Limited throttle
 

Hi, I just bought 1991 750il in great condition but having trouble with throttle. after the car warms up , sometimes it does not accelerate over 2000 rpm. after i shut it off and restart it works fine for about 1 minute then does it again. check egnie lite is off and there is no malfunction codes in the computers. I noticed that when that happens the trip meter resets itself to zeros.
can anyone give me an idea waht could it be?

if i have a question, if you put it in neutral and rev the engine, will it go over 2000RPM? and generally, when the car is fine, does it have a lot of power or no? does it feel sluggish? and what do you mean it wont accelerate over 2000RPM.. does it accelrate but very very very slowly, does it cut off and feels really jerky?

has all the service been up to date? hows the engine oil looking? how many miles does the car have? I owned a e32 735il with a very leaky engine. I also have the bently manual if you want me to look something up.

My E36 had power loss and wasn't reaching any speeds very fast, felt like a turtle. Took the car in and the ASC throttle valve (choke) was seized, also it was throwing an O2 sensor #4 at the same time. They replaced both parts and she was alive once more. Not sure if that your problem but the situation sounded the same. Good luck!

Welcome to UB! :wave (unfortunately I can't offer much technical help on your issue, but I can welcome you, haha. there are plenty of people here who know much more than me and can point you in the right direction though. :thumbup)

oh yeah, welcome to ub :)

Hi and Welcome

You may be in "Limp Home" where only half of the engine is running.

Here is a good reference site for the E32-Bookmark it.

http://bmwe32.masscom.net/

The main links lead to other E32 DIY sites too.

When my car went into limp mode it wouldn't rev past 3k. It had sat for 3 weeks. However, when I turned the car off and turned it back on it reset itself.

That's interesting it resets trip meter...

when the car is fine it is very very powerful. it feels like the computer limits the acceleration. I noticed that the EML light doesnot come at all.

it sound like it

can you rev it past 2000RPM in neutral when it is doin it?

I agree w/Terry the 12 cyls tend to act that way when they go into "limp" mode. Basically shuts down 6 cyls and explains rev limits. Unless you have access to alot of test equipment I'ld have it to the "stealer" or a good reputable shop equipped to diagnose. You can throw mega-bucks replacing parts only to find it was a ground or contact problem. A simple check is test your battery voltage level when it goes into rev limit mode - a low battery, especially in a 12cyl can react like this (including resetting trip meter)

In limp mode the car runs on half cyllinders? I wasn't aware of that...