Cat causing unusual idle?

[b_ron]

My engine started idling really low in neutral at stop lights. I've always had the P0420 code (Cat under threshold) come on once it a while but I always cleared it with my Ultragauge and everything was fine. I cleared the code before leaving work this morning and the low idling started happening on the way back home. When going into neutral from any rpm or gear, the rpm would drop until the car shakes and goes up to 700. I remember it used to idle at 850.

Can the cat efficiency affect the low idle problem? No mods except the K&N air filter on the stock airbox.

[SyckSiR]

You could have a iacv that is stuck closed. Never heard of a cat causing idle problems.

[T_Virus]

I had idle issues before too with random misfires and my car would stall if i didnt give it gas at the stop light. Mine was weird and it turned out to be the valves needing to be adjusted. After the valve adjustment, everything was fine.

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[captaingamez]

My engine started idling really low in neutral at stop lights. I've always had the P0420 code (Cat under threshold) come on once it a while but I always cleared it with my Ultragauge and everything was fine. I cleared the code before leaving work this morning and the low idling started happening on the way back home. When going into neutral from any rpm or gear, the rpm would drop until the car shakes and goes up to 700. I remember it used to idle at 850.

Can the cat efficiency affect the low idle problem? No mods except the K&N air filter on the stock airbox.

If your cat is clogged it could cause that, it would likely also cause a loss of power.

Honestly you should take itout and put a test pipe in if it is throwing the cat code.

It may still be "fine" but its not working as well to do its job and that is because it is getting contaminated,and over time that turns into a clogged cat, and that turns into a not running well engine.

IAC valve should not cause you to idle that low, only higher and fluctuation from my experience.

[b_ron]

If your cat is clogged it could cause that, it would likely also cause a loss of power.

Honestly you should take itout and put a test pipe in if it is throwing the cat code.

It may still be "fine" but its not working as well to do its job and that is because it is getting contaminated,and over time that turns into a clogged cat, and that turns into a not running well engine.

IAC valve should not cause you to idle that low, only higher and fluctuation from my experience.

The cat code comes on occasionally, like every 2 weeks. usually if i push the car to like 4-5k rpm.
the low idle also happens every couple weeks.

i can try the iacv first, then a test pipe if it doesnt work and see what happens.