Misfiring issue

Smokinhot

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I'm constantly getting P0300. I've got new tr55's in, I've tried swapping between my MSD wires and the stock ones to see if it was a wire issue and it doesn't seem to be. I'm thinking maybe a coil?

Is there a misfire config for the HPT scanner someone has I can use to try and log which cylinder is misfiring?
 

6literEat'r

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is it actually misfiring, can you feel a misfire? or is it because of the cam..because an aftermarket cam will set this code.
 

SleeperLS

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Hpt has that parameter when you scan. Go into your scanner and open up the table that just has the grid type display( not the gauge or line chart ones). Click on add a parameter and go to engine i believe. There should be the option to scan for each cylinder misfire 1-8 in your case. Add every cylinder and see what you get. That will isolate which cylinder is misfireing if it is a misfire.
 

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is it actually misfiring, can you feel a misfire? or is it because of the cam..because an aftermarket cam will set this code.
Yea I can feel it. It's got a little stutter/stumble at idle, I can't really tell much in drive but if I clear the code it will come back while I'm driving. I've tried raising the idle a bit, thought maybe it was to low. But I've had it at like 850 and it's still there. :dunno:

Hpt has that parameter when you scan. Go into your scanner and open up the table that just has the grid type display( not the gauge or line chart ones). Click on add a parameter and go to engine i believe. There should be the option to scan for each cylinder misfire 1-8 in your case. Add every cylinder and see what you get. That will isolate which cylinder is misfireing if it is a misfire.
Thanks, forgot about that. I just changed a config :bigthumb:

My misfire codes are still active, but all I get is general P0300
 

SleeperLS

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Nice! Post us up an update on what you find. Since the code is fireing it should show you the cylinder that is acting up
 

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Just started it up, and cylinder 3 seems to be the issue. 128 counts... I have a spare coil i'm gonna try
 

SleeperLS

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I had a crazy misfire issue years ago and it ended up being a bad ICM i think. Maybe you have the same issue with your module?
 

Smokinhot

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It has to be something in the tune. Misses at idle or under 1200, but not while under load... Lol
 

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I really need to proof read when i use tapa. I fat finger the hell out oh keys :doh:
 

SleeperLS

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Haha that is odd. You have had your truck running for a while i thought. Did you get a new tune? I fat finger the shit out of my iphone. I know where you are coming from.
 

6literEat'r

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It has to be something in the tune. Misses at idle or under 1200, but not while under load... Lol
lol, i guess youll be ok then at the track...

fyi, i had a misfire at idle only................







chipped piston on #7
 

Smokinhot

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Haha that is odd. You have had your truck running for a while i thought. Did you get a new tune? I fat finger the shit out of my iphone. I know where you are coming from.
Yea, my brother just went through it a bit to smooth it out with the new parts. There has to be something in the idle settings that's doing it though. The other cam did it too, but its a little rougher with this one

lol, i guess youll be ok then at the track...

fyi, i had a misfire at idle only................







chipped piston on #7
pistons looked good when I had the heads off.
 

6literEat'r

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dosent mean it couldnt of happened from detonation while you were driving after you put the engine back together..exact thing happened to me

rockers tight?
swap injectors around?
 

SleeperLS

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Since he just tinkered a bit then i would lean toward that. Did the new cam feel like this before he messed with the tune? What is the afr at idle? Could be idleing rich. I did think about what 6litre is saying, might be onto something if it is a new cam and some valvetrain crap didnt work as planned.
 

HILROD

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Non stock cams will cause this. The stock tune just gets mad 'cause it don't know lope. Ha, touch up the idle and off idle tune, it should be fine.
 

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