Supercharged111
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Injectors and FPRs are notorious leakers. I've heard of people taking the plenum off, cycling the key, and watching fuel dribble out of the injectors.
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Wouldn't the 0411 PCM swap fix the mapping issue?A Vortec FI is.a creation from hell. As has been stated, increasing the injector size is pointless. Your ECM doesn't have maps for them, and the O2 sensor limits air/fuel ratio in any event. Replace the injectors and fpr. Use GM fpr kit. You cam clamp the fpr sense hose and see if the engine idle cleans up. If the fpr is leaking internally, it'll muck up the idle.
You could have a rocker bolt backing out, or a bad/damaged lifter packing. I'd go with leaky lifter since it quietens up with oil. But you'll be revisiting that soon enough. If it raps too much, it'll hammer the roller off the lifter. Then you got major issues. You cannot adjust the lash on Vortec 7.4.
While under the plenum, you can get to the valve lifters pretty easily. They are not expensive.
If loose rocker stud, lock it down.
These engines leak at the rear lower plenum. It must be chemically clean and the correct sealant used per the book.
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Wouldn't the 0411 PCM swap fix the mapping issue?
Are the O2s still a limiting factor when tuned with the new PCM?
I probably haven't done enough reading, but this is the first time I've seen these issues in writing. I'm very curious to know if I'm barking up the wrong tree. Would save me a lot of headache and money.
As for the tick, I appreciate the input. I'll be on the lookout for a loose stud. Hoping it's that simple. Not really excited about pulling the lower intake if I don't have to. It really isn't leaking enough to notice yet.
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A Vortec FI is.a creation from hell. As has been stated, increasing the injector size is pointless. Your ECM doesn't have maps for them, and the O2 sensor limits air/fuel ratio in any event. Replace the injectors and fpr. Use GM fpr kit. You cam clamp the fpr sense hose and see if the engine idle cleans up. If the fpr is leaking internally, it'll muck up the idle.
You could have a rocker bolt backing out, or a bad/damaged lifter packing. I'd go with leaky lifter since it quietens up with oil. But you'll be revisiting that soon enough. If it raps too much, it'll hammer the roller off the lifter. Then you got major issues. You cannot adjust the lash on Vortec 7.4.
While under the plenum, you can get to the valve lifters pretty easily. They are not expensive.
If loose rocker stud, lock it down.
These engines leak at the rear lower plenum. It must be chemically clean and the correct sealant used per the book.
Sent from my SM-G965U using Tapatalk