Power Loss w/CEL - Have Codes

[jonagne]

INITIAL POST:

I've been having the same problem intermittently for about a year. '97 XLT w/ 86k. It almost always happens after driving on the interstate for awhile (30-40 miles, although last week it waited until 175 miles). I first noticed it when accelerating out of a toll booth, and had no power at all until I pressed the pedal all the way to floor, at which point it downshifted and started to accelerate normally. Last week I had the cruise set at 70, and when climbing a hill (not a steep one) it decelerated all the way to 55 before downshifting and accelerating back to 70. The cruise steadily moved the gas pedal almost to the floor. The engine sounded like it was bogging down as if I was in too high a gear. The CEL light flashed on/off 4 times and remained on.

I initially thought it was a transmission problem, but everything checked out perfect (plenty of fluid, good color, etc.). I was starting to suspect a bad engine computer as this is sort of what happens when mine went on an '89 Volvo, but isn't that usually an all or nothing event?

Maybe I'll change the O2 sensors, and/or take a look at the CATS (I'm assuming catalytic converter). Of course, the Ford dealer is clueless, so any further information would be appreciated.

**********************

Finally had a chance to get the codes:

P0305B: Cylinder 5 misfire
P1151
P0153B

I'm going to follow the advice on other threads and clean the MAF and IAC and see what happens. I'm a little concerned that the misfire might be an injector as I just replaced the wires and plugs 6,000 miles ago.

Any other advice will be appreciated.

 

[TheJMan]

P1151: Lack of H2OS Bank 2 Sensor 1 Switches - Sensor at Lean Limit
P0153: O2 Sensor Circuit Slow Response (Bank 2 Sensor 1)

I'm no expert by any means, and this is just a guess on my part.

There may be two problems here. Since the Bank 2 Sensor 1 switch is not switching and the computer is seeing a slow response, the O2 sensor may be bad and need to be replaced.

The misfire could be caused by many things, but first take a look at the plug and wire to that cylinder. Just because they are new doesn't mean they are still good. Make sure that the wire hasn't come in contact with the exhaust manifold and burnt. You could also try swapping the cylinder 5 plug with another cylinder to see if the misfire moves to that cylinder.

I highly doubt that the cats are the problem. The computer will throw a code if the cats are the problem, and that wasn't one of the codes you listed.

Hope this helps.

 

[V8BoatBuilder]

Clean up the misfire codes, and your O2 codes might vanish. Don't be so quick to blame the O2 sensors - those codes merely indicate that your engine is running lean. This case demonstrates the beauty of OBD-2, but more so how you have to truly analyize what the codes mean.

Since your engine is indeed running lean, that means that something in bank two, most likley in cylinder 5, since its misfiring. A lean condition means that too much air is in the combustion chamer - not enough fuel.

If the ignition system was not firing, then there would be unburned fuel in the exhaust, and the engine would run rich.

This lean condition could be caused by a stuck injector, poor compression (rings, valves, etc).

I'd first try running a bottle of Seafoam through the gas tank, as well as checking fuel pressure at the rail. Then do a compression test on the motor.

 

[Rhett]

I'd also pull the spark plug for #5 to see how it looks.

It may or may not be O2 sensors...but one comment on O2 sensors...the fact that the problem occurs after driving for a little while, is something O2s do when they're bad.