what else can cause a misfire besides plugs/wires
07-25-2007, 04:24 PM
#1
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what else can cause a misfire besides plugs/wires Okay so i am still stumped by this misfire, i have replaced all of my plugs and new wires, taylor OTVC wires, i just replaced the opti-end terminals and i have no burns/breaks in the wires. New opti, new water pump. Ever since i installed my pacesetters/ory i have this damn mis, it is always when the engine is coming down from a rev. Would O2 sensors cause this? Does it just need a tune, the engine idles just fine, no stumbling, no hesitations, just a damn misfire.
07-25-2007, 05:33 PM
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If you are reving the motor high and then letting off and you have a backfire this is a normal thing for the LT1. I would have the same thing happen until I got a tune. these motors a programmed rich from the factory (safety factor)...and the fuel collects in the exhaust and ignites. After I got a tune I have had no further backfires.
07-25-2007, 06:06 PM
#5
By misfire do you mean backfire? As in when you let off the gas high in the rpms and you hear a pop or popping? Like Fad2BLK93 said that is normal for our cars, nothing to be concerned with. My car does it all the time, even a little flames sometimes if the weather is cold 
07-25-2007, 07:40 PM
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Okay so it sounds like its normal, it just never did it before my LT install. how many guys do their own tuning? I have a laptop, im thinking about buying a cable and tuning it myself. So to stop the backfire i would need to lean out the gas right?
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07-25-2007, 11:43 PM
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All right i took it for a drive and it still runs like ****, i am at my wits end to try and figure it out so tomorrow i am taking it to a local performance shop that specializes in camaros/trans ams/gto's and seeing if they can fix it. Hopefully be up and running soon.
07-26-2007, 07:36 AM
#9
Originally Posted by transambandit
All right i took it for a drive and it still runs like ****, i am at my wits end to try and figure it out so tomorrow i am taking it to a local performance shop that specializes in camaros/trans ams/gto's and seeing if they can fix it. Hopefully be up and running soon.
07-26-2007, 07:41 AM
#10
Chk the Fuel Pressue, Ive said this over 3 different post. Its often the most over looked thing. Hook a guage up, tape it to the windsheild and drive her, put a load on it and see how it moves. I myself have replaced opti's when it wasnt needed.
Its call diagnosing.
A motor needs.
Fuel
Air
Spark
Compression
Its call diagnosing.
A motor needs.
Fuel
Air
Spark
Compression
07-26-2007, 11:38 AM
#12
Originally Posted by transambandit
all ready hooked up a guage, get 47 with engine on and 43 at idle.
I said put a LOAD on it, means you need to drive it, the engine in neutral/park does not have the same need while in motion.
07-26-2007, 12:15 PM
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check your rocker arm adjustments. I had a p0300 random misfire code triggered by the number 8 rockers being overtightened. took me 3 months and after purchasing all new distributer equipment
07-26-2007, 12:37 PM
#15
Originally Posted by phirepower
check your rocker arm adjustments. I had a p0300 random misfire code triggered by the number 8 rockers being overtightened. took me 3 months and after purchasing all new distributer equipment
07-26-2007, 12:52 PM
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Originally Posted by lt197formula
I completely overlooked the o2 sensors...they could easily be the problem. Did you use o2 extensions or cut and splice your original sensors?
07-26-2007, 01:42 PM
#17
Originally Posted by transambandit
used an extension on the pass side, the drivers side was long enough without an extension. I am kinda thinking my O2's also but then it would idle funny and it idles just fine.
07-26-2007, 02:40 PM
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Is the missfire at high RPMs? Is it only if the car is cold? Is it running like crap all the time?
If you've got the time and patience, it probably wouldn't hurt to check the adjustment of your rockers and ensure that they are at zero-lash with the proper pre-load.
You also might want to take a look at the harness that goes along the passenger side of the intake manifold, and down behind the water pump where it plugs into the opti. A lot of the time this is over-looked, and can be the culprit for the missfire. It is exposed to moisture, heat, grease, etc. for a very long time, and considering LT1 cars are nearing 14+ years old now, all those elements take a toll on electrical connectors.
Pull your plugs and check them. Make sure they're all gapped properly. Use a little bit of dielectric grease on the inside of the plug wire boots to help keep moisture out, and assist with connectivity with the plugs.
If you've got the time and patience, it probably wouldn't hurt to check the adjustment of your rockers and ensure that they are at zero-lash with the proper pre-load.
You also might want to take a look at the harness that goes along the passenger side of the intake manifold, and down behind the water pump where it plugs into the opti. A lot of the time this is over-looked, and can be the culprit for the missfire. It is exposed to moisture, heat, grease, etc. for a very long time, and considering LT1 cars are nearing 14+ years old now, all those elements take a toll on electrical connectors.
Pull your plugs and check them. Make sure they're all gapped properly. Use a little bit of dielectric grease on the inside of the plug wire boots to help keep moisture out, and assist with connectivity with the plugs.
07-26-2007, 03:17 PM
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the misfire will be right around 3k RPM's. I have looked at the harness and it seems to be okay, checked and double checked all of my plugs and wires and it still runs crappy. It will idle fine but when i go to accellerate it will be really slow and take a while to get any power to it and it will pop like crazy.
07-26-2007, 03:21 PM
#20
Originally Posted by transambandit
the misfire will be right around 3k RPM's. I have looked at the harness and it seems to be okay, checked and double checked all of my plugs and wires and it still runs crappy. It will idle fine but when i go to accellerate it will be really slow and take a while to get any power to it and it will pop like crazy.
