Weird Missfiring Issue
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From: Cincinnati, OH
Weird Missfiring Issue Car has been running great until today...when I have a 2.5 hour trip home. Everything is fine but I get on the highway and while i'm cruising at part throttle and I have a missfire problem. At full throttle it is fine but when I'm barely on the throttle just cruising the car will buck. And it's not all the time. I'll drive for 2-3 minutes and it'll be just fine then it'll start to buck and u can hear it missfiring and the ses light will start to blink and then after about 15 seconds the car goes back to normal. All the horsepower is back and it runs smooth for another couple of minutes then it will do it all over again. Could this be computer related or maybe my opti is going out again. Also I've noticed the past few weeks is that sometimes when my engine drops down to idle (about 900) it will actually go below what it normally idles at and get a lil rough (600-700)
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From: Cincinnati, OH
yeah i've done that...about 3 years ago i had a really bad missfire at 4500 and up ended up my icm was broken into two pieces from all the heat.
On The Tree
Joined: Mar 2007
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From: Tacoma, WA
Check your wires? Maybe your plugs too? I know I've had that problem before and even wires that look good can be bad on the inside. Actually I think I have that problem now.
But I don't know if it's because I don't have my car tuned for the cam I have or if I need to check my wires or plugs. I know the plugs I put in were probably from 1994 or something.
But I don't know if it's because I don't have my car tuned for the cam I have or if I need to check my wires or plugs. I know the plugs I put in were probably from 1994 or something.
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From: Cincinnati, OH
Check your wires? Maybe your plugs too? I know I've had that problem before and even wires that look good can be bad on the inside. Actually I think I have that problem now.
But I don't know if it's because I don't have my car tuned for the cam I have or if I need to check my wires or plugs. I know the plugs I put in were probably from 1994 or something.
But I don't know if it's because I don't have my car tuned for the cam I have or if I need to check my wires or plugs. I know the plugs I put in were probably from 1994 or something.
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From: Cincinnati, OH
funny you mentioned that...i replaced my o2 sensors when i did longtubes and one of them crapped out so i went ahead and bought two from a vendor online...they sent me two but one was square four pin instead of flat so i sent it back (never got my money back or a new o2) but thats besides the point...i was thinking maybe the other side is taking a ****. I'll find out soon I'm heading to the zone to get it scanned in a few minutes so ill post back up with what they find
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From: Cincinnati, OH
alright just went and got the codes looked at and its throwing a p0303 which is a cylinder 3 missfire. thinking maybe a burnt wire, bad plug, or my injector may be leaking
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From: Cincinnati, OH
thanks man
onto the problem
okay right now i'm in the process of taking my plugs out...some thing i have noticed is all the drivers side plugs are completely covered black while i've pulled two passenger side plugs so far and both of them are not completely covered the electrode is still white and the ground is still clean where it sparks. I'm thinking maybe this has something to do w/ the o2 sensor?
onto the problem
okay right now i'm in the process of taking my plugs out...some thing i have noticed is all the drivers side plugs are completely covered black while i've pulled two passenger side plugs so far and both of them are not completely covered the electrode is still white and the ground is still clean where it sparks. I'm thinking maybe this has something to do w/ the o2 sensor?
I would double check all of the spark plug wires, the full length of the wire from the opti to the plug. A small nick/burn/crack in the wire can cause intermittent problems like you are describing.
With the plug wires off, put a little bit of dielectric grease in the plug wire boots, this will help with the connection, plus to keep moisture out of the boots.
What brand were the O2 sensors you replaced? If they weren't AC Delco, you might need to go get some AC Delco sensors. It seems the Bosch O2s you get from your local DAP typically give people fits on the LT1.
With the plug wires off, put a little bit of dielectric grease in the plug wire boots, this will help with the connection, plus to keep moisture out of the boots.
What brand were the O2 sensors you replaced? If they weren't AC Delco, you might need to go get some AC Delco sensors. It seems the Bosch O2s you get from your local DAP typically give people fits on the LT1.
If it still drives like crap, then it is definitely ignition related.
12 Second Club
Joined: Mar 2009
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From: deer park (houston area)
can someway tell me about were the icm is located im having a similar problem and i read everyone’s info above so i would like to look at it and possibly putt washers in there to space it out to keep it cool
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From: Cincinnati, OH
the icm is mounted on the front of the drivers side head right next to the coil. when my icm went bad i had a high rpm miss and i already did that mod..probably the easiest most cost efficient mod for peace of mind