long term fuel trims, what are yours
#1
long term fuel trims, what are yours
I've been looking at my fuel trims while fixing the bank 1 lower O2 sensor.
At idle mine are;
Bank1 ~6%
Bank2 ~0%
However I have no idea if this is typical, due to normal wear and tear, a failing O2 sensor, weak injector or vacuum leak, so thought it would be good to compare to a few other cars.
At idle mine are;
Bank1 ~6%
Bank2 ~0%
However I have no idea if this is typical, due to normal wear and tear, a failing O2 sensor, weak injector or vacuum leak, so thought it would be good to compare to a few other cars.
#2
Join Date: Apr 2012
Location: Summerville, South Carolina
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#3
Join Date: Apr 2012
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Found this previous thread on fuel trims with some good info - specifically should take when engine is warm - took mine when not quite at operating temps. I have a few errands to run later so will take a second set and post
https://www.jaguarforums.com/forum/x...-trims-109508/
https://www.jaguarforums.com/forum/x...-trims-109508/
Last edited by sklimii; 02-01-2014 at 09:29 AM.
#5
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#6
Join Date: Apr 2012
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#7
My last test in park was LTFT1=3.1 & LTFT2=7.8 and at 2500 RPM LTFT1=3.1 & LTFT2=3.9. You may want to compare your trims with the attached chart but before doing this do a hard reset and drive the car for about 20 to 30 mi. At the end of that drive do your test and record your results then do it again at around 50 mi. and see what you come up with. Note do your test outside in an open area. When you do it for the first time you will understand why!
Link JagRepair.com - Jaguar Repair Information Resource
Link JagRepair.com - Jaguar Repair Information Resource
I've been looking at my fuel trims while fixing the bank 1 lower O2 sensor.
At idle mine are;
Bank1 ~6%
Bank2 ~0%
However I have no idea if this is typical, due to normal wear and tear, a failing O2 sensor, weak injector or vacuum leak, so thought it would be good to compare to a few other cars.
At idle mine are;
Bank1 ~6%
Bank2 ~0%
However I have no idea if this is typical, due to normal wear and tear, a failing O2 sensor, weak injector or vacuum leak, so thought it would be good to compare to a few other cars.
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#8
LTFTs about the same and reduce also about the same: classic sign of an air leak. Can't be very big as no codes and LTFT only 14-ish. I'd go hunting for it but up to you.
#9
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Mr. Feathers (02-03-2014)
#12
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I gathered together some odds and ends.
This container has two sealable lids but it is not critical, I used heat glue (faster than epoxy which would be better) to fit the tubes to the two lids and a cigarette was pushed into the tube.
One end goes to a pump used to blow up camp beds powered from the cars 12 volt outlet and the other goes to a tin can which had a bicycle tyre valve glued into it, I drilled out the valve from the body.
I butchered an old battery powered drill to make a "day light" torch for paintwork inspection and this will be handy to use to identify any pufs of smoke. The halogen lamp I used is 12 volt but goes super bright at 18volts.
This is the camp bed pump I used, however it is too powerful as it burned out the cigarette in about 10 seconds, I will rig it up to a lower voltage power supply so it lasts a bit longer.
This container has two sealable lids but it is not critical, I used heat glue (faster than epoxy which would be better) to fit the tubes to the two lids and a cigarette was pushed into the tube.
One end goes to a pump used to blow up camp beds powered from the cars 12 volt outlet and the other goes to a tin can which had a bicycle tyre valve glued into it, I drilled out the valve from the body.
I butchered an old battery powered drill to make a "day light" torch for paintwork inspection and this will be handy to use to identify any pufs of smoke. The halogen lamp I used is 12 volt but goes super bright at 18volts.
This is the camp bed pump I used, however it is too powerful as it burned out the cigarette in about 10 seconds, I will rig it up to a lower voltage power supply so it lasts a bit longer.
Last edited by RaceDiagnostics; 02-03-2014 at 03:39 PM.
#15
I've not tried the smoke machine yet, I'll do that at the weekend, but had another look at the fuel trims. Something I did notice was that the lights and A/C made a noticeable difference to the MAF, so for anyone doing some comparative testing it is best to ensure these are off.
After a 20min drive, in Park, ~ 650rmp, MAF = 4.36g/s, LTFT1 1.56, LTFT2 -1.56 but the trims drifted over the next 5 mins up to LTFT1 7.8, LTFT2 4.48 and then stayed there.
Moving into Drive only changed the RPM down to 600 and the MAF up to 4.73g/s, not too surprising as the engine was now slightly loaded.
At 2500rpm in Park the MAF went to 13.5g/s, LTFT1 8.56, LTFT2 6.24.
After a 20min drive, in Park, ~ 650rmp, MAF = 4.36g/s, LTFT1 1.56, LTFT2 -1.56 but the trims drifted over the next 5 mins up to LTFT1 7.8, LTFT2 4.48 and then stayed there.
Moving into Drive only changed the RPM down to 600 and the MAF up to 4.73g/s, not too surprising as the engine was now slightly loaded.
At 2500rpm in Park the MAF went to 13.5g/s, LTFT1 8.56, LTFT2 6.24.
#16
hi
that's my thread referenced early on, thought I'd add to the end of this section as well. I think I have a problem with bank 1:
IDLE:
Mass air flow rate 4.75
ST Bank 1: 5.4
ST bank 2: 0.78
LT Bank 1: 19.53
LT Bank 2: 7.82
2K revs:
MAF rate 16.35
ST bank 1: 12.5
ST bank 2: 2.34
LT bank 1: 13.2
LT bank 2: 12.5
From what I've read, LT trims under 10% are pretty normal. Around 20% is not! I'm interested to see how this smoke machine turns out.
I have an 02 sensor about to go in; will be a week or two before I can test it as I've got the car up on jack stands for some body work. Good luck with your leak hunt!
that's my thread referenced early on, thought I'd add to the end of this section as well. I think I have a problem with bank 1:
IDLE:
Mass air flow rate 4.75
ST Bank 1: 5.4
ST bank 2: 0.78
LT Bank 1: 19.53
LT Bank 2: 7.82
2K revs:
MAF rate 16.35
ST bank 1: 12.5
ST bank 2: 2.34
LT bank 1: 13.2
LT bank 2: 12.5
From what I've read, LT trims under 10% are pretty normal. Around 20% is not! I'm interested to see how this smoke machine turns out.
I have an 02 sensor about to go in; will be a week or two before I can test it as I've got the car up on jack stands for some body work. Good luck with your leak hunt!
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