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Offline Marshy

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2003 EV Rough Idle on Startup
« on: June 19, 2015, 10:07:01 AM »
Occasionally, at cold startup, the motor tends to idle rough. It only does this when the engine is cold, and only does this for about 30 seconds at the most, then everything goes back to normal and it runs smooth.
It does it regardless to whether the AC is on or off, and doesn't do I at every cold start.
It also doesn't do it with warm starts.
Spark plugs were replaced recently. Coolant temp sensor was also replaced recently.
There is also no CEL or stored DTCs.
Does anyone have any suggestions as to what it may be?

Here's a video of the Choo Choo exhaust, as my kids put it...
https://www.youtube.com/watch?v=gWJGu5RiW-4

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Offline Itsamoto

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Re: 2003 EV Rough Idle on Startup
« Reply #1 on: June 21, 2015, 01:30:03 AM »
This sounds a lot like something I had going on with my own van -- Cole figured it out to be a vacuum leak.

You can see the thread here: http://forums.vwvortex.com/showthread.php?6992023-Hesitation-after-startup-02-Eurovan

My van has the same issue at start up -- with oil in the vacuum line (shown in the thread). My line is broken at the other end -- where it connects to the brake booster.

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Offline Cole

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Re: 2003 EV Rough Idle on Startup
« Reply #2 on: June 21, 2015, 07:40:25 AM »
Just quoting my own post here to plant the info in this thread for future reference.

Quote
I figured I'd take a quick picture of this hose that slips off the end of the valve cover. Seems it gets a touch of oil in it and doesn't stay connected very well. This has been the source of the infamous vacuum leak that creates a lag, hesitation, poor idle, hard brakes, etc.  Its most noticeable right after start up.

I know many people have experienced this issue so maybe this will help!

I cleaned all the oil out of the hose connection and coated it with a sticky aircraft gasket sealer. I'm sure that even using hairspray to add some stick to the rubber connection would help.

This is the drivers side of the valve cover.

Cole

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Offline Marshy

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Re: 2003 EV Rough Idle on Startup
« Reply #3 on: June 21, 2015, 06:10:47 PM »
Just quoting my own post here to plant the info in this thread for future reference.

This was one of the first things I checked. No leaky. :(
Strange as it does it for only 30 seconds, then not again until the next cold start.

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Offline Cole

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Re: 2003 EV Rough Idle on Startup
« Reply #4 on: June 23, 2015, 09:10:18 PM »
This was one of the first things I checked. No leaky. :(
Strange as it does it for only 30 seconds, then not again until the next cold start.

Which is exactly the symptom everyone with a leak seems to experience. Might have to dig around more to find your leak.
Cole

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Offline Marshy

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Re: 2003 EV Rough Idle on Startup
« Reply #5 on: June 24, 2015, 09:25:31 AM »
Keep digging I shall!
The problem is that, if I think I've found the leak and fixed it, I have to wait until the next cold start to see if it misfires.
This encourages excessive beer consumption.
Any tips or tricks in finding vacuum leaks?

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Offline VAG_Tech

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Re: 2003 EV Rough Idle on Startup
« Reply #6 on: July 11, 2015, 09:00:55 AM »
Check fuel trim readings with a good scan tool like VCDS (Vag-Com). You can use leak detection spray whilst watching the fuel trim. If you spray a place on the engine that has a leak the fuel trim number will jump accordingly.
Pipe from the intake to the brake booster is always suspect. Good luck with the diagnosis. 
If I'm not camping, I'm not happy.
2003 Rialta (Louis)
1973 VW Campmobile (Freedom)

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Offline Cole

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Re: 2003 EV Rough Idle on Startup
« Reply #7 on: July 11, 2015, 10:57:42 AM »
All of these vans are old enough now that vacuum leaks can sneak up on you.

It's fairly easy to replace most of the lines with either original or silicone hose for not much money. Worth the preventive maintenance on an aging vehicle.
Cole

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Offline Mikeinthe805

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Re: 2003 EV Rough Idle on Startup
« Reply #8 on: August 20, 2015, 02:19:48 PM »
Cole, your photo led me precisely to my vacuum leak. Thanks man!

I sure do appreciate all the info you share here and over at ev_update. Your knowledge has helped me many times.

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Offline Cole

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Re: 2003 EV Rough Idle on Startup
« Reply #9 on: August 24, 2015, 01:45:48 PM »
Cole, your photo led me precisely to my vacuum leak. Thanks man!

I sure do appreciate all the info you share here and over at ev_update. Your knowledge has helped me many times.

Thanks! Glad it helped!
Cole

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Offline robinson1509

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Re: 2003 EV Rough Idle on Startup
« Reply #10 on: May 07, 2016, 08:04:55 AM »
The diaphragm on the combi valve can deteriorate and create a vacuum leak on start up when the engine is cold. If you use the vagcom go in to basic settings group 000 and look at block 2 and if the number is below 28 you have a vacuum leak.
when I took this pic I disconnected the vac hose to the egr.
« Last Edit: October 11, 2016, 06:36:10 AM by robinson1509 »

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Offline Grandpa Rick

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Re: 2003 EV Rough Idle on Startup
« Reply #11 on: October 03, 2017, 08:19:11 AM »
Occasionally, at cold startup, the motor tends to idle rough. It only does this when the engine is cold, and only does this for about 30 seconds at the most, then everything goes back to normal and it runs smooth.
It does it regardless to whether the AC is on or off, and doesn't do I at every cold start.
It also doesn't do it with warm starts.
Spark plugs were replaced recently. Coolant temp sensor was also replaced recently.
There is also no CEL or stored DTCs.
Does anyone have any suggestions as to what it may be?

Here's a video of the Choo Choo exhaust, as my kids put it...
https://www.youtube.com/watch?v=gWJGu5RiW-4

This is exactly what I have.  30-60 seconds and it's over.  Do we think that this will cause problems in general driving too not just when cold?  Also, I had a bunch of oil in my intake a while back.  Are these related?  If the combi is bad will I definitely have a code? 
« Last Edit: October 03, 2017, 08:52:25 AM by Grandpa Rick »
Sometimes I miss my Syncro Westy.