How to test Cold Start Relay

[Lemon98]

I have a 1990 year 320i which always runs rich even when up to temperature. I tested the ECU reading from the blue temp sensor yesterday and got 3,350 cold and 260 hot so I have ruled this out as being the cause.

I read on the wiki that the cold start relay could cause rich running, how would I test if the relay is working properly?

[tha881]

Not all cars came with the cold start relay, apparently it was an afterthought from BMW when rectifying an issue on some cars. Are you sure that your car has one fitted?

Have you been over the intake and checked for air leaks? Are you having any issues related to the rich running ie idle issues?

[Lemon98]

Not all cars came with the cold start relay, apparently it was an afterthought from BMW when rectifying an issue on some cars. Are you sure that your car has one fitted?

Have you been over the intake and checked for air leaks? Are you having any issues related to the rich running ie idle issues?

Yeah I'm pretty sure I do, I have 3 relays covered by black plastic further down the engine bay from the standard fuse box.

The intake boot has a leak but I thought the unregulated air would make it run lean if anything.

After revving the engine, as the revs drop it sounds like they fall below the idle amount and then recover back up. It does this worse when cold but not at all really when up to temp.
Sitting in the car and when I was revving it slowly like that yesterday sometimes it feels like it's misfiring at idle or isn't as smooth as it should be if that makes sense? It still has the catalytic converter and stock exhaust so I can't hear anything untoward from the exhaust, it does have a mild chip in it though.

You can hear it here:

[Lemon98]

Okay did a quick look at the 3 relays I'm talking about are the same as those at the bottom of this page https://www.e30zone.net/e30wiki/index.php/Relays but are different colours.

White on the left and then brown for the other two.

[tha881]

I would be buying a throttle body gasket, rocker cover to TB breather tube and a rubber bung for under throttle body if it has one.

Check tps operation, listen for the click and do a continuity test.

I think the majority of idle issues can be from over tightening of the four nuts on the throttle body gasket. The gasket is thin so smear some silicone grease on both sides and re-tighten, but only so it wont come loose. See if that helps.

[Lemon98]

I would be buying a throttle body gasket, rocker cover to TB breather tube and a rubber bung for under throttle body if it has one.

Check tps operation, listen for the click and do a continuity test.

I think the majority of idle issues can be from over tightening of the four nuts on the throttle body gasket. The gasket is thin so smear some silicone grease on both sides and re-tighten, but only so it wont come loose. See if that helps.

Okay thank you, I'll get these parts soon.

I'm guessing there's a wiki for how to test the continuity of the TPS? I have checked with the engine off and it does click as soon as the throttle is moved but I'll happily check the continuity as well.

[tha881]

Dont forget the intake boot, eliminating all the air leaks will definitely help reduce the stalling on idle. The continuity test info is in the wiki, if you have any trouble report back as I remember the info given on the pins was a little inaccurate.

[BenHar]

https://www.e30zone.net/e30wiki/index.p ... oubleshoot

Ben

[BristolE30]

Yea this sounds like lean conditions and is exactly what I’ve been chasing for the past 6 months. Good luck

[Lemon98]

Dont forget the intake boot, eliminating all the air leaks will definitely help reduce the stalling on idle. The continuity test info is in the wiki, if you have any trouble report back as I remember the info given on the pins was a little inaccurate.

It never fully stalls on me, just that little bog.

[Lemon98]

Yea this sounds like lean conditions and is exactly what I’ve been chasing for the past 6 months. Good luck

Hahaha sounds like a world of fun can't wait to get into it