power loss @ 3500
#1
power loss @ 3500
I have a big power loss above 3500 rpm's pinging and engine light starts flashing, I just put a 5.3 h.o in the truck it had a 4.8 they both acted this way, parts from the 4.8 on the 5.3 are TB, fuel rail, oil sensor and flex plate that’s it, new parts so far fuel filter and mass air, and updated to a 02 vcm, So all help would be greatly appreciated..
#2
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what do you mean by updated?
is it tuned?
what mods are on the engine, or is it stock?
Mine will do that on cold starts, because of me not being tuned with my cam, but works itself out.
If its something really serious, the engine will go into a limp-home mode.
as I told the last guy...check your coolant temp plug on the front of the drivers side head to see if its securely plugged in.
This will cause your problem too.
have any of the threads on the spark plugs been crossthreaded or stripped? that leaks compression and will stumble and studder, and throw an engine light quickly.
is the maf in the air tube correctly, with no leaks?
It sounds like once you start hitting the power band, it has a problem.
is it tuned?
what mods are on the engine, or is it stock?
Mine will do that on cold starts, because of me not being tuned with my cam, but works itself out.
If its something really serious, the engine will go into a limp-home mode.
as I told the last guy...check your coolant temp plug on the front of the drivers side head to see if its securely plugged in.
This will cause your problem too.
have any of the threads on the spark plugs been crossthreaded or stripped? that leaks compression and will stumble and studder, and throw an engine light quickly.
is the maf in the air tube correctly, with no leaks?
It sounds like once you start hitting the power band, it has a problem.
#3
Yes it’s tuned with a 02 vcm, no mod’s both cold or hot, will check the coolant plug, but like I said the 4.8 did the same thing…your right once the motors hit the power band they both stumbled pinged the engine light starts to flash, no power back get out of the throttle runs great to 3000 rpm’s light stops flashing and go’s off…
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Yes it’s tuned with a 02 vcm, no mod’s both cold or hot, will check the coolant plug, but like I said the 4.8 did the same thing…your right once the motors hit the power band they both stumbled pinged the engine light starts to flash, no power back get out of the throttle runs great to 3000 rpm’s light stops flashing and go’s off…
check for air leaks anywhere, and that the maf is secure in the tube. Its thinking its getting a LOT more air than it really is.
Are you noticing a fuel smell out of your exhaust, or any little black soot deposits?
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Yes it’s tuned with a 02 vcm, no mod’s both cold or hot, will check the coolant plug, but like I said the 4.8 did the same thing…your right once the motors hit the power band they both stumbled pinged the engine light starts to flash, no power back get out of the throttle runs great to 3000 rpm’s light stops flashing and go’s off…
#6
I would say more like lay right there, and so did the stock 4.8 before the motor change, this problem developed when the old motor was in and the timing was never messed with, so I am going to rule out the tune.. No fuel smell out of exhaust and no black soot deposits
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Any ecm DTC codes?
Scan the computer for DTC's and let us know what comes up. Could be a few bad ignition coils since you said it exhibited the same behavior on the 4.8. WOT below 3500 RPM does ok? Part throttle above 3500 RPM exhibits the same behavior? Try doing a scan of the ECM while accelerating and post the recording.