idle studder... at odd times

Recently, I bought another TDI to have as a spare, but I'm struggling to figure out an idle stumble. The car seems to run perfectly down the road at all speeds, but experiences an odd stumble while rolling to a stop. I can hear the motor start to stumble at approximately 7-10mph, but it completely smooths out when the car comes to a stop. It may be starting before 7mph, but I can't really hear it until that point. It will do it if you start from a stop, let off as soon as the car is moving, and listen... forward or reverse.

Any suggestions would be appreciated.

search "slow down shutter" "Injection Quantity Adjustment" and "Hammer Mod" and see if they relate to your circumstance

As Wook stated...Check the IQ...I'm willing to bet money that is your issue...it's not at all uncommon with these

Mine does that and has for several years. I just ignore it.

Wook660 said:

search "slow down shutter" "Injection Quantity Adjustment" and "Hammer Mod" and see if they relate to your circumstance

Click to expand...

This was my suspicion as well. I'd read about it on this forum, but didn't have VAGcom to check. I know a local 'tdi guru' and checked with him to see if we could use his VAGcom to check on the IQ. The IQ was 1.0-1.2 and after some adjustment, it's 3.4-3.6. The 'guru' spent nearly 90-minutes, charged me $50, and didn't fix my 'slow down shudder.' I'm slightly frustrated with my evening thus far...

Any other thoughts, gang?

I toyed with my IQ setting for a while and was able to cure the problem. Eventually my IP started going bad and I was unable to set the IQ. The value would fluxtuate back and fourth as did the timing on the graph. Not saying your pump is bad, but I had to replace mine with a cheap used one I bought off a fellow member that is currently working great. I'll send my original pump out for overhaul when my next TB is due.

How many miles are on the car?

205k

Can anyone tell me why the 'studder' happens when rolling at very low speeds, but completely goes away once the car stops?

Timing and IQ were quite solid per Vagcom

What is the IQ though? I had it for years.

Here is a how to I made...

http://forums.tdiclub.com/showthread.php?p=2689895#post2689895

Maybe this is related to the DMF and not the engine.

brand new OEM clutch. Rrolling' speed should not matter regarding idle, clutch or otherwise, right?. It's unmistakable though. You can hear it start as car slows down and it completely stops as the car stops.

IQ is 3.4 as stated above.

(going to bed)

Jesse_Boyer said:

This was my suspicion as well. I'd read about it on this forum, but didn't have VAGcom to check. I know a local 'tdi guru' and checked with him to see if we could use his VAGcom to check on the IQ. The IQ was 1.0-1.2 and after some adjustment, it's 3.4-3.6. The 'guru' spent nearly 90-minutes, charged me $50, and didn't fix my 'slow down shudder.' I'm slightly frustrated with my evening thus far...

Any other thoughts, gang?

Click to expand...

Hmm...I can set a IQ is less than 5 minutes. Either 1. you have a bad guru or 2. you have a bad pump. At 3.4, you should not have any shuddering.

As can I, but I don't have VagCOM. Needless to say, I'll be ordering it ASAP.

He actually spent most of the time tinkering around, doing things I didn't ask him to do. Yes, I know there are issues I have to solve with that car... but I don't need or want to pay you $50/hr to do 95% of them.

Regardless, can this still be an IQ issue? It's set at 3.4mg/st... which I thought was optimal for most cases.

perhaps yours needs adjusted to be a little higher. I know if I had charged someone to set their IQ, and they weren't happy, I would do my best to make it right.

have you discussed this with your guy?

I'm a novice on this electronic diesel, but the way I understand the "slowdown shudder" is that engine is operating on one control map when car is moving, then transitioning to another map when car is stopped. In that transition, it "hands off" from one map to another and if iq is so and so, it does it smoothly. If iq is off, it will shudder. Not a big deal, and I am certainly used to it.

I'm going to do a bit more research and order VagCom later... then I'll try to tweek the IQ.

ordering the timing belt kit this weekend as well... so I'll need it anyway.

Mine does the same thing, I figured it was something to do with the Vehicle Speed Sensor or something, the computer sensing the car moving faster than the engine and trying to cut the fuel to slow down the engine.

very annoying though, is there a way to use the vagcom to eliminate it?