Erratic patterned STFT at idle

Chmilar · 10-22-2018, 10:28 PM

This is a pic of my STFT at idle. Goes to +6 to -3 and back again up and down and repeats this over and over . It never use to do this before . Any ideas what would cause the trim to do this ... and in such a pattern?

dpark · 10-22-2018, 11:02 PM

Quote:

Originally Posted by Chmilar

This is a pic of my STFT at idle. Goes to +6 to -3 and back again up and down and repeats this over and over . It never use to do this before . Any ideas what would cause the trim to do this ... and in such a pattern?

Have you tried cleaning your MAF sensor? Checked for leaks along the intake?

Otherwise could be a dirty/faulty o2 sensor. Have you scanned for codes?

Chmilar · 10-22-2018, 11:06 PM

Quote:

Originally Posted by dpark

Quote:

Originally Posted by Chmilar

This is a pic of my STFT at idle. Goes to +6 to -3 and back again up and down and repeats this over and over . It never use to do this before . Any ideas what would cause the trim to do this ... and in such a pattern?

Have you tried cleaning your MAF sensor? Checked for leaks along the intake?

Otherwise could be a dirty/faulty o2 sensor. Have you scanned for codes?

no codes. maf was cleaned 2 months ago. I'll try cleaning again. o2s are original from when car was made and did a boost leak check and all is good

dpark · 10-22-2018, 11:57 PM

How's your rail pressure?

Only other things I can think of are vacuum leaks, faulty injectors (dirty or leaking), or exhaust leaks pre-sensor

juld0zer · 10-23-2018, 01:28 AM

Wobbly crank?
What sort of timeframe does it occur in?

Eg. 5x in 10s?

10-22-2018, 10:28 PM	#1
Chmilar Enlisted Member 14 Rep 43 Posts Drives: 2011 335xi FBO Join Date: Jan 2018 Location: Vancouver iTrader: (0)	Erratic patterned STFT at idle This is a pic of my STFT at idle. Goes to +6 to -3 and back again up and down and repeats this over and over . It never use to do this before . Any ideas what would cause the trim to do this ... and in such a pattern? Attached Images
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10-22-2018, 11:57 PM	#4
dpark Private First Class 11 Rep 105 Posts Drives: BMW 335i E92 Join Date: Feb 2012 Location: Sydney, NSW iTrader: (0)	How's your rail pressure? Only other things I can think of are vacuum leaks, faulty injectors (dirty or leaking), or exhaust leaks pre-sensor
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10-23-2018, 01:28 AM	#5
juld0zer Lieutenant Colonel 480 Rep 1,600 Posts Drives: Prev 135i 7DCT, Now 130i 6sp Join Date: Jul 2016 Location: 2153 iTrader: (0)	Wobbly crank? What sort of timeframe does it occur in? Eg. 5x in 10s?
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