In addition to waking up Jetta TDI’s, Malone offers optional calibrations that can bump up the factory engine idle to reduce vibrations associated with stiff aftermarket motor mounts (a common upgrade), a file that increases glow plug duration for easier winter start ups and a launch control tune for when automatic transmission cars visit the track. Malone Tuning is highly respected in the tuning realm, with solid power gains accompanied by great drivability (low smoke, linear throttle, etc.) and what is said to be the best customer support in the business. The general consensus on gains with the stock injectors and turbo still in the mix is 25 to 30 hp, but in our own chassis dyno experience we’ve seen a 33hp gain using Kerma TDI’s tuning, made possible via the company’s Q-Loader programmer. Big names in the tuning game for these cars are Kerma TDI, Malone Tuning, Rocket Chip Performance and TD Tuning. The quickest, easiest way to wake up the ALH 1.9L TDI diesel in ’99-’03 Jettas is to reprogram the ECU. Below, we’ll explore some of the most proven aftermarket parts available for these loveable little TDI’s. As icing on the cake, if you can manage to limit the travel of your right foot, these power adders won’t even cause a drop in fuel economy.
From high-flow injector nozzles to drop-in turbo upgrades and performance camshafts to custom tuning, everything is available for them. In fact, over the past 15-20 years of playing with these cars, so many parts combinations have been tested that-for all intents and purposes-ALH Jetta performance has been nailed down to a science. What to do? Luckily, a vibrant aftermarket exists for TDI’s. However, with just 90 hp and 155 lb-ft of torque available at the crank, these cars feel anything but light on their feet. Adding to the ALH Jetta TDI’s tremendous fuel-sipping capability is the fact that it weighs less than 3,000 pounds. Known for its mechanical simplicity, the ALH 1.9L four-cylinder oil burner features a 2-valve cylinder head, a Bosch rotary injection pump that feeds conventional, pop-off style injectors and a vacuum-actuated variable geometry turbocharger.
Known for their efficiency, simplicity and durability, the Volkswagen Jetta TDI’s produced from ’99-’03 (part of the MK4, fourth-generation cars built from ’99-‘06) are arguably the most fuel-efficient, diesel-powered sedans the German automaker ever produced.