Adjusting 5.0MPI Throttle Cables

[jason78]

I recently had my throttles adjusted or rather the throttle controls sync’d up. After this was done, my Port engine will not cold start without putting the throttle in Neutral and giving it a little gas. Once it runs for a few minutes, you can put that throttle back in N and it will idle OK. I have noticed when both engines are idling in neutral, the Port idles between 550-570 and the Starboard idles between 630 and 650. The Starboard has no problem starting. Is seems the throttle cable needs to be adjusted up a hair when in Neutral on the Port side.

Although the mechanic will probably fix this, I am curious how to do it myself. I have T-5.0MPI. Also, what is the target or ideal Neutral idle RPM range?

Thanks
Jason

 

[Woody]

I recently had my throttles adjusted or rather the throttle controls sync’d up. After this was done, my Port engine will not cold start without putting the throttle in Neutral and giving it a little gas. Once it runs for a few minutes, you can put that throttle back in N and it will idle OK. I have noticed when both engines are idling in neutral, the Port idles between 550-570 and the Starboard idles between 630 and 650. The Starboard has no problem starting. Is seems the throttle cable needs to be adjusted up a hair when in Neutral on the Port side.

Although the mechanic will probably fix this, I am curious how to do it myself. I have T-5.0MPI. Also, what is the target or ideal Neutral idle RPM range?

Thanks
Jason

According to my manual @normal operating temps in neutral idle rpm is 600.

 

[Redhook98]

The funny thing about MPI is that the idle is computer controlled, and not controlled via the throttle cable like a carb'd motor. Not sure how your throttle cable could be so far out of whack as to affect your idle, or if that's even possible....... Just sayin'.........

Generally speaking, if you need to adjust the throttle to allow air to get into the engine to start, then you have a malfunctioning idle air control valve (IAC)..... The IAC is how the engine controls the idle via the computer. It regulates how much air gets into the engine via a separate controlled valve to allow your engine to idle at the correct RPM when the throttle plate is all the way closed (i.e. when the throttle is all the way back). Even if you do not have a throttle cable hooked up to your motor, it would still idle properly at the exact correct RPM if everything is working correctly....

 

[jason78]

The funny thing about MPI is that the idle is computer controlled, and not controlled via the throttle cable like a carb'd motor. Not sure how your throttle cable could be so far out of whack as to affect your idle, or if that's even possible....... Just sayin'.........

Generally speaking, if you need to adjust the throttle to allow air to get into the engine to start, then you have a malfunctioning idle air control valve (IAC)..... The IAC is how the engine controls the idle via the computer. It regulates how much air gets into the engine via a separate controlled valve to allow your engine to idle at the correct RPM when the throttle plate is all the way closed (i.e. when the throttle is all the way back). Even if you do not have a throttle cable hooked up to your motor, it would still idle properly at the exact correct RPM if everything is working correctly....

Thanks for the reply Redhook. I had been told this by someone else but did not know if it was true since I only noticed the problem after the throttle controls were aligned and just assumed a cable needed to further adjusted on either end.

The mechanics went back down and found that part of the IAC assembly was clogged and had to be cleaned to fix the issue. I have not been back down yet to test.

Thanks