NightwalkerLS1

iTrader: (2)

So before I changed my fuel filter the car would start hard since it was clearly starving for fuel. Now when I start it up it fires up nice and quick but it gives itself a little high rev on start up. The cars seems to be running good down the road but I want to get all I can out of it.

With that being said is it possible that the cars computer has compensated for the fact it was starving for fuel before by running rich? If so is there anything else I should do to reset the computer besides just unplugging the battery for a few minutes? Or am I completely insane?

wssix99

iTrader: (5)

Did you disconnect the battery when you changed the filter? If so, you probably just need to drive it for a while so the PCM can "re-learn" its settings. Unplugging the battery will reset the PCM but it won't work properly until you go for a good drive.

NightwalkerLS1

iTrader: (2)

I did not disconnect the battery during the change out. With that said I will go take that drive. Ty

LS6427

iTrader: (2)

Your IAC valve is acting up......it shouldn't be just by changing the fuel filter. But that's the only thing that can allow more air into the intake.......other than a large vacuum leak or pushing on the throttle pedal. But since it only happens on start up.....it's the IAC valve.

The way I've found to reset the IAC is to unplug the IAC valve, unplug the MAF and unplug the TPS. Start it up for a few seconds. Then shut it off and reconnect them all. This worked for my engine/PCM a couple times years ago when I was getting weird fluctuations at start up on my 427ci.

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NightwalkerLS1

iTrader: (2)

It went away after a couple long drives.

wssix99

iTrader: (5)

Maybe it had to run through the re-learn sequence to see what its like to drive and not gasp for fuel. Must have been a really stuffed fuel filter?

NightwalkerLS1

iTrader: (2)

Yeah 111k miles and it was obvious it had never been changed out by anyone. crazy.