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'92 f-250 inline 6cyl, rough starting only...

3K views 2 replies 2 participants last post by  centerline 
#1 ·
I have recently purchased a 92 f250 with a 6 cylinder in it. it seems to run great but on cold startup and sometimes a warm startup, it has a terrible misfire and will not always pickup and start running correctly. sometimes i have to shut it off and restart it...

i am a heavy equipment mechanic and have been around carbureted and diesel engines and wiring problems for the past 40 years, but this electronic automotive stuff is out of my league....

is there anyway to diagnose the problem with my engine or is it a common sensor problem that can be replaced to fix it without much further fuss over it?... does it have an obd connection located somewhere?

there are two sensors at the intake, i suspect the one on the side is the tps, as the throttle cable and linkage is on the opposite side of it, and I suspect the other one that is on top is the mass airflow sensor. when i unplug this one with the engine running correctly, it kinda replictes the startup issue for a few seconds.... then it returns to normal running. i can plug it back in without any running issues... when i unplug it again, it replicates the rough startup again.

if you have any suggestions, toss them my way... Thanks
 
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#3 ·
plugs and wires are new.... i have found out that its actually the idle air control motor that sits on top of the intake... when i unplug it while normal running, it replicates the problem...
i will check the fuel pressure before cold start up and after... what are the spec limits for the fuel pressure?
thanks for the help
 
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