Running rough SES light on

[Goliath]

I was moving my truck one day last week and it was very hard to start. Hard to try and turn it over several times. After I finally got it cranked it sounded almost like a dead miss. After the engine warmed up it finally smoothed out some but the service engine soon light came on. I killed the truck and went back to work and when I got off that day it cranked right up but it still ran really rough and the ses was still on. On the drive home it the engine would tach out completly before it would even shift gears. So I rode with my friend to work the next day and when I got home I changed the oil and filter, the fuel filter, and cleaned the air filter. Got in cranked the truck and it ran fine. Until I started driving back up the road. At the redlight it started idling rough and it would tach out again before it would upshift. I was forced to drive it to work for a few days in a row and found that if i floored the truck the ses light would go off and the engine would smooth out. But just as soon as I backed off the throttle it would run rough again and the ses light would immediately come back on. I changed the cps out about 9 months ago. Any ideas on what would be causing this?

 

[early 99 stroker]

check for codes..my guess would be the wires going from the IDM to the injectors or the harness under the valve cover..you can OHM them out at the 9 pin plug on the VC

Pin Out

G G I I C I I G G

G=Glow Plug +
I = Injector +
C= Injector Common

***The injectors fire with a 115VDC signal from the IDM do not pierce wires to test.***

Ohm between "I" and "C" to test the injectors, should be less than 5.0 Ohms

To check glow plugs Ohm between "G" and battery ground should be between 0.1 and 2.0 Ohms

 

[93turbo_animal]

could also be IPR or ICP check the codes and it should point ya in the right direction

 

[Tail_Gunner]

1 vote for UVC connectors. Very often when there is an intermittant problem like you've described, the UVC connectors coming apart are the cause. Those things are enough of an issue that Ford came out with some little plastic wedges that that lock the UVC connectors together.