Constant Sporratic Backfire
01-03-2006, 01:16 PM
#1
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Constant Sporratic Backfire Hey guys,
A buddy of mine just bought a 98 Z28 with a few bolt ons and a cam. Mods are listed below. Well, he drove it for a while and it was obviously running pig rich because there was lots of black smoke. I figured we would get it tuned later on and it would run tons better. Well, he had it idleing and one of his friends jumped in the car and revved it up almost to redline, and about 50 miles later he noticed something that sounded like a small exhaust leak. It started getting worse and then it started popping very loud randomly. Sometimes it idles just fine for 5 minutes or so but once the engine gets hot, it starts backfiring like crazy. He changed out the plugs/wires/header gaskets/bolts and it still had the problem. Sometimes it says multiple missfires. I have EFI Live scanner and I will attach the file if anyone wants to look at it. I think one of his o2s was out because the ltft's were at -2% one one bank and +25% on the other bank. He will be changing this out soon.
What other problem could it be?
Here are the mods:
Hooker Longtubes/ORY/Borla exhaust w/ no plate
LS6 intake
MTI Lid
Comp Cams 226/226 not sure about the other stuff but 111 LSA
New timing chain w/ the cam swap
I dont think the guy did anything else when he swapped out the cam.
Let me know what you think.
A buddy of mine just bought a 98 Z28 with a few bolt ons and a cam. Mods are listed below. Well, he drove it for a while and it was obviously running pig rich because there was lots of black smoke. I figured we would get it tuned later on and it would run tons better. Well, he had it idleing and one of his friends jumped in the car and revved it up almost to redline, and about 50 miles later he noticed something that sounded like a small exhaust leak. It started getting worse and then it started popping very loud randomly. Sometimes it idles just fine for 5 minutes or so but once the engine gets hot, it starts backfiring like crazy. He changed out the plugs/wires/header gaskets/bolts and it still had the problem. Sometimes it says multiple missfires. I have EFI Live scanner and I will attach the file if anyone wants to look at it. I think one of his o2s was out because the ltft's were at -2% one one bank and +25% on the other bank. He will be changing this out soon.
What other problem could it be?
Here are the mods:
Hooker Longtubes/ORY/Borla exhaust w/ no plate
LS6 intake
MTI Lid
Comp Cams 226/226 not sure about the other stuff but 111 LSA
New timing chain w/ the cam swap
I dont think the guy did anything else when he swapped out the cam.
Let me know what you think.
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01-04-2006, 12:31 PM
#9
Here are the mods:
Hooker Longtubes/ORY/Borla exhaust w/ no plate
LS6 intake
MTI Lid
Comp Cams 226/226 not sure about the other stuff but 111 LSA
New timing chain w/ the cam swap
I dont think the guy did anything else when he swapped out the cam.
Hooker Longtubes/ORY/Borla exhaust w/ no plate
LS6 intake
MTI Lid
Comp Cams 226/226 not sure about the other stuff but 111 LSA
New timing chain w/ the cam swap
I dont think the guy did anything else when he swapped out the cam.
01-04-2006, 02:57 PM
#10
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Originally Posted by 99blancoSS
Did he change pushrods or valve springs?
