Pre facelift 320i high idle

[beemerpete88]

Some help please!

Pre facelift m20b20. Completely standard. Was running fine last week.

Turned it on today and have high idle - sits at 1500rpm - makes no difference when hot or cold. Blipping the throttle brings it down momentarily.

After much research I’ve taken the throttle position sensor off and measured for voltage at the harness itself (Bentley says 5v with centre pin and either side pin). I’ve got no voltage with any combinations so suspect this is my issue.

I’ve taken the ecu plug off and there’s nothing immediately obvious but the Bentley manual doesn’t seem to reflect my ecu pin outs(which is a standard ecu) I’ve got L-jetronic.

Car was perfect last week - has the ecu failed? I’ve got no other wiring issues tracing the tps wiring back to the ecu module.

Any further suggestions? I take it I am meant to have 5v at the harness and this is why I’ve got high idle as the TPS isn’t even receiving a signal?

Help, please!

[Speedtouch]

Quite a common cause of this with the L-Jetronic setup on these is the water heated Air Slide Valve seizing up:
https://www.e30zone.net/e30wiki/index.p ... lide_Valve

[beemerpete88]

Thanks - I’m absolutely going to check that but really need to know whether I should be getting 5v as standard to the harness as if it is the case, I need to fix that too!

[Speedtouch]

Not sure, but I would check the air slide valve first, since this is the most common cause of the problem.

[beemerpete88]

Thank you. Will do!

[BenHar]

Also check for intake air leaks.

Ben

[beemerpete88]

Air slide valve checked
Smoke test complete
TPS itself operating as it should
Performed a continuity test from the harness 3 pins through to main ecu connector in the car

I still don’t appear to have 5v through to the harness?!?! The ecu isn’t giving 5v through to the tps harness.

Any other suggestions please?

[Speedtouch]

Check the engine bay connectors:
https://www.e30zone.net/e30wiki/index.php?title=C101

Also, idle control valve (ICV) and 7th injector, and temperature time switch, if your car has one:
https://www.e30zone.net/e30wiki/index.p ... Idle_Valve

[beemerpete88]

I don’t have an icv. 7th injector and temperature time switch appear to be operating as they should.

Can’t see anything wrong with the engine bay connectors either…

Going to put it all back together at the weekend and see if it’s any different.

[Speedtouch]

Maybe give it an Italian tune-up, i.e., a damned good thrashing!

[beemerpete88]

Update - still not fixed..

Can anyone tell me a bit more about this part please? Basically when I refitted my throttle assembly the rod on this item was sticking out quite far meaning that it was already pushing against the accelerator (meaning it was revving high).

Is there a way to test if this has failed as it won’t push in far enough to refit - there also doesn’t seem to be any information anywhere about it..