MAF tuning

[Walkerbk]

I have a 2004 LQ4 block with PRC 2.5 heads, 228/232 112r cam, Long tubes, and 48lb injectors. I have the VE table dialed in pretty close and am happy with it but am having some problems going forward into MAF tuning and then into closed loop and all.

I have taken my VE tune and changed everything (so I think) over for MAF tuning and the car starts and idles fine (a little lean) but whenever I give her any gas she misfires and runs extremely lean (WB02 pegs out at 22 AFR). I dont know if im missing a setting or if my MAF settings are that far off. I figured I would be better off asking for help before going forward.

Attached is my current VE tune that I am running and then my MAF tune. My VE tune is obviously not in closed loop as I dont have my MAF worked out, but that is my goal.

[gtstorey]

This in the car that is in your signature?

[04silverado6.0]

This file should give you a better start. That ve is rough and unrealistic, this should be a decent starting point.

[Walkerbk]

@ gtstorey - Yes, it is in my 77 Datsun 280z.

@ 04silverado 6.0 - I assume you mean my MAF table is unrealistic? My VE table is tuned based on my WB O2 sensor and is dead on 14.2 all the way up to 6k rpm.

[gtstorey]

If you aren’t running a factory intake setup, you shouldn’t expect any factory maf numbers to be anywhere close.

[blindsquirrel]

It's quite common for an aftermarket DIY-installed wideband to give readings that are offset from reality.

[HATEHPTUNERS]

Blindsquirrel gets a virtual like..

[gametech]

@ gtstorey - Yes, it is in my 77 Datsun 280z.

@ 04silverado 6.0 - I assume you mean my MAF table is unrealistic? My VE table is tuned based on my WB O2 sensor and is dead on 14.2 all the way up to 6k rpm.

No, he means your VE table is completely unrealistic. The only way you are getting fueling anywhere near correct is if your injector flow rate is way off. If you put real numbers in a MAF table with your fuel that far off, of course it is going dead lean. You need to check your fuel pressure. If it is correct at 58psi, then you don't have the right injector data. The best race engines in the world could not hit close to the VE numbers you have in that table without forced induction.

[Walkerbk]

@gametech - Im not sure where my flow rates are off if that is the case. I did fight a bad set of injectors until about 4 months ago when I bought the Delphi 12613412 injectors from the guy blind squirrel recommends. That helped tremendously. I do however agree that it is still off some how. Fuel pressure is right at 58psi and I'm running a corvette fuel filter/ regulator with a returnless system.

[SiriusC1024]

Tune it in CL.

[blindsquirrel]

What fuel pump? Any bigger than 255lph, or a store brand filter-reg with any pump any bigger than stock flow rate, and you will have problems.

Have you verified fuel pressure under load, like in the areas where your VE is showing the crazy high numbers?

Have you run it in closed loop and made sure the wideband agrees with the narrowbands?

[Walkerbk]

@blindsquirrel - 2002 camaro stock pump (for the ls1). I might upgrade to a 255 in the near future. It is plumbed with 6an soft lines and 3/8in hard line.

My fuel pressure gauge is on my fuel rail so I haven't been able to verify but I am looking at where else I could mount another gauge on my dash.

I haven't ran in closed loop. I didn't think I could run in closed loop with just the ve table.

Please forgive my ignorance, I have done everything else on this car from building the transmission to paint and body. I'm still reading as much as I can on tuning.

[blindsquirrel]

You need a fuel pressure gauge that's used for diagnostics, not a chrome polished billet aluminum decoration. If you are working on fuel injection you need a gauge that lives in a nice blow-molded case until you need it, with a hose long enough that you can snake it up under the rear of the hood and see it from the seat while driving. It's as essential a tool as wire crimpers and a voltmeter and a scan tool. A rail mounted gauge is useless for anything but showing people who don't know any better how cool you are.