StealthSierra

iTrader: (1)

It has been a long time coming but last weekend we were finally able to attempt our first start. The car fired up relatively easily... Idled for around three seconds and shuts down. Over and over again. I know what you're going to say... VATS. And according to the shop who did the base tune, it is off and not the issue. Additionally, the throttle body will not operate, unsure if that is hardware, comparability, or tuning related.

I would really appreciate input on other things to investigate.

Parts include: 2008 Trailblazer SS ls2 and 4L70E, E67 ECM. LS3 heads, intake and gold blade throttle body, 07 Monte Carlo SS accelerator pedal, ls3 map, ls2 maf. Additional info upon request. Please help.

tfi racing

iTrader: (2)

Check your wiring on the fuel pump relay,unlike almost everything else it needs to see 12v from the pcm,not ground.For some reason I screwed that up on my TJ project,sounds like the same issue.As for the TB,check your power and grounds, I wouldn't be surprised if these issues are related,btw,who did your harness?

garys 68

iTrader: (1)

There was another thread here that indicated the trailblazer LS2 had 2 VATS systems. The typical one that kills the fuel pump and another that kills spark.
You could hotwire your pump to full time +12V to check if it's the pump voltage issue.

tfi racing

iTrader: (2)

Gary has a good point,I missed the 08 E67 in the first post,VATS bypass on those PCM's can be tricky,there is a lot of good info on the EFIlive site.

StealthSierra

iTrader: (1)

Fuel pump relay has power as does the fuel pump. Harness was built by Modern Vintage Systems. Havent been able to find anything about two VATS systems yet. As far as the throttle body goes the accelerator pedal is showing input to the ECM, but other than adjusting to "home" on initial start up has no input. Does anyone have a schematic or pin out for the throttle body connector I can verify against?

StealthSierra

iTrader: (1)

Would the VATS prevent this throttle blade from moving with he pedal? At this point I am trying to identify if this is one issue or two..

gofastwclass

iTrader: (2)

I thought the Trailblazer SS used the silver bladed throttle body, not the gold LS3 style. They rotate opposite directions and as far as I'm aware are not directly interchangeable.

StealthSierra

iTrader: (1)

You are correct. Gold throttle body is ls3... It is my understanding that ETC scalers can be adjusted to work fairly easily. I hope... Anyway.