Tuning the 1.9 TDI PD engines

Regarded by many as the best Diesel engine from the VAG group the 1.9 offers plenty of tuning potential.

It had a long production run and is still regarded by many enthusiasts as a more reliable engine than the later 2.0 that replaced it.

1.9tdi--tuning

The 1.9 TDi was used in a wide variety of cars from the VAG group and came in different power levels.

All had BOSCH injectors, and Bosch ECU's which are really sturdy and very protective of the engine.

If you want a quick beginner's guide to tuning diesels please see our new video tutorial.

1.9 TDi Common faults & Problems:

There are some reports of the BLE or BXE engines breaking con rods.

The second generation PD engines were bullet proof as most of the kinks had been worked out which is more than we can say for the later 2.0 TDI engines.

The 1.9 TDi is regarded by many as the best VAG group diesel engine.

Early engines suffered from cracked injector looms.

1.9TDi Engine codes

  • PRE PD - 1Z, AHU, AGR, AHH, ALE, ALH, AFN, AHF, ASV, AVB, AVG
  • PD engines - BSU, BRU, BXF, BXJ, ANU, ATD, AXR, BEW, BMT, AVB, AVQ, BSW, BJB, BKC, BLS, BSV, BXE, BPZ, AJM, ATJ, AUY, BVK, AWX, ASZ, AVF, BLT, ARL, BTB, BPX, BUK

1.9 R4 TDI - pre PD units

engine configuration & engine displacement
inline four-cylinder Turbo charged Direct Injection TDI turbo diesel; compression ratio: 19.5:1

Cylinder head & valvetrain
cast aluminum alloy; two valves per cylinder, 8 valves total, bucket tappets, timing belt-driven SOHC
fuel system & engine management
timing belt-driven Bosch VP37 Verteiler Pumpe electronic distributor injection pump, direct injection
Engine codes with power specs
89 bhp @ 4000 rpm; 149 lbf·ft @ 1,900 rpm - 1Z, AHU
89 bhp @ 3750 rpm; 155 lbf·ft @ 1,900 rpm - AGR, AHH, ALE, ALH
109 bhp @ 4150 rpm; 173 lbf·ft @ 1,900 rpm - AFN, AHF, ASV, AVB, AVG

1.9 R4 TDI - PD version

Essentially, this revised engine has the same bottom end but has a revised cylinder head for the PD Pumpe Düse injectors.

Aspiration
hot-wire mass air flow MAF sensor, cast aluminum alloy intake manifold, Garrett, KKK or Borg Warner variable turbine geometry turbocharger VGT,  water-cooled EGR, cast iron exhaust manifold

Fuel system & engine management
Pumpe Düse PD direct injection DI: engine-driven vane-type low-pressure fuel lift pump, four camshaft-actuated via roller rocker arms high-pressure Bosch  27,850 psi Unit Injectors with solenoid valve injection nozzles, Bosch EDC16 or EDC17 ECU

Engine codes with power specs

  • 74 bhp @ 4,000 rpm;  155 lbf·ft @ 1,900 rpm - BSU
  • 89 bhp @ 4,000 rpm; 155 lbf·ft @ 1,800−2,500 rpm - BRU, BXF, BXJ,
  • 89 bhp @ 4,000 rpm;  177 lbf·ft @ 1,900 rpm - ANU
  • 99 bhp @ 4,000 rpm;  177 lbf·ft @ 1,800–2,400 rpm - ATD, AXR, BEW, BMT
  • 99 bhp @ 4,000 rpm;  184 lbf·ft @ 1,900 rpm - AVB, AVQ
  • 103 bhp @ 4,000 rpm; 177 lbf·ft @ 1,800 rpm - BSW
  • 103 bhp @ 4,000 rpm; 184 lbf·ft @ 1,900 rpm - BJB, BKC, BLS, BSV, BXE
  • 114 bhp @ 4,000 rpm; 184 lbf·ft @ 1,900 rpm - BPZ
  • ​114 bhp @ 4,000 rpm; 210 lbf·ft @ 1,900 rpm - AJM
  • 114 bhp @ 4,000 rpm; 229 lbf·ft @ 1,900 rpm - ATJ, AUY, BVK
  • 129 bhp @ 4,000 rpm; 210 lbf·ft @ 1,800 rpm  - AWX
  • 129 bhp @ 4,000 rpm; 229 lbf·ft @ 1,900 rpm - ASZ, AVF, BLT
  • 148 bhp @ 4,000 rpm; 236 lbf·ft @ 1,900 rpm - ARL, BTB
  • 158 bhp @ 3,750 rpm; 243 lbf·ft @ 1,900 rpm - BPX, BUK

Remaps offer good power gains for very little outlay. Pre 2000 cars will require a bench flash in most cases but post 2000 cars will generally be remappable via the OBD port.

Approximate power figures after a remap with no other mods.
(Bear in mind that peak power figures are only a small part of the equation, the whole torque band is improved).

  • TDi90 = 116ps
  • ​PD90 = 120ps
  • ​PD100 = 130ps
  • PD105 = 135ps
  • ​TDi110 = 143ps
  • TDi115 = 124ps
  • PD115 = 150ps
  • PD130 = 163ps
  • PD140 = 175ps
  • PD150 = 182ps

​PD engines generally give a better power gain than the original TDi engines. Further gains are possible on the standard block by uprating the turbo units.

Please watch our video which covers the 5 principles of tuning your car. Be sure to subscribe and support our new channel.

Best mods for your 1.9TDi

  1. Differentials - improving the diff on FWD cars really help you get the power down.
  2. Mapping - remapping provides the most advantage in terms of cost savings,  aftermarket ECUs, and piggyback ECUs are all alternatives.
  3. Intake and Exhaust - Note that on their own these mods will NOT ADD POWER in most cases, but they can help enhance power after other mods by removing the restriction.
  4. Upgrades to turbochargers - forced induction upgrades and hybrid turbo upgrades, in particular, are the most efficient way to increase air supply, allowing you to burn more fuel and make more power. It is one of the most costly upgrades but provides the best gains.
  5. Fuelling upgrades, the injectors and fuel pump will need uprating for larger power gains.
  6. Intercooler upgrades - the stock intercoolers are restrictive when running maps so swap in an FMIC that flows better and resists heat soak for longer.

WARNING: DO NOT FIT A LIGHT SINGLE MASS FLYWHEEL TO THIS ENGINE! The vibrations will drive you crazy and gearbox life will be reduced.

Typical stage 1 mods often include:
Remap, Lighter flywheel (stick with dual mass though, SMF's are not great on the 1.9),  Sports exhaust, Panel air filter.

Typical stage 2 mods often include: Ported and polished head, Power/Sport clutch, Fast road cam, fuel pump upgrades, high flow fuel injector.

Typical stage 3 mods often include:
Engine balancing, Internal engine upgrades (pistons/head/valves), Competition cam, Adding or upgrading forced induction (turbo/supercharger).

Differential upgrades to maintain traction on the 1.9TDi

You will get lots of traction issues around 250bhp, so bear this in mind, while your wheels spin you won't be moving!

For a car that is used on the road in different weather conditions, I think the Torsen diff is the best choice.

Torsen means "Torque Sensing," and it is very subtle in how it works. It comes on very slowly and gradually.

There are some LSDs that aren't very noticeable, and there are Torsen diffs that are a little more quick. This all depends on the diff maker and how the car is set up.

Torsen diffs can be found in a lot of production cars. LSD diffs are usually found in cars with a lot of power or a high price. A, B, and C are the three main types of Torsen diffs. Each one has different applications and characteristics, and some aren't good for everyday use.

One of the diffs our members recommended was a Quaife LSD. Quaife also makes ATB diffs.

Remapping the 1.9TDi

How does VW set the factory maps? It accepts that some countries' CO2, HC, and NOx emission targets differ, necessitating a fudged approach - the lowest common denominator if you will.

Manufacturers do not want customers to be inconvenienced by mechanical failures or poor fuel economy, therefore they build in a large tolerance.

Depending on how effectively the components are machined and assembled, the power output of each engine can vary by as much as 20bhp. Rather than examine each automobile individually and create a custom timing map, they use a one-size-fits-all approach.

Manufacturers also employ remaps to create multiple power versions of the same 1.9 TDi engine, lowering insurance rates and improving fuel economy.

So there is plenty of scope to extract more power from your 1.9Tdi with a remap.

Downsides of remaps.

Service your automobile more regularly, possibly decreasing the interval.

A map optimised for high octane gasoline will need you to repair components that fail due

Additional power puts more pressure on components like turbos, hoses & pipes, and injectors.

Months after a remap, an engine's weak areas resurface. remap issues, see our instructions.

A remap will usually reveal turbocharger and clutch issues.

Also, 1.9 TDi turbos may fail, and critical components like pistons and bearings must be maintained. NASP remaps? A remap will only add a few BHP without a turbo (10 percent is typical).

TorqueCars encourages non-turbo cars to modify first (cams, pistons, increase compression, engine balance, air intake, exhaust, head work, bigger valves etc...)

After that, a remap may help you get the most out of them.

A remap frequently adds boost from lower rpm, making the turbo operate quicker and hotter.

If you don't let the turbo cool, the oil may deteriorate, necessitating a costly turbo repair. Installing a turbo timer will also help cool the engine.

Not all maps are equal so don't compare peak power claims

Be wary of peak power claims. Note: Some tuners are known to create a power blip or surge to draw attention and capture headline power statistics.

See the graph below for an example.

The red trace, at 200bhp, is not that impressive, the peak power happens quite high up and is only a blip, whereas power for the rest of the RPM range is substantially down.

However, the green trace indicates a consistent growth in power across the RPM range and although only 175bhp it will give better power than the 200bhp map.

On the 1.9Tdi you would want peak power early at 2500rpm, which is great for an engine that redlines at 5000rpm.

On a map, we want to see a nice smooth torque climb with no dips or troughs.

Injector upgrades on the 1.9TDi

The 1.9 TDi injectors on the PD130, PD150 will be good for 240bhp, injectors on the lower powered engines including the popular PD100 PD105 and PD115 units will need uprating at 170bhp.

The PD150 injectors are a good option to upgrade with, or you could source some high performance ones.

1.9 TDi turbo upgrade options

Is There a Reason to Upgrade Your Turbo?

Many motorists choose to replace or enhance their cars' turbochargers for the following reasons: Turbocharger upgrades are an excellent way to boost a vehicle's performance and one of the most impactful.

Turbos wear out with time, needing periodic replacement. Additional recent turbos take use of newer technological breakthroughs and provide vehicle owners with more add-on possibilities.

The factory 1.9Tdi turbos are supplied for cheapness and reliability not performance so thankfully there are many upgrade options around for these. Here are some that TorqueCars have found to be particularly effective based on feedback from our members and my own experiences.

On these engines you can choose from the GTB2566VK good for up to 245bhp maxing at 3300rpm. ​GTB2260VK  good for up to 315 bhp maxing at 2800rpm, GTB2056VK  good for up to  255 bhp maxing at 2700rpm and the GTB1756VK  good for up to 235bhp maxing at 2600rpm.

There is also the GT2052V good for 225bhp at 2200rpm which would be our choice on a road car.

Other Turbo upgrade options on these engines exist if you are prepared to change the pipework and manifolds. These include the GTB1749V producing up to  205bhp from just 1900rpm, and GTB1756V which is good for around 225 bhp. Some companies offer hybrid turbos which can push power levels to 240bhp or more with the right additional mods.

NB: Turbos will require conversion to Vacuum actuators and have the VNT system set up.

Choose the turbo where the power band sits in your most-used rpm range, the larger power turbos tend to come on boost later.

On a track where you spend most of your time at high rpm this is fine but in day to day driving lots of lag can be frustrating to drive.

1.9 TDi tuning essentials

110 and 90 VE 1.9 TDi Engines will need uprated fuel injectors as well, the standard injectors on these engines are not good at higher power figures. The 150 head bolts are strong, in all other engines you may experience head lift on stock bolts at large power gains.

Fit uprated head bolts or get some bolts for the 150 and fit these instead.

When pushing another 50 bhp through these 1.9 TDi engines it is recommended to get a hard pipe kit, joints and pipes that are old are more likely to split apart when you run higher air pressures through them.

New clutches are usually ok with power gains to the 220bhp. Worn clutches will often be ok but it depends on the treatment and condition of the clutch. Worn clutches seem to slip in about half of the cases where large power gains have been fitted.

Newer 1.9 TDi CR diesel engines are much much cleaner, and they have better fuel management, and pollution reduction measures but lots of short journeys can lead to clogging up of the DPF (Diesel particulate filter). See our guide on how to clean a DPF for more info.

1.9 TDi Intercooler upgrades

A larger intercooler will also better resist heat soak and would be a good upgrade on these engines.

In a 1.9 TDi turbo, the cold intake charge and hot exhaust temperatures are near each other inside the turbo. This can be a problem. The big rise in air intake heat is caused by the air itself being compressed, so even a supercharged engine will benefit from having an intercooler to help it cool down.

Air gets hot when it is compressed. If you have ever felt the nozzle on a tyre pump you will know that when air is compressed it gets hot. There is more oxygen in the colder the air is, because we learned about this in our chemistry and physics class.

Why is this important?

A 1.9 TDi that has more oxygen has more power because it can burn a lot of gas. You can read more about air intakes in the article.

In a car, what is an intercooler and what does it do?

An intercooler is a radiator that cools the air charge before it goes into the engine.

You should put an intercooler in front of the radiator so that it gets a lot of nice, cold air. Afterward, the air intake filter and the turbo or supercharger, where most of the heat is added, it would be piped into the car.

An intercooler that is well-designed can give you 5% to 10% more power from your mods, and resist heat soak for a longer time.

Keep in mind that you want to get as much air into the engine as possible, so if the internal core of the intercooler is in the way, you will lose power.

Bigger isn't always better, though!

TorqueCars would expect a pressure drop of between.5 and.9 psi for a boost level of 15PSi. In the worst case, some applications could lose 1.3 psi. It's not the intercooler's design that caused the whole loss of pressure, it's partly down to the reduction in temperature, so don't blame it for the whole drop in pressure.

In performance cars, weight is always a concern. Many aftermarket intercoolers are both lighter and more powerful than factory intercoolers, which makes them a good choice for these cars.

As a general rule, if the intercooler is a little bigger, it will be better at cooling, but it will also make the car move slower.

There should be a lot of thought put into how much extra drag this will add to the cooling. More air stays in the intercooler, the better it will cool you down.

Some cars have a spray nozzle that can be used to spray the intercooler with water or nitrous, which lowers the intake temperature even more as the liquid evaporates using the heat from the air that passes through the intercooler. This helps the car run more smoothly.

Between 5% and 10% of power is gained from a more efficient 1.9 TDi intercooler design over the factory one (assuming there was a restriction which depends on the way the engine has been tuned and setup). This is based on a temperature drop of 35C-40C. The bigger the difference between intake temperature and ambient temperature, the more cooling effect there will be.

As time goes on, even the most efficient intercoolers will get hot. When you drive for a long time with a lot of high-boost, the intercooler starts to get hot.

In general, the bigger the intercooler, the longer it can withstand heat soak.

Please help us complete this article, if you are aware of any 1.9 TDi engine codes we have missed, common issues or upgrade options including turbos please let us know, we want to make this as comprehensive as possible.

Tuning the intake and exhaust on your 1.9TDi

Next, we'll examine the best options to improve the 1.9 TDi intake and exhaust to verify adequate engine air and exhaust flow. Please note that on this engine you should be fine on the stock setup to around 220hp.

A comprehensive induction setup maximizes power improvements if you hit a restriction. We recommend a high flow panel air filter on all 1.9Tdi, they will improve the "off throttle" engine running and give me a little more fuel economy on mine without impacting on performance.

Opening the air intake port to match the intake manifold would not help much unless a step obstructs airflow into the 1.9 TDi engine. So most DIY port matching is done on exhaust ports but we don't really see a need on the 1.9 TDi engine.

Extending the port size is only necessary in highly tuned engines when the port size has become a bottleneck and VW did a great job on the design.

The greatest power improvements are generally between 1.5 and 2.5 inches.

Please join our friendly international forums if you want to discuss any aspects of 1.9TDi tuning in detail and let us know in the comments below what mods you've done or pass on any tips to our readers.

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Your Constructive comments on this article




10 Responses to “1.9 TDi tuning”

  1. Dave says:

    Hi, just reading through and think you may have listed incorrect power figures for the choice in turbos you recommend, I was under the impression the gtb 2566 was a hybrid 2260, good for well over 300hp?
    Thanks

  2. TorqueCars says:

    On the 2.0 TDi the GTB2566 is good for around 340bhp on the 1.9 engines you will not get this due to the lower cylinder capacity and supporting mechanical components so 240-300 is about the practical maximum. We’d be very interested to know peoples experiences and results with these turbos on this engine.

  3. ROkkanon says:

    Hello,
    First of all thank you for the article, very good information for everybody.

    I couldn’t find any information about GT2042V. Can you please check if index is correct, if yes, please provide some additional information regarding his turbo may be a link.

  4. TorqueCars says:

    Sorry this is a typo, it should read GT2052V – Darkside developments were selling these internals in the VNT20.

  5. Paul says:

    Just after some advice looking at a 2010 touran it’s got the 1.9 103bhp engine in am I right in thinking this is the pd bullet proof engine many thanks

  6. Jaydee says:

    I’ve just purchased a leon 1.9tdi engine code asv

    I also have an audi a3 engone code bkd and heard about cylinder heads failing on those

    Dorset the leon suffer format the same problem
    Is there a code on the head I should look for as on the audis

  7. Benjamin Masinge says:

    Your article is staight on point.I owned vw jetta 4 1.9 tdi 2003 drove it to 450000 km then sold it..That was a bullet proof car recently I got a low mileage one stil a 1.9 tdi.I think this car is a collectors item and is best to fo minimul to it…replace air intake inclufong egr then fit a 2 inch stainless steel exaust,change all oils including gearbox and you good to go.Power is relative but this car is an engineers show off.

  8. jeff Gresswell says:

    A really good article on VW 1.9TDI tuning. Just one question on a 105bhp how much higher can you go before needing a larger intercooler(assuming there already is one!)

  9. TorqueCars says:

    Its not so much about the power gain, but how hot the intercooler gets, a larger intercooler resists heat soak for longer. A FMIC is a good option, the side mounted intercoolers are not that fantastic. If you drive at high RPM all the time then an intercooler upgrade is important, if you only use boost to overtake now and then and most driving is only spirited in short bursts then your money is better spent elsewhere.

  10. john youngblood says:

    interesting – would like to knowabout conversion to a north/south orientation considerations and issues

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