compression problem?

[grandam01]

ok on startup sometimes my car makes the sound of a reverse back fire, or more elaborately the sound of a blow off valve, and my car is not turboed or s.c. so does anyone have any ideas of what it maybe?

[GrandAmKid16]

You tried a compression test? Check and see what each cylinder is putting out.....I think it should be around 225-250psi if I'm not mistaken. From there check for other problems if the sound continues and compression is fine. You might try taking your car to a dealership or if u have access to a Tech 2 try trouble shooting your PCM to see whats the problem could be .....Good Luck

[grandam01]

thanks man, yeah i dunno i think its either compression or its timing, not sure. but yeah maybe i can see if i can pick up a code at autozone or something.