F115 2002 Idling fast

[JONSNELL]

Just having my F115 serviced, engine is running fine but is idling fast, like 1500RPM out of gear. Timing is advanced 10deg, we have checked the thermo sensor, throttle linkages and flywheel position but all of that is fine. Currently waiting on a cable to run further tests just wondering if anyone has any pointers where else to look.

Thanks in advance

JON

[Sequoiha]

intake or vacuum leak maybe, the first thing i would do is a link and sync. you will need a 4 bank manometer, something like this really needs to be looked at by an experienced technician with the proper equipment.

[rodbolt17]

if base ign timing is locked at 10*BTDC, something broke.
that is the default ign timing if the ECU sees an isssue.
the ECU is attempting to alert the operator there is an issue and keep the motor running.
depending on what broke timing may or may not advance and top speed may or may not be reached.
you can use the diagnoistic test lamp,laptop or check each and every sensor manually.
laptop is quickest.

[JONSNELL]

Thanks Guys,

Will get winky blinky onto it and report back.

Thanks JON

[JONSNELL]

We ended up restricting the bypass hose to get the idle back to 8-900 RPM, engine runs fine. Have connected winky blinky and we get a light every 5sec ( with the restriction in place ) so all is good. As far as we can tell it seems like the IAC is stuck open.

Now looking at getting the PC diagnostic tool to prove that this is the case.

Cheers Snelly

[JONSNELL]

Waiting on the PC diagnostic to arrive. Just wondering if its worthwhile removing the injectors and having them cleaned while I'm at it ?

[rodbolt17]

is base ign timing still locked at 10*BTDC?

[JONSNELL]

Will check and report back.

Thanks JON

[JONSNELL]

Ok got hold of the PC based diagnostic tool. All showed as normal and ran the active test on the IAC valve which didn't change the RPM. I didn't save the data when I ran the motor with the restriction we had in place to control the fast idle. WHat I did notice was the IAC valve was at 65%.

Today I changed the IAC valve over to a new secondhand one and removed the restriction I had. IAC valve now at 30% and timing 4' ATDC Engine Speed 886RPM Throttle Valve Opening 8 deg TPS voltage .733

I ran the active IAC valve test and it showed opening from 0 - 100% but I cant say I noticed much change in RPM .

Anyway looks like problem solved.

I noticed in the data I got that total engine hours is 746 but on my hour meter on the gauges its showing 850 any idea why the difference ?

Thanks all for your help.

Motor has pretty much always run fine but after doing this bit of tinkering I'm wondering if it would be worth removing and having the injectors cleaned. Also on this subject do/should the injector gaskets be changed when you do this ?

Cheers Snelly