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Discussion Starter #1
Hello - Newbie here

Ive got a 53 plate 1800 CMAX Petrol.

For past 3 weeks the idling has become out of sorts. It is sitting around 1250rpm whilst parked. When pulling up to a halt the rpm increases to around 3000 briefly, before settling back down to 1250rpm.

It has been on the computer twice and on both occasions no fault codes have been shown.

The mechanics(2 different ones from different garages) seem to be at a loss. One thought possibly EGR Valve, the other thought possibly the same or the Throttle Body. But he was going to consult another mechanic before meaking any decision on how best to resolve this problem.

Reading some of the posts here there seems to be quite afew people who have experience in cmax probs. I was just wondering if anyone can help.

Many Thanks
 

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suggest you start with the coolant temperature sensor
If it reading as though the engine is cold but still within the range of values that the ECU expects then it won't give a fault code. There should be a check procedure for the sensor
 

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Richard

The engine temp guage is reading normal when driving/idling. Is this relevant or should i mention the CTSto mechanics.
 

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I'm not certain if there are two sensors one for the gauge and one for the ECU or not.
The other obvious thing to check with it being petrol is the idle switch that is fitted to the throttle butterfly lever that indicates to the ECU that the engine is at idle. On a previous petrol Inj cavalier this did have some rotational movement allowance within the fixing screws
 
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