I just posted this on crownvic.net but figured a cross post here wouldn t hurt..

The engine is sputtering and bogging under hard acceleration

I have done some searching, and it sounds like the likely culprit is the MAF needing to be cleaned, and/or spark plug wires. The only weird thing is that in neutral the engine revs up fine!

A little background:

1999 CVPI with just under 140,000 No knowledge of it's maint. history, except a replaced coil pack just before I bought it.

CEL is on and throwing an O2 sensor code. TC shudder had been evident when shifting into overdrive since I got the car. Pings at WOT (even when spitting and sputtering)

I figured it was the MAF, but if that is the case, would it still rev up okay in neutral?

 

If it is an upstream O2 sensor that is kicking the code that can cause a problem. What about the plugs how do they look?

 

I haven't checked the plugs yet. The car has been running with the O2 code that way for a long time without missing a beat, then in the last couple days it's gotten pretty bad (seems worse when it's cold out?)

 

when was the last time the tranny was serviced? at 140K then it sould be on its 7th tranny service. Mercon V only.

also a clogged EGR can cause the bucking.

With a coil on plug motor you cant really replace the plug wires, you have to replace the entire coil pack at around $80 per cylinder

if the motor has been running rich it can clog the O2's and clog the EGR passages

 

I have been putting off doing a transmission fluid /filter change for a while.. I'm sure that wouldn't hurt...

 

How can I test EGR? I unplugged the vacuum line from it and went for a test drive, but no difference. Engine is too hot after driving home to take out the plugs and coil packs, and it got dark real fast, may have to wait till the weekend

 

I have the same problem with the pinging at WOT, but not even at WOT I have it. I'm surprised your not throwing a EGR code, replace it and it should help a ton.

 

I did a bunch of stuff, I cleaned the MAF, no difference.

Ran it with the MAF unplugged, stalled out when put in gear.

Changed PCV valve & air filter.

Accelerates a little better under part throttle, but anything above half still is no good.

 

Injectors?

 

^^