APR 93 Octane ECU Chip Modification Review

Michael Posner
by Michael Posner

Enthusiasts have been tuning vehicles since the first car coughed into life. Back in the day, performance-minded pistonheads could enhance their car’s fun factor by putting stiffer springs on the distributor advance, or changing the top dead center degrees. In fact, there were hundreds of relatively simple ways a clever wrench could wring more performance out of his [formerly] humble four-wheeled steed. Today’s cars are too heavily computer-dependent for such simple tricks. Enthusiast-oriented entrepreneurs have created a whole new market of electronic modifications to fill in the void.

The ECU (electronic control unit) regulates various elements of the modern car’s activities: fuel delivery, spark plug detonation, etc. Manufacturers program the ECU’s software to balance the car’s performance with fuel economy, emissions, safety and reliability. In almost all cases, carmakers leave a large margin of performance on the table. If nothing else (cough warranty costs cough), the extra oomph would sacrifice some of the car’s commercial appeal.

Third party tuners download and disassemble the ECU’s source code (i.e. hack), and then recode portions of the software to unleash unused performance. Some chip tuners can dramatically increase horsepower and torque. In other cases, where power increases are limited, chip tuners improve the overall power delivery, remove top speed limiters and raise the car’s redline.


Until recently, ECU tuning required a hardwire modification. If the ECU software was socketed, a user could remove the factory programmed ROM and replace same with a new chip from the tuner. If the ECU software was soldered, then the pistonhead usually sent the ECU to the tuner for modification. Thanks to OBD-II access (now required by federal law) and the use of flashable ROMs (which allow for reprogramming by the manufacturer), tuners now can simply reflash the ECU without hardware modification.

APR offers several ECU options for Audi, Porsche and VW enthusiasts seeking extra oomph for their German-made, well-designed whips. In addition to modifications that remap the power delivery, customers can pay for the ability to switch between stock and “enhanced” modes, a valet mode (to reduce power below stock), and a 100 octane mode to accommodate race track gas. I tested APR’s competitively-priced 93 octane program upgrade ($599), with one mode ($100), on a 2006 Audi A4 2.0T.

Our local APR dealer performed the installation in about 1.5 hours. Once the software was installed, he showed me how to switch between no-go and go modes using the cruise control set button. Liberating the hidden horses was a bit tricky, and not always successful. In one case, I couldn’t start the car for a few minutes after activation.

APR promises a 41hp increase and a whopping eighty-five pound-feet more torque. The change in the car’s performance was dramatic. In real world testing, I dropped over a second from my normal zero to 60mph sprint time. Equally beguiling: acceleration was notably stronger throughout the entire power band.

APR improves performance in the Audi [in part] by increasing the turbo’s boost pressure. From the factory, turbo pressure at maximum acceleration is about twelve psi. APR ups this pressure by five psi. APR insists that the Audi engine can easily handle twenty psi. As long as you use 93 octane fuel (hence the product’s name), APR claims their upgrade remains safely within this margin. Long-term effects are unknown, but I noticed no engine issues over a ten-thousand-mile test.

This brings us to the thorny side of these mods: their effect on your warranty. Some owners worry that an APR or similar upgrade will void their factory coverage. While some dealers are quick to use modifications to deny a warranty claim, the Magnuson Moss federal warranty act specifically prohibits denial of coverage unless the modification actually causes the claim. But do you really want a protracted court battle with your car dealer?

The chip tuners offer no guaranties– which is worrying. The ability to turn off APR’s modifications and “hide” them from the factory technicians (“valet mode”) offers some peace of mind. HOWEVER, should the factory update your car’s software, the APR software will be overwritten. And this is occasionally done as a matter of “routine” during scheduled maintenance.

Now, some more good news…

The APR upgrade didn’t reduce the Audi’s fuel economy; in fact, I measured a slight increase in fuel efficiency. The ECU upgrade also works well with other engine modifications, such as cold air intakes, headers and larger diverter valves.

Overall, the APR ECU modification is an impressive effort. It greatly improves engine performance with only a slight, ongoing financial penalty (due to its need for premium dino-juice). Outside forced induction, no other modification gives as much bang for the buck as an ECU upgrade. For those looking to increase performance on their Porsche, Audi or VW, the APR program should be on the short list.

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Michael Posner
Michael Posner

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  • Virtual Insanity Virtual Insanity on Nov 26, 2007

    Its only some states that don't have 93. We have it in Texas.

  • Mlexcert Mlexcert on Feb 01, 2008

    Had a 1.8t 04 Audi Avant 6spd.Sport APR'D and was amazed at the transformation and the lack of articles on the inexpensive and totally reliable performance boost. Leased the car for four years and when I turned it in I put the upgrade to slept (valet mode). I also had an ECU upgrade done once when I went in for service and when I got the car back I went to my APR installer and they told me the upgrade was invisable to the Audi Dealers. Amazing product. I miss my Audi. I'm a Lexus salesperson and my wife made me get an automatic IS250. No more sticks for me. What a shame...

  • Scott Le Mans - Steve McQueen. It's an oldy and cult only but those who saw it know who's cars were featured.
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