very hard starting

[gtx446]

got my car dyno tuned by brain this past fridat.. carran great.. yesterday the car was very difficult to start,, it would crank, stop/crank stop//crank stop crank stop.. then car gets flooded..when starts lots of black smke comes out/had a simliar problem at the dyno.we changed the temp sensor and started no problem. could the sensor went bad or some other problemm? thx v

[Mike8675309]

What drove you to replace the coolant sensor at the Dyno? Did someone get a diagnostic report out of the computer? See if there are any codes.


Describe your process. Don't touch the gas pedal while starting it.


Key on, Crank, No Start
Key Off
Key On, Crank, No Start
Key Off
Key On, Crank, No Start
Key Off
Key On, Crank, No Start
Key Off
.
.
.
Key On, Crank, Start

If it is something like that, it could be your CAM sensor. If the cam sensor fails, the engine computer guesses which plug to fire after each cycle of the key. Eventually it will get it right.


You can check by hooking a LED test light (not 12 volt test lamp, as it's not fast enough) to PIN 2 of the Cam sensor connector and the negative side of the battery. When the engine is cranked, the LED test light should blink while the engine is cranking, or running.

Then see if the signal gets to the DIS by hooking the test light to Pin 2 on the DIS connector, and to the negative battery. Same thing, cranking or running the light should be flashing.

If neither, then the cam sensor is bad.