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need some ideas on missfires and both banks lean on the 5.3l


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#1 hooahh3

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Posted 2 weeks ago

Ok guys, need some ideas here.

Got the 5.3 (2005 w/4l60e) running and driving but its giving me P0171 and P0174 codes; Both banks lean. The tourqe app im using also picked up cylinder 1, 7, & 8 misfires ranging from 14-24 times. It will run great, but if I get on it hard or floor it and let off, it pops and shoots me some flames out the exhaust (both very considerably!) then throws the codes

 

Ive changed knock sensors and that code is gone

Swapped in good MAF sensor and that went away (new one of those bought tomorrow)

Done a TB gasket

Checked Fuel pressure at rail. Holding at 60+ psi for full throattle range ( only parked though, not able to check while driving)

Tried to spray for any leaks and couldn't find any vacuum leaks

 

 

 

At this point im down to swapping around those 3 coils, will swap the wires around too if that doesn't give me anything, or then swapping the injectors around.

Run a compression test next if that doesn't work.

 

Im about 80% certain the lean condition is coming from those missfires

Has anyone had and fixed this problem with something other then what I have/will try? Im kinda out of ideas if the coils/injectors/compression doesn't turn up anything.

 

Unfortuantly ls1tech crashes on my browser so im SOL on that wealth of knowledge. Cant read shit when its freezing and reloading every 3 minutes.



#2 Aero Z

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Posted 2 weeks ago

Use the Torque app to also monitor what your 02 sensors are reading as you get on the throttle.  If they're not working correctly it could affect it. i would suspect only one (not throw both codes) would quit though instead of both at the same time. Something to maybe eliminate as the problem. 



#3 hooahh3

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Posted 2 weeks ago

I can read the voltage for them both but not the actual AFR. There new stock type narrow bands. Im just trying figure out what could throw both banks off together, always both banks. Maybe two bad O2 sensors, both purchased brand new for this engine though.

#4 hooahh3

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Posted 2 weeks ago

ok so i've basically narrowed it down to when it's wheel driving the engine. Any coasting that put the engine being driven by the back tires, really bad down hill.

So that would put it on the i take and exhaust system right? Both are very free flowing and it's just sucking in more air then the computer can compensate for on a stock tune during coasting and engine braking. Right???

Seem to be re thinking every thing i thought i knew here with this damn problem. lol




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