Weird surge thing going on

[bock15ch]

When I first start up the truck when it's cold out, I notice that there is a slight surge like the truck slows down a MPH or two for a second or two, then runs normally. It does this off and on every two to three seconds for about the first 10 minutes of the truck running. Then it goes away. When it surges, I can hear a sound like air rushing into something. My truck is a '99 with a stock 7.3L. Anyone have any ideas what it could be?

[lawman349]

...it's your EBPV or Exhaust Back Pressure Valve.

This handy little device is designed to put a slight load on your diesel engine to help the motor warm up. The sensor uses the oil temp to determine the position of the valve. It warms the motor by closing a butterfly valve behind the turbo and closing off some exhaust. You should feel like the truck is slightly under load when the valve is closed...almost like the truck is bogging down a little. You will also hear a rushing sound when the valve is closed.

If the EBPV is malfunctioning is may open and close alot while the truck warms up. Be Careful...the EGTs can get high when that valve is closed. Dont go WOT.

The plug to the sensor is near the turbo pedestal if you want to disconnect it and diagnose the problem. The valve defaults to the open position if the sensor is unplugged.

Good Luck!

[bock15ch]

Thanks, that's a great help. How can you tell if it's not operating correctly?

[Trdltly]

I am having the same problem. If I start my truck on a cool morning then it will sit there with the surging sound. Very annoying. If we unplug the connector then the surging problem should go away, correct? Now, if it goes away then we know what the culprit is, but how do we fix this? Is it the oil temp sensor or the EBPV? Thanks for any advice that you can provide.

[lawman349]

read this thread:

Turbo Surge


it'll tell you everything you wanna know.