backfire at 5,000RPM

**vecaj** · 11-01-2006, 03:42 PM

I have a 95 trans with the 5.7, auto. I put on a magnaflow exhaust a month ago or so, I dont know if that matters and I have chip too...at 5,000 on WOT she just steady backfires and it doesnt shift. A friend of mine saw it and said he saw a small blue flame, and it was loud as shit. I lose all my power, and I cant bring myself to do it more than a second to try to figure out what it is... Im taking my chip off tomorrow prolly to troubleshoot. People said maybe my optispark or valve timing, bad cat? I dunno... any ideas? It drives perfect exept at 5000. sorry for the long post.

-josh

**BlackLT1Z28** · 11-01-2006, 04:49 PM

Yeah, it could be the opti miss-firing that high up in engine speed. Might also be a timing issue, not enough spark advance at that RPM and gas is still burning past the exhaust stroke in the header/manifold.

**Red on Red WS6** · 11-06-2006, 01:04 AM

Originally Posted by vecaj

I have a 95 trans with the 5.7, auto. I put on a magnaflow exhaust a month ago or so, I dont know if that matters and I have chip too...at 5,000 on WOT she just steady backfires and it doesnt shift. A friend of mine saw it and said he saw a small blue flame, and it was loud as shit. I lose all my power, and I cant bring myself to do it more than a second to try to figure out what it is... Im taking my chip off tomorrow prolly to troubleshoot. People said maybe my optispark or valve timing, bad cat? I dunno... any ideas? It drives perfect exept at 5000. sorry for the long post.

-josh

A chip? Do you mean a handheld programer? When was the last time plugs & wires were changed? Can you test your fuel pressure?

**96slow6** · 11-06-2006, 03:51 PM

Originally Posted by Red on Red WS6

A chip? Do you mean a handheld programer? When was the last time plugs & wires were changed? Can you test your fuel pressure?

thats what i was thinking. there is no "chip". and even if you did just do the wires you need to check for arching. when if ever was the opti changed?

**stangereater** · 11-06-2006, 04:48 PM

Is you check engine light on. same thing happen to a car at work turns out the mass air was the problem. Might not be the same thing but might

**vecaj** · 11-23-2006, 02:12 PM

sorry for the late reply... I have a stage one JET chip, it just plugs into my computer... and no engine light, she runs perfect exept till she gets to 5,000 then she just steady backfires... im gettin the msd distributer, msd wires, and ngk tr-55 gapped at .050. ...that should fix my spark problem... she needs a tune up anyway.

thanks guys...

Josh