Surging Problem -> Trans Program

[ChrisC]

Ok...I have been looking around the web a lot and found a good bit of info on the Trans Prog error (for example BMWE34.net), but I still need some help. I have a 1995 BMW 525i with 150k on it.

Here's the symptoms and some history:

- about 50% of the time, when cruising up a long hill on a parkway at around 60mph, the engine would some time surge as I stepped on the gas a bit further to maintain speed. Let up on the gas, apply the gas again and all was fine, the car shifted and went along fine.

- recently, while going up these hills (again, not all of the time), the Trans Program comes up on the screen and into limp mode we go.

- Now, I know this is the GM transmission with this car and my mechanic/transmission guy/family friend said he thought it may be the solenoids. We replaced those, but it is still happening (he didn't guarantee anything). All wire connections, relays, etc he said look fine (the car is garage kept). Some build up on a couple connections that he said was normal, and he cleaned them. Battery and power seem ok to.

- We are still having the problem, the car goes into limp mode when going up those hills on the highway at 60mph. Turn it off, wait a minute, computer clears (no codes to be read) and the car is fine. Shifts great, etc. Cruise control is working also.


BTW, we can go a week driving the car (my mechanic has too) and its fine, running really well, in fact. Shifts great, etc. But, I do want address the problem.

What to attack?? Trans Speed sensor? Throttle position sensor?? Gear selector??
Any ideas on prices of those jobs?

I do not know a lot about cars, so please be patient. Any advice would be appreciated.

Thanks,
Chris

[joshua43214]

The best thing to do is to wait until next time it acts up, then run it over to your mechanic friend and have him read the codes out. Don't shut off the car until the codes are read out.

Anything else is geusse work. If your friend doesnt have a scanner that can read the codes, take it to the dealer and drop the 90 bucks on it there. it could be something really simple or something really expensive, paying for a code read is worth every penny.

[ChrisC]

He was able to get one message off of it that the gears slipped. But he thinks it may be a faulty code. Either way he could only get that code once.

[joshua43214]

if the trans program light is on, there should be a code. If he can't read it, you may have to head to the dealer and have them hook up their tool, it can see things the aftermarket tools can't.

Either way, it does sound like a slipping trans, so I would not disregard the code unless it was set doing donuts and the like.

search for kurt koehler on this site, he is the resident trans guru, he may have a quick answer.

[Jazzman]

I had the same problem a few weeks ago. Had the transmission rebuilt by a former BMW tech that put up his own shop. After the rebuild it was still doing the trans program. To make the story short, he replaced the throttle position sensor, the coolant temp sensor and the crankshaft position sensor. Now the car is running like new, very imperceptible shifts and very smooth idle.......steady at 900 RPM. If I were you I will replace the throttle position sensor first and then go from there.
If you have been driving the car in limp mode for a long while you may have already burned up the clutch packs. If not I will flush out the trans fluid, replace the filter and put fresh fluids.