more reading about "limp" mode, I think I have a better understanding of what was happening. It's not that my car is shifting up or down, it's that a sporadic signal from my TPS or other component is throwing the car into a single gear mode (2nd or 3rd) and setting my tranny fluid line pressure to high-pressure mode. Causing the high rev and the lack of shiftability. This is so I can "limp" home and get it sorted out.

So this is happening both at low and high speed with my car, it's not that it wont up shift, or suddenly down shifts, it's that it's jumping into Limp and the tranny will only access a single gear.

I'll order that TPS today, put my MAF back on and see if the issues dissipate. Fingers crossed.

On that note I'm also considering selling the car. The more I look into DSM vehicles the more I'm sad I'm in an ESI. The fun lies in the AWD, the turbo, and most basic of all a manual transmission. If I can repair it, I still have a vehicle that's safety is good for another week or two, and with a valid E-test. So I might make a few bucks and start TSI shopping.

*digs up thread*

Sorry, school had my number there for a little while. Stock intake has been re-installed and the TPS ordered.