Improved performance and running with vegetable oil for the VW T4 1.9td ABL engine

I often see the Volkswagen 1.9TD ABL engine being put down as slow and poor quality, often followed by advice from others to swap out to the 1.9tdi engine which gives better economy and smoother running but I for one am very happy with the 1.9td engine in my T4 and I hope to explain why here.

Granted, the engine is not quiet, it's probably the noisiest post air cooled engine Volkswagen have produced. It's also slow when set up as standard, but there are ways around that. As for being economic, no it's not that either really, I typically get around 30 miles to the gallon. However, with a bit of modification and change of fuel, the 1.9td can become a great engine.

Before changing anything on my van, hills were a nightmare. Trips to North Devon or Cornwall often meant being overtaken on every hill with the speed dropping down to around 50mph on many occasions, having to change down to 4th gear to get any kind of pull. That's not to say it didn't have torque, no matter how many passengers or heavy the load, the speeds were always the same, just unfortunately that was slow. There are a couple of hills eastbound on the A303, a friend and I use to call Hill of Despair I and II, but no longer.

Adjusting the turbo

The easiest modification to make is to the turbo. This is done by adjusting the actuator arm to make it shorter which means the waste gate will not open until the pressure is higher, giving a lot more boost. There are a few in depth guides available on the Internet to do this. You do need to fit a boost gauge in order to ensure you do not overboost and therefore cause catastrophic damage to your engine. Mine was fitted in place of the hazard switch, the hazard lights are now controlled by a switch from a Passat, as can be seen in the picture below.

Boost Gauge

The hose for the boost gauge just needs to be fitted where the pressure can be read and fortunately there is a place for that on the air intake as shown in the image below. The image also shows another modification and that is the removal of the EGR valve, however, to be honest this makes little difference. Mine was removed due to a fault in the fuel pump which was not operating it anyway.

Boost Hose

Without modification the turbo should give a reading of around 9 psi, so if this is the case you can then go ahead and adjust the actuator arm to increase the boost. Note that the boost only occurs under throttle. Do not exceed 14/15 psi as you may put too much strain on the engine, mine never exceeds 13 psi. This change will make a lot of difference.

Modifying the fuel pump

Next, the fuel pump. At first I adjusted this myself by removing the locking nut on the max fuel screw but I could not get the idle to sit right so in the end I went to somebody who could check the timing. The whole process cost just £60 and I would recommend his services to anyone, please contact me if you need details. The change this made was really quite dramatic, acceleration increased tremendously and this was what allowed me to climb hills at a sensible rate.

Perhaps at some stage I will replace the 5th gear to allow for more economic, quieter motorway driving as even though the performance is now a lot better, it is much louder than the other T4 engines when running at the higher speeds due to the gear ratio. I may well also add an inter-cooler at some stage.


Running with vegetable oil

I'm often asked what is involved in running my van on vegetable oil, often with the expectation that there is a lot of expensive conversion processes involved but the answer couldn't be more different. At first I was very wary of moving away from diesel, as well as the physical implications of what it might do to the engine there was also the legal side of things but after some research I found that as long as no more than 2,500 litres a year is used then tax will not be applied so for most domestic use this would be fine. I also discussed with somebody else I know who had been using it for years and that convinced me to go for it. The other plus side is you can pretend you're an eco-warrior by using a renewable fuel source.

There are a few things to consider when switching to using vegetable oil though. Firstly, during the warm summer months I find there is no problem using 100% oil. There are plenty of places to purchase the oil, most supermarkets have fairly good offers. As I write this, Tesco are selling 2×5 litres for £8.00 which works out at 80p a litre. Being a business owner, I was able to set up an account with Booker, they sell the KTC vegetable oil in 20 litre containers which works out at around 75p per litre.

When first using the oil, it is advised to change the fuel filter after approximately 500 miles but after that the usual service intervals are fine. I do find that starting can be a bit more difficult at times, particularly on colder mornings, this being due to the oil being thicker than diesel. Due to this, if I use vegetable oil in the winter, I usually mix with diesel 50/50. The cold start cable comes in handy on start up.

As well as being more difficult to start, the only other issues I find are just the filling up which takes time and if not careful, can be messy, particularly if it's a windy day. Also, never try and do like I did first time and fill to the top, that makes a complete mess all over the driveway. I would always recommend putting an old blanket or something to stop the splashes getting on the ground. I usually switch the ignition on (not the engine!) and as I fill, check the fuel gauge. It's also not recommended to fill too high due to any spillage which may come out of the fuel cap when driving. Once on the body work, it's a pig of a job to get off and will attract unsightly dirt to the side of the van. If it does spill, I usually remove with white spirit.

I have now driven around 20,000 miles and to date, this has not caused any problems with the engine which is clocking up 160,000 miles now. It's probably worth purgin with diesel every so often, I do less miles in the winter and partly due to it being cold and wet I tend to use just diesel. I use to think that I was not worried about running this engine into the ground as I would just then have an excuse to fit a 1.9TDI, but now I think I would like to stick with the 1.9TD. I also had the expense of a gearbox rebuild fairly recently so need to get the use out of that.

There are a few links listed below which also help to understand the process of running vegetable oil.

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The Author



A complete self-confessed VW nutjob. My VW T4 is actually my first and only VW I have ever owned but I love it. Having bought my van as a straight forward panel van, I enjoyed the process of converting it how I wanted. Now the van is all done, it's getting out and exploring I love to do.