502 MPI idle speed
#11
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just some added insight, i remember now that the last two clicks of the morse throttle control does not change the rpms, so i don't think it's a cable. I would like to try the idle screw adjustment, i will just move a little, and put back if no change is noticed.
#12
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Originally Posted by Dave_N
Agree that you should check the throttle cable to see of it's sticking a little and not allowing the throttle plates to hit the stop.
I do not agree that you should mess with the throttle plate stop screws unless you have ruled out all other causes and have a scan tool on the engine while you adjust it.
You have to first establish if the ECM is driving the high idle (high Desired Idle Speed) or if the engine is not able to achive the Desired Idle Speed due to other causes (misadjusted throttle cable, vacuum leak, bad IAC, etc.)
Dave
I do not agree that you should mess with the throttle plate stop screws unless you have ruled out all other causes and have a scan tool on the engine while you adjust it.
You have to first establish if the ECM is driving the high idle (high Desired Idle Speed) or if the engine is not able to achive the Desired Idle Speed due to other causes (misadjusted throttle cable, vacuum leak, bad IAC, etc.)
Dave
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Originally Posted by cloudmaster_321
This is good stuff to know, but i wanted to be able to exhaust my chances of fixing it in house before taking it to a shop
Not trying to bum you out, but you will need a scan tool to properly diagnose and repair this problem.
Dave
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Well, i found something else out from the previous owner. I did know that the engine was modified, but to what extent i did not know. He told me that the pistons have been replaced with i believe to be JE pistons? It apparently has a different cam and crane roller rockers, so apparently has a full roller valve train now. He also told me that the rev limiter was increased to 5300 and that it had a Tyler Crocket program now?? He does not know if he has any of the paperwork for the engine rebuild, got destroyed during a divorse. So it may be hard for me to get any further details. But he is telling me that i should leave the idle alone. Not sure what to do at this point...........
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You may be in luck. Tyler is a member here and can probably tell you exactly what was done to it and whether he turns the idle up. It may have to have a higher idle to prevent water reversion with the different cam.
You could either PM him through the board or go to:
http://www.crockettmarineengines.com/contact.html
You could either PM him through the board or go to:
http://www.crockettmarineengines.com/contact.html
#16
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Originally Posted by insptech
You may be in luck. Tyler is a member here and can probably tell you exactly what was done to it and whether he turns the idle up. It may have to have a higher idle to prevent water reversion with the different cam.
You could either PM him through the board or go to:
http://www.crockettmarineengines.com/contact.html
You could either PM him through the board or go to:
http://www.crockettmarineengines.com/contact.html
#18
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Originally Posted by Dave_N
I thought we were talking about a stock engine, but my posts above still apply. Did I mention needing a scan tool?
Dave
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Dave
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It is not very likely that someone has changed the idle. Still, the way to find out is to follow Dave´s proposed actions; throttle cable, IAC, vacuum leaks. If it still idles too high it may be the throttleplates or TPS out of adjustment or that someone has in fact programmed it to idle at 750-800.
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Originally Posted by cloudmaster_321
so are you saying that with the above mentioned upgrades, 600 would still be the appropriate rpm??