My 88 f150 started running very rough and when I tried to pull the codes with a reader it did not work. When I put the reader, (which was connected to the star connector), into test mode(koeo) the fuel pump relay turned on but the light stayed solid and did not blink. I checked all the wiring between the star connector and the ecm harness and all wires checked out okay. I checked around the net and am thinking that the ecm is in HLOS mode due to a major malfunction of one or more input sensors. below is a list of symptoms I am experiencing.

-MIL light does not turn on when ign switch turned on (bulb okay)

-when engine started, high idle lasts a few seconds only then comes down and runs rough at idle. The rough idle lasts even after warmup.

-also there is an intermittent miss which is more prevalent during the first few minutes of start-up but occasionaly occurs at all other times

-after engine warms up, idle shoots up to over 1000 rpm in drive instead of the usual 550-600 rpm and stays there. When engine turned of and then restarted, the idle runs normally for about 1-2 minutes, then the idle shoots up again and stays there.

-failed smog test in all catagories

also of note, the air injection pump is not functioning and I replaced the ecm with another unit with no change of symptoms.


If this is a case of the ecm reverting to the HLOS mode, I think that I have to check every sensor to see if it is functioning. I was told that the problem might be with either the MAP, PIP sensor or TFI module. any help would be appreciated on where to start looking for the problem.

 

Have you got the clutch in (standard)?

Did you try doing the test without the tester?

Try doing the test manually instead of w/ a tester.