Run With Exhaust Brake on all the time

[rono]

Dealer call this A. M. said truck was ready, (fifth time in for codes) anyway they left a voice mail that I was to run with the Exhaust Brake on all the time as this would "keep the turbo freed up".



First, this cannot be good for either the EB or the engine, having to 'fight' against the EB all the time.



Second, what is this going to do for my milage, (it sucks anyway)?



Third, what about the heat buildup in the exhaust system and the engine?



Any thoughts on this from the Turbo, EB experts?



Thanks, Ron

 

[KDOHM]

Any time throttle is applied the ecm turns off EB, also I believe once engine is up to temp EB turns of at a certain speed (~15mph)

 

[jelag]

The exhaust brake looks for a signal from the throttle... if it sees a closed throttle, (your foot off the pedal) the exhaust brake will come on... . any other time the exhaust brake will be (read should be) off... .

In the case of the 6. 7 where they do this with the turbo... . I don't understand where the dealer figures it would soot up and not function... . as this turbo changes all the time as it functions and I can't see where it can have a problem.....

There will be no effect on your mileage as the exhaust brake only comes on when you foot is off the throttle... . when I coast on the highway with our trucks... . we leave the exhaust brake on all the time... . we just hold our foot on the pedal and the brake will not come on... .

There is no heat build up when the exhaust brake is working... . the ECM builds into the circuit a very short delay to allow the fuel pressure in the fuel loop to drop off and than the brake comes on... . the only heat there is, is from the truck going up the hill before the brake comes on... .

Hope this answers your questions...

 

[rono]

Jim, it DOES answer my questions. Thanks!!! I did not understand exactly how the exhause brake worked. So I guess it will not hurt to have it on all the time, as it is not on all the time even if the switch is on. Ha, Ha.

Thanks again, Ron

 

[EB]

I've had mine on since the truck was new, never shut it off. It's gone quite a few miles with no ill effects. Mine is a cab and chassis and I don't have to turn it off and on, it stays on all the time.

 

[TKeeler]

Jim, it DOES answer my questions. Thanks!!! I did not understand exactly how the exhause brake worked. So I guess it will not hurt to have it on all the time, as it is not on all the time even if the switch is on. Ha, Ha.

Thanks again, Ron

Mine is on all the time (the switch that is), that is unless I forget to turn it on when I start the truck up which occasionally happens. Once you get used to it being on all the time you do notice right away when you let off the throttle that it isn't helping slow you down. Not sure yet why Dodge didn't make this a maintained switch so it doesn't have to be pushed everytime the ignition is cycled.

 

[Wolfy]

The exhaust brake looks for a signal from the throttle... if it sees a closed throttle, (your foot off the pedal) the exhaust brake will come on... . any other time the exhaust brake will be (read should be) off... .



There will be no effect on your mileage as the exhaust brake only comes on when you foot is off the throttle... . when I coast on the highway with our trucks... . we leave the exhaust brake on all the time... . we just hold our foot on the pedal and the brake will not come on... .



Hope this answers your questions...

Jim, thanks for the comments.



I have another question or two, ... after a few observations.



When coasting-down in 6th gear (auto) I have noted that my EB stops working at about 43-44 mph, which equates to 1100 rpm.



On the few occasions when I hear/feel the brake at lower speeds, it seems to be because I am decellerating in a lower gear, ... again seeming to stop at about 1100 rpm, although the mph is less because I'm in the lower gear.



This suggests that there is some sort of rpm-related shut-off on the EB. Can you explain whether/why this is so? ( Is it because there is reduced exhaust flow to work with at lower rpms? In any case, the EB still seems to be slowing the rig, so why take it out of action at "X" rpm?)



Secondly, re. "keeping your foot on the pedal" to keep the EB from working, and any effect on mpg. I am unclear on this.





If you "coast' (no foot on pedal) with the EB turned off, will not the engine go to a lower idle rpm (more mpg during coasting), than it will with EB turned on, and your foot ON the throttle (higher idle rpm, less mpg during coasting) to avoid EB braking?



Question to all - How does your EB operation compare to what I have described, re. "cut-out" speed/rpm?



Thanks for any comments!

 

[jelag]

The exhaust brake has to lock up the torque converter with fluid pressure like you were driving down the road... . this is a locked torque converter so that the drive train can move the power to the engine so that it can absorb the energy... if it did not release the pressure it would stall the engine at lower speeds, sort of like not pressing the clutch pedal in at a stop sign with a stick... .

However that being said... . on the duramax with the allison transmission the ECM down shifts the transmission to keep it working..... on this set up it really tries to pitch you through the windshield... . and I've seen this sort of action, not 100% but say 70% with the 5. 9 and auto in the 06, 07 trucks.....

I have not driven a 6. 7 personally but have a 5500 on order... . you need to ask, or read your manual... . I assume that the transmission should down shift on its own one gear at a time on a steady slow down... . or if your going down a 6% grade it should down shift to 5th, 4th, etc to hold the truck and trailer on the hill.....

At X speed the ECM will shut down the exhaust brake and release the pressure in the torque converter... ... I don't know what that is on the 6. 7... . Hopefully someone will give us some more input.....

On my 05 with the 6 speed the brake stays on until it comes to a complete stop and about 2 or 3 seconds after the complete stop the ECM shuts down the brake... ... . if I'm on a slight incline and let it roll as soon as the ECM sees some speed it turns it back on.....

"keeping your foot on the pedal will keep the brake from coming on..... sort of a light coast..... but you won't see an improvement in mpg... .

If you coast down hill, no trailer, no exhaust brake and take your foot off the pedal the ECM should see this condition and release the pressure in the torque converter and let you roll..... however the mpg gain is negligible

We run our trucks with the brakes on all the time..... sticks... and when we coast we just either let the brake come on, or touch the pedal and keep it off.....

Hope this helps... . did I answer all your questions... .

 

[Jeepstang]

Turbo related codes

Dealer call this A. M. said truck was ready, (fifth time in for codes) anyway they left a voice mail that I was to run with the Exhaust Brake on all the time as this would "keep the turbo freed up".



First, this cannot be good for either the EB or the engine, having to 'fight' against the EB all the time.



Second, what is this going to do for my milage, (it sucks anyway)?



Third, what about the heat buildup in the exhaust system and the engine?



Any thoughts on this from the Turbo, EB experts?



Thanks, Ron

Ron I can only assume that you had the same code that I had which I can not remember at this time. My code pointed to the actuator which had carbon built up not allowing it to cyle freely and the system did not see sufficient boost pressures. As I understand it

When the key it turned on the system slides the actuator to a position that it should be in at start up and no load. This is when my light would come on since the carbon would prevent it from sliding.

The person in the tech department at Chrysler thinks that in the next TSB flash they will add a program for the system to cyle this actuator a few times before moving it to the position where it would rest

I will call this the park position to simplify things. They have a new Turbo unit waiting for me at the dealership but I don’t think it will fix the problem. A few things they sugested was to drive it with the exhaust brake on and run it hard because it will move the actuator arm more frequently to help stop the carbon build up from possibly unfinished regen cycles. They also suggested to make short trips with the truck or stop the truck after 2 minutes of driving to turn the key off then on again which will cause the acutator to slide again. My light has not come back on for several weeks now. I also make six 1 mile trips each week which helps this situation.



Jeff

 

[2Rowdy]

Jim, thanks for the comments.



I have another question or two, ... after a few observations.



When coasting-down in 6th gear (auto) I have noted that my EB stops working at about 43-44 mph, which equates to 1100 rpm.



On the few occasions when I hear/feel the brake at lower speeds, it seems to be because I am decellerating in a lower gear, ... again seeming to stop at about 1100 rpm, although the mph is less because I'm in the lower gear.



This suggests that there is some sort of rpm-related shut-off on the EB. Can you explain whether/why this is so? ( Is it because there is reduced exhaust flow to work with at lower rpms? In any case, the EB still seems to be slowing the rig, so why take it out of action at "X" rpm?)



Secondly, re. "keeping your foot on the pedal" to keep the EB from working, and any effect on mpg. I am unclear on this.





If you "coast' (no foot on pedal) with the EB turned off, will not the engine go to a lower idle rpm (more mpg during coasting), than it will with EB turned on, and your foot ON the throttle (higher idle rpm, less mpg during coasting) to avoid EB braking?



Question to all - How does your EB operation compare to what I have described, re. "cut-out" speed/rpm?



Thanks for any comments!

I run with mine on all the time. Yes it does cut off at 1100 rpms or when I reach 2nd gear. Usually the only time the rpms stay high enough to reach 2nd gear and the eb on is when I am towing with tow/haul mode on.

 

[Wolfy]

EB cut-out rpm

I run with mine on all the time. Yes it does cut off at 1100 rpms or when I reach 2nd gear. Usually the only time the rpms stay high enough to reach 2nd gear and the eb on is when I am towing with tow/haul mode on.

Thanks for the report 2Rowdy,



(With the 68RFE auto/3. 73 rear axle) The gear/speeds for 1100rpm would be :



1st -9mph, 2nd -15mph, 3rd -20mph, 4th -28mph, 5th -34mph, 6th -44mph.





(With the 68RFE auto /4. 10 rear axle) The gear speeds for 1100rpm would be:



1st -8mph, 2nd -14mph, 3rd -18mph, 4th -21mph, 5th -31mph, 6th -40mph.



To all members: Please comment as to how these figures square with your experience. This will help us develop an understanding re. what constitutes the "normal" EB operating range.



So far 1100rpm seems a likely candidate for the point where the EB is programmed to quit operating during decelleration (at least with the 3. 73).



Thanks for participating,

 

[Wolfy]

The exhaust brake has to lock up the torque converter with fluid pressure like you were driving down the road... . this is a locked torque converter so that the drive train can move the power to the engine so that it can absorb the energy... if it did not release the pressure it would stall the engine at lower speeds, sort of like not pressing the clutch pedal in at a stop sign with a stick... .



-------------------------------------------------------------------------



At X speed the ECM will shut down the exhaust brake and release the pressure in the torque converter... ... I don't know what that is on the 6. 7... . Hopefully someone will give us some more input.....



-------------------------------------------------------------------------



Hope this helps... . did I answer all your questions... .

Thank you Jim, I believe you did. You have helped my understanding a bit.



My grasp is hindered by the fact that I know next-to-nothing about the workings of an automatic transmission. I have just posted asking for help, if you care to comment. The new thread is here:



https://www.turbodieselregister.com...007-5/188723-auto-operating-basics-68rfe.html



I have also just posted, in THIS thread, a list of MPH's at the 1100rpms that has so far(2 reports) been indicated as the EB shut-down speed, for the 68RFE auto, at least.



Thanks again,

 

[RVTRKN]

Mine is on all the time (the switch that is), that is unless I forget to turn it on when I start the truck up which occasionally happens. Once you get used to it being on all the time you do notice right away when you let off the throttle that it isn't helping slow you down. Not sure yet why Dodge didn't make this a maintained switch so it doesn't have to be pushed everytime the ignition is cycled.

Mine never turns off, regardless of ignition position except when ignition is off, I never have to turn it on for it is allways on, I really miss it in my 5. 9 when down shifting and may install it on the 5. 9 if I don't sell it. Only 44K on the 04. 5, maybe I will sell it for the right price if I get a good offer.

 

[TKeeler]

Thanks for the report 2Rowdy,



(With the 68RFE auto/3. 73 rear axle) The gear/speeds for 1100rpm would be :



1st -9mph, 2nd -15mph, 3rd -20mph, 4th -28mph, 5th -34mph, 6th -44mph.





(With the 68RFE auto /4. 10 rear axle) The gear speeds for 1100rpm would be:



1st -8mph, 2nd -14mph, 3rd -18mph, 4th -21mph, 5th -31mph, 6th -40mph.



To all members: Please comment as to how these figures square with your experience. This will help us develop an understanding re. what constitutes the "normal" EB operating range.



So far 1100rpm seems a likely candidate for the point where the EB is programmed to quit operating during decelleration (at least with the 3. 73).



Thanks for participating,

My truck w/ 4. 10's... exhaust brake cutout is at 1100 RPM.

 

[Wolfy]

My truck w/ 4. 10's... exhaust brake cutout is at 1100 RPM.

Thanks, Terry.



So far we have 2 trucks with the 3. 73 (2Rowdy and Wolfy) and one with the 4. 10 (TKeeler), ... all seemingly set to disengage the EB at 1100 rpm or so.



2Rowdy mentions something that suggests that the EB may not activate in 2nd(or 1st?). I will experiment next time I use my rig, to try and see if this is so. I'd appreciate others' feedback on this as well.



Terry, your post made me realize I had put the decimal point in the wrong place for the axle ratios.



I corrected it in my post, but can not correct yours where I was quoted.

 

[EStarns]

I have 3500 miles on my 6. 7 six speed most with the EB on. I have 4. 10s and in Tow/Haul it will shift through each gear down to 2nd and finally disconnect at 1100 RPM. The manual and automatic control of this transmission and the factory EB is why I traded my 01 for it. Power is definitely more but I had a Edge chip, a BD brake and the BD torq loc. so the power is not that much more. Still the new truck drives straighter and rides a little better and has more room inside for the quad cab. The '01 had 125k on it and ran better than it did new. I also had the DSS and a Lukes link. The new truck lost a lot character. no one hears me comming anymore.



Me: 2007 Ram 2500 4x4 LB Big Horn edition. Inferno Red

Wife: 2007 Jeep Patriot Limited, white with Boom Box stereo.

 

[TKeeler]

[QUOTE no one hears me comming anymore. /QUOTE]



You got that right... used to able to hear my 98. 5 a long ways off. This engine unless you know what your listening to doesn't sound like a diesel.

 

[captaindean]

exhaust brake

Has anybody seen a wiring diagram yet to see if we can make these switches a maintained switch just a thought

 

[TKeeler]

Has anybody seen a wiring diagram yet to see if we can make these switches a maintained switch just a thought

I am still waiting for the 2007 service manual to come out on CD as $445 is a little steep for the printed version IMOP.

 

[TKeeler]

Thanks, Terry.



So far we have 2 trucks with the 3. 73 (2Rowdy and Wolfy) and one with the 4. 10 (TKeeler), ... all seemingly set to disengage the EB at 1100 rpm or so.



2Rowdy mentions something that suggests that the EB may not activate in 2nd(or 1st?). I will experiment next time I use my rig, to try and see if this is so. I'd appreciate others' feedback on this as well.



Terry, your post made me realize I had put the decimal point in the wrong place for the axle ratios.



I corrected it in my post, but can not correct yours where I was quoted.

Larry... I fixed your quotes in my post



I checked my EB today and it does not work in 1st or 2nd either as 2Rowdy pointed out.