Random misfire???
Random misfire??? My car has been sitting up for about 6 weeks at a body shop-long story. Today when I started it the SES light was on and it was running really rough. When I tried to take off it wouldn't accelerate very well and the SES light would start blinking. It was shaking like it had a huge cam or something. I had the shop hook up their computer to it and the only code was a random misfire code. I've never had any problems out of my car. They told me that it had probably fouled the plugs because the only time it had been run was idleing it around to move it. They suggested that I "run the **** out of it". So I got out on the road and tried to accelerate a few times. Not WOT, but about 1/2. After doing this about 2-3 times it started running right and the light went off. I made a few more runs at WOT and everything seems normal now. Most of the time it was inside. I know they didn't drive it because I remembered the milage.
What could cause it to do that? It is a 2001 with hooker LT's, ORP, Corsa cat back, and a lid. Has o2 sims on the rear o2's. Everything has been on the car for over a year without any problems.
What could cause it to do that? It is a 2001 with hooker LT's, ORP, Corsa cat back, and a lid. Has o2 sims on the rear o2's. Everything has been on the car for over a year without any problems.
On The Tree
Joined: Jan 2004
Posts: 196
Likes: 0
This is exactly what I'm going through right now...but I still haven't gotten the problem fixed...I'm thinkin it was to do with the TB...I just changed both sensors...I'll see the results once I leave my house in 30 min..
for sitting so long prob didnt help. and just idle prob got some build up in the CC if its fine now then donw worry. throw some 100 octane in and give her some WOT runs 
Thats what I did...only with 93. Runs great now. I just can't figure out what made it do that to start with. I've done the idle relearn thing many times and it was nothing like that. That was the first time my car has ever misfired that I know of.
Originally Posted by Black01M6SS
My car has been sitting up for about 6 weeks at a body shop-long story. Today when I started it the SES light was on and it was running really rough. When I tried to take off it wouldn't accelerate very well and the SES light would start blinking. It was shaking like it had a huge cam or something. I had the shop hook up their computer to it and the only code was a random misfire code. I've never had any problems out of my car. They told me that it had probably fouled the plugs because the only time it had been run was idleing it around to move it. They suggested that I "run the **** out of it". So I got out on the road and tried to accelerate a few times. Not WOT, but about 1/2. After doing this about 2-3 times it started running right and the light went off. I made a few more runs at WOT and everything seems normal now. Most of the time it was inside. I know they didn't drive it because I remembered the milage.
.
.
Running the **** out of it didn't help me at all.
I did make a pretty hare brained blunder though. I recently gutted my cats. After getting everything bolted back up I started the car without checking my work. Well I forgot to put the plug wires for 1,3,5,7 back on. I can't believe the car even started. It did and ran for several minutes why I looked around for what sounded like an exhaust leak.Well of course it wasn't an exhaust leak it was the sound of an LS1 firing on only even numbered cylinders. Blah, I don't want to swap sensors and change plugs on this thing. It's too damn cold outside...
TECH Resident
Joined: Jan 2002
Posts: 754
Likes: 0
From: USA
Being the car sat for 6 weeks unused it sounds like the battery voltage was too low and caused the PCM to reset and lose all the fuel averages and once started the PCM would have to relearn and recal it calibrations with about 1 hour of drive time.
Originally Posted by Black01M6SS
My car has been sitting up for about 6 weeks at a body shop-long story. Today when I started it the SES light was on and it was running really rough. When I tried to take off it wouldn't accelerate very well and the SES light would start blinking. It was shaking like it had a huge cam or something. I had the shop hook up their computer to it and the only code was a random misfire code. I've never had any problems out of my car. They told me that it had probably fouled the plugs because the only time it had been run was idleing it around to move it. They suggested that I "run the **** out of it". So I got out on the road and tried to accelerate a few times. Not WOT, but about 1/2. After doing this about 2-3 times it started running right and the light went off. I made a few more runs at WOT and everything seems normal now. Most of the time it was inside. I know they didn't drive it because I remembered the milage.
What could cause it to do that? It is a 2001 with hooker LT's, ORP, Corsa cat back, and a lid. Has o2 sims on the rear o2's. Everything has been on the car for over a year without any problems.
What could cause it to do that? It is a 2001 with hooker LT's, ORP, Corsa cat back, and a lid. Has o2 sims on the rear o2's. Everything has been on the car for over a year without any problems.
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Team ZR-1, when I first started the car I thought the same thing, but I've done the idle relearn thing many times and this was much different. The battery is also new and it didn't act like it was low at all. "started right up" All is well now. I'm guess the plugs were fouled or something. Would running rich from headers cause that if the car was only moved around for 6 weeks? I know it spent most of the time sitting inside the shop.
Good luck to everyone else with this problem. Mine didn't seem to last very wrong, but I would still like to know for sure what caused it in the first place.
Good luck to everyone else with this problem. Mine didn't seem to last very wrong, but I would still like to know for sure what caused it in the first place.
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Staging Lane
Joined: Nov 2003
Posts: 57
Likes: 0
From: Arizona
most likely the misfires were due to moisture build up from repeated start ups where desired temps were never reached. This type of start up/shut down results in condensation build seen in the oil passages, fuel line and cc. So by running the engine at normal operating temps, this will burn off the condensation and return the engine to normall operations, most of the time. 100 octane gas would also help clean out your fuel system. And is possible to foul the plugs especially if they were worn to begin with and enough condensation had built up in the cc and fuel rails. 
