Turbo on 2000 Limited 5.0

[4pointslow]

Turbo

So at Idle LTFT has learned to add 17% on bank 1.
the others are insignificant at Idle.
At 2000 rpm LTFT has learned to add 27% on bank 1.
Bank 2 STFT was adding 11% at 2000rpm's but for now who cares because the DTC you had was for Bank 1.
With a misfire you will have more oxygen in the exhaust and as the rpm increases there will be even more.
That's why it probably went from 17to 27% at higher rpms.
In this case it looks like the misfire is effecting the air fuel mixture, not the a/f mixture causing the misfire.
If we did not have the misfire code we might think other wise. We will see.

 

[4pointslow]

Notes on fuel trims.

Fuel trims on most scan tools.

STFT and LTFT are a percentage of fuel to be added or reomved from what the PCM calculated(Maf,rpm,other sensors), delivered,
and the engine already burned.
Good fuel trims (STFT and LTFT) should be 0%, plus or minius 5% so -5% to 5% is fine for both.
STFT's usually fluctuate or bounce around 0% in closed loop.LTFT is usually steady.
STFT usually flat lines 0 when in open loop. LTFT will be what ever it last learned in closed loop, when it goes to open loop.
LTFT can only learn new values in closed loop.

STFT is based off O2 sensor readings. If the system is running rich the O2 sensor voltage readings will be high, STFT will take away fuel.
You will see a negative number like (-10%).
If the system is running rich the O2 sensor voltage readings will be low, STFT will add fuel. You will see a posative number like (10%).

LTFT is based off STFT. So if STFT was adding 10% for an amount of time, LTFT would learn to add that value and let STFT
go back to switching around 0%.

Things are different with SCT stuff, it is displayed in lamda instead of % of adjustment. If you enter Lambda of 14.7 then 1=14.7
Fuel has ethanol in it now so lambda should be 14.13 with about 10% ethanol in it if I recall. Since we may not know how much
ethanol is really in there many shoot for 14.4 (middle of 14.13 and 14.7).

The SCT datalogger hardware like the X2,X3,X4 etc and software like Live Link 6.5 or Live Link Gen2 things are different
than other scan tools and that has led to some confusion.
In Live Link When at wide open throttle(70% throttle or more) the STFT shows commanded A/F, not a correction to A/F.
Crazy, but true. Kind of makes sense since when 70% or more throttle you are in open loop so the PCM ignores O2 sensor
readings, doesn't use STFT's, and commands a slightly richer mixture(or lots richer depending on what's in the fuel table with a custom tune).

When not in WOT mode,
If you have STFT higher than 1, then the pcm is commanding a leaner mixture.
Example
STFT 1.03 x 14.4 A/F = 14.832 which is leaner than 14.4

If you have STFT lower than 1, then the pcm is commanding a richer mixture.
Example
STFT .96 x 14.4 A/F = 13.82 which is richer than 14.4

LTFT's are easier, if they are higher than 1 they are adding fuel, if lower than 1 they are subtracting fuel.
1.20 is adding 20% fuel, .80% would be subtracting 20% fuel.
They show what the PCM has learned under all rpm and throttle positions(or loads), even at WOT.

 

[Dono]

Im still bent on the injectors.
I know I could swap in the factory injectors, factory tune, and factory maf and there would be no misfire.
I understand that this doesn't make sense.
I almost think Im best to pull the battery cable for 10 min, then do another log of fuel trims. Then, I'll do a running compression test of some (Maybe all) cylinders as a reference. I'd think running compression is what we really are interested in.

After doing the two above, I want to swap injectors bank 1 for bank 2 and see if the misfire moves, and how fuel trims behave.

Your explanation of the short term trims is interesting. I wouldn't have known they are actually backwards to what I was thinking.

I'll get on this tomorrow, tonight was family stuff and rest. It still feels like someone punched me in the throat (Maybe my wife while I was sleeping?).

 

[4pointslow]

Manual Compression testing

Warm engine if possible
Attach battery charger to keep cranking rpm the same for each cylinder.
Disable Fuel and Ignition (best way is to unplug crank sensor if accessible)
Remove spark plugs, all of them at once.
Hold throttle plates wide open.
Crank engine minimum 5 revolutions (compression pulses or needle increases)
Crank engine same numer of pulses for each cylinder.

 

[4pointslow]

punched

im still bent on the injectors.
I know i could swap in the factory injectors, factory tune, and factory maf and there would be no misfire.
I understand that this doesn't make sense.
I almost think im best to pull the battery cable for 10 min, then do another log of fuel trims. Then, i'll do a running compression test of some (maybe all) cylinders as a reference. I'd think running compression is what we really are interested in.

After doing the two above, i want to swap injectors bank 1 for bank 2 and see if the misfire moves, and how fuel trims behave.

Your explanation of the short term trims is interesting. I wouldn't have known they are actually backwards to what i was thinking.

I'll get on this tomorrow, tonight was family stuff and rest. It still feels like someone punched me in the throat (maybe my wife while i was sleeping?).

lol!!!!! (maybe my wife while i was sleeping)
Please start with manual compression test, you can probably get away with pulling one spark plug at a time and just do cylinder 1 and 5.
Then running test on 1 and 5.
Swapping injectors from one bank to another is a good idea too, I would have suggested that if compression test came up good.
Also, do you have a fuel pressure tester or can you get your hands on one (not aftermarket gauge, real tester)? Fuel pressure leakdown problems can cause misfires at start up and go away after running for awhile. By the way, do you feel the misfire, does it happen all the time or come and go?
I don't think switching to stock maf and Injectors would stop the misfire since when you put the newer ones back in there was no misfire at first. The last time it was fouled plugs, the last picture you posted, if it is #1 (passenger side front) is not fouled. New problem. Makes me think defective plug or injector, unless you swap cylinders and the misfire stays with #1 .

 

[Dono]

ok, I pulled the battery for 10 min, warmed up the motor to 160, and logged.

as expected the long term fuel trims are 1

at 865rpm
stft bank 1. .96
stft bank 2 1.14
analog 2... 14.5
at 2016rpm
stft bank 1 .82
stft bank 2 .93
analog 2... 13.8
so, at idle bank 2 is pulling fuel, then at 2000 rpm its adding? Bank 1 seems to be adding also.

The miss can definitely be felt.

 

[4pointslow]

Fuel trims

Bank 1 at idle adding 4% = negligible.
Bank 1 at 2000 = adding 18% something wrong here. (misfire because you feel it and it sets code for number 1)

Bank 2 at Idle subtracting 14%
Bank 2 at 2000 = adding 7 %
Bank 2 doesn't make sense(but there are possible solutions) but I would not concern myself with it till we find out why #1 is misfiring, fix it and see where fuel trims are then.
When a misfire is detected the PCM often goes into open loop since it knows it can not trust O2 readings from excess O2 in the exhaust showing false lean condition. If the PCM doesn't trust O2's we should not either, except for the fact it is showing lean due to the misfire on bank 1. Otherwise you would think it was fuel starvation on bank 1 since STFT is high at 2000 rpm and not so bad at Idle. Got to fix misfire first.
Can you get your hands on a fuel pressure tester. (after compression tests and only if compression shows good).

 

[2000StreetRod]

Mtf?

Did James finish tuning the MAF transfer function? When you did the open loop testing the actual lambda compared to commanded went from 13% rich at 1,000 rpm to 7% lean at 2000 rpm. Even though James sent you a closed loop tune doesn't mean he was done with the MTF tuning. He normally does his MTF tuning in closed loop except for WOT. The latest numbers for bank 2 match the open loop results on 9 August.

 

[4pointslow]

spark plug

I pulled #1 lug since that is where the code came up. Wire was on tight, and everything looked good. I pulled the plug. This is what I saw. It had obviously fouled at some point.
I pulled plug #2 and it looks the same.

So, another plug change? Please let the consensus be no......

page 18 post 345
Was there green color on this spark plug? Or is it an optical illusion?

I was going through this thread looking for a picture of your fuel rail but have not seen it. Is it still stock or did you upgrade. What about the fuel pressure regulator? Just curious.

 

[4pointslow]

multiple misfires

Another thing that is worth pointing out about misfires and such is that Dono, and 200streetrod both had multiple misfires which drove the wideband gauge to read around 20:1 A/F ratio.
With just one misfire now your wideband looks close to normal but STFT is jacked up to 17-27% (bank1).
You can see how seeing this data could be useful in expecting to find a whole bank of fouled plugs(etc.) or just a problem with one cylinder.

 

[Dono]

I'm not sure if James finished maf transfer tuning, I doubt it.
The pic does make the plug look green, but I couldn't see green myself. I'll take pics of the plugs when they come out today. I'll make some coffee, yank the wheels off, warm the motor up a bit, and start pulling plugs.

The fuel rails and fuel regulator are stock. Using non return style.
The fuel pump is upgraded to the aeromotive A1000 pump, AN6 to the fuel filter. The fuel filter is an aftermarket high flow unit, and then factory fuel line up to the factory fuel rail.

 

[4pointslow]

Fuel system

I think you mean return style if you have a regulator on the fuel rail?
If so and it is stock then the regulator will only lower fuel pressure when vacuum is present, and not raise it when there is boost provided you still have the vacuum line attached. The vehicle would run lean when under boost(without any tuning done) but that can be compensated for in the tune. Might be why bank 2 is lean at higher rpms. Not really important at this point. Finding misfire cause is first.

That's good if there was no green on the plugs.

 

[Dono]

Tim's coming over to help so we can get a reading on each compression stroke. No one in my house would really understand what I'm doing. Tims continuing to be an amazing help.
I tried to get the best pics possible. plug 1 actually looks like there really hasn't been much of anything going on.

I did a 4 pulse compression of cyl 1 and it came in at 170. There is plenty of compression there to fire that cylinder. We will have full numbers shortly.

My apologies everyone. I never wanted this to become a 'lets troubleshoot my truck' thread. I do want everyone to know I really appreciate it.

My fuel system is definitely returnless. There is only one fuel line to the front. Apparently the regulator is in the fuel tank, but there is still some kind of a pressure doohickey on the fuel rail that a vacuum line is attached to.

I'll try to find a fuel pressure tester, but I am sure from looking at the plugs that are running rich on bank 1 this isnt the current issue.
My money is on the injector....Im even going to say the injector in cylinder 1.

The upper intake comes off to switch injectors around, but I think its worth the effort to do this. Unfortunately we can only see an issue with one bank or the other. There are no individual sensors. So, if there was no fuel getting to cylinder 1, the other plugs would be running rich as the O2 see's lean condition. Is this logic correct?

 

[Dono]

compression

Id say this is pretty good for an old girl.

I'm going to re-install the plugs, make sure it runs, then swap injectors bank for bank. Lets see if the fault switches banks.

 

[4pointslow]

spark plug #1

I see fuel residue on cylinder #1 , not burnt but wet looking.
Do you have an ohmmeter?
If so check the resistance of that spark plug compared to the other ones.
Go from the end where the wire attaches and the other lead to the center electrode.
Can you check the wire the same way too please.

 

[4pointslow]

Unfortunately we can only see an issue with one bank or the other. There are no individual sensors. So, if there was no fuel getting to cylinder 1, the other plugs would be running rich as the O2 see's lean condition. Is this logic correct?

Yes

Compression is good you can rule that out.

 

[Dono]

ok, I pulled the upper intake off and swapped injectors around.
No more miss. Go figure.

I used di-electric grease on all injector connectors and checked to make sure all connectors had continuity thru to the injectors while documenting what injector serial number went where, and where they were before.

I'll post a the fuel trims shortly, I'm just waiting for the laptop to charge.

This gave me an opportunity to install the upper intake Tim gave me. Its powder coated and makes my engine bay look way better.

It concerns me that I really don't know what the issue was.

 

[vroomzoomboom]

you must edit your post don. i got to play hookie on you today.
also, why question why at this point. you have been driving yourself nuts with that thing lately so, no code is good news then!
BTW, now that evil is part of your truck now, i take no responsibility in its actions! lol

 

[Dono]

hahaha, Tim, that part of evil looks pretty sexy under my hood.

Ok, I pulled the battery cable to reset the long term trims to 1, so no need to post them.

Idle 830rpm
Analog 2 (Bank 2 Wideband reading) 14.32
STFT Bank 1 1.03
STFT Bank 2 1.00

2069 rpm
Analog 2 (Bank 2 Wideband reading) 13.98
STFT Bank 1 0.96
STFT Bank 2 0.91

I would say things look pretty close. 4pointslow?
What we could be seeing at 2000 rpm could just be that the tuning isn't finished as we are waiting on the new turbine housing to get this turbo spooling faster.

 

[4pointslow]

Stft

4% and 9% change is not that bad, tuning will probably get it closer.
One thing that is sticking out in my mind is you said you made the wires longer for one O2 sensor. Was that the wiring harness or the O2 sensor itself?

The intake looks great! Maybe the old intake or gasket were bad.
Keep us posted on how it is running.