Data Logs! Post them here.

[DocWalt]

Originally Posted by Rezi

Thanks again, DocWalt.

I better leave it as it is now.
Just another small question about those fuel trims.
Negative (-) LTFT means it is pulling fuel so it runs a little leaner?
Positive (+) LTFT means it is adding fuel so it runs a little richer?

Also what i understand. If it shows abnormal high positive (< +10%) LTFT there is probably an exhaust leak.
But if it shows abnormal high negative (< -10%) ..... ?

Searched the forum, but couldn't find anything related to this.
Only if it is within +/- 5% it is considered "good/normal".

Correct. If it's pulling fuel the MAF and O2 signals weren't agreeing exactly with what the ECU thinks it needs to inject based on the tune and it was a tiny bit richer than it needed to be.

It's intended to learn your fuel and exactly how your car behaves. There's always some small variances in how a factory sensor reads or how much fuel injectors flow and the ECU is compensating.

Generally a high LTFT at idle is an exhaust leak since exhaust leaks tend to pull in fresh air between every exhaust pulse at low load when there's minimal backpressure forcing the exhaust out of the leak.

I'm not sure what, if any, issues cause a high negative LTFT.

On my car I had a fairly high negative LTFT but it was clearly the MAF scaling as it was off consistently with zero evidence of exhaust leaks or other issues.

[steve99]

Originally Posted by Rezi

Thanks again, DocWalt.

I better leave it as it is now.
Just another small question about those fuel trims.
Negative (-) LTFT means it is pulling fuel so it runs a little leaner?
Positive (+) LTFT means it is adding fuel so it runs a little richer?

Also what i understand. If it shows abnormal high positive (< +10%) LTFT there is probably an exhaust leak.
But if it shows abnormal high negative (< -10%) ..... ?

Searched the forum, but couldn't find anything related to this.
Only if it is within +/- 5% it is considered "good/normal".

ltft is the amount of correction the ecu is applying to the base fueling in order for the ecu to see the correct afr at the 02 sensor.

if lft is + or minus it does not mean its running rich or lean its just the correction applied at that flow band, ltft correction are done in bands related to flow rates detected by maf sensor so you will see different corrections applied throughout the rpm range as rpm hence air flow changes.

unusually high ltft can indicate intake or exhaust leaks or just that your maf scaling is off due to maybe a leak or an aftermarket intake.

ltft will also vary a bit more arround idle as their will be large changes in intake air temps when idling in traffic or stopping after a track session, as air density changes with temperature.

its pretty normal to see -\-5% or so but if your seeing over 10% then their might be a problem


correct exhaust leaks usually send ltft high positive, o2 sensor sees fresh air and ecu tries to compensate by adding fuel

intake leaks after maf sensor can send ltft high positive as the air bypassing the maf makes car run lean and ecu compensates by adding fuel. on a boosted car may be different as air will escape at leak due boost.

[Rezi]

Thanks, DocWalt & steve99

Now i understand.
You guys are great!

Time to find a "good" catted uel-header

[wangspray]

Originally Posted by DocWalt

I'd check carefully for an exhaust leak if you had that many issues on the 91 tune. Also, it's a little suspicious that the LTFTs are so high at idle on the E85 tune.

Originally Posted by solidONE

Run out this tank and refuel with E85 again. I'm sure the amount of residual petrol as something to say about the fuel trims.

edit: second thought, I think the fuel trims are going the wrong direction for excess petrol.

THis is what happened when I dialed my MAF scale to the first tank of E85: http://www.ft86club.com/forums/showp...&postcount=718

Thanks for the responses guys, I'm hoping it's not an exhaust leak. I just brought it in for some work and had the shop take a look for leaks, which they said everything looked normal.. I'll keep monitoring and hopefully it was just a mix of residual petrol and higher IATs given the weather lately in Socal.

[Rezi]

Hey guys,

did again some logs.

At some point my FLKC was going really crazy and my IAM dropped at 0.88. I really dont know what was going on?

Temperature was 6°C. Coolant/Oil at normal.

It began with 4rd gear at 3800~rpm WOT till 5500rpm.
FLKC showed up at -0.65. Also some little KC. Fuel Trims are looking good.

Also FLKC happened after that at low RPM with 50-60% throttle. It dropped to -1.3.
IAM dropped to 0.88.

log 1: http://datazap.me/u/rezi/wot-high-fl...d?log=0&data=1


At log 2 it started to go away when i was at the highway again. IAM slowly regenerated back to 1. FLKC was at some point positive (+). What does that mean? Did it learned the previous knock?

log 2: http://datazap.me/u/rezi/flkc-goes-p...1?log=0&data=1


At log 3 it was all stable and ok. This what in the city.
Only sometimes AFR dropped to 13.5~ when i was stopping. It only lasted a second and was back to 14.6~ normally.

log 3: http://datazap.me/u/rezi/iam-stable-...c?log=0&data=1

Could somebody please explain me what happened?
Maybe condensation in the fuel tank? (Only about 15litre left. It is in a opened garage.)
Normal that STFT peaks sometimes to +10%/-7% ?
LTFT looked good. In city it was more in the + then negative like on the highway. So thats also normal?
Stage 1 91oct w. 98RON fuel

Sorry about that long wall of text. Was really nervous when i saw that FLKC and IAM going down

[cawith]

Hi guys,

Background info: My car is a mostly stock european GT86 running A00G - mods are CNT UEL catless header, drop in HKS filter and OFT.

I've been running Wayno's 98oct v97.AU.rich with a few changes which are the following: MAF scale is OTS stage 2 UEL, changed Load Limit at 3800 rpm to 1.15, and the throttle tip-in enrichment for smoother of the line.

I did some WOT logs yesterday, two 2nd gear logs and three 3rd gear logs, and found that the lean lump I had around 3500-4200 rpm is mostly gone after I changed the Load Limit tables at 3800 rpm.

However I found that generally I'm running quite rich above 4400 rpm and very rich above 5500 rpm.
Funny thing though in all the logs the AFR is almost spot on in the range of 6200-6500 rpm and thereafter go very rich again.

Now how do I approach this the best way?
Should I first try to lower Load Limit tables at 4000 rpm (which is the highest rpm) from 1.40 to 1.30?
Common for all logs is that above 7000 rpm the LTFT suddenly climbs from a constant -3.12% to +1.56%. Could that be due to PI kicking in with 20% above 7000 rpm? Should I do something about that?

Should I try to apply other MAF values from 3.2V and upwards only - and if so should I then try one of Wayno's tables or do the OL MAF scaling myself? I haven't done MAF scaling before, so I'm not that familiar with the MAF scaling tool.

My fuel trims are generally really good - within +/- 3% in CL with the exception of a slight lean region at 1.7V, which I typically see when driving at 50 km/h in 5th gear with LTFT and often being at +5%. I guess I should just change a cell or two around that spot to fix it.

Here are my logs, done in the posted sequence and all done within 10 minutes:

2nd gear - 1st run

3rd gear - 1st run

3rd gear - 2nd run

3rd gear - 3rd run

2nd gear - 2nd run


Regarding knock, I didn't have much knock during these runs. Only time was during the last 2nd gear run, where knock correction was -0.69 below 3000 rpm. I mostly experience knock during daily driving at tip-in in CL with rpm below 3000 rpm, and it's mostly FLKC at -0.29 and sometimes Knock Correction up to around -1.0 but only for a short while.
Would you say that this is inevitable? My IAM always stays at 1.


Thanks for reading my long post - hope you can help me!

[steve99]

Originally Posted by cawith

Hi guys,

Background info: My car is a mostly stock european GT86 running A00G - mods are CNT UEL catless header, drop in HKS filter and OFT.

I've been running Wayno's 98oct v97.AU.rich with a few changes which are the following: MAF scale is OTS stage 2 UEL, changed Load Limit at 3800 rpm to 1.15, and the throttle tip-in enrichment for smoother of the line.

I did some WOT logs yesterday, two 2nd gear logs and three 3rd gear logs, and found that the lean lump I had around 3500-4200 rpm is mostly gone after I changed the Load Limit tables at 3800 rpm.

However I found that generally I'm running quite rich above 4400 rpm and very rich above 5500 rpm.
Funny thing though in all the logs the AFR is almost spot on in the range of 6200-6500 rpm and thereafter go very rich again.

Now how do I approach this the best way?
Should I first try to lower Load Limit tables at 4000 rpm (which is the highest rpm) from 1.40 to 1.30?
Common for all logs is that above 7000 rpm the LTFT suddenly climbs from a constant -3.12% to +1.56%. Could that be due to PI kicking in with 20% above 7000 rpm? Should I do something about that?

Should I try to apply other MAF values from 3.2V and upwards only - and if so should I then try one of Wayno's tables or do the OL MAF scaling myself? I haven't done MAF scaling before, so I'm not that familiar with the MAF scaling tool.

My fuel trims are generally really good - within +/- 3% in CL with the exception of a slight lean region at 1.7V, which I typically see when driving at 50 km/h in 5th gear with LTFT and often being at +5%. I guess I should just change a cell or two around that spot to fix it.

Here are my logs, done in the posted sequence and all done within 10 minutes:

2nd gear - 1st run

3rd gear - 1st run

3rd gear - 2nd run

3rd gear - 3rd run

2nd gear - 2nd run


Regarding knock, I didn't have much knock during these runs. Only time was during the last 2nd gear run, where knock correction was -0.69 below 3000 rpm. I mostly experience knock during daily driving at tip-in in CL with rpm below 3000 rpm, and it's mostly FLKC at -0.29 and sometimes Knock Correction up to around -1.0 but only for a short while.
Would you say that this is inevitable? My IAM always stays at 1.


Thanks for reading my long post - hope you can help me!

Looks like all you need is to adjust the OL maf scaling over 3.2 v

either calcualte the values manually of use the vgi utility

[cawith]

Originally Posted by steve99

Looks like all you need is to adjust the OL maf scaling over 3.2 v

either calcualte the values manually of use the vgi utility

If I was to calculate it manually, should I then look at each cell in the MAF Scaling table and see how many % it's off at that point in the logs? Or should it be the same percentage increase/decrease allover?
I wouldn't make any sense to copy the OL part of one of Wayno's other maps over?

So I shouldn't do anything further about the Load Limits?

And just ignore the knock?

[Rezi]

Another update.

Fueled it up with Shell V-Power 100RON drove it in the same condition as the knock happened yesterday.
It feeled a little better then BP 98.

Only a little FLKC/FKBC then previous, NO IAM drop.
Got a CEL when i parked. I disconnected the OFT unintentionally while the Engine was running. (The cable is to thick/short).
Can not clear the Communication CEL (Uxxxx) with the OFT. So i grabbed Torque and cleared it.

After that, i stalled my engine when rolling. The Throttle-response was a bit delayed, like after Flashing a tune.
Also after clearing the CEL my LTFT seemed mostly at between +1,5%/-1,5%, while my STFT was "normally". Is that a good sign?
Do i need to relearn my fuel trim after every CEL clearing?
Or can i "smash" it a little "harder" ?

Log 1 right after sipping Shell V-Power 100
http://datazap.me/u/rezi/shell-v-pow...n?log=0&data=1

Log 2 right after clearing CEL (Communication CEL Uxxxx)
http://datazap.me/u/rezi/strange-ltf...x?log=0&data=1

Every help is appreciated! Thank you so much!

-Rezi

[steve99]

Originally Posted by cawith

If I was to calculate it manually, should I then look at each cell in the MAF Scaling table and see how many % it's off at that point in the logs? Or should it be the same percentage increase/decrease allover?
I wouldn't make any sense to copy the OL part of one of Wayno's other maps over?

So I shouldn't do anything further about the Load Limits?

And just ignore the knock?

yes see how far it out at each maf point and adjust accordingly

then maynpbe look at load limits

once you have thge fuelking correct then tackle the knock

[JB86'd]

@Wayno @steve99

latest 3rd gear pull with MAF revisions from Wayno and raised load limit to 1.1 at 3700.
It looks beautiful above 4200, is that little lean lump anything to worry about at 4000rpm?
Also, still a bit rich at 3700, don't know if dropping the load limit back down to 1.0 or so is going to even help me much?

Thoughts?

http://datazap.me/u/joshbustos86/jdl...4&zoom=382-496

[Wayno]

Originally Posted by JB86'd

@Wayno @steve99

latest 3rd gear pull with MAF revisions from Wayno and raised load limit to 1.1 at 3700.
It looks beautiful above 4200, is that little lean lump anything to worry about at 4000rpm?
Also, still a bit rich at 3700, don't know if dropping the load limit back down to 1.0 or so is going to even help me much?

Thoughts?

http://datazap.me/u/joshbustos86/jdl...4&zoom=382-496

It looks fine.

Don't try to fix lumps and bumps caused by AVCS, overlap, etc.

[JB86'd]

Originally Posted by Wayno

It looks fine.

Don't try to fix lumps and bumps caused by AVCS, overlap, etc.

Sweet. As long as I don't see any significant knock at 4k where it's half a point lean I'm assuming it's all good..

[Kodename47]

Originally Posted by JB86'd

Sweet. As long as I don't see any significant knock at 4k where it's half a point lean I'm assuming it's all good..

Yes, unless you know the in cylinder AFR the O2 readings are only an indicator.