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NTC or AMM Posted by Steve Schwedland [Email] (#2368) [Profile/Gallery] (more from Steve Schwedland) on Thu, 1 Sep 2011 10:56:36 In Reply to: surging idle when cold., darcey, Thu, 1 Sep 2011 07:34:47 Members do not see ads below this line. - Help Keep This Site Online - Signup |
There are generally two things that will cause surging idle when cold, the NTC or the AMM. The coolant temperature sensor (NTC) is wired to the ECU and, among other things, helps the system run before the O2 sensor is warmed up. This is much cheaper, about $20, and easy to test. If that doesn't do the trick, then the air mass meter (AMM) likely needs to be replaced (about $200 rebuilt).
Check the resistance of your coolant temp sensor, it is located between the intake manifold runners #2 and #3 on the block, the connector is blue. Pull the connector off and and check the resistance across the two pins. I would do this in the morning before you start the car for the first time. For more precision, you can also pull it out of the car and check it on the bench with a thermometer handy.
According to the Bentley manual (since you don't have yours yet) the resistance specs are:
5800ohms at 32 degrees
3800ohms at 50 degrees
3000ohms at 58 degrees
2600ohms at 68 degrees
2000ohms at 76 degrees
1700ohms at 86 degrees
320ohms at 176 degrees
If yours is not in this range then you should replace it.
posted by 204.126.2...
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