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Misfire under load (sometimes)


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Hey everyone,

I've done an Na+t conversion in my ba falcon, its got a greentop in it (stock atm). I'm currently tuning it myself through pcmtec, I've been slowly refining the tune and getting it good but a little stuck in this one area. It appears that it will misfire underload, to be more specific, this happens generally at 3000rpm when the throttle position is >400, though it can happen really at any time if I step on it hard enough. Since tuning my btr, this issue seems to disapppear after about 15 minutes of driving, though sometimes the issue comes back after a while. Some leaning out of the fuel has improved this issue, though I'm still having this issue at 12ish afr. Please let me know if theres more information I can provide. Apologies for the poor explanation. 

Cheers

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1 minute ago, abs351 said:

Data log the car to see its error .

The odd thing is, datalogger doesn't really show anything out of the ordinary? Like it doesn't look to be pulling out excessive timing or anything.

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1 minute ago, MemeMachine said:

The odd thing is, datalogger doesn't really show anything out of the ordinary? Like it doesn't look to be pulling out excessive timing or anything.

what's the torque source doing when it happens?

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tourque souce in the log, when its at 1 the pcm is thinking everything is great and will be trying to do whatever you ask it to.
if its lower than than something is requesting the car to pull tourque. some requests can be cylinder cut and sound like a missfire.

just make sure its not that also.

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1 minute ago, BeerTurbo said:

tourque souce in the log, when its at 1 the pcm is thinking everything is great and will be trying to do whatever you ask it to.
if its lower than than something is requesting the car to pull tourque. some requests can be cylinder cut and sound like a missfire.

just make sure its not that also.

That sounds like it could be the source of my problem. Tuning the trans changed everything, which i thought was odd. I'll look into it cheers.

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So, update. It all seems fine, I'm thinking it could be related to my timing, though when it happens the pcm doesnt seem to be pulling out much/any timing? It's so odd this issue, in the same drive it can be going like shit as soon as i hit 300ish on the TPS and then 5 minutes later its going well and then after another 10 minutes its back doing what it was (with no obvious causes in the datalog). 

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