Hoping someone can help me diagnose this.

I have a 92 civic cx. 01/93 production date. 1.5l - 5speed.

Little over 300k on the clock.

The car fires right up. Idles good. Engine sounds good. It will pull up to redline and feels like it's making a healthy amount of power.

Problem. Just above idle the rpms jump up and down (dieseling?) and I am pulling my hair out trying to figure out why. Parts for this thing are cheap and given the mileage I figure I'll end up replacing everything anyways so I've been shotgunning it with new parts hoping to fix the problem.

It seems to get worse when the engine is hot. Being a manual the car is nearly undrivable. I basically have to mat the pedal and dump the clutch to get moving. It's not conducive to stop and go traffic.

What could cause this? I have a short video I will try to post after I get this initial post up.

Edit: the video was taken before the fuel pressure regulator was replaced (didnt help) but I did notice that it would do the same thing at idle when we unplugged the vacuum line to the fp regulator.

New parts:

Battery
Complete distributor, plugs & wires.
Fuel pump, filter and fuel pressure regulator.
TPS sensor.
Map sensor.
Main relay.

I'm probably forgetting a few things as I've been going at it for a while now.

Any recommendations?

Thanks!

 

I don't know how to post the video ☹️

 

It's fine when it's cold? When cold the FITV on the bottom of the throttle body controls idle. When warm the IACV takes over. If that's unplugged or has an issue you'll get the fluctuating idle and very spotty throttle response.

 

It still does it when it's cold but it's worse at operating temperature.

I'm at work right now but I'll check that out as soon as I get home this evening. Thanks for helping.

 

upload to YouTube, then post the YouTube link here.

 

Try the grounding wires. There are three of them: One for the battery, one on the transmission, and one on the engine block. They're cheaper than some of the sensors you've been throwing money at. here's a good option: https://www.ebay.com/itm/27717031856...Bk9SR86zrMzDZg

Also, make sure your distributor rotor has been screwed in properly. It's common for aftermarket ones to have a spring in them that will cause random misfires.