Cold start idle problem

[Tankbuster]

Hi all

Not sure if there is a compound isse with my 940 2.3 LPt 1997?
Battery was flat yesterday. Charged it up and engine turned over ok, attempted to fire but refused to idle from cold unless throttle was applied.
No obvious issues re vac / turbo hose leaks, etc.
No probs when warmed-up and runs well when warm.
Could I have your advice please?

[Tankbuster]

Any takers?
I've looked at some threads for similarities but none of the issues in those threads appear to be identical to the problems my car has. Have checked the HT leads, fitted new dist cap and rotor arm, plugs, airfilter etc......it was due those anyway.
All advice welcome

[CTCNetwork]

Hi,

This topic should help:
Poor Cold Idle...

Idle control valve, and similar phrases! There are a couple of useful links in the above topic.

Des. . .

[Tankbuster]

Thanks for the pointers. Looks like I have a defective coolant temperature sensor which also acts on the fuelling system. Fault code 123. OBD reader shows 123.......followed by a few seconds pause, then shows -4- -5- E (not sure what the 4 5 E is though?)
Removed the sensor to clean it up......multimeter shows that it's open circuit so will replace this and hopefully that'll do the trick.
Dealer wants 45 quid for the part but was hoping to get an OEM from somewhere other than dealers......any ideas re where to buy?

Cheers.

[CTCNetwork]

Hi,

Personal opinion I would try to stick to OEM although with standard bits I would think you'd be Ok.

However, try getting a price from FRF - see This topic as they do a pretty good discount...

Des. . .

[kevham]

Originally Posted by CTCNetwork

Hi,

Personal opinion I would try to stick to OEM although with standard bits I would think you'd be Ok.

However, try getting a price from FRF - see This topic as they do a pretty good discount...

Des. . .

I'll second that.

FRF provide a very efficient mail order service and postage on a coolant sensor won't be too much. With the discount it will probably be cheaper than going to your local dealer.

[mjk164]

I think your problem lies in the idle air control valve (IAC). If it dosent see the full 12 volts at the stepper motor inside it, then the stepper will not set the valve at the right angle for cold running...the symptom you seem to have. You can check what voltage is at the unit by removing the plug and test with a meter. If its down to 9 or 10 volts then thats your problem. The most likely fault will be with the radio supression relay which supplies the injectors and the IAC. I'm not familiar with the 940 but I think the relay is near to the ABS unit on the drivers side in the engine compartment. You can either remove the cover and clean up the contacts (know what you are doing before trying this) or get a replacement.

[Tankbuster]

Originally Posted by CTCNetwork

Hi,

Personal opinion I would try to stick to OEM although with standard bits I would think you'd be Ok.

However, try getting a price from FRF - see This topic as they do a pretty good discount...

Des. . .

Many thanks.....duly noted

[Tankbuster]

Originally Posted by kevham

I'll second that.

FRF provide a very efficient mail order service and postage on a coolant sensor won't be too much. With the discount it will probably be cheaper than going to your local dealer.

Thanks v much

[Tankbuster]

Originally Posted by mjk164

I think your problem lies in the idle air control valve (IAC). If it dosent see the full 12 volts at the stepper motor inside it, then the stepper will not set the valve at the right angle for cold running...the symptom you seem to have. You can check what voltage is at the unit by removing the plug and test with a meter. If its down to 9 or 10 volts then thats your problem. The most likely fault will be with the radio supression relay which supplies the injectors and the IAC. I'm not familiar with the 940 but I think the relay is near to the ABS unit on the drivers side in the engine compartment. You can either remove the cover and clean up the contacts (know what you are doing before trying this) or get a replacement.

I did suspect the IAC but the diagnostic check indicated 123....coolant temperature sensor.
I will check that voltage on next cold start though...will also clean the relay you mention.
Issue only exists for the first minute or so....car starts from cold.....engine struggles to stay fired, then ticks-over at about 500rpm. After a minute or so....and a few gentle revs.....idles at about 750 - 800 and runs & pulls just fine.
There appears to be 2 sensors in the cylinder head, just below the intake manifold. One is about middway point along the head (temp guage) the other sits further towards the dizzy cap (ECT). I presume neither of those 2 should read open circuit on a multimeter?