ECU coolant temp sensor location

[911motorsport]

Pre-serp 4.3 Chimaera.

Can someone tell me where the ECU coolant temperature sensor is located please? I suspect mine needs replacing as car is holding on to 2000 RPM most of the time.

PH Search is currently disabled.

Thanks

[Johno]

I think it's the same as a serp . .

On top of the inlet manifold, in front of throttle assembly near front on o/s directly behind oil filler.

[911motorsport]

Brilliant.

Thanks Johno

[PRTVR]

Here is a link with some pictures I took when changing mine,
http://www.pistonheads.com/gassing/topic.asp?h=0&a...
this was on a serp engine 1996, so may be different. but may be worth a check.

[Cider Andy]

Coolant temp sensor shouldn't show those symptoms. I would have thought it was more likely to be the stepper motor or an unmetered air leak into the inlet tract.

Coolant temperature sensor would more likely cause the car to run roughly when hot and it would use a lot of fuel.

[911motorsport]

PRTVR said:

Here is a link with some pictures I took when changing mine,
http://www.pistonheads.com/gassing/topic.asp?h=0&a...
this was on a serp engine 1996, so may be different. but may be worth a check.

Excellent. Thank you. Same as mine except I don't have the brass secondary one.

[911motorsport]

Cider Andy said:

Coolant temp sensor shouldn't show those symptoms. I would have thought it was more likely to be the stepper motor or an unmetered air leak into the inlet tract.

Coolant temperature sensor would more likely cause the car to run roughly when hot and it would use a lot of fuel.

The car does use a lot of fuel but runs with good smooth power output.

I have now changed the ECU temp sensor, which has made no difference at all!

Symptons: I start the car and let the idle settle to a nice 950RPM (ish). I drive off and things are all good. When I stop at a junction etc and push the clutch in the revs hold at about 2000RPM. Sometimes there is a noticable dip down towards 1200 RPM but it is as if something cuts in and raises the RPM back to 2000. If I stay still long enough the car will eventually stabilise back to the base idle of 950RPM but this rarely happens as other drivers get a bit funny if I just sit there for 20-30 seconds

In other words, the car at lives at 2000 rpm+ 99% of the time.

Edited by 911motorsport on Wednesday 23 July 20:17

[paulathome]

It sounds to me like you have a dirty stepper motor or as Andy said you may have a leak on the engine side of the throttle butterfly.
Have a look round at at all the pipe work around the plenum chamber, brake servo and purge valve pipes.
You may also have a leak between the plenum and the gasket below.
I would clean the stepper motor as a matter of course and then proceed from there.
Cheers.
Paul

[911motorsport]

Thanks Paul. I've already done the stepper motor thing (cleaned etc. and swapped for another). It's not that :-(

I've also sprayed easystart all round the plennum area etc. to detect false air getting in, but found nothing.

Does anyone know where the road speed sensor is for the ECU please? I seem to remember seeing somewhere that it detects when you're on the move and adjusts the idle speed.