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at least i get good parking
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So i am having the exact same freakin problem. except i have LT and no cats is one of my only mods, but i have alot of black smoke and crappy driving.

I just swtch out my plugs, didnt help a bit, so i guess wires are next.

Oh and my codes are ( random misfire, and bank 1 and 2 are lean)
clean mass air for lean codes and also check for vac leaks and if you can check whats your stft at stft is whats happening now and ltft is whats been happening
 

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Kal,my cats were bad so I replaced with Kooks headers and cats,1400$,my problem is going on ,not the miss fire but the crank positioning sensor,I had 2 replaced back to back,my car wont stay running so I cant get it returned,she is at the tuners.I have less than 25000 miles and my cats were shot....I only have bolt ons,ported in take,polished throttle body,KN air,MSD wires,160 stat,Kooks system with Magnaflows,Billet shifter,Dont know how she sounds and shifts or even run yet.........
Sorry to hear that man,

I've haven't come across the problem with the crank sensor... yet. I'm hoping a new cat will work. I don't plan on upgrading to headers yet b/c of cost. Even tho my car is a salvage veichle its still under warranty for emissions which includes cats... so i can't beat free.99 :) ha ha.

Good luck with your car. Let us know what you find out.
 

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Finally got a Goat
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Dealer is not really sure why the car was missfiring but they replaced the front pass o2 sensor and found out the cat is plugged so they replaced that and the car is running fine now.
 

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Car has 15k miles on it, sometimes it will happen after 30 minutes of driving, sometimes I can drive it for 2 hours straight and not have it happen.


Randomly the check engine light will start flashing and there is definately something not right with the car when that happens, feels underpowered, sounds like it's breaking up, a misfire.

Usually after 15-20 seconds, the light will stop flashing and the car will quit acting like it's misfiring terribly, but it has not felt quite right since this first happened 3 days ago.

The last time that it happened, the light was flashing, the car felt like crap, and then all of a sudden the light stayed solid, so I hooked up my scanner and pulled the code, Cylinder 7 Misfire.I


Turned the car off for about 30 minutes, started it again, CEL was off.

It has done it probably 6 times the last couple days, it has never stayed solid again though, blinks for 15-20 seconds, feels like crap, goes away.


Any ideas? I would assume spark plug and/or wire but I haven't had a car that did this randomly, usually when I've had a spark plug/wire go bad it was constant until they were replaced.


Thanks in advance.
Kal, are you still having the same problem?In my case my pax side cat was bad,I replaced with Kooks system, no more code,CPS problem I was having is no longer, bad ECM,dealer fixed no cost,had the tune done at AD.366.96HP,365.30 Torque..Good Luck..
 

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Kal, are you still having the same problem?In my case my pax side cat was bad,I replaced with Kooks system, no more code,CPS problem I was having is no longer, bad ECM,dealer fixed no cost,had the tune done at AD.366.96HP,365.30 Torque..Good Luck..
I haven't got it fixed yet... The dealer seems to be draging there feet. It took a week for them to get the cat and then they told me it was "cracked" and they need to order another one. Its now been 2 weeks and i haven't driven the car since... its driving me crazy! :)

Kal
 

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FYI

I finally got my cat replaced and it feels like that was the problem. The car now pulls all the way to redline and isn't doggie. Also, no check engine light. :)

Hope this helps someone!

Kal
 

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I deserve to be BLOWN!!!
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Thanks for posting back.

Sucks when you're searching thru threads that never have closure
 

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To all,my car is finally running great,the dealer found 2 groung wires on the back of each head that were loose causing all the problems,car dynoed at 366 HP 365 Torque. my cats were bad,replaced with Kooks headers and cats,no more miss fire codes.I had 2 crank case pos sensors change,1 ECM......
 

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Discussion Starter #50 (Edited)
I've had my car to the dealer 4 times and it's still happening, I've had a lot of fun with it.

1st time- They claim the hose connected to the throttle body was loose so they tightened it and it was resolved.

2nd time - They ran fuel injector cleaner through it and did an "injector balance test" and claimed it was resolved

3rd time - They replaced the fuel pump, spilt fuel inside the car so it smells awesome, and claimed that injectors 3 and 7 were "plugged" and now it was resolved

4th time - Took it back an hour after i picked it up, service manager was able to get the Tech 2 hooked up and logging. Was lucky enough to have the car doing its misfiring while idling in the parking lot. The Tech 2 was showing Cylinder 7 misfire counts of 100+, when revved the counts would go higher and then the other 7 cylinders would get a few counts. Then the misfires just stopped for about 10 seconds, Tech 2 was reading 0 misfire counts on all 8, and then they started again, the car was never turned off or moved, just revved a bit in neutral.

2 days later, they said that an oxygen sensor wasn't getting data back to the ECM fast enough, causing it to lean out the cylinder and make it misfire, and that it needed to be replaced. They replaced the oxygen sensor, and said that it did not fix the problem. They told me that what was happening was that the ECM was receiving signals from all sensors, and then all signal just stops and starts. They then replaced the ECM today and claimed it was resolved.

I picked up the car today, drove it for an hour and it started misfiring for about 30 seconds then went back to normal. Now the car also has a lovely 12" scratch on the passenger side, and the inside still smells of fuel.

Will check into the wires behind the head, harmonic balancer and crank sensor.
 

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I've had my car to the dealer 4 times and it's still happening, I've had a lot of fun with it.

1st time- They claim the hose connected to the throttle body was loose so they tightened it and it was resolved.

2nd time - They ran fuel injector cleaner through it and did an "injector balance test" and claimed it was resolved

3rd time - They replaced the fuel pump, spilt fuel inside the car so it smells awesome, and claimed that injectors 3 and 7 were "plugged" and now it was resolved

4th time - Took it back an hour after i picked it up, service manager was able to get the Tech 2 hooked up and logging. Was lucky enough to have the car doing its misfiring while idling in the parking lot. The Tech 2 was showing Cylinder 7 misfire counts of 100+, when revved the counts would go higher and then the other 7 cylinders would get a few counts. Then the misfires just stopped for about 10 seconds, Tech 2 was reading 0 misfire counts on all 8, and then they started again, the car was never turned off or moved, just revved a bit in neutral.

2 days later, they said that an oxygen sensor wasn't getting data back to the ECM fast enough, causing it to lean out the cylinder and make it misfire, and that it needed to be replaced. They replaced the oxygen sensor, and said that it did not fix the problem. They told me that what was happening was that the ECM was receiving signals from all sensors, and then all signal just stops and starts. They then replaced the ECM today and claimed it was resolved.

I picked up the car today, drove it for an hour and it started misfiring for about 30 seconds then went back to normal. Now the car also has a lovely 12" scratch on the passenger side, and the inside still smells of fuel.

Will check into the wires behind the head, harmonic balancer and crank sensor.
We’re you ever able to figure out what it was? Mine is doing the same thing misfire for about 30 seconds then idles up a tad and clears up tried Erving it to get it to pop a code and it did p0300 random multiple missfire then one time I got it to pop a P0301 cylinder 1 so I put a new coil on it and still does it any info would be greatly appreciated
 
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