Weird Trans Problem

[Phatty5BMW]

Whats up guys, new to the posting part of the forums, I have been helped on these forums many times before with my e28 and i love how nice you people are. Anyways I just bought me a 89 535i for 2500 bucks with 168k on her. Its an automatic, the guy i got it from says theres a new transmission in it, it visually looks new. I noticed today, I was on the interstate going about 80mph, i flipped it to sport mode and mashed on the gas, at about 4900 rpms it feels like the tranny slips, it jumps down about 200 rpms, then just keeps pulling from there, its never done it before in any gear when going slow, i dont know if it is a problem or its normal.(doesnt seem normal)
What do you guys think? Has anyone experienced this?



83 528e 178k
89 535i 168k

[Kalevera]

Nope, but the first thing I'd do is change the fluid and filter :). How old's the "new transmission"? If it's been 15k miles since the last change (do you have the service records?), definitely. Get some Redline, or - Jeff's favorite - Royal Purple. Could also be a software or sensor switch. Talk to Javier about that - he knows a lot about the 4hp-22's electrics....and e34 electrics, in general.

Good luck!

Best, whit

[Phatty5BMW]

Well from what I was told is the transmission had 2k miles on it, I am not for sure. I asked for service records and he did not have any. He assured me it was new, i was also told that the people who owned it before him (he only had the car a year and never really drove it) the guys wife worked for bmw so got all the oem parts for price and he worked at a benz dealer that did all of the work. I was also thinking maybe the engine needs a tune-up. I havent had the chance to replace the ignition parts, but why when the rpm's are climbing it drops down 200 rpm, then just keeps going.

[Javier]

moment you switch E to S program at 80 mph (never tried myself). Since you are changing shifting schedule, the trany control may want to down shift, and at that speed, not sure it will succeed or not, even more if you are also reving up the engine. Does it happen frequently? Every time you switch program, no mater the speed?

If once in S the shifting work fine I wouldn't mind.

I'm not a trany expert, though, hope some experienced guy like Winfred or Bill may post his opinion.

Javier

[Phatty5BMW]

I put it in S program about 15 seconds before I hit the petal, to let it downshift, because when i have it in E my trans shifts at 5500 everytime and 8 outta 10 times it doesnt downshift to the lowest gear, but then again it is in E and im not exactly sure on where shift points are. I know on my moms 735i even in E it hits the 5900 mark. I noticed today frustrated with it, i took it out hit 110 mph 4 different times and it never did the "slip", so i think it could be a sensor or module or something. Maybe I need to change out my plugs/wires do some tune-up. I just raced my moms 735i and we were dead equal until about 90mph we had to slow down. Shouldnt the 535i be faster?