short shifting shudder/vibration

We have an 05 New Jetta TDI. At about 8,000 miles we started experiencing a shudder or vibration at about 1200 to 14/1500 RPM in 4th and 5th gears. It got worse and we brought it to our dealer where a tech with 30 plus years experience drove the the vehicle and duplicated the problem. We do not experience this when first starting out. It generally happens after about 20 miles of driving when the opportunity presents itself. VWof A started with a check of the EGR and replacing the fuel filter on the basis maybe it was starving for fuel. We drove the car and the problem still persisted and the dealer susequently replaced the clutch. Upon the return of the vehicle to us the problem still exists and the dealer will get the vehicle back this week. My question is do many of you TDI drivers short shift and accelerate from around 1100 RPM in 4th and 5th gears and if you do, have you experienced anything like this? Any suggestions from the more mechanically inclined members???? We are not afraid of VW's or Diesels and would really like to get this figured out.
Thank you in advance for any and all reponses..................

Don't take off from that low. It's not the old 1.6. These cars need some revs, The shudder is the dual mass flywheel. You also create surge in the turbo if you floor it at low revs. Very bad... Bring the revs up to at least 1800.

This AINT a PETERBUILT!

Shift at NO LESS THAN 2500 when the engine is cold!!!
Shift at NO LESS THAN 3000 when the engine is warm!!!

Shift at that low of an RPM will cause the turbo to $hit itself, Coke up the intake, jam the compression rings, cause poor fuel atomization due to the 30,000 psi PD system and low fuel pressure from low rpm operation and many many more problems you CAN'T AFFORD TO FIX!

This car is not a "Diesel" but a different type referred to as an "HSDI" this means it has a short stroke, high compression bowl which is designed to operate ideally in the 2000-4,200 rpm range. The engine does not even hit peak economy until in the 2,100 rpm range.

By the way shifting that way if you live at high elevation will cause that VNT Turbo to grenade if you keep up this habit.

DB

By the way add power Service, your low rpm abuse is causing the fuel system to inject fuel too slowly and the low cetane fuel you are using is causing it to miss. Increase the Cetane of your fuel by adding about 4-6 oz of Power Service and this will eliminate the issues you describe.

And yes this is directly related to (1) Low cetane fuel (40 Cn) where your car is designed for NO LESS THAN 49, (2) driving at low rpms that prevents the fuel from having sufficient pressure to inject it fast enough thus causing further retardation of the already severly retarded timing due to emissions regulations.

DB

peterbilt said:

. My question is do many of you TDI drivers short shift and accelerate from around 1100 RPM in 4th and 5th gears and if you do, have you experienced anything like this? ...........

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Absolutely, and the car runs as smooth as silk, and no I have not experienced anything like this.
So, there is something amiss with your car for it to run smoothly on some occassions, and to not run smoothly on other occasions.
If it were fuel quality, then it would be most likely to occur when the engine is cold, and not warmed up as you relate.
It could be some kind of injector/piston deposit thats interfering with combustion once warm and for the cost it would be worth using an injector cleaner, such as Lubro Moly Diesel Purge, Howes Meaner Power Kleaner, or Chevron Dieselmotive, just to see if that makes any change.


My own car has covered 85,000 miles, over four years, and has not experienced a clogged intake, or any other ailments that I have been warned about by others on this site many times. I regularly get into 5th gear without exceeding 2000 rpm in any gear, and sure sometimes I'll take it to 3500rpm in 2nd when I need to accelerate on the highway on-ramp, As long as you use a firm right foot, accelerate with purpose, you'll be ok. Ie do not drive soft, with a gentle right foot, and do not floor it, use half to threequarter right foot, is good.

This engine is capable of producing plenty of HP for driving like this, and it is not lugging, the engines computer control map sees to that, nor is the turbo in any danger as long as you do not floor it while driving at high altitudes.

hth

Do you have a boost gauge? You'd be suprised the amount of boost these cars make at less than 1/2 throttle when you accelerate at that low of an RPM. Spikes to 15+ at half throttle are not uncommon. They can be a LOT higher than that too. But hey, it's your car. Drive it the way you want.

gdr703 said:

If it were fuel quality, then it would be most likely to occur when the engine is cold, and not warmed up as you relate.

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Incorrect, as the engine warms up the ECU retards the injection timing further to reduce NOx output. TDI engine regardless of year advance the injection timing when cold to promote smoother running and easier starting again whether it is a PD or VE pump engine. As the engine warms the timing is backed off placing greater reliance on the cetane rating of the fuel to prevent missing. Adding a cetane booster in a PD motor compensates for the retarded timing and improves the autoignition characteristcs of the fuel and reduces or eliminates the missing when the engine is warm.

DB

Thanks for the input. I neglected to say that we drive the car just like we did our 03 TDI. We only updated cars for the better amenities. The tech that drove the car and duplicated the issue referred to the dual mass fly wheel. I am of the opinion that this vehicle would have been massacred by the press if this were a common problem at the vehicle launch. I am also of the opinion that the manufactures of any vehicle can do all to R&D they can and when it gets to the general public some issues are still going to happen. Time will tell but I will say it is a privilege to be able to bounce this off fellow TDI owners and techs.