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Omega Help Area => Omega General Help => Topic started by: terry paget on 08 August 2018, 14:35:20

Title: On cold start engine does not fast idle
Post by: terry paget on 08 August 2018, 14:35:20
2.5 petrol manual estate
Unlike my other 2.5 petrol estate, this car starts at 500 rpm idle, suggesting failing engine temp sensor. Any comments?
Title: Re: On cold start engine does not fast idle
Post by: Doctor Gollum on 08 August 2018, 16:08:15
Have you seen the outside temperatures recently  ???
Title: Re: On cold start engine does not fast idle
Post by: Marks DTM Calib on 09 August 2018, 13:34:45
check engine temp sensor and maybe the idle valve (although this would give other symptoms to), the 2.5 should rev higher on start-up no matter what the ambient temp as its a requirement to get the secondary air injection to operate correctly
Title: Re: On cold start engine does not fast idle
Post by: terry paget on 09 August 2018, 20:47:48
check engine temp sensor and maybe the idle valve (although this would give other symptoms to), the 2.5 should rev higher on start-up no matter what the ambient temp as its a requirement to get the secondary air injection to operate correctly
Thanks. As I suspected. I am still reassembling after replacing cam cover gaskets, so it's a good time to change the ECU temp sensor. I hope they are common parts.
Title: Re: On cold start engine does not fast idle
Post by: terry paget on 17 August 2018, 11:12:46
Since August 8th I have done much work on this car, with little success. I have changed the the ECU temperature sensor and the idle control valve. Now on cold start it fails to fast idle and is inclined to stall, but it does idle too fast (900rpm) when warm. My fear is I have created an air leak somewhere, and the ICV is sticky, though I have attempted to clean it. I have also changed the mass air flow sensor. 
Title: Re: On cold start engine does not fast idle
Post by: terry paget on 20 August 2018, 08:30:22
Fault is now cured, my thanks for all advice. Yesterday I removed the plenum, and the breather bridge from the plenum. I replaced the top hat gasket, thought the existing was not broken. I confirmed that the 6 large O-rings were in place. I replaced the idle control valve, and the hose to the ICV, with its side arm to the injector unit.
This 18 year old, rust free car, now is running well, but not yet as new. There is a distinct clonk in the transmission caused by a worn crown wheel and pinion. I shall change the differential when my wounds from removing diff from scrap 2.2 have healed.