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Automotive Technical Theory Forum

Professional automotive forum for discussion of the theory of operation for any automotive system or component. Discussions include electrical and electronic theory, engine propulsion theory, fuel system theory, ignition systems theory, and much more. This forum is for experienced automotive repair professionals only, membership required.

Continue to the description of our next automotive discussion forum, the Technical Tips Forum.

Recent Automotive Discussions in the Automotive Technical Theory Forum

Question Emission Valve
11/06/2020 in the Technical Theory Forum
[Driveability: 06 Dodge Ram 1500 SLT 5.7L] I am getting emission codes P0440, P0456, and P0457. The gas cap message is coming on the instrument cluster. I started by checking for leaks. I hooked up my smoke machine to the fuel fill and found smoke coming...
engine overheating
10/23/2020 in the Technical Theory Forum
[Engine: 06 Chevrolet Cobalt SS 2.0L] First, a little background. Customer called a couple months ago for a price on replacing the head gasket on this engine. He stated that the oil was chocolate brown. Took about 6 weeks to call to bring it in. He said ...
Old Ford starter info
10/20/2020 in the Technical Theory Forum
[Electrical: 82 Ford F700 7.0L] We have a customer that has an F700 about 1982 with a 370/429 engine. It has a history of having starter issues for quite a while. I have used a 3165 starter... 91-02-5827 pn(wilson I think) and lastly a 3174. Is anyone fa...
10/19/2020 in the Technical Theory Forum
[Driveability: 05 Jeep Grand Cherokee Limited 4.7L] explain how exhaust manifold leak causes 420 yet fuel trim lt. is 00. new o2s and cat.
Wrong TAC Module?
10/13/2020 in the Technical Theory Forum
[Driveability: 98 Chevrolet Corvette 5.7L] Got a bit of a strange issue here. Vehicle sets TAC codes at Key Up. P1121, and 1516, as well as TPS correlation codes. And, of course, there's zero throttle response, as it's in 'limp' mode. TPS voltages read c...

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