88 528e "seta" motronic 1.1 coolant sensor resistor ???

[royemello]

hello - anyone still out there ? i have a 88 seta 5/87 mfg. no matter how many ( aft mkt) ICValves - i put in - it has a hi idle of 1500 rpm.
heard - ( somewhere) bme had issue with some - so they installed a resistor inline on coolant sensor wore to help this. i did smoke test & every DME test in bentley, ALL OK.
i have 3 "good" DME's all do the same. ZERO VACUUM LEAKS not even at the elbows on throttle body. removed evap canister lines - even AC ( interior) temp sensor line) almost zero oil leaks - & yes even the dipstick o rings & oil return tube
ANYONE HAVE ANY HINTS ?
BMW says too old - so no help there.
i loosened the set pins - on a ICV & rotated it some to lower idle & it does - starts ok - & warm idle is - ok ( ish)
but i want to know why ???
ANYONE STILL OUT HERE ??
THX

[82eye]

the only fix is the drilled penny trick to lock the idle at a set rpm. there is no aftermarket iacv that works and bmw refuses to have bosch do a run. the only other thing you can do is keep cycling used / reman / aftermarket parts in the hope one works.

[royemello]

ok whats the penny trick ???

[82eye]

ok whats the penny trick ???

insert a penny into the iacv with a small hole drilled to allow a little air to pass. this locks the idle at a fixed point when the throttle body is closed. the size of the hole determines how much air gets past and effects idle speed. bigger hole = higher idle.

[NCHD2001]

I have the exact same issue in 84 528e. So frikin frustrating for the last 3 yrs. Not a daily driver, more of a keepsake. But I used a Nickle and it works. I still feel the fluctuation in idle, like 50 rpm fluctuation but at least it idles. I believe this issue has what has caused my Auto Tranny to go, reved too high, too many times while trying to correct.

[royemello]

what size hole did you use ?- or end up with ?. i also have a 4hp22 - its why i rotated the (china) iscv to lower idle. with AC on im about 900 rpm- ( should be about 800spec). so im close.
your 84 might have a vacuum leak - i used a hand pump & a cigar to make a some tester- laugh - but it works- look on you tube - several ways to make one.
your ICV might be dirty or the contacts on sm motor inside could be worn out ( i took one apart) there is 3 contacts to sm elec motor - the center one wears out. gets enough contact to test - but not enough to work correctly- ALL THE TIME.
also make sure temp sensors, idle switch ( under throttle body) & main relay ( contacts) are good. seal the leaks at elbows on TBody- ck o rings on dipstick - a good smoke test will show ALL.

[royemello]

i got things to work - ill fill all in when i get another ISCV to ( china) to tear apart - i think i know the issue