running rough

[dkrace67]

We are working on a '96 Windstar that is running rough and has NO power. Pressing on the gas pedal yields poor throttle response and an acceleration that can be measured in glacial time periods. At first we suspected a plugged cat, but when we pulled the O2 sensor to investigate we found the cat completely hollow! (that's a completely separate issue I'm curious about). Regardless, we then turned our attention to the EGR system, so we pulled the intake manifolds (upper and lower), THOROUGHLY cleaned the lower (4 out of 6 EGR passages were plugged with carbon), the gaskets WERE shot, reassembled, flushed the cooling system and have no change. We've tried a new PCM (junkyard), no change. Still backfires and has no power. It has good spark on front three cylinders (13-18kV with 1-5ms burn time), computer does not register any misfires, noid lights say all injectors are working...we're confused! Next we are going to try a cam position sensor, seems our spark advance is not responding well to engine RPM. We are stuck at 18 degrees and rarely go above 24. Any suggestions!???

[rodeo02]

Like ModMech pointed out in the previous post, check your MAF sensor.
G/luck
Joel

[dkrace67]

We didn't notice any codes from the scan tool and the MAF sensor has "normal" voltages and percentage values so sez tool...

[rodeo02]

Man this is a tough one, especially since you are not getting any malfunction codes, which unusual with it running so poorly . Does the exhaust smell rich? Sounds like spark timing is the way to look at this point.
G/luck
Joel

[ModMech]

Classic MAF symptoms. No power (post warm-up), and no codes.

Ford MAFs RARELY "go bad", but when the sensor wires get covered in junk the sensors read less air than is really there.

Since spark, fuel, shift points, line pressure and a whole host of other things are derivitives of "load" (which is calculated from MAF voltage), even a 10% drop in signal will cause the EEC to miscalculate spark, fuel etc.