PCM Diagnostics & Tuning HP Tuners | Holley | Diablo

Will poor tuning cause random misses?

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Old Oct 24, 2014 | 03:45 PM
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Default Will poor tuning cause random misses?

LQ4 L92 and got a mail order tune, not sure how good it is
truck is running lean, i do not have wideband to hook up to get it more fine tuned.
truck has random missfires and then sometime cyl. 6 will have a dead miss. going to swap injectors over and see if the miss follows it
but will poor injector scaling maf and map scaling cause it to miss?

also noticed a wire on bank 1 o2 sensor that was worn thru so im going to solder that and see if it helps at all, it thru a code once and only once.

thanks in advance

I have EFI and have the tine file if anybody would want to glance at it and see if it is close for a rough tune or **** is way off?
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Old Oct 24, 2014 | 05:09 PM
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well i spliced a wire on driver side o2 sensor with no change.
#6 misses frequently and when it does its dead, coil plug and wire are good. #2 misses a decent amount and then 4 and 8 miss some. so its subject to one side. at like 2k rpm there isnt much of a miss, if you pop the throttle 100% it kackles some and then goes.
going to swap #6 injectors and see if miss follows, also before that change 02 sensor.

Im only running fron o2 sensor and no cats, currently just open headers. afr was something like like 15-1 according to EFI Data at 80% throttle.
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Old Oct 25, 2014 | 07:46 AM
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Running it that lean @ WOT is a good way to fry something.
The random miss issues could be tied to the lean condition.
Also, if the headers have the O2's near the end of the collectors, you may be getting bogus O2 input. Put some pipes on it.
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Old Oct 25, 2014 | 08:28 AM
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ok i never thought about that on the o2 sensors, they are set in about 4"s
going to swap injectors around and see if it follows
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