J3Cub

Is there any way to adjust the amount of pressure or braking on the turbo exhaust brake.
My E Brake runs around 3 to 4 psi, when I am running 60MPH, and let off the throttle.
This is the reading on my Edge, I would like to see 5 to 6, normal.
I am saying that at normal, flat road at 60MPH, I let off and see 3 to 4psi, now if I gear down and get the RPM up, I see higher numbers.
The question is, Can I adjust the amount of Choke (for lack of a better word) to increase the amount of E Brake at any given point??

ShibbyEng.

In theory if you put a resistor in line with the pressure signal returning back to the ECM you will fool the ECM into thinking that there is lower pressure than there actually is. The lower pressure will trigger the EB to hit harder and with the harder hit it will get better deceleration. I have no idea what resistor value will be needed so the first few trials should be conducted with a potentiometer first. also a drive pressure gauge needs to be tapped in to make sure you don't over restrict the manifold and blow your head gasket.

AH64ID

3 to 4 psi sounds more like back pressure not exhaust brake pressure. The exhaust brake should be running MUCH higher than that. On the 5.9 the exhaust brake is 20psi at idle and up to 63 psi at full braking, never does it read below 20.

What are you using on the edge to read it?

ShibbyEng.

Also to the original poster here, do you have any deletes done, have you checked to make sure all your gaskets are intact. There have been quite a few instances of gaskets blowing out on cumminsforum.

jthorpe

I've been trying to find a way to make the EB go full bore every time it comes on. Just because really. I hate it when it lets up while I'm on a hill or something. Gets on my nerves.

Lil Dog

From what I have read/understood the EB has a ramp curve and it relieves the back pressure under about 1500 RPM to reduce the braking force. The pressure you read on the EDGE must be boost pressure? I don't see how that correlates to the braking pressure at all.

The Cummins Brake is already 20% more powerful than anything on the market. Higher back pressures are only going to do damage to the exhaust system. If the pressures are above 65 psi, thats higher than any drive pressure under WOT conditions.

If you need more braking, downshift..

mega-engr

I would agree with Lil Dog. When the EB is on it is most likely closed off sully and producing the maximum amount of deceleration at the given RPM. It is meeting its maximum designed restriction to the flow.

AH64ID

Yeah, unless you put a DP boost pressure sensor in the edge has no way to know EB back pressure (aka Drive Pressure)... and because the EB is part of the VGT it will produce boost while it works, unlike my EB. So I agree the 3-4 must be boost, if you want to know how much exhaust backpressure the EB builds you will need a mechanical gauge hooked up like this one.



I have read the VGT EB will make about 45psi of backpressure while braking, which is about 10psi of boost. Which is odd because the 5.9 EB will make 63psi, but the 6.7 is rated at more retarding power

J3Cub

Yes I am reading the pressure on the Edge unit under Boost, that is the only thing I have to give any reading. The other question asked, Yes I have the EGR delete, and BADP Deletes on the exhaust, from turbo back.
My original question, I was asking if there was some adjustment on the Turbo for the EB, or someway to program it.
Thanks for the input, I think I had better leave it alone for now, as all systems are working, For Now!!

ShibbyEng.

on the 6.7's it is easier to cut and splice in a run tee for the factory drive pressure sensor than try and drill and tap it into the manifold, should you want to go back to stock it also allows you to return to stock easier as well

AH64ID

I didn't realize they had a backpressure sensor on the manifold, I thought they were just down by the DPF.

Not sure how to adjust it, but if you want a real status of how much retarding you are getting I would add a back pressure gauge.

ShibbyEng.

Look at the manifold where the cut away is just outside #3 cylinder, the line is chrome so it is hard to see on the cut away, but it goes up towards the front of the engine. The actual sensor is just behind the lifting ring at the front of the engine. The engine uses that sensor to measure back pressure and modulate how much to move the turbine slide.

Lil Dog

It also can trip a "Catalyst Full" code when using higher level performance products, even though you may have done the DPF Delete. Drive pressure too high and the code gets tripped.

tinbanger

Really? i would have to disagree.. i had a pacbrake on my 99 and it would bark the tires when i downshifted( i tried to avoid that) and it seemed.... more positve... than the new OEM EB in my fathers 08. towing and all..... JMO

caper11

What were the running conditions where you got 3-4psi n the intake under e-braking, how long do you let the e-brake engauge before you get this reading?
Your intake boost gauge under e-braking should increase to your maximum engine power turbo boost, when the operating conditions allow the boost to get that high, because the exhaust is still spinning the turbo turbine and the compressor wheel is still compressing into the intake. The intake boost will take longer to rise under a retarding event. If you have a load heavy enough and a grade long enough the intake boost should reach maximum power boost, during e-braking.
I'm also curious about the statements about the exhaust brake not turning on full bore all the time and letting people down, which leads me to believe that some do not understand the operation of a exhaust brake (6.7L turbo brake or the 5.9l exhaust brake)or engine retarder commonly found on the bigger engines.
My exhaust brake has been consistant in strength across the rpm band and road speed. If your engine is turning 1200rpm and want to maintain that road speed and your still in 6th gear you WILL NOT have the same engine braking power as if you downshifted into a lower gear getting the rpm up to get the turbo to spin up quicker to increase you engine cyl pressure to maximum braking power, while taking advantage of the extra torque given to you by the lower gear ratio through the driveline at that road speed.
the vgt turbo in theory still works the same as the old wastegate system. the freightliner I used to drive made 32psi of full power boost and 32 psi of fully loaded engine braking boost (keep in mind if I was unhooked from my trailer It was harder to get the boost that high when using the retarder because the truck would slow down too quick), before the wastegate started to dump to control the intake boost pressure yes this was a engine brake retarder.
Compared to the turbo or exhaust brake on our 6.7. the theory still works the same it's just a different way to increase the engine cyl pressure to transmit the braking power to the ground.