Concerned and aggrivated

[Whippled 496]

Hey...thanks for that.
I've had so many people look over this thing...the more the merrier.

Thanks (you have mail)

Email sent! Thanks!

[izaks]

You have PM

[Whippled 496]

Cool, i will try these suggestions Izak. I will let you know what i find.

[Aloicious]

Y'know, I'm getting the exact same problem, and I'm N/A, lean at all throttle tip in, and I also get rich spikes on decel. and its screwing with my AutoVE.

I am thinking I may have some heatsoak problems, so I'm trying to work on that...but any info people have would help out, I'm going out of my mind trying to get this sorted out.

edit:
I'm running a 1996 Vortec L31 motor with a ZZ4 cam, MPFI intake running 24# SV1 injectors (flow tested at 259CC/min @43.5psi) running @ 45psi. using a 122000411 PCM with a 2002 Xvan L31 base tune on a 20020003 COS.

I'm also going to try SSpd's post about how he fixed the rich decel on his SVO injectors by altering the B3701 table. but I wanna get this heatsoak fixed tommorow.

[Whippled 496]

Y'know, I'm getting the exact same problem, and I'm N/A, lean at all throttle tip in, and I also get rich spikes on decel. and its screwing with my AutoVE.

I am thinking I may have some heatsoak problems, so I'm trying to work on that...but any info people have would help out, I'm going out of my mind trying to get this sorted out.

edit:
I'm running a 1996 Vortec L31 motor with a ZZ4 cam, MPFI intake running 24# SV1 injectors (flow tested at 259CC/min @43.5psi) running @ 45psi. using a 122000411 PCM with a 2002 Xvan L31 base tune on a 20020003 COS.

I'm also going to try SSpd's post about how he fixed the rich decel on his SVO injectors by altering the B3701 table. but I wanna get this heatsoak fixed tommorow.

Are you running COS3? Is everyone who has this problem running COS3? Wonder if COS5 people have this problem?

[Aloicious]

Are you running COS3? Is everyone who has this problem running COS3? Wonder if COS5 people have this problem?

yeah its a COS3, however, I was running the same COS 3 before I swaped to MPFI and swapped cams, and never had the problem. so I'm thinking at least in my case, it is problably some overlooked injector setting, and/or the heatsoak...it may be a simmilar issue for you as well, but just amplified due to the boost. I'll let you know if I find anything out.

EDIT: I should mention that I've also been smoothing the VE table, but I'm going to do a few drives today w/o smoothing like was mentioned earlier and see if it makes a difference.

[hquick]

Well....I've just switched back to COS3 because the stock op system just had the truck running like crap.
This morning I ran the STFT BEN correction method and got ALOT of the table sitting at 1.0.
After a couple more passes and narrowing down the filters a little...I'll try bringing the MAF back into the equation and see if I can get rid of that lean spike.

[dc_justin]

Would like to see that doc , I have the GM calibrator tool for the early stuff with every calibration variable , all 4000+ of them , nothing that looks or documented as a pump shot or delta enrichment.

Wall wetting calculations may allow it to be fudged though.

Trust me Ross and I have looked for years as a transiant acceleration factor for rnleanment and enrichment would be great - especially on big cammed stuff and blown combo's

Looking at that log then engine is lean for a long time after the throttle movement , I would be looking more at the mapping of the VE

The document that made mention of an "Acceleration Mode" just popped back up in the search today:

http://carprogrammer.com/Z28/PCM/LS1/Holden_LS1.pdf

Looks to be on page 95.

Acceleration Mode

When the driver presses on the accelerator pedal,
air flow into the cylinders increases rapidly, while
fuel flow tends to lag behind. To prevent possible
hesitation, the PCM increases the pulse width to the
injectors to provide extra fuel acceleration. The
PCM determines the amount of fuel required based
on throttle position, coolant temperature, manifold

air pressure, mass air flow and engine speed.

[hquick]

Is that Holden specific perhaps? (like lean cruise is).
I have a buddy who works in Holden writing the cal's....I could ask him...if I knew WHAT to ask him???

[hquick]

Well...I asked the question of my GMH buddy.

Is this something that's actually used in the fueling of the Holden vehicles?


Acceleration Mode
When the driver presses on the accelerator pedal,
air flow into the cylinders increases rapidly, while
fuel flow tends to lag behind. To prevent possible
hesitation, the PCM increases the pulse width to the
injectors to provide extra fuel acceleration. The
PCM determines the amount of fuel required based
on throttle position, coolant temperature, manifold
air pressure, mass air flow and engine speed.

His reply.


"Yep, thats transient fuel, which is what I used to look after as well.
Its a horribly complex algorithm in our software, but the inputs are basically what was described there".