Working on my girlfriends car, just replaced the PVC valve tube because of a vacuum leak that was causing rough idle. My temp tape fix worked for a while but finally wasn't doing the job anymore hence the permanent fix. After the replacement she's still idling really bad. Press on the gas and things smooth out almost totally.
Does the engine need time to readjust or am I missing something here? Should I clear the comps memory by disocnnecting the battery? Anyone?
Rough idle? Not much to work with here in terms of a description. How is the fuel pressure? How old are the plugs and wires, cap and rotor? Is the idle air control valve dirty? The large air hose feeding the intake, is it cracked? Any codes from the computer? How about the air filter?
Could be a lot of things... start digging and post your findings. Simply disconnecting the battery for a few minutes is not going to help you.
Did you go over the entire system looking for vacuum leaks? In particular, there are a bunch of very small push-on vacuum connections up on the firewall on the passenger side, check them carefully.
Does your PCV valve plug directly into the engine block, or is there a hard plastic extension piece that runs up the front of the engine and moves the PCV onto the top of the crankcase? My engine has the hard plastic piece. I've found that either this piece has shrunk or the rubber grommet on the engine block is bad - probably both. As a quick and very nasty hack, I shimmed up that plastic piece so it makes a better seal when you push it into the grommet.
Another thing I would advise - having been down this route myself with the exact same problem on a 98 Escort SE wagon - is to clean the MAF sensor and make sure the sensor itself and the other sensor just downstream of it - I'm not sure what it is but it's plugged into the side of the air intake manifold just after the air cleaner - are both connected solidly.
I had my car (well, it's actually my wife's) in service for a long time trying to solve the idle issue, but they never really fixed it - it took the futzing I describe above to get rid of the symptom. At its worst it sounded like the engine was trying to rip its way out. Ford said it needed new ($680 P&L) motor mounts, which I'm glad I didn't get!
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