Rough Idling in 1996 Mazda Protege

[dom_is_gone]

Good Day!

The issue that I am having with my Mazda is that I am currently experiencing rough idling and shaking at stops.

At first, the code that came up with Massive Air Flow Malfunction, and we changed the Air Flow Sensor. That stopped the car from shaking so bad that it would stall. But, still at lights and while stopped, the car would shake. The code that now comes up is P0170- Fuel Trim Malfunction. Somebody suggested replacing the EGR valve, but I have been warned that this could not fix my problem at all. I am wondering if anyone else has experience this and who has fixed this issue. It's gotten quite a lot worse now, back to the way it was when I first got the car.

Thanks.

Dominique

[Doug Tatham]

I had a similar error when I had a vacuum leak. I replaced the breather hose and the small hose that goes to the PCV valve.
How new is your valve cover gasket? If it leaks and the oil drains down around the coil packs it causes it to miss pretty badly.
If the idle is going up and down then it may be the idle stabilizer valve.
You my want to try fuel system cleaner such as sea foam.
If your air filter has more than 20K on it, replace it.
Check your plugs.

[kh1p3h]

Might want to check the timing, a missing tooth on the belt can cause trouble!

[mrmikey]

Daughters car, '99 1.8L Protege, was doing the same thing, can't remember the error code but I think it was something to do with lean condition or similar. Hers was bad at a stop sign after the car was warmed up. It would shuddder, revs would drop down to almost stall, pick back up to 1K or over and keep repeating.
If you think it might be the problem, get a piece of hose 'bout 2-3' long, put one end to your ear and move the other end around the sealing surface between the manifold and head. When you come across the leak you'll know it.
Another method is to get a can of WD-40 or similar and spray it around the sealing surface, the revs will increase when you spray it on a leaking seal. Just be careful, WD-40 will burn.
Ended up being the intake manifold gasket was broke between cyl's 1 & 2. Not a bad job to repair, worst part was the egr tube from the exhaust manifold to the intake. Parts total was $25.00 and 5 hours± time.
When you find out what it is, post back and let us know....Mike