Self Test Timing Advance Problem...

[Thunderboy]

Need Help ...Please!!!

I have an 87 Mustang GT with the H.O 5.0. I ran a self test diagnostic on it and noticed that when I had started the car the engine timing didn't advance like it should. Instead the my car made this loud sucking noise like you get when you have a cold air intake on and hit the gas. Then the idle got a little rough and then it just ran like normal again. Any suggestions on what to check out for this would be appreciated greatly. Thanks

 

[jrichker]

That's exactly what it is supposed to do. The running self test opens the EGR valve at idle, which makes the engine cough and run rough. I recommend that you get a Chilton's shop manual to get all the info on running the tests.