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TrailblazerSS
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Discussion Starter #1
As stated in the topic. I have a 06 with 90k on it. I'm getting a p0300. Things I have done.

Replace plugs and wires
Gm wires
T5 plugs set at .40
Cleaned MAF

When I look at my data history with my snap on scanner I'm getting history on 5 and 8. I have swapped ignition coil packs and injectors around to see if the misfire would move cylinders. It does not.

My biggest issue with this code popping up is that the converter won't lock when it is preset. I'm worried about the heat in the trans from a converter not locking.

Dumb question. But if I go in with efi live and turn the mil off for p0300. Will it still cause the converter to unlock with the ecm not looking for this mil?. I know it doesn't fix the problem. I just leave for vaction tomorrow and don't want the trans to over heat.

Btw the car fun smooth doesn't feel like it is missing at all. And if I want live data. I don't get and recorded misfire on 5 and 8 till I reach 1500 rpm

Any input is appreciated. Thanks
 

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secret squirrel
TrailblazerSS
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1,280 Posts
bad lifters..they are bleeding down. get the new ls7 lifters. remove, replace, have a beer. done.:burp:

edit: dont forget to get new lifter buckets. cheap insurance.
 

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Premium Member
TrailblazerSS
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1,957 Posts
double check plugs and wires on those cylinders.. replacing lifters, if bad is not the easiest job and is not a common problem. It would be accompanied by a distinct ticking noise also.. It still sounds like something electrical/spark wise. DId u replace all those things mentioned to try and fix this problem? or did it happen after you replaced those things?
 

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TT AWD TBSS Jeep
TT AWD SS Pwrd Jeep
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5,825 Posts
Is it a higher stall converter. If it is, have your tuner change the misfire tables. The new stall changes the crank harmonics and the ECM interpets this as misfire. Simple adjustment to a common problem. It also explains why you are not feeling the misfire.
 

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TrailblazerSS
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Discussion Starter #5
As far as I know it is a completely stock car. I replaced plugs. Wires cleaned maf. And still have p0300. I'm going to check compression soon. And no noticeable tick as in lifters.

I want to get the misfire fixed before I start modding the car
 

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TrailblazerSS
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that is random misfire right? mine has about 87 or 88k on it and cats were clogged. i got this code and tuned it out but eventually started getting the flashing cel. finally put high flows on problem solved.
 

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TrailblazerSS
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I've heard of a p0300 being caused by a cracked cylinder head. A guy I know was throwing money at his truck left and right and that's what it ended up being. A compression test should reveal what's going on.
 

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Discussion Starter #9
I've heard of a p0300 being caused by a cracked cylinder head. A guy I know was throwing money at his truck left and right and that's what it ended up being. A compression test should reveal what's going on.
Plan on doing a compression test next weekend. Did he have any coolant loose?
 

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Sry it's been so long work has been crazy for me. No coolant loss just the p0300 code. Did u get the compression test done?
 

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Discussion Starter #11
I did some searching a seen that a guy with a gto had the same issue I was having. 5 and 8. He had a faulty cam sensor.

I figured hell for $30 it's worth a shot. Did the cam sensor and a CASE learn. Been good ever since
 
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