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Idle man idle just idle man

2K views 20 replies 4 participants last post by  woodenbmw 
#1 ·
So i had an L shaped idle motor (wrong one for my car) it had a jumpy idle from the day i got it and if in park or neutral my car would I would 2000 rpm I bought a new motor and put it on in now when I start my car off it immediately goes puuuut and dies the only way i can seem to get it to idle is to adjust the screw on the monifold (a no no i am aware of ) otherwise it just kills over i am going to put the old one on because it ag least ran but do you have any ideas? And where is my tps


Wicked Fast Entertainment
 
#5 ·
Is that out of a bently manual? And why would my new idle motor not open? And if erratic idle is a syptom i may have a problem. When i stop the rpms wil jump from 750 to 1000 for a few and if i am at a long light it will eventually drop to 500 to 750 and so on until it is barely staying running it has only died from this once

Wicked Fast Entertainment
 
#6 ·
At 500 rpm it should idle smoothly even if that is a little low. Yes, those are pages from the E30 Bentley Manual. You REALLY need to get one. Erratic idle is almost always vacuum- leak related.
 
#7 · (Edited)
TPS with built in Potentiometer

While we're at the TPS :)
Is there a TPS that will fit in the place of this E30 B20 unit that measures actual throttle position ? Like all civilised vehicles :tsk:

Oh yes, to get back to your problem. If the TPS does not see a closed throttle it cannot tell the idle motor to adjust the idle ;)
 
#10 · (Edited)
Correct. Continuity means zero resistance. 0 ohms. It's really two switches in one housing. It tells the ECU it's either a closed throttle with one switch, or a wide open throttle with the other. In between (throttle part-way open) it should have infinite resistance between the center contact and either of the outside ones. When the throttle is closed, the idle side turns on the idle control valve (through the ECU). If the TPS is bad or adjusted incorrectly, the ICV can't regulate the idle.
 
#12 ·
That is completely backwards from what it's supposed to be. You should have continuity (zero ohms resistance) between pins 2 and 18 with the throttle closed, and continuity between 3 and 18 with it wide open, and that's all.
 
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