Throttle body replacement?

Hi everyone! I'm relatively new to bimmerfest forums (even though I have gone on it quite a bit) and more native to bimmerforums, but figured I would post in both to have two different crowds for some input. Now that I finally made an account, I will probably be around here more as well

But anyways back to the issue at hand....

This has been an on going issue for about a year and a half, but is getting progressively worse. What happens is, when I start the car, occasionally I will get wild rpm jumping from about 500 to 1200. If I leave it on long enough, the engine failsafe program will kick in and cut the fuel. This has gone from happening from intervals of months to a few days in between. I usually reset the throttle as a local bmw indy has suggested and all is fine (sometimes, but not always).

Also, sometime it will happen when driving and give the engine failsafe message while cutting the fuel off without warning. In this case I coast to the nearest shoulder and try to pull the car over (hard to without power steering).

Most recently when my baby has given me all this drama, she didn't want to reset and wasn't acting right at all. At the first attempts, it seemed to act like normal, but then 100 ft down the road it would cut the fuel off. Then when I was finally able to drive it, she idled at 1500rpms, was gulping gas, and wasn't responding correctly to the throttle. With all this previous drama in the last paragraph, it finally gave me a CEL and some codes to read. Came up with

p1634: throttle valve adaption spring test failed
p1637: throttle valve position control, control deviation

Sounds like a bad throttle body, am I right? I have drive by wire which I forgot to mention. Since the last episode, I have stored the car in the garage away from the elements and it probably won't leave until I fix this issue at hand.

Something else I have forgotten to mention is that last night when I tried to start it, it would ignite like normal but then the rpms would drop right away and the engine would die. I did this about five times with the same results. I then tried to get it to at least idle correctly by feathering the throttle after initial ignition. It was able to idle at 500rpms like normal, but if i hit the pedal to rev it a lil, the rpms would drop a bit too low and almost stall. It still was able to correct itself though. I would imagine that since the car was running, its functions were all working giving it the ability to correct itself instead of the short burst at the previous start ups.

Last put not least, I started her up this morning and she started, idled, and revved like normal........This was after I cleared the codes, but idk if that has any effect though.

Even though it starts and runs like normal, I am absolutely SICK of the feeling of driving somewhere and not knowing if I will make it home without trouble. It frustrated the hell out of me

I know this was an extremely long post, but I tried to put any helpful information that will help the issue at hands. I would really appreciate any input.

Andrew

P.S....tomorrow I am going to see if coolant is being siphoned up the wire going to the DME connector as a forum member has suggested. Heard its not too uncommon and can cause some issues.

EDIT: Hope everyone had a great christmas!

Sounds like a throttle body intermittent failure. Requires replacement; cannot be repaired.

Originally Posted by edjack

Sounds like a throttle body intermittent failure. Requires replacement; cannot be repaired.

So it sounds like I should pull the trigger on buying a new throttle body

The tb has plastic gears that wear out.

Originally Posted by Topaz540i

The tb has plastic gears that wear out.

So this isn't as uncommon as I thought it was. But if the plastic gears were worn out, wouldn't it be failing every time and not intermittently? or is it able to catch the gears just sometimes and not others?

its not really a matter or the teeth braking off. Its more like the teeth wear down and the gears get sloppy. Notice if you mess with the tb plate it has a little looseness to it. You can probably jiggle it open and closed just a lil. Its the worn teeth. The slack prob made the plate angle just out of tolerance.

Originally Posted by Topaz540i

its not really a matter or the teeth braking off. Its more like the teeth wear down and the gears get sloppy. Notice if you mess with the tb plate it has a little looseness to it. You can probably jiggle it open and closed just a lil. Its the worn teeth. The slack prob made the plate angle just out of tolerance.

Ohh okay thanks. I definitely understand it now. Ordered a new tb today

Report back in this thread if it improved idle or throttle jerkiness.

Originally Posted by Topaz540i

Report back in this thread if it improved idle or throttle jerkiness.

will do

Just received the parts. Any hints on installing the m60 manifold and new throttle body without any vacuum leaks?

Did it work ??

Sorry I forgot to update this page, but yes the new throttle body solved the problem! works like a charm