sr20det misfire

[connerw0]

I have a misfire (running rich/ backfire) at idle, but when I turn on the AC, the misfire seems to get a little better. As well, when I unplug cylinder 1, it seems to smooth out, and it is less rough. Does anyone have any idea what could cause this?

[flartius]

Could you offer a little more background of the engine? Have you checked the timing? Is it running on a stock ecu or aftermarket? Is it flashing any codes from the CEL?

[VStar650CL]

If pulling #1 smooths it out then you have to have something going on in 2 or 3 as well. The SR20 has a 180 degree crank like most L4's, so the only way inducing a miss on 1 or 4 makes the engine smoother is if it already has a miss on 2 or 3. Anything else creates a worse imbalance and makes the engine thump. Also, don't assume because you have fuel smell in the exhaust that it automatically means rich, a lean misfire will also send unburned fuel out the pipe (simply because whatever fuel there is isn't igniting). Inspecting the plugs will tell you rich or lean, the tailpipe may not.

[tunermt]

I have a misfire (running rich/ backfire) at idle, but when I turn on the AC, the misfire seems to get a little better. As well, when I unplug cylinder 1, it seems to smooth out, and it is less rough. Does anyone have any idea what could cause this?

When was the last time she got fresh spark plugs or injectors cleaned/serviced. These lil SR’s are getting old
Old ignition coils also go bad often but easily replaced by something more modern like R35 coils (no longer need an ignitor chip that way either)