Idling when cold

[Mr Plow]

Hi

I'm having trouble getting my S to idle when cold, as soon as it is warmed up it is fine. For the first couple of minutes after initial start up I need to keep the throttle slightly pressed to maintain tickover.

Car is an S3C so 2.9 engine.

Am I right in thinking this could be the coolant temp sensor (I think this is what they are called)?
If so how can I test this and also does anyone have a part number or a good source for them?

Thanks

Liam

[Ceejay73]

Hi Liam, ECT can be tested in situ or removed from car. You will need a thermometer and electronic multi-meter. If you remove it then just need to immerse in water of a known temperature and measure the resistance across the terminals and compare compare to those below (don't immerse the terminals). This would probably give the best results as water temp can be controlled more accurately. Alternatively with ECT in situ, run car up to desired temp ( use a proper thermometer again not engine temp guage). With ignition off, disconnect ECT and measure resistance and compare to those below. OR with ignition on and ECT connected, measure voltage across terminals and compare to those below.
All values courtesy of Autodata and appear to be indentical for all 2.9 engines regardless of cat or not.
Hope that is of some help.
Regards,
Carl.

Temp(celcius)----------------Resistance (ohms)------------------Voltage(approx)
.----------------------------Disconnected IGN OFF---------------Connected IGN ON
.----0------------------------88000 to 102000--------------------------3.8
.---20------------------------35000 to 40000---------------------------3.0
.---40------------------------15000 to 17000---------------------------2.0
.---60--------------------------7100 to 8000---------------------------1.2
.---80--------------------------3000 to 4500---------------------------0.7

(edit to try and correct table layout)

Edited by Ceejay73 on Wednesday 17th March 11:44

[Mr Plow]

Thank you for the info.

MOT time on Saturday, so I've a few jobs to do this week, I will check this out at the same time.

Thanks again.

Liam

[Gerald-TVR]

Temp(celcius)	Resistance (ohms)	Voltage(approx)
-	Disconnected IGN OFF	Connected IGN ON
0	88000 to 102000	3.8
20	35000 to 40000	3.0
40	15000 to 17000	2.0
60	7100 to 8000	1.2
80	3000 to 4500	0.7

This is how formatting a table works

||Temp(celcius)||Resistance (ohms)||Voltage(approx)||

Edited by Gerald-TVR on Sunday 21st March 21:52

[Ceejay73]

Gerald-TVR said:

Some smart ass stuff

Thanks Norman, I had gone keyboard blind and lost the | key.

[jimed]

Have you checked the idle control valve at the front o/s of the plenum chamber? That needs to be cleaned every now and then so could be worth a go to see if it helps. 2 small bolts to get it off and a blast with carb cleaner (can take it apart if you like to ensure it is clean inside) and then replace with a new gasket - I used some cereal packet cut to shape with a little vaseline on it t help sealing and it was fine and easy to get off next time too.
Jim

[jonesy80]

Mr Plow - any chance of an update as to what you found wrong as I am having the exact same problem.

[Mr Plow]

Hi

I ended up changing the coolant temp sensor, I got mine from ebay as per the listing on the other thread thats going.

http://www.pistonheads.com/gassing/topic.asp?h=0&a...

This led to an improvement, I then cleaned the ISCV again using carb cleaner, problem solved.

So a combination of new sensor and good clean of the ISCV.

Cheers

Liam