I'm a machinist by trade and made my own egr valve spool plug. The plug does the same thing as unplugging the egr valve. But what I notice is on the egr valve, the bottom valve doesn't seat all the way into the seat and you can see an air gap. Will this small air gap cause issues, IDK. Even with the plug in and the egr valve plugged in and tied to the side, you may still get an CEL for p0401- insufficiant exhaust flow. You can get an SCT with an custom tune to turn off the CEL for the EGR valve not seeing enough flow. If you go with the plug, it would also be a good idea to put in or make a blocker plate where the cooler mates up to the exhaust or get an egr delete up pipe. This will prevent hot exhaust gases from hitting the egr cooler to help reduce coolant temps.
Most people go with the full delete because it eliminates the egr cooler from failing. You can also put on an coolant filter to help eliminate the chance of blocking up the oil cooler, but it is also important to monitor ECT and EOT to make sure that the oil cooler isn't getting blocked up. Those who just delete the egr cooler need to still be aware that without monitoring the ECT and EOT, still take a chance of a blocked up oil cooler.
As far as I'll effect on unplugging the egr valve, I have noticed when my egr valve was unplugged the VGT would not cycle and Nylyon had posted up a link from ford truck enthusiast that a ford diesel tech noticed the clutch fan didn't work properly with some ECM strategies. Here is a link to my VGT experience.
Also click onto the link that Nylyon posted up.
Egr valve and VGT cycling experience? - TheDieselGarage.com
2004 F350 CC DRW King Ranch
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