Medium and Heavy Trucks
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Hi John, my name is***** will be glad to try to help. If there are no codes and the fuel system checks are good, Overhead is good then try recalibrating the throttle position sensor. IGN switch on push slowly to the floor and back up to the top 3 times then IGN switch off. Next check your engine position sensor for problems as this gives the ECM engine speed signal. Check your ECM switchable and battery power and grounds to verify you do not have low voltage to the ECM and finally try a test ECM or have yours reflashed with the most current updates. Be sure all your battery to starter connections and grounds are clean and tight, batteries test good and the charging system tests good. Let me know
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We pretty much had already tried everything you suggested. Still haven't
resolved the problem. The fact that you can time it each time to 15 to
16 Minutes is what is baffling me. Its got to be some temp sender sending a signal to the ECM. If it where wiring or settings, it would do
it when it was first started in the morning as well. But it has to run for
a consistent amount of time when started cold. Then stays at 1000 RPM the rest of the day. It starts to come off of 650 RPM around 13 Minutes.
It is set at 650 RPM in the ECM. ( Strange )
Thank You !!