e38 tuning gen 6 bbc help

[yevgenievich]

I will put logs up. I have logs but hard to tell where in the log it is triggered. Because it sets it during run time, and then throws code up on next start up cycle

[yevgenievich]

Without the log file showing it doing the thing it will forever remain a mystery.

Uploaded one of the scans for reference. But will try to log the exact point when it triggers tomorrow. Did not think about it earlier, but will enable check engine light on first instance for it to make it more obvious that it is triggered.
run88_tune34.hpl

[Alvin]

Have done a number of updates from last year. Intake actually ended up being changed out, but was not that much of a difference with that change until started playing with the tune again. Felt that it did gain rpm with intake change. I still had P1174 code coming in that I could not trace down, and interestingly the couple of days when towing a trailer it did not show up. I am trying to find on how to adjust temperature dependent variables as it feels like it has large swings in fuel trims with temperature changes. Have an idle hunt with ac on and a lean bleep on sudden throttle application that have been trying to identify on how to adjust. Attached current tune for reference.Attachment 139167

Hi,

without a log it's hard for me to tell for sure but this sounds like a problem that was with LT1's and some other engines specifically with shorter intake runners. Try searching for "split BLM's" it was never a thing for LS motors but common in LT and older stuff.

By LT I mean 1992-1997 LT1's

[Alvin]

Edit. saw the log. It's possible its a split blm problem. BLM is a old term for long term fuel trims. It wasn't in the vocabulary for LS stuff but it is for the LT and older stuff. I'm using it so that if you search google you will find stuff on it.

I'm sure you swap o2 sensors left to right ot see if the condition follows?


Typically the split blm problem shows up with one bank rich or lean then following a drive and another stop/idle the rich/lean banks switch.

[TheMechanic]

I was thinking maybe O2's are crossed? Try disconnecting one to see what side goes to .450v just to verify the O2's are not crossed from side to side.
Wow Alvin, took me WAY back on the "Block Learn". Hahahaha

[yevgenievich]

I did a check on O2 sensors to verify left and right position along with swapping sensors them selves from side to side with same results. What I am currently thinking is that it might be my intake set up it self, as it is a short runner intake with a 90* elbow that is pointed to the side of the engine. Attached another log that had the code show up at the last 30sec to 1min of the run time.

run90_bank_balance_code.hpl

[blindsquirrel]

Injectors wired cross-bank will give the same result as O2s crossed up - O2s are the input side mixed up, injectors are the output side crossed up. In either case the ECM ends up adding fuel to the rich bank based on the opposite bank's O2 reading and pulls fuel from the lean bank.

Since this is a 18436572 7.4 being run by a tune file from a 18726543 LS, and the injector bank select table in the file hasn't been changed, did you change the wiring for the injectors instead? #7 injector wiring actually going to cylinder #4, etc.?

[yevgenievich]

Injectors wired cross-bank will give the same result as O2s crossed up - O2s are the input side mixed up, injectors are the output side crossed up. In either case the ECM ends up adding fuel to the rich bank based on the opposite bank's O2 reading and pulls fuel from the lean bank.

Since this is a 18436572 7.4 being run by a tune file from a 18726543 LS, and the injector bank select table in the file hasn't been changed, did you change the wiring for the injectors instead? #7 injector wiring actually going to cylinder #4, etc.?

It is running 8.1l cam core to match ls firing order. Ringed out injectors and coils multiple times to verify pinouts.

[yevgenievich]

Some of the engine information:

Block (P/N 19256820): Tall Deck (10.2")
Bore x Stroke (in): 4.280x4.250
Heads Brodix race rite Ovals cnc 112cc chamber, springs 160/400
Cam# BBC8.1, HR73353-114 233/233 @.050" .353"/.353" Lobe Lift .600"/.600" Valve Lift 114 LSA
COMP Cams Ultra Pro Magnum Rocker Arms 396-454
19260247 58x timing kit

[blindsquirrel]

Well for sure it does not have the banks crossed up, the logs for those look very different. Your trims look pretty normal to me (they will always do some weirdness in coastdown because of changing between Fuel Trim Cells), I'd just disable those P1174/5 codes.

If you do have a vacuum leak, it's not someplace that affects one bank more than the other (based on what the trims are doing), and so wouldn't trigger either of those codes.

[yevgenievich]

I am wondering if it is purely because of the 90* elbow. The code seem to stay off when towing a trailer. I was thinking of doing a test run with rotating the elbow and running temporary to see if it would move to the bank 2.
20230727_091916.jpg

[Alvin]

I am wondering if it is purely because of the 90* elbow. The code seem to stay off when towing a trailer. I was thinking of doing a test run with rotating the elbow and running temporary to see if it would move to the bank 2.
20230727_091916.jpg

I'll bet its because of the intake, not so much the elbow. Cylinders share air with reversion. with a shorter runner they can share easier. sometimes this runs away a bit and one side will report leaner than the other.

Honestly if it was me.. and I've been though what I think you are experiencing.. turn of LTFTs only use STFT's and disable the bank imbalance codes.


If anyone else has ever been on a engine dyno with 8 widebands running at the same time.. Its a horror show.. one cylinder might be 12:1 another might be 13.8:1. Do another pull and those cylinders might switch. It's wild how much they vary.

[blindsquirrel]

Nah, that's a carburetor thing. EFI is supposed to be perfect.

[yevgenievich]

Well, today the balance code stayed off. Either changes in the tune or cooler air today. I changed the vve zones to match lz1 camaro and retuned vve based on it's configuration. Adjusted timing(lowered) at low spark air mass areas around 2k to 4k rpm as well. Will drive next few days and see what it does.

Still have a bit unstable idle that will some times go to 200rpm surge, especially to reverse transition. I tried smoothing spark corrections up to 200rpm numbers but that made idle worse, so changed it back for now. A bit of a lean tip in spike as well that is present on sudden throttle.
97_burb_e38_t42_tune_41.hpt
run93_tune40.hpl

[yevgenievich]

I did have the code show up again but under different conditions. I think to have figured out what triggers it. Watching the logs and when it shows up, looks like there are some spots with very light load(some times on throttle release) higher rpm that current tune has lean spikes greater than usual dfco. That is when the code seem to come up. Adjusting timing on low spark mass mid rpm area down made one of the conditions go away, but later driving there was some other spot that made it come on. This also explains why it would not show up while towing, as loads were always greater.

[blindsquirrel]

I'd just disable those P1174/5 codes.

[Alvin]

I'd just disable those P1174/5 codes.

yes what he said