Shell VPower Diesel

[AlanM]

Two or three years ago I filled up my 3.0 TiD with Shell VPower Diesel after 20 miles of a 200 mile trip, so the car was well warmed. At the end of the journey, mostly motorway, the SID was showing 50 m.p.g. instead of the 45 m.p.g usually shown. This seemed like a good idea so I started to use it regularly.

The following spring, the car began to run roughly and so I booked it in to my local SAAB specialist for investigation but he couldn't see it before I went on my bi-annual 400 mile round trip. Fault cleared, so I decided to revert to Sainsbury's diesel with Miller's additive, which I have used for years.

Last autumn I put in two tanks full of Shell again as not near a Sainsbury's which lead to this problem http://www.saabtechtalk.com/forum/index.php?topic=2547. Went back to Sainsbury's/Miller's again.

As it was only a minor problem, I ended up doing nothing more about it as I felt that the fuel was the problem then, a couple of weeks ago, the car returned to normal.

Has anyone else had problems with Shell VPower Diesel?

[Audax]

It may not be directly related to the fuel, it might be that when you try a more calorific fuel that the car is trying to map it's performance differently and *something* is out of spec somewhere, (injector, fuel pump, sensor) and it can't attain the right performance from this. So it means when you just use the less calorific fuel your car never attempts to reach the more optimal parts of the mapping so it doesn't show up the problem

[AlanM]

A good point, though the change has taken several months to come about after I stopped using the Shell fuel. Would not the improvement happened fairly soon after the fuel change?

The Shell would have disappeared from the tank fairly quickly as I always run the tank quite low before filling it with just over 50 litres (65 litre tank). Also, the Miller's additive is supposed to increase by 4 points the cetane number and, in spite of being a Yorkshireman, I do tend to be generous in helping the sales of a local company 

[Audax]

A good point, though the change has taken several months to come about after I stopped using the Shell fuel. Would not the improvement happened fairly soon after the fuel change?

Sorry, I'm a bit confused as you seem to suggest that the improvement and fault came about at the same time after filling up? Then you changed back and it went away and then came back after you filled up again with V-power? If they are not that linked then it's probably a sticky fuel solenoid or failing sensor that just so happens to sometimes flare up around the time you change fuel.

Anyway, did you ever get the fuel filter changed and the fuel pump solenoids tested as I suggested in April? 

[AlanM]

Sorry, I'm a bit confused as you seem to suggest that the improvement and fault came about at the same time after filling up?
Anyway, did you ever get the fuel filter changed and the fuel pump solenoids tested as I suggested in April? 

After re-reading what I wrote, I'm not surprised

A couple of years ago I used VPower for a while until the engine started to run roughly at idle, even cutting out on one occasion. Shortly after returning to Sainsbury's/Miller's the roughness disappeared and the engine ran normally for quite some time.

Some months ago I had to fill up twice with VPower and, towards the end of the second tankfull the high power reluctance appeared and I changed back to Sainsbury's/Miller's. As it was a performance area that I very rarely used, I let things continue in the hope that there would be an improvement. It took quite a while but, after the fuel filter was changed during the service mid-August, I gradually felt an improvement so I was able to get the car through the "flat" period and eventually get full throttle and 4400 rpm in third. The hill is about half a mile long.

A couple of weeks ago I just floored the throttle and the acceleration was back to normal.

Something gradually becoming unstuck?

Anyway, it's now working satisfactorily and I shall watch with interest to see if the problem re-occurs with my present fuel.

Thanks for your valuable input, I shall just hope that your further suggestions prove unnecessay

[Audax]

I wonder if the V-Power aggravates the fuel pump in some way, there is a Saab diagnostic procedure to check if the solenoids are bad or not however I've only ever worked on 2 or maybe 3 V6 TiD ever and only one had this problem. The symptoms precisely matched those that Saab said cause the problem in the bulletin, we told the customer the bad news and then replaced the fuel filter "just in case" and the problem *never* reoccurred although I think he got rid of the car 6 months later, so maybe the VPower is somehow different in a way that upsets something, I'd say just don't use it.

[David]

At the risk of being flamed can I suggest that next time you fill up add a few capfulls of 2 stroke oil. You may well be surprised at the difference it makes. Following recommendations from other diesel users, I have been adding it to my diesel engine for over three years and it continues to run much smoothe

I have found it increased the mpg and also lubricates the fuel pump. My wife commented only a few days ago how much quieter it was compared to a  new diesel Nissan Juke, which had pulled up beside us. 

[AlanM]

Thanks for the suggestion David but I think I shall continue with the Miller's Diesel Power Economax, as I have for around 20 years.

I first started using it in my wife's Citroen ZX 1.9D after I reading an article in "Diesel Car" about a strip down of a fuel system/engine after more than 100,000 miles. There was no measurable wear in the system. As the Citroen ran without a hiccup for 160,000 miles, I feel justified in continuing.

I shall be more circumspect about using Shell VPower 

[Audax]

I first started using it in my wife's Citroen ZX 1.9D after I reading an article in "Diesel Car" about a strip down of a fuel system/engine after more than 100,000 miles. There was no measurable wear in the system.

What I'd like to know is did they strip down another one that had also run for 100,000 miles with fill ups of fuel at the same places which ran without additives

[AlanM]

I first started using it in my wife's Citroen ZX 1.9D after I reading an article in "Diesel Car" about a strip down of a fuel system/engine after more than 100,000 miles. There was no measurable wear in the system.

What I'd like to know is did they strip down another one that had also run for 100,000 miles with fill ups of fuel at the same places which ran without additives

I suspect that you know the answer to that already