500 Efi Idle problems

[BlakeSullivan]

I recently installed a 500 efi in my 22c with 14 hours on it and it runs great but when i come back to neutral after a run it rev's up to 1500 or so rpm and then slowly comes back down. I know its not the throttle cable because it is bottomed out where it should be and I installed a new IACK valve thinking that was the problem but know luck and suggestions . Thanks Blake

[Tidbart]

Is it just doing this once, then settling at normal idle, or doing it multiple times?

Also, did you use a Merc or aftermarket IAC motor?
Do you have a Merc scan tool?
Got a Merc Service Manual?
B

[BlakeSullivan]

Is it just doing this once, then settling at normal idle, or doing it multiple times?

Also, did you use a Merc or aftermarket IAC motor?
Do you have a Merc scan tool?
Got a Merc Service Manual?
B

It does it each time and it is a Merc Iack but to answer the other questions no

[Tidbart]

Blake,

I didn't ask the question properly. Does the idle go up to 1200 and then back to normal and then go back up and then down, etc.? Or, just go up once and then back down to normal and stay there?


B

[BlakeSullivan]

Blake,

I didn't ask the question properly. Does the idle go up to 1200 and then back to normal and then go back up and then down, etc.? Or, just go up once and then back down to normal and stay there?


B

It stay's at 1200-1500 and they slowly (Like a Minute) goes back down. Thanks

[dsparis]

Sounds like a lazy IAC

[mrfixxall]

The iac reacts to the tps's %..If the tps is registuring 2% then the iac will stumble and get confused where its soppose to be..scan the Tps first.

Is it a oe 14 hours or `14 hours on a rebuild? if rebuilt look for a vacume leak..

[BlakeSullivan]

The iac reacts to the tps's %..If the tps is registuring 2% then the iac will stumble and get confused where its soppose to be..scan the Tps first.

Is it a oe 14 hours or `14 hours on a rebuild? if rebuilt look for a vacume leak..

it is 14 hours on a new motor but I will check the tps

[roadtrip se]

Unless it does this for a long period of time, typically after coming off plane, I wouldn't worry about it. It is normal and has no adverse effects. Before the re-build, I ran mine well over 200 hours, it did this fairly often, and my IAC and Mefi always checked out normal.

I would recommend the "number six" service manual for this engine from Merc.

[BlakeSullivan]

Thanks Will do