Misfire

Lucas Higdon

Lucas Higdon

Greenie N00B Member
Misfire when Decelerating, cant notice lack of power, chanced spark plugs, gapped coils, no stalling , no weird rpm jumps or stalls at idle, only thing is, at wot afr hangs around 13ish on accessport, hpfp readings are normal too
 
Lucas Higdon said:
Misfire when Decelerating, cant notice lack of power, chanced spark plugs, gapped coils, no stalling , no weird rpm jumps or stalls at idle, only thing is, at wot afr hangs around 13ish on accessport, hpfp readings are normal too
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Grab a log and upload it here. Don't go to redline at WOT, just something small to demonstrate the behavior.
 
So to clarify, what is making you think there are misfires, are you getting a code? From what I can tell, your AFRs in boost are looking good in the 11s, I don't see anything too wild off the top of my head, except your Long Term Fuel Trims are a bit high indicating a boost leak somewhere, wouldn't hurt to do a simple boost leak test, capping off the valve cover vent port.

On deceleration (in full vacuum) your AFR is going to read 29.25 because there is almost no combustion happening in the cylinder, ergo mega-lean reading, which is expected and normal.

What are your mods?
 
jdab555 said:
So to clarify, what is making you think there are misfires, are you getting a code? From what I can tell, your AFRs in boost are looking good in the 11s, I don't see anything too wild off the top of my head, except your Long Term Fuel Trims are a bit high indicating a boost leak somewhere, wouldn't hurt to do a simple boost leak test, capping off the valve cover vent port.

On deceleration (in full vacuum) your AFR is going to read 29.25 because there is almost no combustion happening in the cylinder, ergo mega-lean reading, which is expected and normal.

What are your mods?
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Yes ever so randomly im getting a p0300 code, I changed my spark plugs 3 weeks ago code went away, well I fucked a plugged up cause it started idling funny got another p0300 , changed the plugs 3 days ago, misfire is back and more consistant than ever, and Its hard for me to tell if the engine is acting rough cause I have all bolt on mounts, so im constantly vibrating.
Cobb rmm
Jbr pass and trans mount
Autotech hpfp internals
Corksport 3 inch sri, i have the new turbo pipe just have not installed and thats about it
 
Lucas Higdon said:
Yes ever so randomly im getting a p0300 code, I changed my spark plugs 3 weeks ago code went away, well I fucked a plugged up cause it started idling funny got another p0300 , changed the plugs 3 days ago, misfire is back and more consistant than ever, and Its hard for me to tell if the engine is acting rough cause I have all bolt on mounts, so im constantly vibrating.
Cobb rmm
Jbr pass and trans mount
Autotech hpfp internals
Corksport 3 inch sri, i have the new turbo pipe just have not installed and thats about it
Click to expand...

Are you tuned by someone other than a Cobb OTS? A larger than stock MAF (2.5" is stock size) has to be tuned for or the car either won't run or will run like shit. Plug gap should be at .026 to .028 max, unless otherwise stated by your tuner.
 
jdab555 said:
Are you tuned by someone other than a Cobb OTS? A larger than stock MAF (2.5" is stock size) has to be tuned for or the car either won't run or will run like shit. Plug gap should be at .026 to .028 max, unless otherwise stated by your tuner.
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No i just use cobb stage 0 tune, and I had the plugs gapped to .28 by a bud at advanced cause i didnt wanna fuck them up
 
Lucas Higdon said:
No i just use cobb stage 0 tune, and I had the plugs gapped to .28 by a bud at advanced cause i didnt wanna fuck them up
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If you are sure your SRI is a 3", you need a tune. Your car won't be able to understand the airflow past the MAF without a recalibration. Do you still have your stock airbox? Try swapping that back on.
 
jdab555 said:
If you are sure your SRI is a 3", you need a tune. Your car won't be able to understand the airflow past the MAF without a recalibration. Do you still have your stock airbox? Try swapping that back on.
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No I dont have the stock airbox, but Ive had that same intake since Ive bought the car and 5 months ago and it never caused misfires for the first 2-3 months so I dont think that could be it, however I managed to catch a misfire on two logs, the logs i uploaded last night never threw a code during the log, im gonna upload these 2 new logs maybe you see somthing different.
 

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