I recently purchased a 1994 civic vx for my son, manual trans, when it gets warm it won't hold a cruising speed in any gear. bucks and jerks at steady throttle, but responds fine under heavy accel. thanks to anyone with some ideas.

 

Is the Check Engine Light ON?

Check for fouled plugs, wires, distributor cap, and rotor.

 

I have a similar problem that only pops up when the IACV code is triggered. I haven't had a chance to diagnose it, cuz it doesn't sound like an idle circuit related problem.

A tune-up is always a good idea with a new vehicle anyway, not telling when the last one was performed. If you don't know the history of the vehicle too well, it's best to perform a full tune-up with PCV valve and fuel filter, cap and rotor,plugs, wires, seafoam (before you change the plugs though), clean out the throttle body, adjust the throttle cable, check and adjust ignition timing (accordingly).

 

what speed are you doing when it jerk ?

 

car has been recently tuned w/new fuel filter, symptom is not speed dependent, seems to be more rpm related(around 2000), along with throttle position (1/4 to 1/2) I'm wondering if it is a load calculation issue.

 

Sounds like a distributor related issue. could be spark scatter at certain rpm's.

 

My '95 VX did the exact same thing when the oil pressure was low - check the PCV valve (under the intake manifold and a PITA to get to). The hose to the PCV valve on mine was actually disconnected (I had recently rebuilt the head and missed it when setting the head back on).

Not to mention the VTEC module gaskets were leaking like a sieve (reused the old ones since I couldn't get new ones anywhere locally), and dropped the oil pressure so low the VTEC would cycle in and out around that same rpm range (I didn't realize how much had leaked out at the time). M

y IAT sensor was shot as well - although I think it was unrelated.

Once I hooked up the PCV, replaced the VTEC gaskets, and installed a new IAT, it was like a new car.

Let us know what works for you.