Back Fire Diagnosis Anyone?
Thread Starter
Teching In
Joined: Dec 2002
Posts: 2
Likes: 0
From: Marstons Mills, MA
Back Fire Diagnosis Anyone? I'm getting small backfires "pop" when idleing with warm engine after mildly aggressive street driving. I have the equipment as seen below with ORP's in place with O2 sims. Had LS1 edit done on the dyno after H&C and all the rest equip. listed below. Car was running fine. Then it started backfiring as described and "missing" under agressive acceleration. I was receiving no PCM codes or check engine light. I don't own an OBD II device so I did the following:
1. I re-torqued the 10 bolts holding the new intake on. (most of them had indeed backed off quite a bit)
2. I inspected all spark plugs and wires. The wires showed no abnormalities with an ohm meter. The plugs were all clean and white. I regapped from .050 to .045
3. I reset the computer by disconnecting the battery overnight.
4. I checked the torque on the new headers...all was fine.
5. I visually inspected the underside of the headers and the O2 sims...all looks fine.
The car now runs very strong with no discernable "misfires". No hesitation what so ever when running up to redline through third gear! But when I come to a stop and sit at a light or whatever...she goes... "pop" ... a small backfire! Any ideas on how to cure this? Thanks in advance for any information.
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98 MN6, Z51, Pro Flow+, No Screens, Powerduct, 76mmTB, FLP: Headers / Cats / X pipe,o Cats, Z06 Titanium Exhaust, Hurst, Momo ****, Fikse Mach V, Pilots, NGK TR55IX, MSD 8.5, Taylor socks, TEA 5.3 stage II, TR 224/.563/112, rollmaster double, LS6 intake, PCV Mod, MCM Hood. 397 RWHP / 380 RWTQ
1. I re-torqued the 10 bolts holding the new intake on. (most of them had indeed backed off quite a bit)
2. I inspected all spark plugs and wires. The wires showed no abnormalities with an ohm meter. The plugs were all clean and white. I regapped from .050 to .045
3. I reset the computer by disconnecting the battery overnight.
4. I checked the torque on the new headers...all was fine.
5. I visually inspected the underside of the headers and the O2 sims...all looks fine.
The car now runs very strong with no discernable "misfires". No hesitation what so ever when running up to redline through third gear! But when I come to a stop and sit at a light or whatever...she goes... "pop" ... a small backfire! Any ideas on how to cure this? Thanks in advance for any information.
_______
98 MN6, Z51, Pro Flow+, No Screens, Powerduct, 76mmTB, FLP: Headers / Cats / X pipe,o Cats, Z06 Titanium Exhaust, Hurst, Momo ****, Fikse Mach V, Pilots, NGK TR55IX, MSD 8.5, Taylor socks, TEA 5.3 stage II, TR 224/.563/112, rollmaster double, LS6 intake, PCV Mod, MCM Hood. 397 RWHP / 380 RWTQ
