Surging when cold 99.5 7.3l

[skeeter7310]

So I thought it might be the airbox temp sensor, I was wrong.
When the outside air temp is below 55 and the truck is cold it surges.
It does it at idle and while driving. When driving it feels like something is opening and closing off the exhaust. like a exhaust brake on full then open.
Again, only when cool to cold outside and when the truck is cold. Even when I will let it warm up for 10 plus minutes, it will still happen.
I havent changed anything, just started about 3 months ago.
Any thoughts?

Thanks

[skeeter7310]

Anyone have thoughts?

[rooney77]

Sounds like the EBPV might be having issues.

[bigcountrysg]

Injector buzz test and cylinder contribution test are needed. If the truck is surging when cold but runs normal when at normal op temp. You have an injector that is bad.

Injector Buzz test will test the wiring to the injectors to see if it is getting the signal to fire. The cylinder contribution test will test the injector to see if it is working properly.

You have to do this test when the engine is cold. Because if it is done when the engine is warm you may not get accurate results.

[skeeter7310]

Thanks for the replys.
You may be on to something with the EBPV
It is definatly a mechanical opening and closing of something.
Anyone know if this is mechanical or vac. operated?

Thanks

[bigcountrysg]

Originally Posted by skeeter7310

Thanks for the replys.
You may be on to something with the EBPV
It is definatly a mechanical opening and closing of something.
Anyone know if this is mechanical or vac. operated?

Thanks

The EBPV is electrically/vaccuum operated. Has an electric soleniod that opens tells the ebpv to open and close. The actual action is done with an actuator arm on coming off the turbo pedistal.

I am still going with an injector problem though. Because I been through it twice with my truck.

[skeeter7310]

With your problem you had, and finding the injectors at fault. Did it also surge at idle?
Also the one thing I noticed at idle is the rpms do not change, just the sound of the exhaust.
sounds like a rush of air then normal this goes back and forth.
when driving the rpms dont jump they fall and the truck feels like you hit the brakes and you can hear the same sounds
thanks

[bigcountrysg]

Originally Posted by skeeter7310

With your problem you had, and finding the injectors at fault. Did it also surge at idle?
Also the one thing I noticed at idle is the rpms do not change, just the sound of the exhaust.
sounds like a rush of air then normal this goes back and forth.
when driving the rpms dont jump they fall and the truck feels like you hit the brakes and you can hear the same sounds
thanks

Yes it surged at idle as well. It was really bad when driving it until the engine was at normal op temp.

The air rushing sound could be the ebpv. It could be sticking, but when you hit the brakes it should close. Also the ebpv should not be opening when driving.