Quote:
Originally Posted by COcyclist
Thanks Mario, I have been trying to find this out for myself due to problems with a U.S. EGR cooler recall. From what I can find it is better to leave the EGR intact for lowest fuel consumption.
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This is another area where I intend to settle this once and for all, hopefully, at least on a VW TDI.
I participated with the people on lostkjs.com to build and use a device that mimicked the presence of a functioning EGR system on the Jeep Liberty CRD. The EGR valve and AFC valve were both disabled, and a circuit inserted into the MAF line to modify the air flow signal according to what the ECM requests. Mileage improved universally, reported as between 1 to 4 mpg increase on a baseline of mid-20s, for a 4% to 16% improvement.
I am building a similar circuit for the ALH TDI. Most people who disable the EGR on the TDI simply live with a CEL, or modify the EGR flow using the VDCS software, in both cases the ECM is aware of the lack, and may make fueling and advance changes to compensate and avoid emitting NOx. My device masks the absence, so the variable is only the lack of EGR to make mileage assessments.
I have disabled mine and driven with the CEL, and my mileage did suffer along with driveability.