So I was doing another EBPV Brake Mod with an auto trans. It went pretty good until I tried to make anything work. No EBPV Movement at all, and the TC Lock would not stall the truck.

I have good juice to the EBPV and all the wiring was correct but I could not get the EBPV to close. When I asked the driver did not remember hearing it close either. I scanned the truck and sure enough fault on Exh Back Pressure valve.

So I searched and other than a blocked tube/ bad sensor nothing. The owner will pull this and check it out. Is there a way to test the sensor out of the truck? Is it even worth it? Besides the sensor going bad I can manually send a signal to the EBPV and still nothing.

The real problem was the TC Lockup. Finding the purple w yel tracer was hard. Finally on a grey plug coming out of #6 hole was a purple wire w yellow trace. I ground it and nothing. The test used to be; run it put it in drive and ground the wire. Motor should stall. This one absolutely nothing. I have checked and rechecked. I cannot find another purple wire from #6 plug so I am sure I have the right wire. With my truck even when cold it will stall the motor, but this truck sat for about 1.5 hours before we tested it.

Any thoughts would be helpful. I am mostly concerned with the truck without the mod as now I have disabled the mod and still there is no EBPV movement.

What are some of the mechanical failures of the EBPV? From what I remember the EBP sensor sends a signal to the solenoid at the base of the turbo to send oil to a plunger to open and close the EBPV. Pretty simple? Do they plug up with soot and the oil cannot move the flapper? Short of pulling the exhaust down pipe and tugging does anyone have a suggestion?

I am most concerned with fixing the basic truck than making the Mod Work.

 

Moved to the 7.3L forum.

Stewart

 

It sure sounds like the EBPV is/was not working. The actuator can fail and mechanically the valve can fail as well. The tube can be disconnected from the exhaust through the passenger side wheel well without taking off the wheel. A flashlight and stool to sit on are helpful. Some guys have had luck cleaning out the tube with various types of flexible speedo shafts, weedwacker cable and/or brake cleaner. Me, I just replace the thing with 5/16 aluminized flared brake tube, using the original fittings. The signal for the EBPV itself probably comes from the PCM, not the EBPV sensor. The sensor can also be cleaned, if you use two wrenches to remove it from the mounting fitting. I have read a procedure for testing the whole setup. An old power brake bleeder with motor oil could be adapted to test the valve mechanism. Are you sure the torque convertor was actually locking before you messed with it? It might be a good idea in the future to test drive these rigs before you work on them. Maybe someone else can chime in here that actually knows what they are talking about. Larry

 

The truck belongs to a fellow cop and of course I trusted him. Oh well next time. At least the codes showed him it was his truck not my mod. He got a free scan off me but I will have to find a way to fix his truck now too. I really do not like working on others trucks as no one cares for a car or truck like me. Clean clean clean. His is oily oily oily. Leaks everywhere and hard to see where the worse leak is.

 

This is the same problem for tuners. It's hard to sell a tune for a 14-year-old diesel and not have the work bounce back on you.

 

This mod is quite easy to make and install. I have done dozens with little problems. This last one just is difficult as it can lead to several hundred dollars in additional repairs. I do not have the time to sit in a shop and pull apart the entire system on a poorly maintained truck.

Today another one came in but he wanted a scan first as his truck is sputtering alot and dying. No mod for him but I did scan it. Afterwards he told me it has been 8000 miles since last oil change and he used regular straight 40 weight oil. No matter how much I told him the oil is very important on these trucks he refused to agree. I refused his job and gave him the parts list instead. It is simple to make and install on a well maintained truck but I think I am done with these as too many do not take care of their trucks and I do not want to be the blame for their negligence.