Electronic Diesel Tuning

Tinkering with your EFI controlled diesel engine

Words by Andrew Leimroth

In this era of increasing emission control, it was only a matter of time before diesels entered the world of electronics. Every road registrable diesel sold in Australia nowadays has an EFI controlled engine. The first ones sold over a decade ago had a simple control system, with few sensors. It included a traditional injection pump that pretty much had electronics pulling the levers inside it for you. The latest diesel engine is fully electronic, and resembles more of a petrol car engine with individually controlled injectors.

This new technology has allowed precise control of emissions and power output, but it can result in lack of power when towing. The old fuel screw can’t tickle up for a little more pulling power. With the new EFI diesels you need to start playing with the electronics. Luckily, tinkering with electronic signals is easy thanks to the raft of diesel tuning chips on the market. Simply plug in most of these new devices to instantly get the gains you want – more power, more torque, and hopefully better economy.

One problem is – these finely designed engines also come with finely matched components. Any changes to how things work may severely upset the running of the engine and its many parts.

Turbochargers now vary their size (so to speak) electronically during driving, negating the need for high flow turbos. Exhausts are integrated pieces of the design containing highly sensitive exhaust filters, and mufflers rarely have unacceptable backpressures or restrictions. Even the good old flywheel is no longer safe. New diesels are coming out with dual mass flywheels that contain many sections and springs to dampen engine vibrations from the new breed of sensitive electronic engine/transmission combinations. Simply put – it’s all matched for perfect operation.

Correct tuning of an EFI diesel really becomes an important phase of any power improvement. Just pouring in fuel alone with a cheap chip or chip/ exhaust combo will no doubt give an instant power result. But, the physics of how that power arrived may lead to a sad event in the future.

It’s important that you observe a few simple things and request various results in a dyno report. Exhaust AFR ratios is an important graph, as it indicates if things are getting too rich. The other important item to have graphed while your motorhome or vehicle is on the dyno is turbo boost. The dyno operator should explain how and why the changes, before and after, have taken place: vehicle in standard form, then with exhaust changed, and finally with the chip added. One last consideration is that EFI-controlled diesels generally settle down to normal repeatable power levels after they are fully warmed up, and run many times on the dyno. So be sure you see repeatable dyno lines to be certain the changes you are getting are true and accurate.

Safe Driving

Andrew