Hello all:

I have a 1986 F-250, with the 5.0L and MPFI (EEC-IV). A problem started about 2 months ago where the truck becomes difficult to start cold. The only way to get it to run is by putting the pedal to the floor (cutting off the injectors) and cranking... then it would start, run like junk and stink for a few minutes, and eventually even out. After replacing what I thought were the usual suspects (EGR valve, IAC motor), there was no improvement. Here is a list of components I have replaced in an effort to fix this problem:

Fuel injectors
IAC
EGR/EVP
Plugs, wires, cap, rotor
IAT
TPS
Coolant temp was replaced a couple of years ago, so I assume its ok.

I finally tried invoking a KOEO test to see if any codes were stored. I can hear the computer go into the test (solenoids actuate, fuel pump cycles) however that's it. The "Emissions" bulb does not flash. I ended up purchasing an Auto Xray 6000 to read the codes, and the only thing I get from the computer is during a KOER test, and it tells me the ECM is saying I have 4 cylinders. The rest odf the tests result in the scanner telling me the "Vehicle is not responding." I cleaned all the contacts on the test plug and single wire associated with these tests. I also swapped out the computer with one from an '87 mustang. the mustang computer says I have 8 cylinders, but fails before the rest of the test is complete. Any ideas anyone? I'm thinking either a bad ground wire, or a break, or corrosion in one of the wires associated with the test plug.

Any advice would be appreciated. Thanks!

 

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the mustang compter is not the right type to even run your truck so that wont work. I have an ecu from an 88 bronco running a 302. its in working order if your interested. pm me