High idle that fluctuates when moving
High idle that fluctuates when moving I've researched the answer to this to death, but need some help still.
My 99 Z28 (just bolt ons) idles high, so I swapped out the TPS and did the relearn procedure. I still show tps % at 3-4% at idle and the idle will go down when unplugged. I replaced it with a GM sensor. The idle also increases when I'm moving and lowers when I come to a stop.
I cleaned the maf, IAC, throttle body, etc. I also checked the best I could for vacuum leaks and cannot find anything.
Any ideas?
My 99 Z28 (just bolt ons) idles high, so I swapped out the TPS and did the relearn procedure. I still show tps % at 3-4% at idle and the idle will go down when unplugged. I replaced it with a GM sensor. The idle also increases when I'm moving and lowers when I come to a stop.
I cleaned the maf, IAC, throttle body, etc. I also checked the best I could for vacuum leaks and cannot find anything.
Any ideas?
This is normal behavior, throttle cracker function (in
the PCM code) props up idle until you come to a stop.
You can modify this behavior in the tune but it won't
respond to messing with parts (to the extent that the
cracker is the only problem).
the PCM code) props up idle until you come to a stop.
You can modify this behavior in the tune but it won't
respond to messing with parts (to the extent that the
cracker is the only problem).
A car with a cable throttle should show zero % TPS at idle, unless the Max Allowed TPS at Idle parameter in the PCM has been raised. You need to close your throttle blade using the throttle stop screw. The PCM is not looking at the idle RPM table like it is now. If it is just a "bolt on" car (stock camshaft) there is no need to screw with the tuning. If you have an aftermarket TB, the TPS could be "clocked" wrong in relation to the throttle shaft. Seen a lot of that. Most, IMHO, are crap. Had to slot the screw holes in the TPS to enable it to be rotated, to get the %TPS back to zero when the throttle is shut.
Hope this helps.
Hope this helps.
