502 MPI idle speed
#21
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Originally Posted by cloudmaster_321
problem is, i don't know who did the actual engine work, i think just the computer was sent to him. Hopefully the previous owner can shine some light on it, but it doesn't look good.
#22
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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??
That said, I looked at some recorded data files I have from similar modified 502 MPI's (Arizona Speed and Marine reprogrammed ECM's) and they had increased the minimum Desired Idle Speed to 750 RPM from the 600 RPM minimum on stock 502's.
So to try answer your original question, if your ECM is programmed for 750 RPM idle speed, there is no way you can reduce the idle speed without sending it in to be reprogrammed.
Dave
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First - you should take Dave N's advice. He knows his stuff!
As Dave said, the ecm program controls the idle speed, NOT the throttle plate set screws....and don't attempt to change the set screws unless you have a scan tool and know how to use it. It is very common to have the idle spped increased when an ecm is reprogrammed, especially when installing a larger cam. If that was done then there is no way to lower the idle speed without reprogramming the ecm.
As Dave said, the ecm program controls the idle speed, NOT the throttle plate set screws....and don't attempt to change the set screws unless you have a scan tool and know how to use it. It is very common to have the idle spped increased when an ecm is reprogrammed, especially when installing a larger cam. If that was done then there is no way to lower the idle speed without reprogramming the ecm.
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turns out my computer was not programmed by Tyler, but was reprogrammed for an idle of 775 in gear. So it is doing what it is supposed to. Thanks for the responses though.
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If you have trim tabs--drop em down at no wake and it will slow you down a little. If you have a cam change it will probably need to idle that high.
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my 454 MAG MPI has a Arizona Speed and Marine "program" in the ECM and it idles at 750 rpm, if I advance the static timing 2-3 degees it picks up another 25 rpm. this was checked with my dealers scan tool.
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This might be a shot in the dark but you might want to check what setting the tach is on. That can also throw you off a bit. Other than that you can cheat it a bit with the cable. Just a bit though.