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Cold Start saga continues.
I opened up and cleaned my WUR yesterday. It didn't look bad at all, but I don't think it would take much to gum up the inside of it.
Today, I cleaned my fuel distributor. But, as I was taking the air boot off, I saw that the inside of the air funnel, and the inside of the throttle body were covered with a black sludge (oil overflow no doubt). I've had the car nine years, and have never over flowed the oil, so this stuff has been in there for a very long time. I cleaned it all up to a nice shine with carb cleaner, and proceeded to clean the fuel distributor (it wasn't bad looking).
After it was all back together, I started the car up. It ran, but very rough. I had my CIS tester connected, and the control pressure looked OK. I reached into the airbox with my hand and gently lifted the air flow plate, and the engine started running smooth at a high idle.
THEORY: All of that sludge on the inside of the air funnel caused the mixture to be rich because the obstruction of the sludge would cause the sensor plate to rise more. My previous mechanics, rather than cleaning the funnel, simply adjusted the mixture leaner. Now that the sludge is gone, the mixture is way too lean. I believe this has been the cause of my cold start problems, because the sludge also messed with the geometry of the funnel, that causes enrichment of the mixture at idle.
QUESTION: I want to roughly adjust my mixture. What is the proper tool to adjust the mixture with? Looks like a thin, no handled screwdriver or something like that would work.
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Bill Krause
'79 911SC Euro
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