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Hmmm Trans Can't Make Up It's Mind



my 97 did that once.. then gears were gone... my 98 doing that after i changed fluid.. and tcc lockup came up... just a heads up of the possible..
 
DanPrixGTP said:
Trans filter was also changed, thankfully.

So your saying drop the pan, catch all the new fluid that was just put in, and re-use the fluid?

What will that do?

The shop also said bring the car back after a little bit and they will drop in some trans additive to help it out. I dont know what though
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i was referring to do that if the filter was not changed. no sense in wasting 30 bucks worth of fluid to change a 14 dollar filter, and the last thing you want is more NEW fluid.

id have it scanned even if the check engine lights not on. you never know what might come up. your trans shop should be able to do this for you.
 
DanPrixGTP said:
its an engine problem that the trans cant make it up its mind? plus no metal chunks in the pan so thats a good sign also.
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Well, think about it. The EMC uses engine data (throttle position, mass air flow and manifold air pressure among other things) to determine when to tell the tranny to shift. If it has bad data from a partially failing part, it could cause mis-shifting. Is the tranny just mis-shifting, or is it slipping? TCC could be the culprit if it were at highway speeds only and it was locking and unlocking, but TCC is not engaged in 2nd so it wouldn't affect a 2-3 shift. If the tranny is slipping it could indicate a drop in line pressure. Road test it in 2 then 3 instead of D and see what it does. The TCC lockup is disabled in those ranges (I believe, but will double check). If the problem is still there, that pretty much eliminates TCC. If the tranny is slipping, a proper road test may tell you where the problem is.

Besides, checking the MAP and TPS is free. Cleaning the MAF is like $8 for a can of cleaner. Would you rather take a chance of at least checking those things, or spend several hundred dollars and kick yourself in the rear if I turn out to be right?
 
Well i'm still kind of a noob so, isnt the MAP sensor somewhere behind the supercharger and what do I check on the MAP sensor. Also cleaning three MAF, does that require you to take off the throttle body? And lastly, what is the TPS, where is it located and what can I check from it?
 
Alright so not trying to thread jack here but how is changing the trans fluid bad? I thought that it is good to get all the old/used fluid out and put in new fluid?
 


DanPrixGTP said:
Well i'm still kind of a noob so, isnt the MAP sensor somewhere behind the supercharger and what do I check on the MAP sensor. Also cleaning three MAF, does that require you to take off the throttle body? And lastly, what is the TPS, where is it located and what can I check from it?
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I don't know the GP engines, so I'm unsure of the locations. You can check the MAP sensor (once you find it) with a volt meter. The MAP should have 3 terminals on it, (+5v) (PCM) (GND), the (PCM) terminal may be labeled something different, but it doesn't matter. Check for voltage between (GND and (PCM) with the key on, but engine not running. You should have somewhere near 5vdc. When the engine is running, the voltage should drop. Working the accelerator, you should see the voltage changing. If it is, your MAP is probably OK.

When cleaning the MAF, you should remove it from the car, but I don't think you have to remove the throttle body. It should be in the intake air duct. Be extremely careful not to touch the wires inside as they are very fragile. Simply spray the entire inside with MAF sensor cleaner and let it dry.

The TPS is the throttle position sensor. It will be located in the throttle body across from where your throttle cable connects. It has a 3 terminal connector as well. Without knowing your engine, I can't tell you which two to use. You would connect an ohm meter between the two terminals and move the throttle (with the engine off). You should see a steady change in resistance through the entire range of travel.
 
sorry if someone else said this, but my rule for a non-regularly maintained transmission is only replace fluid when you absolutly have to, like replace an axle and top with Sea-Foam im runniong a 3.4 setup on a stock tran with 200,000
 
fisher580 said:
sorry if someone else said this, but my rule for a non-regularly maintained transmission is only replace fluid when you absolutly have to, like replace an axle and top with Sea-Foam im runniong a 3.4 setup on a stock tran with 200,000
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Trans fluid has already been changed, so now we will just wait and see if i need a rebuild or not.

Keeping my fingers crossed.
 


I'm with poster number 2 and Monty. Although Monty kept saying MAP when he meant MAF.

If your transmission is hunting for gears and doesn't appear to be slipping, likely that is the PCM reading engine load, torque output etc etc as needing to downshift. When was your last tune up, what fuel are you using, heck..what the heck are you driving (I don't remember seeing it), when was the last TB cleaning and maf cleaning?

Trans flush does not hurt a transmission. It will cause more slippage if you already have worn out clutches etc. That's not a direct cause from fresh fluid though. It can also happen on a pan drop service.
 
Nope I meant MAP. Manifold Air Pressure is an input to the PCM as well. The PCM compares MAF, MAP and TPS data (along with other data of course) to determine shift timing. I don't know of any way to actually test the MAF sensor.
 
Unplug maf, make the pcm run off tables for the data instead of possibly skewed (actual data). I missed MAP, typically MAF has much more of a bearing on it. Thanks for the reminder (our current up to speed trans guy).
 
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