Idle fluctuation problem 92 Protege 1.8 DOHC

[nuthaus]

I just purchased 92 Protege with 1.8L DOHC, with approx. 110,Km/70,000mi, am 2nd owner, & a 2 hour drive to the nearest Mazda dealer. I hope someone could take the time to share a bit of advice.
The RPM's are fluctuating between stalling, but it hasn't, to about 1800. I am not experiancing any power loss, no miss & I don't think fuel economy has suffered, & starts fine, but I believe the problem is getting worse.
After reviewing all posts I have;
-when I replaced the air filter I found no cracks in the boot, & throttle body & what I thought was the mass air flow sensor looked clean, but I still clean sprayed
-timing belt was replaced, timing adjusted, new plugs & wires installed 10,000km/6,000mi ago, & cap & rotor replace recently.
-checked grounds.
-ran some injector cleaner through the fuel tank
-a post commented on a valve lash adjustment, I don't think that is my problem, but I believe in the 1.8 you can replace shims & that is more of a replace when you have a problem, than a maintaince measure.
**-a post suggested resetting ECU, restart & let idle for 5-10 min. What is it & how do I do it?
-one post recomended to look at Idle Air Control Valve, will it require ajustment, cleaning or replacement? Is it that flapper valve that sits on top of the air filter? I am leaning towards this being the problem
-The previous owner had an occasional problem with it not restarting when at operating temp, after waiting 10min, would fire up. I expericenced this once, the motor would turn over & created spark, & after 10min, started fine
Any insight would be appreciated very much, & I will post a reply as to the results.
Thank you

[Doug Tatham]

The idel control valve attaches to the throttle body - the metal thing that the speedometer cable attaches to. Remove the intake air hose and the throttle body. The idle stabilizer is the thing that has a wire harness attached to it and is attached with phillips screws. Remove the idle stabilizer and spray it out with carborator cleaner. If I remember right, the valve slides side to side to allow air through. You may also want to clean out your EGR valve. It attaches to the backside of the intake manifold. The tube that leads to it is at the bottom of the intake manifold and gets blocked up with carbon deposits. You'll get an engine error code - EGR excessive flow- when this needs cleaning.

I just realized you said 1992, rather than 2002. I'm not sure how the stabilizer is set up on your model, but it acts as a bypass to the throttle body. On my VW it has hoses attached on either side and on my protege it is mounted to the throttle body.

The ECU is the engine control unit. It takes in info from all your sensors and controls the fuel mix. I've read that removing the battery and repeatedly applying the brakes will reset it, but I don't know anything about the source.

[lau_lhk]

May b u can try this,
start ur engine, let it "flucuate". disconnect the ISC valve connector (locate under the throttle body, near TPS connector). See whether the idle is stable.

If so, u may need to clean the throttle body and ISC valve. It should be too much carbon build there.


Hope this might help.


Lau
Protege '92 1.8 turbo