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Discussion Starter #1
I posted on TDIclub with this same question but after a few days it seems to have fallen to the wayside.

Does anybody know what is different about the injectors, glowplugs and glowplug control module that are installed when the "rough idle when first started" TSB is done on the PD motors? The dealer didn't know what was different.

One gentleman on TDIclub mentioned something about raising the ignition temperature. But how can this help right away when it is first started? Has anyone with the TSB done noticed a loss of performance or decrease in fuel economy?

I have noticed that my glowplug indicator does not stay on as long as it did before. The car starts at a higher rpm for a couple of seconds before dropping down to the normal idle speed. It does not run rough anymore when first started.

Also, is there a valve in the fuel filter or fuel system that is temperature sensitive that allows warmed fuel from the engine to recirculate into the fuel filter or return back to the tank. If there is, it might explain the slow 1/16 tank oscillation of the fuel guage when the air temperature drops.

Thanks in advance...:D :D

Steve
 

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In general, the new glow plug control module will keep the glow plugs hot longer than before. The new injectors allow slightly more fuel for a cold start, and smoother running. The original injectors could do some very bad things in extreme cold weather. In rear cases VW was replacing motors due to extreme cold conditions that caused injector malfunction.
If you look at the top if the fuel filter, you will see a plastic 'T' that the return hose goes to. When cold, the warm fuel is diverted into the filter.
 

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Discussion Starter #3
hannaco said:
The new injectors allow slightly more fuel for a cold start, and smoother running.
Are the new injectors able to deliver more fuel when doing a cold start, but otherwise have the same flowrate once everthing starts warming up. In other words, are the new injectors capable of delivering more fuel only if needed, or are they always going to deliver more fuel than the originals under the same running conditions? Will the new injectors decrease my fuel economy?

If you look at the top if the fuel filter, you will see a plastic 'T' that the return hose goes to. When cold, the warm fuel is diverted into the filter.
Will the valve deliver only to the tank or only the fuel filter, or does it have the capability to blend where it delivers the warmed fuel to? I checked again and my fuel guage is oscillating only about 1/32 tank or halfway between the small dot's. It will pause on each side of the oscillation for about 2 or 3 minutes. It only does then when the temperature is below 20F. Maybe this is normal if the valve does not blend the fuel return lines. Maybe I just never noticed it before..
 

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The injectors will give the correct amount of fuel for a cold start. Once the motor is running properly, they will only deliver the amount of fuel needed under the current driving condition. Your fuel mileage should remain the same. Remember that your mileage will decrease in the winter.

The thermostat controlled 'T' connector will divert warm fuel to the fuel filter in the cold. Once the filter temperature is brought up to operating temperature, the warm fuel is then diverted back to the fuel tank. In times of extrema cold, most of the fuel will be recirculated through the fuel filter to keep it from gelling.
 

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Discussion Starter #5
Thanks for the info. I suppose going from 43mpg in the summer to 38mpg in the winter is still pretty good.

I have a 20 mile commute (all highway except for the first 5 miles from our house to the highway - country roads) each way to work. On the really cold days (~0F) I am halway to work or halfway home before the blue temp light goes out. By the time I get to where I'm going the engine is probably just reaching reaching a good operating temp, then I shut it off only to repeat the process all over 8 hours later.

This is my first "complete" winter with the car, I bought it the first week of March 2005. When I bought it last year the temps were already pretty warm (for a Minnesota winter anyway) and we only had a couple of days when it got below 20F.

Also, about the 'T' connector. Can it send fuel to the filter and tank simultaneously, or only to the filter OR only to the tank.

I guess I never really did officially check my winter MPG's until after the update. I had only been looking at how many miles were on the tank when I put more fuel in. I am only going down to half a tank in the winter.
 

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Yes, the fuel can be split between the filter and the tank depending on the temps. The poor fuel mileage is due more to the winter fuel, than the outside temps. The fuel distributors blend in #1 diesel with the #2 diesel for better cold temp operation. The result is that there is less energy (BTUs) per pound of fuel. The higher the energy content, the better the fuel mileage.
The object is to keep the fuel from gelling into a big glob of Jello.
 

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Discussion Starter #7
hannaco said:
The fuel distributors blend in #1 diesel with the #2 diesel for better cold temp operation.

The BP station has the pumps marked #1 and #2. The pumps marked #2 also have a notice on them that it is NOT blended. This is a new station that just opened last spring. They say thier two automobile pumps share the same tank as the #2 tank for the large trucks, but yet the automotive pumps are not marked that the fuel is not blended. I have been getting my fuel from the large truck pumps marked #2 and adding the Power Service supplement, that way I know what I am getting (at least that's what I thought). Maybe I will have to see if I can catch the actuall delivery truck and ask the driver if he (or she) knows if the fuel they are putting in the tank for the pumps marked #2 is pure #2 or if it has been blended.
 

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In MN your fuel needs to be treated in some way with a antigel using Kero (d1) is the most cost effective options to the Fuel station so I would say it is all blended maybe it has to do with Bio or somthing else. In MN you fuel would gel if not treated.
 
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