Mk4 idles rough when slowing down

My newest car runs pretty good, but when you throw it in neutral or push in the clutch while coming to a stop it idles rough till you come to a complete stop and then instantly smoothes out. Seems electrical, anybody?
2000 jetta turbo greasel

Maybe vagcom would show something, I'm not sure where to look off hand.

Sounds like a deceleration stumble. Your IQ is probably low.

Search for slowdown shudder.

sounds like its the ecu?? who has one?

Why would it be the ecu?

V-DubLuv said:

Sounds like a deceleration stumble. Your IQ is probably low.

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Question: Can this be caused by a constricted inlet manifold? Mine didn't use to do it and it's probably due for a clean. I don't want to tweak any settings if it's for something else that should be fixed anyway.

I'm 99% sure that it's slowdown shudder. I had the same thing with my car until I adjusted the IQ (injection quantity) using VAGCOM. If it's doing this then your IQ is too high and needs to be lowered. When I check mine it was at like 1.5 and should be around 3-5. I've since adjusted it to 3 and haven't had the slowdown shudder a single time since. It's nothing to worry about, not causing any damage, just an annoyance. You need to get your hands on a RossTech VAGCOM cord and adjust it whenever you get a chance.

I was just reading through the threads and saw that if adjusting the IQ didn't fix it then its the ecu.
I'm going to get a vcds soon. Thanks guys.

98 jetta said:

I was just reading through the threads and saw that if adjusting the IQ didn't fix it then its the ecu.
I'm going to get a vcds soon. Thanks guys.

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Trust me, it's definitely just the IQ, not the ecu. What you're describing is exactly what mine was doing. And I saw that one other person said your IQ is too low, which is misleading. Actually the amount of fuel being injected is a bit too high but the value in VCDS that you need to adjust is currently set too low which translates to more fuel. So yours is probably less than 3 and you want it around 3.5 and raising that number actually decreases the amount of fuel being injected. Hope that makes sense.

Here's a great article that will teach you everything you need to know about the injection quantity on your car, it's what I used to diagnose and fix my slowdown shudder:
http://www.myturbodiesel.com/1000q/multi/IQ-adjust-hammer-mod-TDI.htm

^The only reason you would have to do the "Hammer Mod" is if VCDS can't adjust your IQ enough to fix the problem.

Hope that helps.