Fuel Quality and Turbo Vanes

[tactdi]

I have had my 2005.5 Jetta for over 2 years. Bought it with 142K, knowing that the manual trans was bad, and replaced the transmission, cam (it was bad), and the timing belt.
During this time, the car runs great, and still runs great. It had shown symptoms of the sticky vane (actuator) and a hiccup at highway speeds.
With the sticky vane the RPMs would stop at about 1800, and the engine would clack. The way to get through the sticky vanes was to lift and then accelerate, which would also cause a cloud of black smoke out the tail pipe.
At first this would occur infrequently, but then it started to occur almost everyday. Reading about the sticky vane, I was sure that I would be either adjusting the set screw or using the tie wrap fix.
BUT, several months ago, I found a fuel station selling 47 cetane diesel, and started to use that for every fill up. I noticed an immediate difference in how the car drove from the first fill up, and since then, I have not had the sticky vane symptom, or the hiccup at highway speeds.
Any insight on the higher cetane fuel preventing the sticky vanes?

 

[Henrick]

Sticky vanes is a mechanical problem when soot and carbon coats the vane geometry and the variable geometry simply does not work because vane don't move/can't be adjusted. This is usually caused by bad driving style. Follow Drivbiwire's break-in instructions and you should be okay.

If you follow the instructions, the sticky vanes might get exercised and start moving again. However, is the effort is useless, then it might be that carbon and soot deposits are excessive and only mechanical cleaning will help. I highly doubt this is actuator problem.

 

[tactdi]

The turbo is original to the car (as far as I know), the cam I have had in the car for 50K.
Would the higher cetane fuel, help clean the carbon out, or lubricate the vanes?

 

[tdiatlast]

I can't answer your question, but I'm wondering, where are you getting 47?

 

[Ski in NC]

Probably coincidence. Higher cetane won't affect the vanes. Nearly impossible to detect difference in cetane on these unless it is way low out of spec. Could be some additives in the higher cetane that makes it through the exhaust and helps. But hey, what works, works!!

 

[Henrick]

I doubt cetane or any other fuel characteristic might have any effect on vanes. Neither fuel, nor oil touches the vanes. It's only exhaust gasses soot and carbon what the vanes see. Proper driving style might help the vanes. It's such design....

Now I'm investigating if sticky vanes is a problem at all on DPF-equipped cars. Never came across one with stick vanes.

 

[Bob_Fout]

I've noticed a direct relationship between cetane and boost spikes / overboost. Higher cetane, lower EGTs, less spikes / overboost.

Then there's the very noticeable difference in lag and acceleration between standard and higher cetane fuel.

 

[tactdi]

I can't answer your question, but I'm wondering, where are you getting 47?

Murphy station in Bedford, VA (in front of a Walmart). Fuel is less than other places selling 40 or 42 cetane, and a few penny's less if I use a Walmart gift card.

 

[DPM]

premium fuel may have more detergent action.