Gasoline Direct Injection

[Seeker]

Hyundai/Kia have been having issues with engine failures and it's related to oil contamination on their direct injection petrol engines (they call it GDI).

I didn't know that the GDI systems work with very high fuel pressures: 2000 psi. These pressures allow fuel to push past the rings and contaminate the oil.

It seems to be a second problem with direct injection engines because they also suffer from carbon deposit build up. On a port injection engine the fuel/air mixture goes past the valves and, to an extent, cleans them but on DI engine this doesn't happen. In their defense they are more efficient (until they break )


https://jalopnik.com/hyundai-and-kia...d-b-1851622686


I follow "I do cars" on youtube where he tears down a damaged engine weekly and every DI engine he dismantles has excessive carbon build up.

[Craig380]

Interesting, I wonder how much of that fuel contamination is caused by a lot of short-run driving, in which the engine doesn't properly warm up so that it doesn't get to proper running tolerances?

A few years back I had a Volvo V60 with the then-new modular VEA diesel engine. After just 5,000 miles the EGR cooler blocked up. It was replaced under warranty. 8,000 miles later it happened again: EGR valve and cooler replaced. 10,000 miles after that, the cooler blocked up again, and was replaced.

It wasn't just my car: the Volvo main dealer told me they were doing 20 to 30 EGR / cooler replacements per week under warranty, and the Volvo forum was FULL of people with problems. But the problem was mostly confined to UK owners, it happened far less with the same cars in mainland Europe.

What had happened was this. To meet Euro 6 emissions standards, Volvo decided to use a complex electronic EGR valve and cooler system instead of AdBlue to cut NOx output. The system worked fine during Volvo's testing - which involved lots of long journeys where everything got properly warmed up.

What the engineers DIDN'T account for was typical UK short-run usage patterns with journeys of under 10 miles in stop-start traffic. These usage patterns quickly choked the EGR system with a mix of soot and condensation, killing the EGRs. The cars were not tested adequately in these conditions, so the problem didn't show up until the cars had been on sale for a few months.

Volvo eventually gave up and started installing AdBlue systems.

See also Honda's 'chocolate cams' in the early V4s in the 80s: another case of marginal design that wasn't adequately tested before being released to the public.