1988 325i misfire

[Sambino]

Evening all

I'm experiencing a slight misfire when car is cold from start- the car holds back a bit then when warm drives fine - but it cut out today as I was turning!

Lucky I was somewhere safe. Any thoughts on the cause? Many thanks

[Speedtouch]

Check the notorious blue temperature sensor is working as it should:

http://www.e30zone.net/e30zonewiki/index.php/Blue_Plug

[Sambino]

It's brand new? Since owning the car 3 years back I changed it along with the brown one. Not done more than 2.5k miles on it - if that

[Speedtouch]

Worth checking the resistance at the ECU socket anyway - even new sensors can go faulty, along with the wiring and connectors that link them to the ECU...

[Sambino]

How do I check the resistance? And why would it cut out whilst turning?

Started yesterday and the problems gone ? But sure it will be back as it's cut out 3 times

[Brianmoooore]

How do I check the resistance?

Measure the resistance at the pins of the engine ECU stone cold, plug the ECU back in, bring the engine up to full temp., and quickly measure the resistance again.

And why would it cut out whilst turning?

Load from the steering pump.

Started yesterday and the problems gone ? But sure it will be back as it's cut out 3 times

On a facelift M20, 'blue temp sensor' problems are far more likely to be with the wiring (plug and socket under the inlet manifold) than the sensor itself.
Note that your symptoms aren't typical of a temp. sensor problem (normally good when cold, getting worse with temp.)

Check out that the throttle position switch is working, and working when it should.

[Sambino]

Thanks Brian. My car is pre facelift - I have a volt meter but not sure where to connect the contacts - and what values I should be expecting - thanks

[Brianmoooore]

About 300 ohm hot and 4000 ohms cold. Where you connect depends on which ECU you have.