Audi A4 tuning

Modifying and improving: "Audi A4 Tuning"

The Audi A4 has had a long and successful production run, taking over from the Audi 80 and is actually very nicely put together. The car handles well and is offered with a wide range of engines which are just begging to be tuned up.

Because the car shares many parts from other VAG group cars A4 tuning is relatively cheap and simple. It is worth noting that the engines in the A4 are longitudinally mounted whereas in the A3 and Golf the same engines are fitted transversely. Most A4 owners will be looking to the S4 for inspiration on their own A4 tuning project. We will look at the most popular mods for the A4 and suggest the best way to maximise your enjoyment of your car.

So onto the A4 tuning tips:-

See our video which covers all the principles of tuning your Audi.

The 1.6 and 1.8 NASP engines are really a waste of time from a tuning point of view they seem barely adequate power wise on such a large car (particularly the 1.6). The 1.8T is a real star though and this is the engine of choice to have if you want a simple tuning project with a large power gain.

The car was also offered with a range of TDi engines that all respond quite well to remapping but the A4 did not have the most powerful TDi VAG engines fitted. As a general rule of thumb the better your base power the greater your return on investment will be when it comes to tuning making the 2.5 V6 the Diesel engine to go for.

When it comes to modding the NASP 1.8 we should point out that for the same financial outlay you could do an engine swap to something like the 1.8 Turbo and get an instant 100% power hike.

The larger V6 2.4, 2.5 and 2.8 engines will need some major work doing to them if you are after a good power gain from these. Ideally we would suggest getting larger valves, porting and flowing the head and have a 3 angle valve job done. Blueprinting and balancing the engine will allow you to fully exploit the top end power of this engine and this will help to raise the rev limit. Finish this all of with a fast road cam and a remap with a good sports exhaust and high flow air filter and you have a very satisfying car.

Early A4 mods and upgrades

The 20 valve 1.8 Turbo engines are stunning and with something as simple and easy as a remap is all you need to raise the power from 150bhp to around 225 bhp. The KO3 turbo fitted to this engine is not brilliant, they are prone to crack on the exhaust and they run out of puff quite low down in the rev range. By increasing the turbo you can dramatically alter the dynamics of this engine and your choices are either a larger turbo, like the KO4 or KO3s or getting your KO3 hybridised.  On these engines it also pays to get an uprated recirculating diverter valve (atmospheric dump valves have been known to cause problems) and it makes sense to uprate the tiny standard intercooler. A 20V 1.8 Turbo engine should cope with power figures of upto 300bhp on standard internals.

If you are getting some head work done on your 20V 1.8T we strongly recommend a larger exhaust port as the two valves on the exhaust prove to be a bit of a bottleneck.

We've covered the main methods of tuning for the A4 engines but you should consider the following tuning mods for your A4 engine. Fast road cams, air intake and sports exhaust & port matching.

If you want a short burst of extra power then one fairly easy mod for all these A4 engines would be adding a nitrous injection kits, this alone can add around 50bhp more power to your engine.

What other modifications are worth doing to your A4?

A4 Brake upgrades

Brake upgrades should be high up your list. Depending on your PCD and offset you might find other VAG group cars larger brakes fit. Look at the Golf, Cupra and even Porsche for suitable upgrades to brake disks and calipers. As long as you have the clearance and your stud pattern matches you should be ok.

The standard suspension on the A4 is adequate but uprating this with a good suspension kits like a fully adjustable coil over will allow you to greatly improve the cars handling and reduce body roll. A drop of around 30mm for most models is considered optimum.

A4 Quarter mile times after Mods

We are assuming an average 1610kgs kerb weight, & Manual transmission with Quattro in place for power levels exceeding 200hp.

Base power Quarter Mile Tuned to Kerb Weight Quarter Mile
118hp 18.96 130hp 1610kg 18.38
168hp 16.91 205hp 1610kg 15.86
225hp 15.39 240hp 1610kg 15.07
328hp 13.63 *735hp 1610kg 10.98
*635hp 1400kg 10.99

According to the specs and performance numbers, the 118hp A4 takes 19 seconds to run a quarter mile; normal engine power upgrades will reduce this to 18.38 seconds.

Power ratings of 250hp or more must be sent via the Quattro or rear wheel drive otherwise the vehicle will become undriveable due to traction concerns.

The finest engines are turbocharged ones, which can withstand more tune and create more power from a remap, allowing quarter mile times to drop into the 16 second zone.

*Building a 10 second A4 would need a lot of power, as the final two estimates illustrate, with a 210kg weight loss virtually equal a 100hp power boost.

For most projects on a turbocharged A4, we find improvements of 30-40%, which works fairly well.

Weight reduction is usually a smart way to go with your project, so hunt for lighter components and try to shave off as much weight as possible.

The best modifications for your A4 based on power increases

  1. Fast road camshaft remapping
  2. Intercoolers
  3. Intake and exhaust of (including catback & headers)
  4. Differential
  5. Fast road camshafts for maximum performance

I'd be shocked if you've discovered that a Motorsport camshaft is a joy to drive in congested metropolitan locations.

This is due to the fact that a competition cam generates a very lumpy idle and makes the vehicle more prone to stalling or jerking along in stop-and-go traffic; unfortunately, many people disregard this and wind up damaging a perfectly decent car and having to switch back to a fast road, or OEM cam profile.

Competition cams boost the top end band, but as a consequence, the vehicle does not idle smoothly, and low end power is almost always reduced.

Set your engine up on a rolling road to see how it reacts to excessive camshaft durations.

The ECU settings, as well as the fuel pump and injectors, have a significant impact on the horsepower improvements you'll get.

Changing the durations of the valves may change the power band, and on most engines, the exhaust and intake durations do not have to match; nonetheless, although most cams and tuners employ matched pairs, there are certain benefits to increasing the intake or exhaust durations.

Modifications for your A4 which are the best

  1. Mapping - remapping offers the largest cost reductions, however aftermarket ECUs and piggyback ECUs are also options.
  2. Fast road cams are one of the most important mechanical adjustments, but they must be fitted by someone who knows what they're doing, and they're not always easy to locate. However, you may be able to find a local outfit to regrind a standard camshaft.
  3. Intake and Exhaust - Keep in mind that these changes will NOT ADD POWER ON THEIR OWN in most circumstances, but they may aid boost power after other mods by eliminating the limitation.
  4. Upgrades to turbochargers and superchargers – forced induction is the most efficient way to increase air supply, enabling you to burn more gasoline while producing more power. It is one of the most expensive modifications, but it delivers the finest results.
  5. Porting and flowing the head's aims are to get air flowing into the engine while reducing flow limitations and turbulence.

Remaps/piggyback ECU, Intake headers, Fast road camshaft, drilled & smoothed airbox, Panel air filters, Sports exhaust manifold, Suspension improvement are common stage 1 upgrades.

Sports catalyst and performance exhaust, high flow fuel injectors, fast road cam, ported and polished head, induction kit, fuel pump modifications, and sports gearbox are common stage 2 mods.

Internal engine changes (head flowing porting/bigger valves), engine balance and blueprinting, adding or upgrading forced induction (turbo/supercharger), crank and piston upgrades to modify compression, competition cam, and twin charging conversions are common stage 3 mods.

You should strive for a large power band over the rpm range rather than a small top end power surge to maintain as much low end torque as feasible.
Check out our video, which covers all of the fundamentals of tuning your Audi.

Here are some of the Audi engines we've discussed in further depth, and the majority of them will work as engine swaps in your A4 (keep in mind that several of these engines have transverse variants).

Tuning tips and articles Engine tuning Transmission tuning Care care Intake & exhaust mods Improve handling Forums

What are the best A4 engines

From a tuning standpoint, we would suggest the 1.8T power plant on the A4 range, which really stands out as the tuner's option (along with the newer 2.0 TFSi and the 2.0 TDi.)

This engine was also available in Quattro form, which sacrificed a little efficiency and quickness but gained a lot more grip. The 1.8T offers a solid balance of economy and power.

This was eventually replaced with the fantastic 2.0 TFSi engine, which is very dependable and readily customizable. A remap, for example, produces a power number close to 270bhp. Later Quattro vehicles were equipped with a 220bhp engine (BUL code in the LeMans and Limited edition cars - it's certainly worth chasing one of these down if you can).

In the diesel lineup, the 2.5 TDi has a maximum output of 150bhp, which leaves plenty of room for power improvements when remapped. All other TDi models will benefit from a remap, but only the 2.5 TDi will see a significant increase for a little investment.

Mods for the A4

Fast road camshaft, remap, induction and exhaust, and suspension are the greatest changes we propose for your A4.

If you remap NASP engines, you will not see significant power improvements until you have made major changes. This is not the case with turbocharged engines. A remapped turbo will provide substantial power improvements and completely unleash the engine's maximum power.

When adding forced induction or a bigger compressor, a lower compression ratio or water injection is frequently required.

In terms of performance models, the early S4 Quattro and the latest RS4 re-established Audi as the developers of a vehicle that every driver desires.

Some may argue that the S4 and RS4 variants are unattractive, but this automobile appeals to drivers who don't want to draw attention to themselves, making the A4 range a car for purists.

In 2001, the automobile was modified, the floor pan was somewhat enlarged, and a variety of more powerful engine choices were provided.

The 2.0 FSi engine provides a decent power-to-economy ratio, with the A4 Quattro reaching 220bhp by 2006, while diesel tuners have a range of 2.5TDi engines ranging from 163 to 180 bhp that are crying for a remap.

A 3.0 NASP petrol engine produced 220bhp (until the rebirth of the powerful S4) but was not especially efficient.

Modifications and Upgrades for the Audi A4 Turbos

With the correct tweaks and improvements (remap and intake mods), your K03 can produce up to 180 horsepower!

This is a simple power boost, but pushing the turbo too hard could shorten its life.

KO3 vs K03s versus K04

The K03s is more powerful than its sibling, the K03. Most tuners won't push it above 215 horsepower with K03s, but if they do, they'll run into problems and limit the turbo's lifetime. This turbo can produce up to 250 horsepower, but don't expect it to survive very long.

A K03 is typically 25 bhp more powerful than a K03. You can squeeze even more out of your automobile and make fairly spectacular power improvements if you're prepared to shorten the lifetime of your turbos or conduct additional maintenance.

The K04, in turn, outperforms the K03s. It is larger and more powerful than the K03 and K03s.

You'll need the correct hardware to make the K04 run faster. The KO4's safest power limit to maintain manufacturer dependability is 220 horsepower.

Turbo power limitations

The safe settings should maintain factory dependability and durability; the Max, on the other hand, is pushing the boundaries and will almost likely lower the turbo's lifetime.

Maximum Turbo Safe K03 190hp 220hp K03s 215hp 250hp K04 220hp 350hp
There are turbochargers from the VAG Group's newer generation.

The most recent versions of VAG turbochargers include the IHI IS12, IS20, and IS38 turbochargers. They are intended to replace IHI's K03, K03s, and K04 turbochargers.

Because Audi and Volkswagen manufacture their own turbos, the IS12 and IS20 were designed to operate with their 2.0t MQB engines.

Tuning Mods for the A4 Intake and Exhaust.

The intake and exhaust are the next areas to be modified.

If the car's air intake is straining, air induction systems will only assist to improve performance! Adding an induction kit to the majority of conventional engines results in NO POWER GAIN AT ALL.

If you have substantially changed your engine and its requirement for air has increased DRAMATICALLY, an induction kit is the solution and will assist in removing this constraint.

Derestricting the air feed into the engine is a key objective of automobile tuners, therefore acquire a better flowing air filter only if the car is running lean. Induction kits may sound amazing, but owing to the heated air in the engine compartment, they will not boost power and will often deprive you of power.

Sports exhausts will undoubtedly improve air flow from the engine, but avoid exhausts that are too huge or you may end up with a lower flow rate. As a matter of thumb, keep it between 1.5 and 2.5 inches.

Professional polishing and porting may significantly boost airflow through the head. These should match and be configured to take into account any other engine modifications. When you start tuning your A4, you'll notice that the normal clutch begins to fail, so acquire an upgraded clutch.

A4 Suspension/Handling Upgrades

The first objective in your A4 tuning effort should be to improve the handling for automobile owners.

Cornering will improve dramatically if you put the front toe out to 0.8 to 1.3 degrees and add some negative camber.

Drop the vehicle by up to 30mm - 42mm and install performance firmer dampers; larger drops will need extra modifications in most cases.

Upgrades to the A4's alloy wheels.

Because alloys are lighter, they boost performance and also assist to cool the brake discs.

If you're serious about performance, you'll want to choose your tyres carefully, preferably with a directed tread pattern.

The disadvantage of huge alloys on your A4 is that you're changing your final drive ratio and adding unsprung weight, which will reduce performance.

As a result of this effort, the total rolling diameter of the wheel remains the OEM arrangement.

On the A4, we recommend sticking with 18-inch wheels since, although 19-inch wheels look good, they suffer from tram lining and are fairly hefty. To ensure the speedometer is true, the wheel size may be modified through an OBD menu option, so before changing wheels, check your dealer and verify that the studs used are proper.

When it came to tyres, I discovered that Dunlop Sport Maxx, Goodyear Eagle F1s, Michelin Pilot Sport, and Continental Premium contacts all performed well on my A4.

I didn't like the Pirelli P6000s at all; the wet grip and overall feel were so awful that I ditched them after 4 months. I'll be trying the Pirelli P Zero neros next, so I'll keep this piece up to date.

If you want to learn more or simply get some friendly advise on tuning your vehicle, please join us in our friendly forum where you can discuss A4 options in more depth with other A4 owners. It is also worthwhile to read our impartial Audi tuning articles to fully understand the pros and downsides of each adjustment.

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As a result, we can keep our instructions and advice up to date and assist others with their customised automobile projects. Your suggestions and comments are utilised to keep this website up to date and to enhance the accuracy of these articles, which are continually updated and edited.

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A4 buyer's guide and flaws

When purchasing an A4, avoid the low-spec basic cars since they are difficult to resale; instead, choose for the S line or limited edition vehicles with leather seats.

I would claim that there was a reduction in quality between 2007 and 2010, as was the case for many motor manufacturers during the financial crisis, with several ridiculous electrical relay and switch failures.

The Quattro and Avant models keep their worth the best and are the most desirable.

There are a few small flaws to be aware of on the 2.0 TFSi and DPF-equipped engines. To begin, you must use the proper oil specification; neglecting to do so is asking for disaster.

DPF-equipped diesel engines: DPF filters are notorious to clog if you just drive short distances and the engine does not warm up. Even highway trips aren't always enough to get rid of everything.

Running the automobile at high RPM for 15 minutes will usually do the work; it also helps to drive it hard.

Cars that are driven cautiously and at lower RPMs are more prone to soot buildup. To assist you, we have created a DPF cleaning guide.

The 2.0 TFSi engines are highly powerful and deliver good power to economy, but there are two things to keep an eye out for. You will prevent difficulties if you notice this early enough, and they should be treated as service items. (Later engines, to a significant extent, overcome these concerns.)

To begin, the cam follower that operates the mechanical fuel pump is coated with a specific black low friction coating. It resembles a thimble and rests on the bottom of the fuel pump.

Check for wear every 30,000 miles. If the coating has worn away and a metal surface is exposed, this can soon wear through the follower and the cam shaft, resulting in decreased fuel pump pressure. It is a basic check, and as long as you are cautious of the very high fuel pump pressures, it is an easy DIY procedure, just slightly more difficult than replacing a set of spark plugs.

Second, carbon buildup on the valves of the direct injection engine. Because the gasoline is not being injected across the valves, there is no cleaning going place.

Most direct injection engines suffer from this, and a decoke is suggested after 70,000 miles.

The direct injection engine of the RS4 is significantly more prone to carbon buildup. The carbon buildup will drain you of power rather than causing significant harm, but cleaning out the head will significantly improve performance.

We have found no evidence that water/alcohol injection adequately cleans the intake valves.

Running a fuel cleaner also has minimal effect since the fuel is not splashed on the intake.

As the saying goes, prevention is better than cure, so what can be done to avoid this carbon buildup problem? Using high-quality clean-burning gasoline that is devoid of bio components; higher-octane fuels also tend to burn cleaner.

Get the engine up to temperature as quickly as possible (don't idle it, just drive it consistently at roughly 2000rpm till it warms up) and keep it running at 3000rpm for 15 minutes every week.

The engine is built to operate hotter at these RPMs, which may help burn off some of the carbon deposits.

Keep a watch on the recirculation valve; the oil that deposits into the intake when it fails has been identified as a key source of carbon buildup.

If you observe excessive oil usage, get this valve examined as soon as possible.

Cleaning the head is normally done by removing and refitting it, although we've seen some outstanding results using intake cleaners that are sprayed into the intake at high pressure.

An inspection probe inserted into the intake or into the spark plugs will provide information on the status of carbon buildup.

The DIY spray cans of carbon cleaning only perform a little job; the challenge is to get the cleaner to all of the valves equally. To get the greatest results, remove the intake manifold and spray the cleaner directly into the problem area, allowing it to soak. (Always follow the manufacturer's directions, since certain formulas should not be kept on for extended periods of time.)

To assist burn off deposits, the VAG group is studying self-cleaning valves using catalytic coatings, tiny quantities of fuel sprayed in the intake, and "leaking valves."

Further reading.

We suggest that if you want a bit more information on A4 Tuning you consult the following sources. TorqueCars have a comprehensive  very active, friendly and helpful Audi tuning forum.

If you have any tips to pass on please use our comments box below and we will update this article, after all we are all here to share knowledge. Please also let us know if we've missed out an engine or performance mod that you feel should be included in here or if we have just plain got it wrong!

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One Response to “Audi A4 Tuning”

  1. m0nkeymafia says:

    Great article. You are totally right the 1.8T engine is the one to have, I had the same engine in my old Golf GTI and it can be tweaked to hell.

    I think thats the same engine thats in the Audi TT too.