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Discussion Starter · #1 ·
So rough idle on my 2004 passat 1.8t, especially in the AM. Been getting P300, P301, etc codes to my OBDII. Was planning on changing plugs this weekend, but while taking cursory look at motor, I spotted this: Imgur: The most awesome images on the Internet

I can't seem to get the two ends to stay together, I'm thinking it's broken or perhaps snaps together with more force than I am able to give it.

Can someone ID this part? Perhaps it's related to the poor high idle? Also, I failed inspection due to the evap and cat(?) codes not clear? Guy said I need to drive it for 100 miles to reset. I'm thinking this might be related to my clearing the miss-fire codes :)

I know, a lot of info and kind of scattered, sorry. It's my old car, now being driven into the ground by my 17YO son.

Thank you.
 

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I had a steering knuckle in my shed. Really!
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That looks like the suction jet pump. A typical failure point. A vac leak will definitely cause idle issues.

Yes, clearing your misfire codes reset your readiness monitiors for evap and (most likely) heated catalyst have not passed yet. Evap can take a little while to pass; usually it's the last one to pass. You can check the readiness monitors with your OBD2 scanner.
 

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Discussion Starter · #5 ·
Whoa, really? I can check the readiness monitors? Is that using the torque app? And yes, the suction jet pump for sure, I found other posts on vwvortex. I'm going to try to glue it together short term. I believe I'm getting the misfire codes due to rough idle on cold mornings. Is there an easy way to increase the cold/high idle? I imagine this is computer controlled.

Planning on swapping out plugs this weekend, any pitfalls I might need to be aware of? I will of course search the forums for DYI's.
 

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I believe I'm getting the misfire codes due to rough idle on cold mornings. Is there an easy way to increase the cold/high idle? I imagine this is computer controlled.
The misfires when cold are because that big air leak (you should be able to hear it at idle) makes the engine run lean, when it needs to be rich. If you try to repair with adhesive, I'd recommend using Epoxy. I wouldn't try to change the idle speed, just correct that air leak. I would also take the opportunity to inspect the various small "vacuum" hoses, and the check-valves (there is one in your photo). These break eventually and will cause problems.

Regarding the spark plugs, you might want to correct the air leak first, then see if there are any misfire problems after that. If the engine runs smooth at all throttle settings, then the plugs are doing their job already.
 

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Discussion Starter · #10 ·
Wicked. I guess I was mixing my troubleshooting thoughts there. Once I found the open valve/pump I should have known it was source of rough idle. I will hold off on the plugs. Oh, and I found the section of Torque that shows the ready coeds. Guess I have some driving to do to set them: Volkswagen Emission Monitors Not Ready

Thank you all, this was a very informative day.
 
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