LS6 944 Misfire

[pormgb]

My car is running a bit rough so I did some logging. I see quite a bit of misfires and I'm not sure what is causing the issue. I'm trying to figure out if there if this tune related. Once in a while, I get a flashing cell when starting from cold but it goes away after a restart. I have attached two logs and the current tune, any ideas would be useful.



222512225222253

[joecar]

First, check for airleaks in the exhaust (before/after front O2 sensors), and at the intake manifold (after the MAF sensor).

[pormgb]

First, check for airleaks in the exhaust (before/after front O2 sensors), and at the intake manifold (after the MAF sensor).

Checked everything out and I do have what sounds like exhaust leaks after the O2s.

I also took a look at my VE table and looked at some recommendations you gave me some time back.

I compared my VE table to a stock LS6 and my numbers were low in many cells. I took your recommendation of copying the VE table from a stock LS6 then added 8% form 3200 rpm to 5600 rpm. I took the car for a run and done some logging. Misfires have reduced allot.
Take a look at the attached logs.

[joecar]

Checked everything out and I do have what sounds like exhaust leaks after the O2s.

...
These leaks allow air to be pulled in in between the exhaust pulses (i.e. on each low pressure pulses).

[joecar]

...

I compared my VE table to a stock LS6 and my numbers were low in many cells. I took your recommendation of copying the VE table from a stock LS6 then added 8% form 3200 rpm to 5600 rpm. I took the car for a run and done some logging. Misfires have reduced allot.
Take a look at the attached logs.
I'll take a look.

[pormgb]

I'll take a look.

Thanks!!

[joecar]

July 15 Misfire.efi (https://forum.efilive.com/attachment.php?attachmentid=22259&d=1531697244)
July 15 Misfire1.efi (https://forum.efilive.com/attachment.php?attachmentid=22260&d=1531697260)

Misfire1.efi shows quite a few misfires counts on a few cylinders.
Misfire.efi shows some initially, and then they go to almost none, a big improvement, what changed...?

[pormgb]

Misfire1.efi shows quite a few misfires counts on a few cylinders.
Misfire.efi shows some initially, and then they go to almost none, a big improvement, what changed...?

Nothing changed. I started with misfire (from cold start), stopped for gas then logged misfire1. Misfire was a longer run, I returned from the gas station with misfire. The only real difference would be the car sat in the gas station for about 10min and could have experienced heatsoak.

I do notice that the car runs rougher when warm. On nice cool days, its a ton faster.

[ProperTuningOG]

Any special reason why you are running a, what we assume, stock ls6 MAF only?

[pormgb]

Any special reason why you are running a, what we assume, stock ls6 MAF only?


No, I decided to use the LS6 MAF due to the integrated IAT. Is this a bad thing?

I did some research at the time of the build, and that seemed to be the best way to go.

[ProperTuningOG]

That’s not what I’m asking. You are running the engine off the MAF only, why? Have you tuned the new MAF cure 100% since that’s what’s controlling the fuel. Misfires can come from many things and a bad mixture is one of them.

[pormgb]

That’s not what I’m asking. You are running the engine off the MAF only, why? Have you tuned the new MAF cure 100% since that’s what’s controlling the fuel. Misfires can come from many things and a bad mixture is one of them.

I see. I was not aware I was running MAF only, that was not my intention.

I just checked my tune and found B0120 set to 400. I think I did not set B0120 back to 4000 after my last Calc Vet.

[ProperTuningOG]

Is the engine a stock ls6? Is the maf a later cartridge maf or truck maf?

[pormgb]

Is the engine a stock ls6? Is the maf a later cartridge maf or truck maf?


Specs;
Stock LS6 Intake
226,229 578,585 Cam
LS6 Heads with Manley Valves
Professional Products 85mm TB
Delphi LS6 MAF
SVO 40lb Injectors

I set B0120 back to 4000.

[ProperTuningOG]

And you VE tuned then maf blend or maf tune and ve blend?

[pormgb]

And you VE tuned then maf blend or maf tune and ve blend?

I used the results of Calc Vet and blended both MAF and VE tables. I use a WBOS for the AFR reference.

My old VE table is probably right. Calc Vet produced it. I never saw the benefits of the corrected table because it was never used (B0120).

[joecar]

Ah, good observation by Team208...

is your MAF corrected...?

looking at your log LS1B_133, it seems to me that MAF looks like it is under-reporting (i.e. MAF table needs to go up in some places).

[joecar]

Something else: if this is a transplant, then te MAF ducting will be different than the donor car... post pic of engine bay showing MAF ducting... any bends too close to the MAF will not be able to be tuned out.



( also: after MAF is corrected, you will want to correct VE table )

[pormgb]

Ah, good observation by Team208...

is your MAF corrected...?

looking at your log LS1B_133, it seems to me that MAF looks like it is under-reporting (i.e. MAF table needs to go up in some places).

Yes, the MAF was corrected via my last Calv Vet.

Do you recommend running another Calc Vet or can I manually raise some of the MAF table areas?

[pormgb]

Something else: if this is a transplant, then te MAF ducting will be different than the donor car... post pic of engine bay showing MAF ducting... any bends too close to the MAF will not be able to be tuned out.



( also: after MAF is corrected, you will want to correct VE table )

MAF Plumbing.

22268

[pormgb]

Ah, good observation by Team208...

is your MAF corrected...?

looking at your log LS1B_133, it seems to me that MAF looks like it is under-reporting (i.e. MAF table needs to go up in some places).

What areas of the MAF table seem low?

[statesman]

Check the condition of your spark plugs and plug wires.

[joecar]

MAF Plumbing.

22268 Seems ok, even tho you have no choice.

[pormgb]

I checked the plugs and wires, and everything looks good.

I completed a Calc VET but the results made the car run very rough. I then tried applying only the MAF table and the car idled in the 12s AFR.

Not sure what's going on here. I have attached my Calc VET log, and the values applied to a tune.

I ran the car yesterday with B0120 set to 400 with the pre VET tune (iLS6 944 Derron.ctz), and the car ran quite well. Ran a short log and attached the file (LS1B_Calc VET July 28th.efi)


Calc VET log = (LS1B_0143 orig.efi)

Calc VET applied to original tune (July 20th (MAF+VE Applied) B0120 4000.ctz)

Short Calc VET log collected yesterday with the original tune (LS1B_Calc VET July 28th.efi)


Whats odd is the car ran very well with the tune that I originally posted.

[statesman]

When you do a Calc VET, you need to be in open loop (disable your fuel trims). You also need to be in MAF only mode... your log LS1B_0143 looks like you were in blended mode.

[pormgb]

When you do a Calc VET, you need to be in open loop (disable your fuel trims). You also need to be in MAF only mode... your log LS1B_0143 looks like you were in blended mode.

I wasn't aware of the need to disable fuel trims. I read the Calc VET tutorial and summary notes and did not see that step.

Are fuel trims disabled by setting B4205 to something like 140 degrees disabling closed loop?

[joecar]

( BTW: in your tune, B3618 PE table is set to EQR 0.86 which is incorrect... set it to EQR 1.175 (i.e. 1/0.85) )

[joecar]

If it idles that rich that something is going wrong...

[joecar]

...

I completed a Calc VET but the results made the car run very rough. I then tried applying only the MAF table and the car idled in the 12s AFR.
...
Short Calc VET log collected yesterday with the original tune (LS1B_Calc VET July 28th.efi)

This log show idling at Lambda 0.982 (AFR 14.4).



Whats odd is the car ran very well with the tune that I originally posted.

Let's compare current tune to that one...

[joecar]

I wasn't aware of the need to disable fuel trims. I read the Calc VET tutorial and summary notes and did not see that step.

Are fuel trims disabled by setting B4205 to something like 140 degrees disabling closed loop?I think statesman is inferring that your front NBO2's are switching slower than usual (about 1.5/s vs 3/s)...

[pormgb]

( BTW: in your tune, B3618 PE table is set to EQR 0.86 which is incorrect... set it to EQR 1.175 (i.e. 1/0.85) )


Changed properties to display EQ Ratio and set B3618 to 0.85

[pormgb]

This log show idling at Lambda 0.982 (AFR 14.4).



Let's compare current tune to that one...

Yes. The short log represents the pre Vet tune. The car ran rich after applying the Calc Vet results but I did not log that run. I immediatly went back to the old tune.

[pormgb]

I think statesman is inferring that your front NBO2's are switching slower than usual (about 1.5/s vs 3/s)...

Ok, does this mean there is a problem with the O2s? or is this a configuration issue?


Two months ago, I was getting P0133 and P0153. I switched out my front O2s for bosch 13111 and the problem went away.

[statesman]

I think statesman is inferring that your front NBO2's are switching slower than usual (about 1.5/s vs 3/s)...

No, I just didn't word it very well. You don't actually 'need' to be in open loop, you can do closed loop tuning with fuel trims BUT the LTFTs work in blocks... so it's not a very precise way to tune. I should have said that you 'should' tune in open loop because it's more precise.

[statesman]

Changed properties to display EQ Ratio and set B3618 to 0.85

NO!.... joecar said "set it to EQR 1.175".

[pormgb]

NO!.... joecar said "set it to EQR 1.175".

OK, changed back display properties back to AFR. If I set all fields 1.75 they default to 1.80. Is that normal?

[pormgb]

No, I just didn't word it very well. You don't actually 'need' to be in open loop, you can do closed loop tuning with fuel trims BUT the LTFTs work in blocks... so it's not a very precise way to tune. I should have said that you 'should' tune in open loop because it's more precise.

Just to be clear, Calc VET should block LTFTs. Since I'm running Calc VET with a WBOS, why do you think after applying VET results the car ran so bad?

[statesman]

OK, changed back display properties back to AFR.

Why did you do that? :ermm:

[statesman]

why do you think after applying VET results the car ran so bad?

Because you're not following instructions. Joecar told you to set table B3618 to EQR 1.175 and you set it to 0.85 and when I pointed out that joecar said you should set it to EQR 1.175 and you change display properties back to AFR. If you can't follow one simple instruction like that, who knows what you've done with setting up your Calc VET. :nixweiss:

[joecar]

OK, changed back display properties back to AFR. If I set all fields 1.75 they default to 1.80. Is that normal?
Be careful... EQR 1.175.

[joecar]

statesman is correct, using LTFT's provides a coarse correction, look at the LTFT 4x4 array of cells that covers the MAP x RPM range;

usually LTFT's work ok in Calc.VET when there is very little change in an LTFT cell;

but it looks like your case requires trimming disabled (including B4206), use CALC.WO2BEN to apply corrections to MAF...

you will need to correct VE separately on similar manner.

[pormgb]

Be careful... EQR 1.175.



Yes, I type in 1.175 and 1.180 is displayed. If I copy the contents of the cell and past it to a text editor, I see 1.1750601 so I think the display rounds up to 1.180.

[pormgb]

statesman is correct, using LTFT's provides a coarse correction, look at the LTFT 4x4 array of cells that covers the MAP x RPM range;

usually LTFT's work ok in Calc.VET when there is very little change in an LTFT cell;

but it looks like your case requires trimming disabled (including B4206), use CALC.WO2BEN to apply corrections to MAF...

you will need to correct VE separately on similar manner.

Got it, makes sense why my VET was so far off. I previously stated my EQR 1.75 but I entered EQR 1.175.