intermittent high idle on 1.6 na

[upchuck]

sometimes the idle stays high between shifts when driving.  if i pull the clutch out and begin to stall the engine to slow it down it stays down after i let up on the clutch.  but i wonder why it revs in the first place.  the first couple times it happened, messing with the cold start cable alone would bring it down, but that no longer has much effect.

the engine is newly built with only about 4000 miles so far (although not completely oil tight apparently :roll: ), injectors are also rebuilt by a bosch shop, but the IP is in original condition with about about 200k miles on it.  i read about a similar issue here with an older rabbit posted by vegfuel, but i don't have the smoke issues he reported:

http://vwdiesel.net/phpBB/viewtopic.php?t=7373&postdays=0&postorder=asc&highlight=high+idle&start=0

should i still be taking the same approach recommended to him to mess with the max fuel and idle stop screws?  any other suggestions before i break down a seek help from the super expensive VW shop nearby?

thanks folks!
 

[upchuck]

also...  

i've observed that this will only happen once the engine has warmed up - seems to suggest that i'm burning vented oil fumes
 
but...

when i got home today, i let it rev then i pulled the breather hose off of the valve cover but it continued to rev for a minute or so before i finally turned it off - seems like that would suggest something else

 :?

[burn_your_money]

Since it's only been happening a bit this might not work. Take a rag (or your finger) and wipe the inside of the tail pipe. If it's covered in a black gooy tar like substance you're burning oil, although that could be from pre-rebuild.

It could also be the pump, my NA used to do that was well and I had to fiddle with the screws on the pump.

[wikdslo]

Since it's only been happening a bit this might not work. Take a rag (or your finger) and wipe the inside of the tail pipe. If it's covered in a black gooy tar like substance you're burning oil, although that could be from pre-rebuild.

It could also be the pump, my NA used to do that was well and I had to fiddle with the screws on the pump.

The turning mechanism that the throttle cable is attached to got gummed up on mine and would tend to stick sometimes. Just giving the throttle a blip or two would bring it back down.

Just a suggestion to check as it was an easy fix. WD-40 that mofo for about 87 seconds and you're good to go.

[upchuck]

thanks for the feedback guys...  i'll check the tailpipe.  also, i've confirmed that the throttle mechanism on top of the pump that the cable pulls on is not stuck.  the engine will idle high and lower with it in the exact same 'idle' position - although it will only go down after partially stalling the engine (without the throttle mechanism moving though)

anyway, thanks again, i'll update if i figure anything else out

[jimfoo]

I'd try the residual fuel screw, I think what you are referring to as the idle stop.

[upchuck]

ok, so i just discovered that a couple bolts that hold the mounting bracket between the IP and block have come loose!  :shock:  the bracket is loose and jiggling around but the pump still seems secure from the other timing bolts.  anyway, maybe this is the root of my trouble.  at least i'll have to start there.  darn bolts are tough to get to. i think i'll have to at least pull the fuel lines to get to them.  i guess that's my lesson for apparently neglecting to torque them down thoroughly!
 
again, thanks for all the help for this frustrated DIYer who is apparently over his head!

[upchuck]

problem confirmed... this was a case of a few loose screws!   :oops: