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Thread: Misfire cyl #3 HELP!!!!
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03-27-2009, 06:59 AM #1
Misfire cyl #3 HELP!!!!
I drove the vehicle last night - got on the gas - now I have a misfire. I noticed the misfire when I was parking the car and it was idling. I'm having the misfire on cyl #3 only (P303). I drove the car to a friends house nearby and changed some parts around. still has the misfire. Then I'm driving home and the vehicle is stumbling bad and decelerating, I press the gas and the car has no power, then all of a sudden it has power and lost power again. I barely made it into my garage from the lack of power. I changed some more parts around trying to move the problem to a different cylinder, but no luck. I have no cats, so only the pre-cat 02's. Did I maybe screw up an 02 sensor or not have enough fuel pressure?
I've checked everything below
1. coil pack - changed with cyl #1
2. spark plug - changed with cyl #1
3. Compression test - ok
4. Injector - changed with cyl #1
5. Plug wire - checked ohm reading and changed with cyl #1
6. Installed stock tune - no help / reinstalled custom tune
7. Cleaned MAF sensor
checking fuel pressure next and pulling valve cover off. any other ideas?
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03-27-2009, 07:14 AM #2
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blacker than wesleysnipes- 98' trans am
maybe the injector plug..clean off the plug and make sure it has slack
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03-27-2009, 07:15 AM #3
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blacker than wesleysnipes- 98' trans am
but yeah for sure take the vlave cover off and take a look.
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03-27-2009, 07:33 AM #4
Like said above, double check the injector harness and also the 02 harness.
J2001 SS, Its not the car its the Driver that matters....
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03-27-2009, 07:38 AM #5
I can hear the injector firing with a stethoscope, I did an ohm reading on it as well and checked it to another injector. I'm scratching my head on this one a little bit.
I smelled a real faint burning smell last night in the garage also now that I think of it - I'll check the 02 wiring. I remember zip tying it pretty good though - thanks for the help.Last edited by blownh2x; 03-27-2009 at 07:42 AM.
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03-27-2009, 07:41 AM #6
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- Jan 2006
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blacker than wesleysnipes- 98' trans am
the way you discribe it though..sounds like it would be alot more then 1 cylinder misfiring...a possible fueling issue or i also hate to say it..did you check the main injectors plug..the white one with the blue locking thing ? when i removed my intake once i forgot to plug one side in...
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03-27-2009, 07:42 AM #7
- Join Date
- Jan 2006
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- Age
- 36
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- 11,770
blacker than wesleysnipes- 98' trans am
opps never mind about the injector thing..you can hear it spraying
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03-27-2009, 07:49 AM #8
I can unplug inj#3 and vehicle stays the same because of the misfire on that cyl. If I unplug any other inj the vehicle idle changes so I know my prob is with #3 and I also had the P303 code. I don't hear anything going on in the valve train though - at least nothing rattling or out of the ordinary.
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03-27-2009, 07:52 AM #9
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03-27-2009, 08:24 AM #10
Will the valve covers come off pretty easy or is it a pain in the a$$
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03-27-2009, 08:32 AM #11
- Join Date
- Jun 2007
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- Parma Heights, Ohio
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- 34
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SOM- 99 Trans Am
They arent bad. Just take the coil rack off and then you just unbolt it.
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03-27-2009, 09:02 AM #12
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03-27-2009, 09:22 AM #13
swap entire coil packs left to right and see if it moves. If it does, since you already looked at the coil the main coil harness connector is suspect. I have definitely had issues with that before.
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03-27-2009, 09:38 AM #14
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03-27-2009, 06:10 PM #15
Update
OK, so I have a couple of bent push rods, a few rocker arms that are loose in the bearing department, and a electrical connector with some corrosion for the coil packs. I need to fix this problem and hopefully my problem above will go away. I'm thinking about going with 1.8 rocker arms and some chromemoly push rods, what do you think? Anything on sale you know of? I'm buying this weekend. Why are there different lengths of push rods? Is stock length 7.4"?
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03-28-2009, 08:45 AM #16
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- 34
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SOM- 99 Trans Am
stick with stock rockers.. Or if you wanna good stock upgrade use ls7's. not sure on stock length of the rods though.
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03-28-2009, 11:06 AM #17
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