Miss when hot

[dieselgus]

Developed a strange one recently. Car developed a pretty good miss when warmed up. Figured it was time to change some things:

-New distributor, cap, rotor, wires, plugs
-New IACV
-New fuel pressure regulator
-Bled coolant, and re bled and bled some more just to make sure
-Timing is bang on, advances as it should
-No difference with 3 different TW sensors
-Engine is pulling 20-22 in-HG of vaccuum at idle

Only other clue I have is excessive fuel consumption (lucky if I get 400km out of a tank. Used to be closer to 600), and a recently failed emmissions test with high CO under load.

Only other thing I can think of is either a bad injector, or a clogged cat. Maybe an iffy MAP sensor or TPS.

Any ideas?

[Oldblueaccord]

Just a wag but maybe o2 sensors.

[dieselgus]

Also stuck a new pair on. This definately has me scratching my head. Thinking next step is probably timing belt and a valve adjustment, swap in a new MAP sensor while I am at it from the box o spares. Probably pull the coil off the carbed 3G and stick it on there just for fun. The worst bit is not once has the CEL popped on, and the only code I have seen on the ECU is for the IACV, which prompted a lot of this with some idle issues. Only other thing I can think of is an intermittant advance control solenoid or an EGR issue. It does seem down on power, yet is heavy on the fuel. Not to the point of black smoke, but the exhaust smells a bit rich. My flex pipe just secided to finally shit the bed this evening as well, so while I am under there changing out that I am going to see what is up with the cat as it looks to be original and the car had just ticked over 280,000 km.

[HelpMeHonda]

No codes or anything?

[dieselgus]

I had one for the IACV, cleared it when I stuffed a new one on there. Then set another one when I unplugged the TW sensor but other than that, no code. Now I am suspecting either something is off in the mechanical timing or the cat is slightly plugged.

Of course nothing like this ever happens when I am slow in the shop or it doesn't need to go for emissions lol. As the Canadian French would say...... tabernac.

[Dr_Snooz]

EGR problems would tend to cause rough running more than a distinct miss. Does the IACV control choking when the engine is cold? If so, a failure there could cause an overly rich condition. It's kind of a long shot, but have you checked for a dirty air filter? Have you checked for vacuum leaks?

For the high CO, you're on the right track with the MAP and O2 sensors. Another possibility would be the throttle position sensor or the PCV. If you use crap gas, then it might be time for a can of injector cleaner too.

[dieselgus]

Well, seems my issue is solved. Was down at Napa grabbing parts for work and decided to order up a set of injectors. Surprisingly cheap, reman ones (made in Canada, all 4 are Kehin ones at least) and got around to swapping them this evening. There were zero signs of leakage at either end, until I got them all popped out and started having a closer look. Right above the plastic where the connector attaches, pretty much all of them were slightly gooey looking. Looks like my problem is found. Car runs really nice and smooth once again. I was not going to play the exactly which injector is bad game by swapping one at a time, as for less than $90 for all of them I figured I would just change all 4 seeing as it was apart anyways. Dunno if I had one that shit the bed spray pattern-wise or if all of them weren't atomizing properly, but the thing just smoothed right out, 100% purring right along as it should. Hammer it through Aircare in the morning and call it good.