Phase-out of EGR valves?

General Discussion
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It seems many of the newer car engines don’t sport EGR valves. I can understand the motivation, EGR problems tend to be hard to diagnose. But how is the EGR function accomplished with no EGR valve ?

Update Edit: A little Googling indicates some engines as long ago as the early 90’s went EGR-less. Some explanations I found for the no-egr configuration: (1) O2 sensor signals can be used by computer to modify mixture ratios in order to control combustion temperature; (2) variable valve timing can be used to as a sort of substitute internal-EGR valve; instead of routing exhaust gasses through EGR valve, configure intake & exhaust valve opening and closing timing to make use of the exhaust gas already there.

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Combination of 3 way catalyst and the ability of VVT to adjust how much exhaust is scavenged.

I don’t believe that is any of the motivation. It’s all about the cost. Why include complex systems that increase product cost when the problem can be solved by systems that already exist on the car for multiple purposes? Car manufacturers care very little about how much trouble you are going to have down the road diagnosing failures…follow the benjamins…

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IMO they might prefer that diagnosis is difficult so that owners are more likely to use dealer service centers.

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At least skipping the separate EGR eliminates one system to fail and need diagnosis.

However, I wonder if VVT based EGR is responsible for some of the intake valve deposits in direct injection engines.
This study suggests it’s not all from PCV spooge.

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They have a number of ways to affect that without negatively impacting COGS. :wink:

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Interesting idea … hmm … no direct experience on the topic, but it seems unlikely that an engineering team would purposely go out of their way to design a product so it was difficult to diagnose. They might however do a design that made the diagnoses easier for a well-trained company tech with all the gadgets and gizmos the company provides to aid their technicians, while more or less ignoring the needs of less well-trained technicians.