Hi all,

I have a 1999 Honda Accord 2.3l. The car is has a manual trasmission(this may be relevant, I'm not sure though). I have been fighting an issue with stalling and idling rough, rough as in the tach is barely above 0 rpms. This happens whenever I am coming to a stop and have the clutch pressed in.

The only thing is, is that this issue is completely random. Sometimes it does it, sometimes it doesn't do it. There doesn't seem to be any rhyme or reason as to why it does it. It might do it after its warmed up, it might do it as soon as I crank it up in the morning, or it might not do it at all. There's really no telling when it will do it.

The check engine light was on and throwing codes for a catalyst deficiency and both o2 sensor. I replaced the catalytic converter with a magma flow direct fit cat, and I replaced the downstream o2 sensor with one from denso. I replaced those about a month ago and the CEL has yet to come back on so I believe that issue was fixed.

I was hoping that the new cat and o2 sensor would fix this issue, but this morning as I pulled the end of my street and as soon as I stopped it began to idle poorly. I really have no clue what this issue may be because the car has no codes and as I said, does not do this all of the time.

In addition to the new cat and o2 sensor the throttle body has been cleaned, the valves were adjusted, and a standard tune up has been done in the past 3 years.

Any help would be greatly appreciated! Thank you!

 

did you replace the upstream one ? you might want to swap the cap rotor and plugs as well...gap the plugs

 

just the downstream. I will probably go ahead and replace the upstream one, but do you think it could possibly be the IACV or the TPS malfunctioning?

 

no, just the downstream. But I just cleaned the IACV and throttle body, and while doing that I noticed that the air intake hose was ripped almost completely in half. I taped it back together with some Christy plumbers tape(it's like a thick electrical tape). Do you think that leak could have been throwing off the air fuel ratios causing a rough idle/stalling?

 

Any vacuum leak will cause it to run poorly. Watch some Scotty Kilmer YouTube videos like "Finding Engine Vacuum Leaks with a Cigar" and "How to Fix a Car that Idles Poorly"

 

okay, I will. thank you! The only thing that gets me is the randomness of it. Sometimes it runs fine, and other times it will idle poorly and there seems to be no reason as to when it will do it. You would think that it would do it consistently all the time.

 

vacuum leaks will cause it to idle higher not lower

 

Have you tried inspecting or cleaning the Air Intake Control Valve. Mine was gunked up with black tar and barely moved with a screwdriver. Cleaned it with intake cleaner and it moved and clicked like it's supposed to. Solved my low idle/idle surge/stalling issues.

 

I actually just did that this morning! Along with cleaning the throttle body and fixing a huge crack in the air intake pipe. I haven't driven it yet, but it seemed to idle fine after. But time will tell because the problem happens randomly and is not consistent.

 

Just curious, how did you go about fixing the crack?