Engine/Transmission (1994 - 1998) Back fire out of exhaust

[JLewis]

I noticed that when I rev my truck up to 3000 RPM's I get some back-fire poping noise comming from the tail pipe, also some white smoke too when it pops. It seems to do it only when there is no load on the motor, like going downhill and letting the rpm's slowly ciimb. Any ideas why this is happening? The truck is a 98 12 valve 5-speed with a custom plate, 5 in. exhaust, big k@n cone filter, 370's, 4000 GSK and 16 cm housing.

 

[zjones]

Me too I have this happend once or twice? Mine only does it when I have no boost. I think it is caused by the lack of compression (i. e. no boost) in the cylinder (the fuel is not being burned enough & is trying to burn out the pipe - your ctd is saying NEED MORE AIR PLEASE GIVE ME MORE AIR!! When in gear the boost has time to build up enough psi to burn the fuel. I first noticed this when I installed the TST light afc spring kit. The addition of larger turbo's & turbine housings & lighter AFC springs just compound to worsen the problem.



Stop revving you CTD to show off I never do this



Just my $. 02

Zac

 

[R.ebel]

Most likely its the overflow valve, if that don't cure the problem check you pump timing.