L
LarryK 87
Guest
New info, I had posted this once before, and like most others i assumed a possible Vacuum leak somewhere.
Problem:
When first started the engine has a very high idle 1700+ rpm
it will hold this rpm for 2 -3 seconds, then idle back down to normal range. It does this warm or cold
Have replaced all flexable vacuum lines
Checked and reseated all Vacuum connections
T.B. disassebled and cleaned
New IAC
TPS adjusted to spec.
Throttle linkage is not binding
what i have since found is this. If i put the ECM into Diag. mode, Key On, Engine off,disconnect the IAC, turn ign off, re-connect IAC, remove Diag jumper, The very next time the engine starts it will start with the expected idle, and maintain just as it should. when i shut the engine down and restart again, Idle is right back to a High RPM for 2-3 seconds, then idles down again. This condition is repeatable.
My question is: Does the ECM hold some sort of memory setting to command the IAC Steps to a specific position on start up? This would be upset when doing the steps listed above, and then re-set it'self for the next start?
Is there a set of steps for reseting the IAC "Home" position?
Problem:
When first started the engine has a very high idle 1700+ rpm
it will hold this rpm for 2 -3 seconds, then idle back down to normal range. It does this warm or cold
Have replaced all flexable vacuum lines
Checked and reseated all Vacuum connections
T.B. disassebled and cleaned
New IAC
TPS adjusted to spec.
Throttle linkage is not binding
what i have since found is this. If i put the ECM into Diag. mode, Key On, Engine off,disconnect the IAC, turn ign off, re-connect IAC, remove Diag jumper, The very next time the engine starts it will start with the expected idle, and maintain just as it should. when i shut the engine down and restart again, Idle is right back to a High RPM for 2-3 seconds, then idles down again. This condition is repeatable.
My question is: Does the ECM hold some sort of memory setting to command the IAC Steps to a specific position on start up? This would be upset when doing the steps listed above, and then re-set it'self for the next start?
Is there a set of steps for reseting the IAC "Home" position?