Rifter
Registered Member
Ok new issue!
Had backfiring last week at high throttle i tracked down to a loose plug wire, this is different enough i believe the two issues are unrelated so i started a new thread.
Now it backfires ONLY at low throttle, if i floor it it will backfire like CRAZY for 1-2 seconds(like 20-40 pops in that 1-2 seconds down through the exhaust, sounds like a popcorn machine is under my feet) then it kicks in and runs fine and pulls hard right till 5000+ rpms. If i apply like 40-60% pedal sometimes it backfires a little sometimes it does not. so middle throttle works ok but low trottle will backfire like crazy, and full throttle will backfire like crazy till it catches then runs fine all through the rpm range.
Does not do it cold at all that i noticed only after warmup. Unlike last week this time it DOES NOT backfire at all in neutral, can rev it up all i want with all kinds of pedal pressures in neutral it will not backfire.
So before i drive it off a cliff what should i look into this time.
What makes me think its unrelated is last week was very small pops through the tailpipe, very small backfires. This week its much louder and i can feel truck shudder when it does it and much closer together with the poping sound. last week was a pop every second or two now its mutiple pops a second even at under 1500rpm.
think its ignition related?
Timing is 12-13 degrees at the crank tested when i got to work today.
Taking off the vac advance from the distributor has zero effect on this issue just causes a stumble at 2000-3000rpm when its looking for that timing thats no longer there.
Had backfiring last week at high throttle i tracked down to a loose plug wire, this is different enough i believe the two issues are unrelated so i started a new thread.
Now it backfires ONLY at low throttle, if i floor it it will backfire like CRAZY for 1-2 seconds(like 20-40 pops in that 1-2 seconds down through the exhaust, sounds like a popcorn machine is under my feet) then it kicks in and runs fine and pulls hard right till 5000+ rpms. If i apply like 40-60% pedal sometimes it backfires a little sometimes it does not. so middle throttle works ok but low trottle will backfire like crazy, and full throttle will backfire like crazy till it catches then runs fine all through the rpm range.
Does not do it cold at all that i noticed only after warmup. Unlike last week this time it DOES NOT backfire at all in neutral, can rev it up all i want with all kinds of pedal pressures in neutral it will not backfire.
So before i drive it off a cliff what should i look into this time.
What makes me think its unrelated is last week was very small pops through the tailpipe, very small backfires. This week its much louder and i can feel truck shudder when it does it and much closer together with the poping sound. last week was a pop every second or two now its mutiple pops a second even at under 1500rpm.
think its ignition related?
Timing is 12-13 degrees at the crank tested when i got to work today.
Taking off the vac advance from the distributor has zero effect on this issue just causes a stumble at 2000-3000rpm when its looking for that timing thats no longer there.
