Erratic Idle

[sketchman]

Going back to totally stock other than a mushroom filter on the VAF it was still doing it, and actually it was worse. Depending on load the engine would completely die idling sometimes. I have since replaced piping from the stock VAF rubber adapter to the TB with hard pipe and have checked for vac leaks.

I have installed a different VAF just to rule out the VAF as an issue. No air filter. Idle set by throttle stop screw on a Escort ZX2 TB with the stock IAC gizmo totally gone and everything plugged off. No TPS. I have hooked up the TPS and played with it at idle to see what effect it had. Simulating an open but not wide open throttle raises and stabilizes the idle for a moment, but it goes back to unstable quickly. I also have the TB coolant lines removed and one line going from the T in the heater hose to the IM nipple. It seems to warm up noticeably faster like that. I also have the EVAP line unplugged and the nipple capped.

The issue: the idle is jumpy from startup with a variance of about 150-200 RPM, and then(after it starts to warm up) at times it will just decide to rise to 1100-1300 RPM with no throttle input. That's from an idle set at 900 RPM.

Any suggestions welcome.

[Movin]

The only thing left to wander around is timing?
If the idle sounds better when it bumps timing up by itself it could be timing is not hot enough or the engine is getting tired..low compression or worn valves?

[sketchman]

Hmm, I can check the timing soon, and I'll do a comp test. Last time a B3 did this to me it was the rings going. It does sound better when it idles up, and it does not like to idle below 800-900. Gets a little stumbly.