93 Metro Bucking

[larry221]

Hey - can you guys give me some advice as to where to start looking to fix this problem? 93 Metro 1.0 5 speed.
The problem is:car is fine when cold , fast idles as it should till warmed up. And accelerates normal with no bucking.
Once warmed up when driving ,as long as you accelerating it is fine but once you get up to speed and then just hold gas pedal steady if you let off gas just a little it acts like the engine drops to idle. You have to give it a little more gas and then it will come out of it and jump back to where the rpms should be. Sometimes it does this even when accelerating just bucks you might say. Very aggrivating. I suspect the TPS but it seems to do it at all rpms not just one spot in throttle position. Is worse at low gears and hi rpms as when it drops to idle it about throws you thru the windshield.

I'd appreciate the help. Thanks in advance.

[geozukigti]

Sounds like the dash-pot is shot, or your throttle stop is off-aligmnent. If the TPS was off that much, your car would stall, or throw a check engine light when it bucks. The dash-pot is basically a small "damper" that slowly closes the throttle when you let off it. I'm not 100% sure if your metro uses a dash-pot or an electronic solenoid though.

[larry221]

thanks for responding. I have already adjusted several times the manual idle speed screw which did raise and lower the idle speed but did nothing to fix this problem. Also when car is bucking(I dont know what term to use here) bucking sounded good. but it nevers throw a check engine lite.

Where is the dashpot located. Is it easy to get to on top or outside of throttlebody??Or do you need to tear it apart. I cant find any vacuum leaks anywhere either. Weird problem but very annoying and downright dangerous if somebody is behind me,