High idling problem 7.4l mpi 2001 sr 270 sd

[jimmydenmark]

Hi there

I have a 2001 Sea Ray 270 SD with a 7.4L MPI (L29) engine and MEFI 3 ECM. Problem is:

When i start her up(cold) she starts very fine but immediately she goes up to about 1800/1900 RPM.

When she reaches running temperature, 160 deg she will then drop to about 1000 RPM and then drop til 850/900 RPM and rest there.

I have changed the IAC valve, but still the same problem.

I do not at the moment have access to a scantool.

Any one have clue on what's going on and what the problem might be?? :huh:

Thanks..

Jimmy

 

[NJMatt50]

Vacuum leak? Maybe when its hot it seals up?

 

[jimmydenmark]

Hi.

Have checked all vacuum lines and they seem to be in good working condition. can't feel or see any cracks or leaks.

Thinking the problem could be the ECT sensor or maybe the IAT sensor....... But I'm waiting for a cable and program from OBDdiagnostic so i can hook her up with a computer and "hopefully" there will be a code... to fix the problem....

Jimmy