My Dad has a 01 Chevy S10 with a 4.3L Manual Trans. He is having a problem with the RPM hanging while he is driving. If he hits the brakes or clutch it will drop. He bought an IAC valve from Autozone but that did not fix the problem (I believe Autozone parts suck). One of the reasons I bought an EFILive was to help with this problem.
I figured I could BBX the truck during the problem (Maybe even pass through). What PIDs should I be loading and looking for?
Since no one gave any inputs I picked the some I thought I would want to see. I made a couple BBX runs and saved the tune which is currently on the truck now. My Dad bought a new IAC valve and we replaced it before making any runs. I found a couple interesting thing. It will hang longer when around 1800-2500 RPM. I was driving the truck at about 2000 RPMs when I popped it into neutral and took my foot off the accelerator pedal. The RPMs stayed between 1800 to 2200 for a while. Then it would slow to about 1500 and then jump up to about 2500 (surging). I then pulled in the clutch pedal. The RPM dropped to normal.
I also did some runs on the freeway and got a similar result.
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Compare an auto vs manual file, and look at the idle and IAC settings. Some big clues there. GM had these setup to prevent issues with shifting, but if you're slowing down and stepping in the clutch first--instead of braking and allowing the engine to slow you down (which is driver error in your dads' case), you'll have a hanging throttle.
He is letting off the throttle and is expecting the vehicle to engine brake but the RPMs hang (does not change with his foot off the throttle). If he pushes on the brake and then lets off it will try to go back to the same RPM. If he pushes in the clutch the RPMs will fall to idle.
I am pretty sure Chevy design it that way. I believe it is either the Throttle follower decay I need to change or Cracker.
I finally made it to my Dad's house and flashed a changed tune. I made the changes to the follower and cracker. It seems to be working. THANKS YOU