Originally posted by Big Jim:
It does not sound like the cat or the fuel filter would have any bearing on this.

A plugged fuel filter would cause problems when there is heavy fuel demand such as under heavy acceleration.

Also a plugged cat would be worse with high air flow through the engine. At idle, there is minimal air flow.

You might try putting the original PCV valve back on and seeing it it makes a difference.

A possibility is a vacuum leak of some sort, so that is why the wrong PCV valve is a possibility. Look for vacuum leaks in general. Look especially at all the vacuum lines.

It is probably a simple problem.



Well, first off, i'm glad that its not the cats; i didn't really want to deal with that right now. Other than the idle, i have no performance losses at any other engine speeds.

As for the old PCV valve....why put it back on? The condition was worst with that one.

When i blew through both valves, there was very little restriction in the old one; in the new one, it restricted air blown from the top...which is how it should be...i think.

I will say that the purolator PCV valve didn't fit perfectly in that bottom hose, so when installing, i actually used a worm clamp and tightened it until it was snug (not too tight, because i didn't want to crush it). The one line that connects to the top of the valve [and has to be squeezed on the grey clip part] was a little loose on the tube, but then it was loose on the old one too.

I'll try to check my vacuum lines some more tomorrow.

But, the other thing is that while exploring the ford service CD i read that the PCM needs like 15 minutes (iirc) of idling to calibrate....i'm hoping that will solve my problem.



As for the IAC valve, i only have 55k miles. My dad has a 99 stique which idles perfectly; so maybe in the future, if i feel the need, i'll borrow his to test.



1998 Mystique LS: -2.5 Duratec ATX -Vibrant White -------------------- =Pics= =Info=