250 OX66 idle warmup

[flyin fisher]

I have started having trouble with my 2001 250 OX66 on warmup idle. The motor when cold used to rev up to around 1400 rpm for a minute or two, then idle back down to 700 rpm. Now when it's started, it doesn't go to high idle to warmup, just to around 600 rpm, no matter what the outside temperature. Which sensor tells the ECU it needs to idle up when cold. I've replaced the engine water cooling temp sensor, as it was showing signs of coming apart. It tested just out of spec, but the new sensor did not fix the problem. The motor is 30 hours into a 200 hour service. Also throttle and shift cables were just replaced, as well as a link and sync, and TPS set at .50 with throttle valves fully closed, read .60 with throttle link connected. All new filters, LP fuel pumps, O2 sensor has been cleaned. Any insight would be appreciated

 

[flyin fisher]

Re: 250 OX66 idle warmup

Anyone? I'm pulling my hair out.

 

[flyin fisher]

Re: 250 OX66 idle warmup

Just had the fuel injectors cleaned and tested the O2 sensor, which was within spec. Still having trouble with the motor not wanting to go to high idle when first stared cold. Anymore ideas? Thanks

 

[99yam40]

Re: 250 OX66 idle warmup

not sure if that motor has a system to to hook up to with a light or something else to see if there is a code showing, but a service manual should give that info.

Might look at timing at cold start up to see if it is advancing during warm up, my C40 raises RPM by adjusting timing.
But not sure about your motor

 

[jeffersondodson561]

Re: 250 OX66 idle warmup

Engine coolant temperature is what sends info to ecm but agreed winky blinky may show something else?