Wednesday, Dec 30, 2015 at 14:44
Gordon, at 250,000 kms, the engine would be rated as "
well worn". Have you replaced/overhauled any fuel injection components in recent years?
The Hyundai 2.9L engine is actually made by Kia, and it uses computer-controlled, lean-burn, common rail injection, along with a turbocharger, and air-to-air intercooling. It's a high-tech engine.
With all CR fuel systems, the injectors are critical items and wear out first, due to the enormous pressures they have to handle - the needle valve in the tip starts to not seal as it should, resulting in fuel dribble.
The multiple orifices in the injector tip commonly get clogged with carbon, resulting in poor fuel atomisation.
In general, CR fuel system injectors should be cleaned on a regular basis, as they are critical items,, and very prone to poor performance caused by carbon buildup.
The second component that suffers from wear, and reduced performance due to carbon buildup, is the turbocharger.
You can
check turbo performance easily enough with a simple boost gauge, which displays the manifold boost pressure and which will alert you to low levels of boost.
The other area that can affect fuel economy in a diesel, is air supply, so it pays to ensure that the air supply isn't restricted.
If your vehicle uses EGR as an emission control device, it pays to regularly inspect the EGR system for clogging, which is common in EGR systems, and which leads to reduced performance and poor fuel economy.
Lastly, you need to
check the intercooler for cracking, which results in the turbo-boosted air supply being lost to the atmosphere.
The result is the same as having a defective turbo - the engine isn't getting the air it should, manifold boost pressure is low, and both fuel economy and power levels will suffer.
Cheers, Ron.
AnswerID:
594306