DieselTune VP44

Why Tweak the TiD?

In short, because it’s cheap and easy to do and yields good results. And at the time a remapping service was too expensive.

As standard, the first generation Saab 2·2 TiD offers drivers a combination of an ambling gait with a multivalve turbodiesel willingless to rev to 5,000 rpm. Power delivery is typical for the breed, there’s relatively little under 1,800 rpm, then a surge of acceleration which starts to taper off once you pass the 4,600 rpm redline. Thanks to gearing that sees the tachometer at 2,000 with 58 showing on the speedometer in top, motorway acceleration is acceptable too. But at the same time, the engine is capable of achieving more... so I went to a relatively local company, DieselTune, based in Barton-upon-Humber, to buy the VP44 module.

DieselTune’s VP44 module connects between the ECU and the injector pump. This module adjusts the sensor readings and allows the injector pump to put more diesel into the engine if demanded, thus, dramatically improve power.

The headline figures for the default setting show an improvement in power and torque of over twenty one percent, maximum power rises to 140 brake horsepower and peak torque to 233 foot pounds.

The default setting? Yes, because the VP44 can be adjusted to raise (a little) or lower (a lot, down to standard) the performance enhancement. By default it comes set at seven and it goes from zero to ten.

The module does not change the power delivery of the engine, just provide more of the same, so whilst there is some small improvement in flexibility it is subtle.

The hike in power has made a big difference to certain parts of my commute, such as when I join the busy dual carriageway, which is discussed in my Diesel ‘vs’ Petrol article. Now that I have a lot more acceleration and flexibility I can keep the car in higher gears.

Fuel Consumption and Soot

There was no obvious difference in fuel consumption or soot when using the VP44 on summer diesel. However, when running on winter fuel there is an appreciable increase in soot and turning down the device does reduce the visible sooty trail under hard acceleration.

Adjustable Settings

As I’ve alluded to the VP44 has adjustable setting to change the power enhancement. Fresh from DieselTune the unit uses a setting of around seven from a scale of one to ten. This setting feels aggressive enough to result in a hefty increase in acceleration but with it comes a good dose of soot running on winter diesel.

Toning the unit down to somewhere close to two still provides improved acceleration and noticeably less soot.

Putting the unit to zero means you get standard performance and soot output.