jibs

Holy cow I haven't posted on here for a long time. Hope someone has an idea for me.

Month ago my daughters 98 ex with 200k miles threw a code for a cylinder 2 misfire and a random misfire. I found the plug wire for cyl 2 seemed wonky so I replaced the plugs, wires, cap and rotor. Problem solved.

Now she says the engine feels like its "chugging". There are no Codes or a CEL! I look at it it and in "park" (it's an AT) and when it's warm it runs fine then the rpms will drop out and the engine sputters like a misfire. Then it idles fine for a few seconds, then repeats.

The problem gets worse when there is a load like A/C. It will sputter to the point where on one occasion it died.

I cleaned the iac valve, and that seems to be working. Checked compression (ok) MAP sensor, cleaned fuel injectors(took them out), replaced the coil, and module( had new ones on hand)

At a loss right now any help appreciated.

Swap'DShuttle

Sounds like a vacuum leak or the ecu somehow missing a distributor fault.

jibs

Should add that the car is all stock. Obd2 scan tool shows the o2 sensor after the cat consistently at 1.25v. Sometimes dipping as low as .6 but for the most part over 1 volt. Is this normal?

jibs

Just to update on the solution for the sake of completeness...

I found that the radiator fan wasn't kicking on. My scan tool read the coolant temp at 220 degrees.

Tested the fan relay, fuse, and tested the fan switch in hot water. Everything was ok.

Found that the thermostat was bad. It would open in hot water, but I think it was somehow plugged.

Replaced the thermostat, and now it's running great again.

motegicivic

I find it hard to believe that a stuck thermostat made it missfire. When is the last time you adjusted the valves?