Oliver Unger

Hello! I currently have an EM1 Civic with about 223K miles on the original B16A2 engine, and i've had a weird idle issue for about a year now, so, lets get to explaining shall we?

Cold starts are fine(Albeit unless i'm low on fuel, then it takes a couple more cranks than usual, not an issue if i let the fuel pump prime, old car thing i assume), it idles at around 1-1.5K RPM until it warms up, then drops to around 1K. Warm starts are also fine. The issue arises when it's cold outside, say, 55°F and below, once my car gets up to temp, it'll do this weird thing where it'll drop to 700-ish RPM, then quickly go back to 1.5-2K RPM, then, if i ever so slightly push the gas, it'll start too...Sputter? Cough?. It'll bounce a couple hundred RPM consistently, without me varying pressure on the throttle. If i shut the car off & turn it back on, it goes away until it's able to sit for about 45 seconds without any throttle. And again, this only happens when it's cold. I've checked the codes, one for the Catalytic Converter(been there since i bought the car one and a half years ago, doesn't seem to me like it's effecting it), and one for the IACV(P0505, if i recall correctly). I've tried cleaning the throttle body to no avail.

Before i throw money at the problem, i'd like to know if anyone has had a similar issue, and what you did to fix it.

Another thing that happens, is when i'm in 5th gear, going about 27MPH, it starts to violently buck. This doesn't happen if the idle issue isn't happening. It also happens in 4th at about 24MPH, and so on with the other gears. Also, when i'm cruising at a normal speed, and let off the gas, no matter how slowly i do it, it bucks a little, same with going on the gas. Again, none of this issues happen when the idle issue isn't happening.

If a video is helpful to diagnose the issue, i can get one, any help is appreciated!

aw614

Did you check all your vacuum lines to the intake manifold and have you cleaned out the IACV?

tamboo

could be time for a new tps, they don't last forever.
i've had good luck with dorman brand.
blox..not so much.

Oliver Unger

I have done neither. I don't hear any obvious vaccuum leaks, but i will check. Where is the IACV? Dumb question i know but i can't find it

Oliver Unger

Interesting, thank you! I will look into it