QuestionHello,
I am stumped by a few problems I've been trying to diagnose. It's a 96 Ford Taurus 3.0L SOHC ohv auto. For some time now it occasionally starts to run crappy during hot weather and will not go when gas is depressed. Almost like it is killing itself, but doesn't stall. I have to wait a few minutes and then it will be ok for a bit. It had codes before for O2 sensors and now all are new. I pulled 3 more codes today out of it. P1131 P1151 and PO306. The first two are like the O2 sensor codes before, but the 3rd is the one that troubles me(cylinder #6 misfire). I'm thinking coil or wire etc along that line and just ordered the coil today to atleast rule that out. The temp guage was rising and lowering in hot weather also, but hasn't done it lately. I figured this was a separate problem, maybe a temp sensor. My question is this for the misfire PO306 code. Couldn't a bad coil act fine when the engine is still cold and act up or break up when hot, like on very hot days? This was my reasoning for ordering a new coil. I originally thought ignition module, but this car doesn't have one. Thanks for your ideas.
AnswerThe ignition module on this vehicle is incorporated in the PCM. A single cylinder misfire is not usually contributed to the ignition module or PCM. I think you are on the right track with the ignition coil, check for pinholes or black/white spots on the coil boot, a sure sign of arcing.
Hopefully you are not using Bosch plugs, which can reek havoc on Fords.
The O2 codes are telling us the PCM is correcting rich for a lean condition. If you did not disconnect the battery to clear the PCM memory after replacing the O2 sensors, this could be the problem. If this is correct, the PCM has learned to compensate for the sensors you replaced.
Here is a list of things to check for the problem causing these codes. P1131 and P1151 are NOT sensor codes, they are indicating a problem causing the incorrect fuel trim.
Good luck.
Possible causes:
Fuel system
Excessive fuel pressure.
Leaking fuel injector(s).
Leaking fuel pressure regulator.
Low fuel pressure.
Contaminated injector(s)
Induction system
Air leaks after the MAF.
Vacuum leaks.
Restricted air inlet.
PCV system.
Fuel purge system.
Improperly seated dip stick.
EGR
Leaking gasket.
Stuck open EGR valve.
Leaking diaphragm.
Base engine
Oil overfill.
Cam timing.
Cylinder compression.
Exhaust leaks before or near the HO2Ss.
Check air intake for leaks, obstructions and damage.
Check air filter, air filter housing for blockage.
Verify integrity of the PCV system.
Check for vacuum leaks.
