Exhaust Brake Unavailable

[EZeis]

I know there is nothing wrong. You’re confusing the exhaust brake function with TH function. The brake itself is capable of the same retarding power as that is only a function of vane position and rpm, nothing else. TH will have a more aggressive downshift schedule and hold the torque converter locked longer, but that doesn’t mean the brake is making more retarding power it just means it’s more usable, which is great with a load and annoying (for me) when empty.

I will go on to say that if you think it’s pointless to run without TH then there is something wrong with your truck, as it’s very beneficial. It’s does feel different than in TH but it’s still very usable, especially in conjunction with CC for speed management downhill.

Dads 17 works identical to my 18, they work as advertised and designed. Nothing wrong, just you’re interpretation of what’s actually happening when you engage TH.

I’ve run TH lots and know the difference, as well as what creates the difference. The brake isn’t programmed different in TH, just the transmission. This is my point that you’re missing.

It would be nice if activating the EB would change the lockup schedule, but not the downshift schedule.

I ran both a Jacobs and a PRXB on my 05/NV5600. They both worked similar but a little different. The PRXB was much stronger below 2000 but the Jacobs was stronger above 2500, but that’s not a normal condition. The cam I had would run the back pressure up over 75 on the Jacobs where the PRXB stayed at 60. More pressure means more braking.

Not at all. You're not understanding the TH runs higher rpms for stronger braking. Exhaust brakes work on cylinder pressure and the higher the rpm and the lower the gear, the stronger the braking. It's so simple. So running the TH does provide significant night and day braking. We can argue this every day for the next 20 years if you'd like. It's just how exhaust brakes work.

My truck is good to go. Yours definitely has an issue if exhaust braking performs the same with and without the TH enabled. Is your PCM and TCM software current?

Do a test, pull up your exhaust braking horsepower and report what your highest braking hp is with TH enabled and disable with braking on the same road and conditions. You should find in the lower gears where with the TH enabled will be higher than vs disabled as the rpms won't hold when TH I'd disabled. If you don't see a difference, you have an issue. You should have a lot more engine braking with TH enabled. With it disabled, you just don't hold the revs. Exhaust brakes rely on high rpm to be fully affective. High rpms and lower gears really brings on the braking power. That can only be fully achieved with the TH enabled. I prefer the exhaust brake to do most of my braking. Wish the torque converter could stay looked at lower rpm. Do miss my manual trans truck with the pacbrake as it would brake down to idle. This truck kicks out at about 18ish mph and you're like crap. Took me a long time to get use to no exhaust braking below 18mph. Even to this day I sometimes get caught off guard by it.


Earl

 

[AH64ID]

Not at all. You're not understanding the TH runs higher rpms for stronger braking. Exhaust brakes work on cylinder pressure and the higher the rpm and the lower the gear, the stronger the braking. It's so simple. So running the TH does provide significant night and day braking. We can argue this every day for the next 20 years if you'd like. It's just how exhaust brakes work.

My truck is good to go. Yours definitely has an issue if exhaust braking performs the same with and without the TH enabled. Is your PCM and TCM software current?

Do a test, pull up your exhaust braking horsepower and report what your highest braking hp is with TH enabled and disable with braking on the same road and conditions. You should find in the lower gears where with the TH enabled will be higher than vs disabled as the rpms won't hold when TH I'd disabled. If you don't see a difference, you have an issue. You should have a lot more engine braking with TH enabled. With it disabled, you just don't hold the revs. Exhaust brakes rely on high rpm to be fully affective. High rpms and lower gears really brings on the braking power. That can only be fully achieved with the TH enabled. I prefer the exhaust brake to do most of my braking. Wish the torque converter could stay looked at lower rpm. Do miss my manual trans truck with the pacbrake as it would brake down to idle. This truck kicks out at about 18ish mph and you're like crap. Took me a long time to get use to no exhaust braking below 18mph. Even to this day I sometimes get caught off guard by it.


Earl

You really need to go back and read what I am saying again. Bottom line, you’re not following it at all.

Others have agreed with my comments because they are following the conversation.

I agree, it really is so simple but somehow you’re reading what you want to read and not what I’m saying. You’re even trying to convince me I was wrong by repeating some of what I’ve said as part of your argument

Please just re-read it all again.

TH is not the only way to get higher rpms. The ERS works great too, even better than TH depending on the circumstances.

 

[Cummins12V98]

Sorry what is ERS?

 

[Ozymandias]

that was my point. I would never run without TH as SnoKing did as you never know when you need to stop fast.

For a "fast stop" you need the service brakes anyway and then the EB with TH has very little influence.

 

[EZeis]

You really need to go back and read what I am saying again. Bottom line, you’re not following it at all.

Others have agreed with my comments because they are following the conversation.

I agree, it really is so simple but somehow you’re reading what you want to read and not what I’m saying. You’re even trying to convince me I was wrong by repeating some of what I’ve said as part of your argument

Please just re-read it all again.

TH is not the only way to get higher rpms. The ERS works great too, even better than TH depending on the circumstances.

Pretty sure you said there was no difference in braking with and without TH enabled on your truck, several times. That's what I'm going off of. You even said my truck has an issue cause mines night and day with TH on. So you tell me. Did I confuse you with someone else? So does your truck brake better in TH or doesn't it?

Earl

 

[EZeis]

Sorry what is ERS?

Electronic range selector. Manual control of the gear. Up and down arrows on the shifter or steering wheel if you have the dash knob.

Earl

 

[SnoKing]

Electronic range selector. Manual control of the gear. Up and down arrows on the shifter or steering wheel if you have the dash knob.

Earl

Problem is the Cummins diesel with the EB off does a very poor job of slowing an empty truck much less one with a load.

 

[Wiredawg]

Problem is the Cummins diesel with the EB off does a very poor job of slowing an empty truck much less one with a load.

Sno,
You're so right... I had standard trans I installed BD exhaust brake that could be adjusted for Max performance... 4.10s and 6spd standard was pure magic.

Cheers, Ron

 

[Wiredawg]

Pretty sure you said there was no difference in braking with and without TH enabled on your truck, several times. That's what I'm going off of. You even said my truck has an issue cause mines night and day with TH on. So you tell me. Did I confuse you with someone else? So does your truck brake better in TH or doesn't it?

Earl

Earl,

TH has second order effect on EB... EB functions on RPMs... TH has longer shifts up and faster shifts down that raises RPMs, hence the better performance on the EB. You can do the same thing TH off, you manually downshift, and take you foot off the accelerator in EB normal mode. Does that make sense?

Hope this helps.

Cheers, Ron

 

[Ltngdrvr]

Pretty sure you said there was no difference in braking with and without TH enabled on your truck, several times. That's what I'm going off of. You even said my truck has an issue cause mines night and day with TH on. So you tell me. Did I confuse you with someone else? So does your truck brake better in TH or doesn't it?

Earl

Exhaust braking works the same amount with or without the tow/haul engaged, no difference in strength. What the tow/haul does to help with the EB process is continue to downshift as the truck slows to keep the EB in a working RPM range, where if it is off the truck will not downshift as the truck slows, it slows down as much as whatever gear it's in allows, then the converter unlocks when RPM drops below 1100 and it no longer has EB applied.

 

[AH64ID]

Pretty sure you said there was no difference in braking with and without TH enabled on your truck, several times. That's what I'm going off of. You even said my truck has an issue cause mines night and day with TH on. So you tell me. Did I confuse you with someone else? So does your truck brake better in TH or doesn't it?

Earl

What I said is that TH has no bearing on EB function. The benefit, as stated, is from the transmission. The brake itself works the same.

I never said you don’t slow down faster in TH/EB.

You weren’t following and assumed I had an issue, when I don’t.

You also stated it wasn’t worthwhile to use your EB when not in TH. That itself is wrong on a properly working truck.

If you haven’t don’t it yet go back and re-read what has been stated.

Problem is the Cummins diesel with the EB off does a very poor job of slowing an empty truck much less one with a load.

Yep. Just the nature of a diesel with an unregulated intake. The butterfly valve on gas vehicles aids in compression braking. Even the 6.7 Cummins has a intake valve and will slow faster than a 5.9. One small benefit to emissions I guess

 

[Ozymandias]

In a Gas engine it's actually vacuum braking, not compression, but anyway it helps to slow down.

 

[Cummins12V98]

For a "fast stop" you need the service brakes anyway and then the EB with TH has very little influence.

If I dynamite my brakes true but for a fast deceleration all three work well together.

 

[Cummins12V98]

Electronic range selector. Manual control of the gear. Up and down arrows on the shifter or steering wheel if you have the dash knob.

Earl

thanks. Yes I use mine a lot in descending grades with cruise control.

 

[Cummins12V98]

Problem is the Cummins diesel with the EB off does a very poor job of slowing an empty truck much less one with a load.

with the 4:10’s I have to disagree. Since my turbo actuator died I ran only TH and was surprised at how well it slowed the 10k truck.

 

[Cummins12V98]

Exhaust braking works the same amount with or without the tow/haul engaged, no difference in strength. What the tow/haul does to help with the EB process is continue to downshift as the truck slows to keep the EB in a working RPM range, where if it is off the truck will not downshift as the truck slows, it slows down as much as whatever gear it's in allows, then the converter unlocks when RPM drops below 1100 and it no longer has EB applied.

When I get my truck back I will Have TH n EB on and hit brakes hard at 60 and then same with EB off. I will bet I get higher turbo breaking hp with both on.

 

[bcbender]

Max performance... 4.10s and 6spd standard was pure magic.

Man now you pulled a tear....... I hope my new girl has skin in the game to keep me happy on the down hill.....

On my old faithful 04'; about 45/50Mph... 4th gear.... 25K GCVW.. and she'd ride all the way down a grade w/o any service brakes!!!!

 

[AH64ID]

In a Gas engine it's actually vacuum braking, not compression, but anyway it helps to slow down.

Correct. I knew compression didn’t sound right, but vacuum wasn’t coming to kind.

 

[Ltngdrvr]

When I get my truck back I will Have TH n EB on and hit brakes hard at 60 and then same with EB off. I will bet I get higher turbo breaking hp with both on.

You get higher braking power with RPM and load, that's where the tow/haul comes in, by downshifting the trans, the RPM and loading stays higher, but RPM for RPM the braking power is the same whether tow/haul is on or not.

 

[EZeis]

What I said is that TH has no bearing on EB function. The benefit, as stated, is from the transmission. The brake itself works the same.

I never said you don’t slow down faster in TH/EB.

You weren’t following and assumed I had an issue, when I don’t.

You also stated it wasn’t worthwhile to use your EB when not in TH. That itself is wrong on a properly working truck.

If you haven’t don’t it yet go back and re-read what has been stated.




Yep. Just the nature of a diesel with an unregulated intake. The butterfly valve on gas vehicles aids in compression braking. Even the 6.7 Cummins has a intake valve and will slow faster than a 5.9. One small benefit to emissions I guess

Good old

Problem is the Cummins diesel with the EB off does a very poor job of slowing an empty truck much less one with a load.

Yep, throttle plate so no engine vacuum like a gasoline engine for engine braking.

Earl