Rough idle when cold - 2005 Golf TDI

Leebro61

Active member
Joined
Sep 3, 2005
TDI
2005 4dr. Golf GLS
Hi everyone,

Recently I've noticed that my '05 golf tdi with ~126k miles has a rough idle while the car is cold. As soon as the car approaches operating temperature the idle smooths out. When the car is idling rough, not only does the car feel rough (in terms of transmitted vibration) but the engine speed will also oscillate between ~900 and ~1000 rpm.

Within the last ~5k miles I have performed the following maintenance (admittedly not all is related to the problem):

- oil and filter
- air filter
- fuel filter
- cleaned intake
- strut bearings, tires, alignment

Within the past ~25k miles:

- alternator pulley
- belt tensioner and belt
- timing belt, waterpump, etc.

I am not very well versed in the world of the diesel, so I could use some help in sorting this out. I recently received a glow plug recall notice from VW, and I have not yet had the chance to drop the car off for the service. Could the glow plugs contribute to this issue or are they not a factor after the motor is initially cranked? Also, I do not use any sort of fuel additive... is there something I should be using that could help remedy this issue?

I would appreciate any help on this topic. I apologize if I've omitted any valuable information or if any of my questions are extremely basic. I do not have a VAG-COM but I may be able to track one down if it is absolutely necessary to help troubleshoot.

Thanks,
Lee
 

PDJetta

Top Post Dawg
Joined
Nov 6, 2003
Location
Northern Virginia
TDI
'04 Jetta GLS TDI Pumpe Duce Platinum Grey w/ Leather
I would fine tune the camshaft timing using a VCDS scan tool. Here is the procedure:

http://www.myturbodiesel.com/1000q/multi/PD-adjust-Idle-TDI.htm

And check to see if your in-tank electric fuel pump is working. Lift up the right rear seat bottom and turn the key to "ON" (don't engage the starter) and listen for a 2-second pump sound at the top of the fuel tank. Sound = good pump. These pumps fail anywheres from 70,000 miles on and sometims the tandem pump on the cylinder head can pull enough fuel to keep the car running, but not optimally.

If its still an issue, you may want to inspect the camshaft and lifters:

http://www.myturbodiesel.com/1000q/multi/camshaft-inspection-replace-vw-tdi.htm

--Nate
 
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Leebro61

Active member
Joined
Sep 3, 2005
TDI
2005 4dr. Golf GLS
I would fine tune the camshaft timing using a VCDS scan tool. Here is the procedure:

http://www.myturbodiesel.com/1000q/multi/PD-adjust-Idle-TDI.htm

And check to see if your in-tank electric fuel pump is working. Lift up the right rear seat bottom and turn the key to "ON" (don't engage the starter) and listen for a 2-second pump sound at the top of the fuel tank. Sound = good pump. These pumps fail anywheres from 70,000 miles on and sometims the tandem pump on the cylinder head can pull enough fuel to keep the car running, but not optimally.

If its still an issue, you may want to inspect the camshaft and lifters:

http://www.myturbodiesel.com/1000q/multi/camshaft-inspection-replace-vw-tdi.htm

--Nate
Thanks to both of you for the quick response. Regarding the fuel pump, yes I can hear the pump prime with key on power. Regarding cam wear, if this were a lobe issue, wouldn't the issue remain even once the car were up to operating temperature?

I will get the car into the dealership asap for the recall and I'll report back as soon as the car is returned :)
 

Leebro61

Active member
Joined
Sep 3, 2005
TDI
2005 4dr. Golf GLS
It seems like the problem is rapidly becoming worse!

Today the car had a difficult time starting. It would start and die within a second or so. This repeated ~3-4 times before the car would finally stay running. Once I got to work, I shut the car down and immediately restarted, and it started perfectly.

In the afternoon, I tried starting the car and it also required 3-4 tries before it would stay running. To make matters worse, the car actually stalled twice on the ride home (typically while decelerating to make a turn, clutch in). I was able to release the clutch both times to restart the car. Particularly on the ride home, the idle was rough and surging between ~850-1000 rpm even once the car reached operating temperature.

I called the VW dealership to schedule the recall work and their first availability was Wednesday. I'm trying to plan for the worst and assume that the recall work will NOT fix this issue. With that in mind, I could use some help determining the proper troubleshooting steps. Currently, I do not have a vag-com (VCDS). I will ask around and see if I can track one down locally. Are there any simple diagnostic tests that I can try without the vag-com?

Thanks,
Lee :)
 
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Leebro61

Active member
Joined
Sep 3, 2005
TDI
2005 4dr. Golf GLS
The car is in for recall service right now. The dealership just called and said that the work is done. They informed me that the car had a code stored for the cam position sensor. Since the ecu was reflashed the code has obviously been erased... but I will vag scan the car tomorrow to see if it comes right back.

Are failing cam position sensors common or is that an indication of another issue? :)
 

Leebro61

Active member
Joined
Sep 3, 2005
TDI
2005 4dr. Golf GLS
I scanned the car tonight and the "G40 - Cam position sensor implausible signal" code is already back. I also followed the link posted above to measure the Torsion Value and at idle my car is reading 6.9 kW! I checked the injection quantity (block 013) and found that two of my four cylinders have significant deviations ( > 1 mg/str).

I'm guessing that at a bare minimum, I'm going to have to adjust the injection timing and replace the cam position sensor. The author of the link suggests 'Diesel Purge' to clean the injectors and reduce the cylinder to cylinder injection deviations. Does this sound like a good idea? Thanks :)
 

PDJetta

Top Post Dawg
Joined
Nov 6, 2003
Location
Northern Virginia
TDI
'04 Jetta GLS TDI Pumpe Duce Platinum Grey w/ Leather
"I also followed the link posted above to measure the Torsion Value and at idle my car is reading 6.9 kW!"

I think this may be your sole problem. Adjust it to +.5 and perhaps the cam sensor signal will be read by the ECU and the sensor and related wiring is fine. If the timing is too far off (and anything over 3 is), then the ECU omits the camshaft sensor input and uses the crank sensor. This may be what is happening.

At 126,000 miles, you must have had the timing belt changed. When was this done and by who? They may not have gotten it timed correctly. Were the lock down tools used? Also, take a look at the adjustment slots on the camshaft sprocket. At 0 KW torsion, the bolts should be about in the middle. If at the end of the slot, the camshaft pulley was put in a tooth off and you may not be able to get the proper adjustment out of it.

--Nate
 
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Leebro61

Active member
Joined
Sep 3, 2005
TDI
2005 4dr. Golf GLS
Hi Guys,

My location is Greenville, SC. The timing belt and related parts (water pump, tensioners, etc.) was done at ~99,xxx by Troy (TNTKNC) in Atlanta, GA. The car ran great after the timing belt install, however I've recently started to notice that my fuel consumption is marginally worse than normal. I had attributed this to the warmer weather, more city driving and switching to 18" wheels (OEM GLI BBS RC's), but it seems like maybe this could be a large portion of the economy loss.

I'm going to have a go at setting the timing this evening. The vag-com belongs to a friend of mine so his availability sets my schedule and he was busy this weekend. I'll report back the results on resetting the timing and if the cam sensor code comes back.

Thanks again for your continued help Nate :)
 
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