F115 idles at 900-1k rpm

[Extreme26]

Hi all,just updating my follow up testing....checked my linkage & noticed my idle adjustment screw on the throttle body was off when i inspected the factory markings on the screw.Wonder how it could have moved by itself..vibrations maybe??

Decided to redo the link & synch according to the service manual...got my rpm down to specs but i do not have a vacuum tester yet so i could not do the intake vacuum check yet.

Here is my diagnostics test results...anyone willing to analyse if all sensors are within specs?Have not test it on the water yet.

[Extreme26]

I did the isc function test,the isc raised to 100% down to 50% with incresed engine rpm heard....i set the tps at 0.733v at engine off,is it normal it raised to 0.743v at idle?The values are still within specs- 0.732v +- 0.014v....should it stay at what i set or its suppose to raise?

[Extreme26]

These are the values at engine off.....is my link & synch done correctly?the valve opening is at 0.8 degree at engine off.

[rodbolt17]

start the engine. shut it off. carefully listen for the ISC rattle while it is resetting for the next start cycle.

[Extreme26]

Done that....,isc rattle heard after engine off.Does that means the isc is ok?

[99yam40]

Some times Rod says he cannot open thumbnails so I am enlarging the pic to make sure he can see it.
also I thought the ISC was suppose to go to 100% when shut down, but I have no idea how the screen should look with engine off. 65% has me wondering

[Extreme26]

Engine would start right up after 1-2 seconds of cranking though i have an intermittent issue of delayed cranking after the continous testing.(more of that later).

After start up engine raises rpm to around 1500rpm decreasing gradually stabilizing to normal rpm at around 750rpm...at key off rattle is heard every time.

[TownsendsFJR1300]

Engine would start right up after 1-2 seconds of cranking though i have an intermittent issue of delayed cranking after the continous testing.(more of that later).

After start up engine raises rpm to around 1500rpm decreasing gradually stabilizing to normal rpm at around 750rpm...at key off rattle is heard every time.

The RPM's shouldn't rise that high on start up. You still have some issues...



Quote: "Decided to redo the link & synch according to the service manual...got my rpm down to specs but i do not have a vacuum tester yet so i could not do the intake vacuum check yet."
End quote..

How did you do a link and sync without a Manometer?

And the "idle adjustment" you made, what screw(s) exactly, and where are they located? (between the throttle bodies?)

[Extreme26]

Hi townsendsfjr1300,sorry if i mislead u,i am confused myself...i actually redo the control systems & tps adjustments as on service manual,i have not syncronised the throttle valves yet as i have not got a manometer...hopefully i can borrow it from a friend soon.

The adjustment screw that has moved is numbered 1 in the 1st photo on the throttle body.

[Extreme26]

I had the screws back aligned on factory markings,thats how i got back the idle down to around 750rpm..engine not as smooth & silent as it used to be which i believe synching the throttle valve needs to be done with a manometer.

[Extreme26]

I have a single gauge vacuum tester...can i make do with it & vacuum test the 4 intakes individually?

[walleye1]

Check 0'reilly auto parts, they may have one to loan out. [manometer]

[99yam40]

I have a single gauge vacuum tester...can i make do with it & vacuum test the 4 intakes individually?

you really need to compare them all while adjusting