Hello, I had problem starting the car and replaced Air Mass Meter with rebuilt one I got from Ebay for $40 a while ago. The car starts fine but idles poorly until warms up. I tried to adjust the AMM while it was idling but it did not help.

When I bought a car ~3 years ago I put in the cheapest spark plugs and did not replace them since then. I bought Bosch 4510 Ir plugs and want to put them in and do compression test while at it.

I looked in Bentley manual for 240 and I saw that they recommend to loosen the plugs by one turn and start the engine to blow off the carbon deposits from the threads before doing compression test, so the carbon deposits would not get under the valve seats and affect the readings. I never heard of such practice before. I would think it can damage the threads... Is anyone doing it like this ?

Thanks for advice,
Serge