Need help LQ4 stg3 cam and supercharger

[TheSlowestCars]

Hello Guys
Really could use some help with the tune on my brother's nightmare of a Hummer H2. Hummer sat at our local chevy dealer for about a year and a half after it broke down on my brother while driving. Chevy changed out body control module, ECU, Interior lighting and hacked up a major part of the harness under the dash. Had my brother pick it up and bring it over to my shop and started checking compression leak down test and fuel pressure readings. I tracked the issue down to cracked heads. We ended up rebuilding the full motor and installed a stage 3 BTR supercharger cam kit with dual spring kit and trunnion kit. we also had to bore the block .030 over. Installed new factory heads which should have been upgraded but wasn't my money to make those choices. Hummer had a Kenne bell side mounted supercharger and a course the chevy dealer reprogrammed the old ecu before installing the new one. So, we towed this thing to 2 different tuners around town and this thing is running horrible. second tuner left it worst then the first. So decided to try it myself if not just planning on ordering a remote tune. But hoping to learn how to do it myself and been trying to do as much research as possible. So if I could get any help, it would be greatly appreciated.

2003 Hummer H2
LQ4 bored .030 over
BTR stage 3 cam
Kenne bell supercharger 3lb pulley
3200 stall torque converter
kooks headers with high flow cats

[TheSlowestCars]

Hello Guys
Really could use some help with the tune on my brother's nightmare of a Hummer H2. Hummer sat at our local chevy dealer for about a year and a half after it broke down on my brother while driving. Chevy changed out body control module, ECU, Interior lighting and hacked up a major part of the harness under the dash. Had my brother pick it up and bring it over to my shop and started checking compression leak down test and fuel pressure readings. I tracked the issue down to cracked heads. We ended up rebuilding the full motor and installed a stage 3 BTR supercharger cam kit with dual spring kit and trunnion kit. we also had to bore the block .030 over. Installed new factory heads which should have been upgraded but wasn't my money to make those choices. Hummer had a Kenne bell side mounted supercharger and a course the chevy dealer reprogrammed the old ecu before installing the new one. So, we towed this thing to 2 different tuners around town and this thing is running horrible. second tuner left it worst then the first. So decided to try it myself if not just planning on ordering a remote tune. But hoping to learn how to do it myself and been trying to do as much research as possible. So if I could get any help, it would be greatly appreciated.

2003 Hummer H2
LQ4 bored .030 over
BTR stage 3 cam
Kenne bell supercharger 3lb pulley
3200 stall torque converter
kooks headers with high flow cats

Hummers first log.hpl

[gtstorey]

Injectors?

[TheSlowestCars]

Injectors?

Yes sorry totally forgot about that it does have 46lbs fast precision flow injectors

[TheSlowestCars]

Just changed the base set for RPM's and seems too have made the startup and idle a lot better actually keeps the truck running. Also changed the map sensor to a 3 bar. Because i had the second tuner tell me to change it to a 3 bar then he never changed it when we took it back for more tuning, so it was running unplugged before. Izzy's Map and base idle.hpt

[blindsquirrel]

There is no GM-format data for FAST injectors, they're made for aftermarket systems where none of that stuff matters.

[Alvin]

There is no GM-format data for FAST injectors, they're made for aftermarket systems where none of that stuff matters.

A lot of the injectors they sell are OEM injectors for some application..

[blindsquirrel]

Yeah, great if you can work out the cross reference, and it's something with data available. Knowing they're OE Volvo injectors or whatever doesn't do much good.

[TheSlowestCars]

Yeah, great if you can work out the cross reference, and it's something with data available. Knowing they're OE Volvo injectors or whatever doesn't do much good.

Perfect yeah looking at changing those out too 8.1L truck injectors. Question tho what would cause my intake temps to be so high?

[blindsquirrel]

Why 8.1 injectors? Those are only 30lb-hr.

As for high IATs, maybe drawing in hot air to start with and then running it through a supercharger?

[edcmat-l1]

Perfect yeah looking at changing those out too 8.1L truck injectors. Question tho what would cause my intake temps to be so high?

Is the SC intercooled? Those sideways mounted blowers are kind of crappy by design.

Sure is a strange story. Why would they do a bunch of module replacement and electrical work under the dash if had internal engine issues? Sounds like part of the story is missing.

[TheSlowestCars]

Is the SC intercooled? Those sideways mounted blowers are kind of crappy by design.

Sure is a strange story. Why would they do a bunch of module replacement and electrical work under the dash if had internal engine issues? Sounds like part of the story is missing.

[TheSlowestCars]

No, it does not have a intercooler installed. From the invoice they said it was a voltage issue in the ecu causing the problem. After arguing with my brother a few times about that not being the problem with it. He said that chevy should know what they were doing. And approved the repairs and then came the parts changing from chevy. Hummer had no previous issues with electrical and was running great on new transmission. So good that my brother couldn't get his foot out of it. So, when it went down, he had it towed straight to chevy. And when we were talking about what happened he said " I was on it when he heard a small backfire" Then drove to work and got out and drove it to the store but was running rough and then at the store it wouldn't run no more. So I rite away knew he blew something and didn't need an ecu. So after he spent around 5,500 at chevy we towed it to my house and i fixed it. But tuning has been an issue for me.

[TheSlowestCars]

Why 8.1 injectors? Those are only 30lb-hr.

As for high IATs, maybe drawing in hot air to start with and then running it through a supercharger?

I was just thinking of putting those back in because that's what it had in it originally before they started changing everything. But I just seen the injector reference's and I actually have a set of ls3 injectors on a shelf. Would you recommend me dropping those in?