2010 Camaro w/LSA fuel problem

[doorev800]

I have a LSA conversion on my 2010, zl1 injectors and stock pulley. I have the 2 bar op system. I have a wideband and did the speed density to near perfect then did the same with Maf. It ran great in both modes. I did 3rd gear pulls from 2000rpm to 6300 with perfect a/f errors of less than 5%. Now when I go back to dynamic it falls on its face to around 3000rpm with a a/f ratio of 16-17afr then at 3000rpm it kicks in and fuels as it should the rest of the way. Not sure what is going on. The mass airflow sensor state goes from no fail to reading -4- right when it starts fueling good.

In the log it happens at 20 seconds in then at 1:19. I will attach the tune aswell.

It fueled perfect in speed density open loop aswell in maf open loop. Just not sure what to do next.

Has a Vararam Intake and shorty headers, the rest is stock.

thanks!

[doorev800]

I just tried it in MAF only and fueling is perfect at WO from 2000 to 5500 so that can eliminate a bad maf sensor. Tomorrow I will put it back in speed density again to check fueling but I suspect it will be on point. Not sure what is happening...

[doorev800]

I tried SD OL today with a run from 2000 to 5000rpm WO and runs perfect. Fueling error is 3 to 6% with VVE operating system.

So question is why does it run as it should in MAF only and SD only then shit the bed in DYNMIC mode? It is sure weird why I get the -4- in the MAF sensor state when it should read no fail when in DYNAMIC.... but it works fine in MAF only and reads no fail for sensor state then air calc mode reads hi speed which tells me maf sensor itself is ok

Here is a current VVE dynamic tune I tried with the same results as the 2 bar speed density dynamic tune had.

open to suggestons, i could run MAF only or speed density only and call it a day, but I want to run in Dynamic...

[kevin87turbot]

I'm not certain what's causing the issue in your application, but I would run MAF only.
A couple of other things to consider...
I'd increase table 34971 to above the max expected MAP kPa.
I'd also recommend speeding up the knock recovery table (12744) considerably.

[doorev800]

I'm not certain what's causing the issue in your application, but I would run MAF only.
A couple of other things to consider...
I'd increase table 34971 to above the max expected MAP kPa.
I'd also recommend speeding up the knock recovery table (12744) considerably.

I did miss that in my VVE tune but did have it set correct in the 2BAR tune, but thanks for pointing that out.

As for the knock recovery table, I do have that table almost tripled from my stock ss tune... I was under the impression that the higher the value in that table the faster the knk is removed? or am I looking at it the wrong way?

Also, since this is a mild build being a stock ls3 with zl1 injectors and stock pulley and only shorty headers with cats and muffler delete, does someone have a good working VVE tune file for this lsa with DYNAMIC mode working that I can try and see if I can figure this out? I would copy all your tune settings to mine and use my maf and VVE table and give it a whirl...

thanks!

[danmw2003]

Did you upgrade to the zl1 fuel pump and make changes to the FPCM?

[doorev800]

I have a fuel pump ordered and FPCM has appropriate changes. you cant see the FPCM in my tunes because I loaded the FPCM with the changes then left it out of the current tunes.

The fuel pressure holds at 58psi to 4900 then drops after that. I know i am out of fuel there after but the issue happens well before the pump drops.

[smokeshow]

I'm not certain what's causing the issue in your application, but I would run MAF only.
A couple of other things to consider...
I'd increase table 34971 to above the max expected MAP kPa.
I'd also recommend speeding up the knock recovery table (12744) considerably.

This should help out.

Looks like you copied over the prediction coefficients from a ZL1 but missed some other critical stuff that allows them to work. Once conditions force leaving MAF steady state mode and using blended airflow for the transition, the ratio of the blend depends on the prediction coefficients. The speed density contribution to the total airmass is clipped based on that max estimated MAP value. If estimated max is too low, then any fuel to match SD air mass for MAP values above the max estimate doesn't get delivered. Its also upsets some rationality diagnostics because it doesn't expect that mass airflow from that MAP value. Ideally you'd calibrate the prediction coefficients, but I don't have a write-up on that yet lol. Increasing estimated MAP should help though.

[doorev800]

This should help out.

Looks like you copied over the prediction coefficients from a ZL1 but missed some other critical stuff that allows them to work. Once conditions force leaving MAF steady state mode and using blended airflow for the transition, the ratio of the blend depends on the prediction coefficients. The speed density contribution to the total airmass is clipped based on that max estimated MAP value. If estimated max is too low, then any fuel to match SD air mass for MAP values above the max estimate doesn't get delivered. Its also upsets some rationality diagnostics because it doesn't expect that mass airflow from that MAP value. Ideally you'd calibrate the prediction coefficients, but I don't have a write-up on that yet lol. Increasing estimated MAP should help though.

I am going to change that tonight and see what if it helps. If not, i have been reading up on the prediciton coefficients issues so might try the zeroing out aswell.

Thanks for the insight!

[doorev800]

Well zeroing out the predicted coefficients fixed the issue. Runs great in dynamic now. I should have did more research before posting but my nerves got the better of me! thanks ppl!

[smokeshow]

Right on, good to hear. They're not simple to dial in so yeah sometimes removing them is just the most reasonable option. I gave the topic some more detail here.

https://forum.hptuners.com/showthrea...l=1#post631265