89fast5oh

I'm stumped. Fall/winter will be here in Canada in 1 month so I am out of time to be tinkering around.

I have the EBL Flash 2 ecm in my 1987 Camaro with 383" and 700r4. I have done enough VE learns that VE tables are where the ECM expects them to be for stoich. The INT/BLMs are almost always 128/128 when cruising.

I need to add more fuel at certain cruise RPMs because the engine wants more fuel. Currently I am getting some mild surging/bucking at certain RPMs. If I add more fuel in the VE table it smooths out, but then the INT/BLM try and take it out to get back to stoich. Its chasing itself in circles.

What I understand is that I need to change the INT Rich/lean/mean tables. This is where I don't know what to do. I know how to physically change the data in the tables, but do not know what values to use.

I do not know how to read the datalog to get the relevant O2 sensor voltage data that would allow me to change the INT Rich/lean/mean tables.

Could someone please review the EBL datalog and point me in the right direction with values?

RBob

iTrader: (1)

There is enough reading material here on this subject to keep you busy all Winter. Two examples:

https://www.thirdgen.org/forums/diy-...-contants.html
https://www.thirdgen.org/forums/diy-...ng-points.html

And those are easy to find as they are from the tuning guide book sticky.

RBob.

89fast5oh

That's good information. Explains all about changing the O2 mv tables. I did learn some things, which is good.

Now I can go into the tables and start guessing at values... because If I can't read/understand the datalog then it would be just guessing.

RBob

iTrader: (1)

The values to use will be a guessing game. No way around it as there isn't a direct correlation between the NB O2 sensor output and an AFR. Other then a higher mV is richer and vice-versa.

Try moving the values by 50 mV at a time.

RBob.

Dominic Sorresso

There are several threads involving modifying the O2mv for motors with greater overlap. Traxion and RBob have written at length about this. My LT5 has cams and I have changed the O2mv but only for idle purposes so as not to “stink up the joint”. Otherwise my O2 settings are OEM.

Just separate thought here.Has anyone looked into patching code allowing separate Left/Right O2mv tables to possibly address the “split BLM” issue in TPI systems? Is it possible?

ULTM8Z

not sure how that would be possible on a system that fires all 8 injectors simultaneously.

Dominic Sorresso

The LT5 is bank to bank with separate O2s modifying injector PW. Each of the secondary injectors get firing signal off their corresponding primary injector while using drivers external to the ECM. When the secondaries are energized, the ECM reduces calc’d PW by 51%.

ULTM8Z

Interesting. But yeah, on the TPI systems, it's all 8 or nothing... lol

I had to build that little idle air manifold to try to get a handle on the split BLM problem (which manifests especially prominent on Miniram style intakes).

ULTM8Z

89fast50h, do you have a WB O2?

I basically did exactly what RBob is recommending (albeit with the 7730 ECM, but the process is likely exactly the same)... going about 50mV at a time until my WB showed no lean spots (but you need the O2 sensor to see that). I then let the BLM's settle in to where the fuel trims not moving around anymore. Then did a VE update based on where the BLM's settled in at. After that, a computer reset.

Don't be afraid to have fairly high O2 thresholds, especially on a modified engine. My thresholds settled in at about 650mV at low engine loads (which is essentially where the factory AUJP was), but the higher loads ended up into the 750mV range. It seems to give a smoother transition into PE since there isn't this jump from over 14:1 down to 12.5:1 when you have a slow transition from non-PE to PE.... i.e., if I'm at 40% throttle and moderately high load, I don't want 14.7 to 15:1... I want down around 13.5 to 14:1...

One thing I also did was to slow down the response time of the ECM to the O2 sensor (especially during throttle transitions). I'm not sure what parameters are for doing this is in the EBL, but it seems to help give a better feel to the throttle during AE events. The ECM isn't reacting so quickly to pull fuel due to the temporary rich condition during AE.

Originally I had the parameter set for reset integrator when AE in progress (same as the 4th gen LT1's), which I believe was for that purpose. And it worked ok.

But, it seems by the time the integrator is reacting, it's already too late. It's the immediate response to the O2 sensor that seems to be the most effective. So I un-set that reset integrator parameter and slowed down the response to the O2 sensor (once RBob and Elky and others finally got it through my stupidly thick skull how the O2 parameters work together).

89fast5oh

Thanks for the info. Yes I do have a WB sensor. I will increase the O2mV especially in the ranges it is too lean. It's mostly just steady cruising I'm having issues with. I'm sure I could stand to have the mV at idle adjusted to clean up the smell ans steady the idle out.

I have read about slowing down the O2 update or such as to smooth out pulsing/surging while at a steady cruise rpm.

Dominic Sorresso

I recall u doing that. There was something in LT5 lore that showed something experimental like that during development. Would be nice to be able to modify fueling bank to bank. At idle things are polar opposites. Typically the left bank is lean and vice versa, so basically straddling 128.

ULTM8Z

Yeah I got the inspiration looking at a 92-93 LT1 manifold wondering how GM mitigated split BLMs with a batch fire system on short runner intake.

At one point I was also trying to figure out how to retrofit a 94-97 LT1 PCM to get the sequential injection... Trying to figure out how to get the opti guts into a HEI distributor housing was the big stumbling block.

But after how well the idle air manifold worked I abandoned that idea.

Dominic Sorresso

Maybe I could talk RBob into patching the LT5 code to try separate O2mv tables for each bank.
😉😂