LXi cracked plastic air intake duct: repair possible ?

I started this thread during my troubleshooting of hesitation/stumbling problem. The hesitation problem was found to be bad spark plugs. I never had a spark plug failed on me until this time. The plugs look fine on the outside but after swapping them out for an old (but good) set, problem went away. Below is my original post:
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I searched. I even don't know the name of that part. It is the plastic U-shape duct connecting between the throttle body and the air-filter box. On the U-shape duct, there are one larger and one smaller vacuum hoses connecting to the mysterious box at the right side of the firewall close to the ignition coil.

The car idling and runs rough. Definitely like running on 3 cylinders. I heard hissing sound so I checked things around. Last time I checked the U-duct, it already had some fine cracks at the side connecting to the throttle body, but it didn't affect driverability. This time I pulled it off and the crack is a lot bigger. The big crack is located at the underside of the duct (when it is in the installed position) that's why I did not see it at the beginning.

I noticed the opening at the air filter box has a larger diameter. So without going to the junkyard, what are my repair options ? I'm leaning towards using stretchable electrical tape. Anyone had the same problem ?

Thanks,
- AC
pics attached

Certainly that can be found at the scrap yard, some body here nay even have one they took off , but there is an epoxy tube kit for plastic repair that would work possibly.

PM me , i know i have a spare one of these in my part pile

Quote:

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Originally Posted by gp02a0083

PM me , i know i have a spare one of these in my part pile

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PM sent, thanks.

When in doubt pull the jb weld out...

Sent from my SGH-T999 using Tapatalk 2

Quote:

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Originally Posted by ghettogeddy

When in doubt pull the jb weld out...

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I thought about that but that cracked part is not entirely hard plastic. It's a little softer than hard plastic but definitely much harder than rubber. I think JB may not hold well and eventually detached.

Update: I electric taped around the duct pretty well and reinstalled it just for the sake of troubleshooting. It wasn't the cause of the problem. Stumbling and roughness persist. I still hear some hissing sound from the back side of the throttle body so I think there may be more problems there, most likely vacuum. Next suspect: IACV/fast idle control value etc. I also plan to take out the throttle body and clean it completely. I have new cap/rotor and NGK spark plug wire set measured fine on multimeter. Haven't check the spark plugs yet but last time they were out of the car 500 miles ago, they looked fine to me. Fuel injectors are new with less than 1k miles on them. Only other thing older is fuel filter, around 60k miles. But I had left fuel filter in for longer time and never have such problem. Glad the problem is persistent (not intermittent) so I think eventually I will find the problem.

Other suggestions of areas that I may have overlooked ?

the Accord is a speed density setup so a leak in the intake pipe will not make any difference unlike mass airflow cars. Just seal it up to keep debris out of your engine, duct tape electrical tape etc.
A hissing sound is usually a vacuum leak but it is normal for the throttle body/IAC to have a hiss at idle since the engine is being throttled.
Use a piece of hose (2-3 feet) as a stethoscope and listen around for leaks. Spray starting fluid near the vacuum hoses, intake manifold gasket, etc, anywhere you hear hissing. If the idle speed picks up when you spray in a particular spot you found the leak.

Of course, keep the starting fluid spray away from the exhaust manifold and spark plug wires, have an extinguisher on hand whenever possible.

I would use carb cleaner or MAF cleaner for the diagnosis. Spraying starting fluid around a running engine gives me the creeps.

One way to test for a major vacuum leak:
1. Remove intake piping
2. Start the car, and let it warm up
3. Start covering the throttle body opening

If the car runs even with the throttle completely covered, then you have a major vacuum leak. If the car dies when covered, its just a minor leak. If the clear spray test does not find anything, then you will need to start eliminating all vacuum items till one of those solves the problem.

IACV, FITV, brake booster, cruise control, and all the sensors going into the control box.

I did a little more digging around today (I work night shift so troubleshooting the car can be difficult sometimes). Took out all spark plugs, they look good, nothing bad stands out.

I then check the EGR and here's what I found: I can push the diaphram using my finger and it seems to move freely without stickyness. I unpluged the vacuum hose from the EGR, pushed the diaphram, then blocked the vacuum connection and release the diaphram. The diaphram slowly moved back to the center, I say in about 5 seconds or so. I don't know if there is supposed an absolute seal inside the EGR diaphram, meaning if I pushed the diaphram and block the hole, the diaphram should hold position as long as I block the hole for vacuum hose connection.

I also check ECU LED, no blinks and LED light was off at the ECU when ignition at run position.

I opened the mystery box and completely lost in there so I just closed it back.

Additional background: The headgasket was blewed about 1000 miles ago, it was changed. I did it with a mechanic friend in his shop. The car ran fine after headgasket change. The only thing we did not do was to flushed the cooling system. We drained and refilled after the job. I'm certain there are some small debride from the old gasket when we scraped it off got dropped inside the coolant channels and got circulated throughout the system. I read here that incompleted bleeding of cooling systems can cause stumbling problems. We did bleed the system but wondering if the leftover debrides may cause same problems too ???

(I also wonder if I should start a new thread for this troubleshooting because it now seems the cracked duct is not the cause of the problem)

Tks,
-AC

I'd say let's get the vacuum leak fixed before looking for other stuff.

Problem fixed, my luck. I think I was too paranoid about the crack on the air duct which kept me thinking of a vacuum leak somewhere. Out of nowhere, I tried the idea of putting a set of old but good spark plugs and the stumbling problem went away. Now the car runs well. The set of bad plugs was autolite APP63 double plat. I know this is not NGK and shouldn't have used it. The set in the car now is Bosch plat. Will be getting a set of NGK and swap them out.

Thanks everyone bearing with me.
AC