Occasionally backfiring? Anyone else have this?

T

TopherSho

New member
Have not been able to log it yet.. but 1:10 wot runs from first gear through second result in a small single backfire. Then shift.  It occurs RIGHT BEFORE the shift and NOT during the shift.  It feels like a rpm overrun.. but it is not in my observation overreving ..

Thoughts (yes emailed Brad)
 
I would check your spark plugs or COP or your CAC (intercooler) to make sure its not pooled with crud.
Did you happen to check for Codes?  Z
 
ZSHO said:
I would check your spark plugs or COP or your CAC (intercooler) to make sure its not pooled with crud.
Did you happen to check for Codes?  Z
Click to expand...

Na no code checking.  But I will now that you mention it. 
 
Not common on this platform at all... I have not run across it on the forums...

Usually a timing issue... but could be a fouled plug or COP... check a log for misfires, pull the plugs (all of them) and check for issues.

Z has a good idea with the CAC... but as much as your on it, I’m sure the CAC has been cleared out by now lol.
 
StealBlueSho said:
Not common on this platform at all... I have not run across it on the forums...

Usually a timing issue... but could be a fouled plug or COP... check a log for misfires, pull the plugs (all of them) and check for issues.

Z has a good idea with the CAC... but as much as your on it, I’m sure the CAC has been cleared out by now lol.
Click to expand...

I think it is a timing issue as well, interestingly i have been hard on it all week data logging and have not had it happen.  But when it did happen it was with the wife in the car + groceries .. so it might be load + high rpm + timing related. 

No codes were found .. but it has been at least 10 power cycles since the last !bang!
 
Is this happening on meth with meth tune, last I recall you were running meth full time?  If it is happening when you are spraying I would disable the meth system and run a non-meth tune and see if it still happens.

If it goes away completely then time to look at meth system for issues.  Could be tune related, but highly doubtful knowing Brad and the fact that tune ran fine for quite a while.

Did it all happen on a single tank of fuel?  or on sequential tanks both filled from a single station in a short amount of time?  Maybe bad fuel?
 
It could be that concocted pale of Methanol you purchased IIRC.  Z
I would verify its the real-deal IMO.
 
Well to answer several Q's. The meth is pure VP in thier can.  No mixxing at all.

No codes so far

Boost looked ok. 

Have not pulled the plugs.. but they are less than 10k old

Meth rev3 did not do it.. but it was WARMER then

I think this is cold weather + load in weight + high rpm... But just need to catch it in the act to know more..
 
Did you see an actual misfire in your log?

An unhappy shift setting can cause all kinds of mayhem.

I guess a better question is are you feeling it or hearing a big boom?

If so could it be you are missing an intermittent shift and ecm starts shutting down cylinders but your meth doesn't know?

 
It feels the same as when I derp it and forget to shift in manual mode :).  You can hear it a d feel a tiny thump bang. 
 
Sometimes a TSS/OSS sensor or a solenoid body or even a trans range sensor issue can be responsible.  You can easily track with the X4.  When was trans fluid last changed btw?
 
SHOdded said:
Sometimes a TSS/OSS sensor or a solenoid body or even a trans range sensor issue can be responsible.  You can easily track with the X4.  When was trans fluid last changed btw?
Click to expand...

sadly never.  no-one in town wants to touch it.. i have 3 years on a platinum warranty so i am prepped for a full on replacement eventfully.
 
TopherSho said:
SHOdded said:
Sometimes a TSS/OSS sensor or a solenoid body or even a trans range sensor issue can be responsible.  You can easily track with the X4.  When was trans fluid last changed btw?
Click to expand...

sadly never.  no-one in town wants to touch it.. i have 3 years on a platinum warranty so i am prepped for a full on replacement eventfully.
Click to expand...
Wait, you can't find anyone to do a simple drain and fill?
 
I have decided to turn off the meth for now.  It is too cold and I am wondering if the issue is the meth not vaporizing..  at 375ml maybe I am getting wet in the cylinder but not enough to misfire.  Weather in Oregon is moist as hell and cold so I am betting the meth is wasted a bunch as is .. bummed out.
 
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