My 91 Explorer 4.0L excellently maintained before my recent purchase of it. One very cold AM, minus 10F. I started and drove it before I felt it warmed up properly. (I mention this as this is the first time I remember the start of the problem.) It began running rough and surging amp meter also. After 10 mins the check eng light came on.

I preformed the 1st portion of the diagnostic with the Actron code scanner. It gave the O2 sensor and PIP (profile ignition pickup fault) from the continuous memory. The O2 sensor made sense because the light only comes on after it heats to its 600F. I changed the O2 sensor. I have changed everything else I can figure; plugs, PCV valve, drive belt, naturally oil and filter, air filter and even the fuel filter (which supposedly doesn’t ever need to be changed). The problem continues as running rough, amp meter surges, very black exhaust, it lags when starting acceleration and in 5-10 mins check eng light appears.

What is the profile ignition pickup and how do I fix it? Is this the cause of my problem or a symptom? I wonder if this is a timing problem but have not been able to check it and if so, all references tell me, in the case of timing problem take to dealer.

Any words of wisdom?
phil
aac@acsalaska.net

 

PIP, is one of the signals used by the ICM to control spark timing. PIP code could be wiring, ICM (ignition control module), bad spark plugs/wires, or other fault. If you can, get a hold of a circuit test from a proper manual (I go the the library and find them). Here's the first part from a '95 manual