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Need Help! LS2 with LS3 head upgrade

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I am building a 67 Camaro for the wife and purchased a 2009 Trailblazer ss with a 6.0l and a 4l70E trans that had been upgraded with the LS3 heads and a cam and dyno tuned. He wrecked the trailblazer and it was a front end hit but didn’t get to the engine. I will add the build info below. My problem is it will not idle and runs so rich it fouls plugs within minutes of trying to get it to idle. It ran fine before the accident and I did a compression test all at 200lbs! I smoke tested the intake to be sure it wasn’t cracked and no issues there. I tried a different MAF (LS7 blade style) because I thought it might have been damaged but made no difference. When I look at the HP tuner info (very green to tuning) all I see is the STFT’s seems to stay at -27 all the time both sides. Fuel pressure is 58psi with an adjustable regulator not the filter regulator. It seems like the injectors are just dumping fuel. The fuel system hold pressure when engine is stopped so no leaking injectors. I’m having problem figuring out why it is running so rich when it ran fine before the wreck. I would appreciate any help or thoughts.

Thanks, Rick!!


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Grind Number 13157R / 13021R HR 114 + 3 Specs 222 / 243 114 + 3

Lift 0.6018 0.6239

Intake Manifold L92

Injectors FAST 46 lb/hr.

Nick Williams 103mm TB

4” One piece Intake w/ LS7 MAF by PCM of NC

Efans: Three Relay Spal Fan Kit

ARH Long Tube Headers w/ cat-less Y-pipe Circle D converter 3000-3200

Comp 850 Lifters

Comp Rocker Arm trunnion upgrade NGK TR6 plugs

160 Thermostat

LS2 MAP sensor

Are you using the ECU from the vehicle the engine came from?

Do/did both vehicle use a lambda and if so, are they the same type?

Is it possible the regulator was fitted backwards?

Is it possible you missed, or made a mistake with, any connections or vacuum lines?

Before you go any further, make sure the ignition side is in tip-top condition with new spark plugs and leads, if required. Because the lambda measures the oxygen in the exhaust, any mis-fire will give a false-lean indication from the lambda, if used, and the ECU may be trying to add fuel to compensate, often causing a rich mis-fire which further compounds the problem.

Thanks for your help! It was running this way with the original setup before I pulled it from the Trailblazer so yes it did it with the original harness and ECU. I have changed to a PSI Conversions LS swap harness which required an E38 ecu with their wire harness and went from the E67 to an E38 Ecu that PSI programmed from the original E67 ECU. I replaced the filter regulator style to an areomotive regulator and filter and adjusted the pressure to be sure I had 58 PSI. The ignition side is in tip top shape and have replaced the plugs due to fouling.

Thanks, Rick

Can you log injecton time or pulsewidth and compare it to factory values?

Relatively small deviation in base fuel pressure will not foul plugs.

We usually reply within 12hrs (often sooner)

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