Truck loses all spark at part throttle from a stop in 1st?

[crutt]

2010 silverado 5.3, LSA blower, 212/218 vvt cam,3 bar map sensor. When giving gas to start rolling from a complete stop timing gets pulled/afr goes lean but nothing in the scanner is commanding the pull as far as I can tell. Truck will almost die then take off once timing comes back Log files shows when I give it a bit of a gas the idle spark goes from 14* to 0, sometimes slightly negative. Once it gets rolling (over 1100 rpm/4-5mph) truck runs fine. Dont know where to start.

Thanks for any help.

[5FDP]

Disable desoot mode in the tune for one, that's under the fuel tab.

MAP sensor settings are wrong if you are using a GM 3 BAR map that comes on the ZL1 lid. They are 312.5/-11.25. The MAP should not read 110kpa with the key on engine off. It should be between 100-102ish kpa depending on altitude.

I think part of the problem is that you are reading boost when you aren't even on the gas, it will at 105-112 kpa when you are just sitting at 700rpm, so it going to try and yank everything away. Fix the MAP settings and see if anything changes.

[crutt]

Thank you, I'll give it a shot.

[crutt]

Disable desoot mode in the tune for one, that's under the fuel tab.

MAP sensor settings are wrong if you are using a GM 3 BAR map that comes on the ZL1 lid. They are 312.5/-11.25. The MAP should not read 110kpa with the key on engine off. It should be between 100-102ish kpa depending on altitude.

I think part of the problem is that you are reading boost when you aren't even on the gas, it will at 105-112 kpa when you are just sitting at 700rpm, so it going to try and yank everything away. Fix the MAP settings and see if anything changes.

Seems a bit better, truck now reads 100 kpa after I turn it off. Should I increase the base spark in the high octane table for the low rpm range? 800-1100?

[Overclock This]

I just took a quick look at your log. I think that you should get injectors in there ASAP before you throw more timing at it and go further

[crutt]

I''ve got 42lb ls3 injectors, but yeah I need to source some LSA ones.

[5FDP]

Is that wideband accurate?

Seems that it's off if you are commanding 10.67 and seeing 13's. Pulse width and o2 mv show a pretty rich mixture. Though o2 sensor aren't the best way to determine AFR they are still way up in the 950mv range, where as I've seen vehicles that are actually lean showing 890's.

Or you have it behind the cat converters and it's reading wrong. 42's should make 500hp on pump gas. Also 10.67 commanded is way rich and will max out the injectors far quicker, running a 11.4-11.5 AFR will gain you back some duty cycle.

Also the VVE and MAF need more fine tuning.

[crutt]

I've got a new wideband harness on the way, I repaired the old one and I think its off. Any tips on fine tuning the maf and the vve? For the vve, disable the maf/codes, reset and log ltfts, apply the ltft correction percentages to the vve table then apply the coefficients? as far as maf tuning I'm lost. If you have any books/etc you recommend I'll pick them up. Ive been eyeing banish's books on amazon but wasnt sure if I should get them or not.

[5FDP]

Use the write up's for setting up the scanner in the VCM scanner section. There is one for both the VVE and MAF.

Don't use fuel trims if you own a wideband, use the wideband as the tuning tool. You can fine tune with fuel trims once you are done tuning with the wideband.