Dies after start on cold starts

[DavidMcgwier13]

Im working with a fresh LS built for a 67 camarro resto mod... the Motor and ecu is out of a 07 Avalanche. It had been tuned by someone at one time but was way off. I have it running good now but only on cold starts like first start of the day it will die right after start up. It will rev up a bit and as it comes back down it will fall on its face and die. It acts like a carb motor until its ran for a bit. Ive gone through the start up tables and compared to stock tune thinking maybe it will like more stock tune on cold cranks. Its helped in some areas like warm starts so I thought to try it on cold starts.. Still same problem. Any ideas what I can look at or check?

[5FDP]

A stock rebuild or one with mods?

Post the tune file and perhaps and logs of the issue.

[DavidMcgwier13]

I don't have a scan file of the issue.. like I said its only on cold starts 5 min of run time with help from the pedal after a few min it clears up runs great will start no prob the rest of the day. The only mods.. Holly intake.. and for some reason he lowered the injectors to 24lb.. I increased the fuel pressure to help compensate. It would starve it for fuel before and lean it way out. But here's the tune.

[5FDP]

I would put back in the correct injector data in for the tune, not a good idea to work around a issue like that. Make it easy and have the proper data for whatever size injectors you are running.

Then I'd start re-tuning from there for the different intake manifold change. Someone turned off the VVE table, so it's basically a MAF only tune, ve is disabled above 500 rpm. Using the VVE can be a benefit. It would be something a wideband would come in real handy for, I'd suggest one always when trying to tune vehicles like this.

[DavidMcgwier13]

The injectors are 24lb injectors. I dont agree with that or his reason but i sugjested going back to at min factory. I tryed to use my wide bsnd to tune but after a few min they went to 19.5 and would not change. I also found water in the clamps after i removed the wide band. Also the breather he user to fit in te car cuts air flow in half. Where in the tune do i get the VVE back enabled?

[schpenxel]

The injectors are 24lb injectors. I dont agree with that or his reason but i sugjested going back to at min factory. I tryed to use my wide bsnd to tune but after a few min they went to 19.5 and would not change. I also found water in the clamps after i removed the wide band. Also the breather he user to fit in te car cuts air flow in half. Where in the tune do i get the VVE back enabled?

What wideband are you using?

Airflow-->Dynamic, disable to something like 4000, re-enable to something like 3800 is how stock files usually look

[DavidMcgwier13]

Daytona WEGO 4. dual channel. I tested it when I first got it did the free air calibration on it and ran it on my work truck to see if it worked right and it did.. you think the condensation in the exhaust messed up the 02s?

[schpenxel]

Maybe. Just a guess though.

[DavidMcgwier13]

Correcting the VVE Table my best bet to get it to start and idle from dead cold? Like first fire of the day..

[DavidMcgwier13]

Current tune... and scan file. Still has small issue with cold start and hesitation on throttle up. Hesitates on hard stab, but climbs nice with slow throttle up.

[schpenxel]

It shouldn't really matter as long as either the MAF or VE tables are right. Plenty of cars run MAF only and cold start just fine

[Aaron407]

Assuming the injector data is correct, it sounds like an open loop equivalence ratio issue to me. I had the exact same issue previously on my MAF only supercharged G8 and was able to richen up the AFR at startup temperatures to get it working much better.

[10_SS]

Assuming the injector data is correct, it sounds like an open loop equivalence ratio issue to me. I had the exact same issue previously on my MAF only supercharged G8 and was able to richen up the AFR at startup temperatures to get it working much better.

same for me. Something with the supercharger is throwing things off. Mine was an RPM dip though, but if it was worse it would stall. Fixed by richening it up 15% in the cold cells.