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Super lean at cruise, idle surges, but WOT is perfect?! Turbo silverado. Videos, data logs, details included.

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Single 7875 turbo, 2007 Silverado 1500 Classic 4.8l 4x4 (LR4)

Computer: P59, ECM, GM Gen3 V8

Tuning: HPTuners


Dual Valve springs, Trunnion upgrade, Chromoly pushrods.

TSP Stage 3 truck cam



Lobe lift: .353/.353

Valve lift @ 1.7: .600/.600

Intake center line: 110

Melling High pressure oil pump.

Trick turbo T4 manifold, VS racing billet 7875, VS Racing 44mm Wastegate with 10PSI spring, VS Racing 50mm BOV with larger spring.

Fueling: Single Hellcat 525LPH fuel pump, Flex Fuel sensor in line, Snake Eater "Flex Fuel" 1000cc/min, 96lb/hr@43PSI Injectors

Return system with adjustable regulator set at 58PSI.


TBSS Intake, Maf in charge piping, Chevrolet Performance "3 bar" Map Sensor PN:12592525

So lets start with some back story.

I have a hunch my tuner is miffing my tune to keep me coming back and spending money.

At the same time I don't want to point fingers as it could be a number of things on the truck.

All's I know is after dyno tuning using smaller flex fuel injectors everything was perfect and non return style system.

I had to go to return style because the fuel pressure was so much it would tear the fuel pump to fuel hat line when the truck would sit overnight.

What have I changed since it ran good:

Swapped in the injectors I was told to, ran a return system and fuel pressure regulator.

Had a bad o2 sensor so I put a new one in and now the issues are worse.

Noticed the BOV was sticking WIDE open at idle so swapped in the bigger spring and it did not fix the issue but no longer sticks open.

So what's it doing? VIDEO: https://www.youtube.com/watch?v=35nLIzV2NUU

Yes I know my RPM tack is broken.

What I do know:

Fuel pressure to rail is good during surges.

WOT runs fine.

Didn't have these issues with same o2 setup prior to injectors/Return fuel setup.

Tunes & Data log/s attached.

WTF.hpl =

Data log from the videos drive. When it was good - dyno runs.hpl = Data log from the dyno run when it was good.

currernt 10-12-21.hpt =

Current tune that is on the truck.

Stock reference NON 4x4 NON 3.73 gears.hpt =

Stock reference of a 4.8l silverado 1500, difference is it's non 4x4 and non 3.73 gears. Mine is 4x4 and has 3.73 gears.

Attached Files

Hello, this looks to me like only wide-open throttle has been tuned and a lot more time needs spending on the tuning of the rest of the map

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