DDEC specialist question

[Blacksheep]

Presently have a DDEC 2 in our bus and am wanting to know how hard and how costly it would be to upgrade to a DDEC 4? What are the advantages and or disadvantages?

Reason for asking? I found a killer deal on a complete BRAND NEW crate engine but it is built as a DDEC 4.

If the price wasn't so good I wouldn't even consider it but it's really too hard to pass up!

Ace

[luvrbus]

Ace, the only advantage you gain is a DDEC 4 will work with the B500 Transmission and you can have up to 500 hp on the 8v92 plus they have a waste gate turbo   good luck

[Sean]

Ace,

Not sure what you're asking.

Upgrading an existing DDEC-II engine to DDEC-IV is well-nigh impossible.  DDEC-IV requires engine sensors that don't exist under -II and would need to be retrofitted to the engine.

But it sounds like you have a complete engine to swap, which is quite a different matter.  The new engine should come with the DDEC-IV ECM, and all the engine sensors already in place.  The only issue you'd have to deal with is the "chassis" or vehicle sensors, such as throttle position, etc.  Many of these are plug-compatible.  HOWEVER:  The connection to the tranny might be problematic.  If you have an older Allison with CEC (formerly ATEC), you will likely have a "throttle interface" between the DDEC ECM and Allison ECU.  This brings road speed into the DDEC, and throttle position into the CEC.  It may do other things, too, depending on whether you have the "basic" or "maximum feature" throttle interface.  You'll need to hunt around for it to find out.

Also, you will need to have the new ECM programmed for your application, unless it was already set up as a direct replacement for your coach.  Programming can only be done by Detroit and costs a pretty penny, ~$2,000 or so IIRC.

HTH,

-Sean
http://OurOdyssey.BlogSpot.com

[Blacksheep]

Sean in my coach, i dI not have a cec or an atec that I know of! It's a 740 allison and have never seen the ecu for it.

As for the new engine, yes, it is complete including all the sensors, the ECM, starter, etc. from top to bottom and front to rear minus the fan of course but pulleys are there.

It was originally going to go into a firetruck but they went a different route so they put the engine up for sale. It's still on the facotry crate or skid.

Let me also add that for what they are asking, shipped, I couldn't rebuild the one I have!

Can anyone tell from this info if it is compatible?

8V92TA
Serial Number    DD 8VF181356

and a picture of it

[luvrbus]

Ace,you need the model number from the engine also if it has a tag on the valve cover that will give you a world of info on the engine, like injectors, timing and so on       good luck

[Songman]

My first bus started life as a DDEC II and was upgraded to a DDEC IV. But it was a complete engine and tranny swap at once. I mean it was the same type of transmission but a different one. It was a ZF. I honestly can't tell you what was gained by the upgrade. It was done before I bought the bus.

[Sean]

Ace,

A 740, as you've noted, is a strictly hydraulic tranny.  No electronics.  So you should be fine there, although I suspect there is some kind of mechanical interface to the throttle somehow, and you'll need to make sure that gets preserved.

Note that the DDEC ECM for a fire apparatus often has the engine safeties disabled, so even if everything else was the same, I would at least double-check the programming to make sure that you'll get an engine stop on low oil, high temp, and overspeed.

You may have to change throttle senders.  I can't think of anything else that would present a problem, but I've got a -II, not a -IV, so you might want to double-check with your local Detroit distributor for the straight skinny.  You will almost certainly have to reprogram the pulse count for the Vehicle Speed Sensor.

-Sean
http://OurOdyssey.BlogSpot.com

[TomC]

The simple way of running an electronic engine with a mechanical automatic is to retain the mechanical throttle linkage (whether it be mechanical or air) to have the transmission throttle position sensor, and then just have the electronic engine throttle in the engine compartment. Good Luck, TomC

[RTS/Daytona]

-- as I posted on the BNO board --

Actually It's even simpler than you think -

#1 - You DON'T NEED need the "DDEC-II to DDEC-IV conversion kit #18sp546 - ALL those wiring changes and adapter changes and 2 new sensors (air temp and ?) are ALREADY installed and wired on your DDEC-IV replacement motor

#2 - The Cruise Control wires connects (up front on the dash) on the DDEC-II can be SLIGHTLY DIFFERENT - a VERY simple change

#3 - three (2 wires plus a shield -(J1939 communications) have been added. This requires a new diagnostic plug

#4 - You'll need to get a multi-protocol & DDEC-IV cartrige for your PRO-LINK

NOTE-> The DDEC-IV monitors more parameters - records better SNAPSHOT data - provides many more - USER settable options than the older DDEC-II

Pete RTS/Daytona
 

 

[Len Silva]

Wow Ace, Going from "trashing this piece of crap" to a major repower in the same week?

[Ace]

Well I'm a firm believer that things happen for a reason and when this crap happened sitting in my driveway, this engine became availlable at the same time! You tend to sit there and wonder, is someone trying to tell me something?
I probably will just fix what I have unless of course its a major fix and then go another route but in the meantime, were still diagnosing!
The problem is the phone help and internet help is all great but it appears that those specializing in electronics still feel its lies somewhere in that part where those that are specialist in mechanics feel it lies there!
Me? I'm just following instructions and it tends to get a little frustrating going from one to the other.
I will say this, Pete Pappas has been a HUGE help on the phone every day, morning and night, and if nothing else, it helps to have moral support! Thank you Pete and we'll get it figured out sooner or later for sure because I feel we are getting closer every day either to fixing it or the gas station up the road!

Ace

[RickB]

Ace,

If you decide your not interested in that 8v92 let me know. I may be interested.

rick@rickbarronmusic.com

Thanks and we hope you figure that DD out soon!

Rick

[NJT5047]

Ace, doesn't your transmission have a 'push button' shift selector?  If so, you probably have an HT748, which is an ATEC transmission.  It has an electronic valve body and it will almost have to communicate with the engine ECM.  May want to verify your transmission could be managed by a DDEC IV ECM.         
An HT740, used typically on MUI engines, will have a manual shift selector with a lever...or an air shifter.   If you actually have an HT740, a DDEC IV would be a bolt-in.  The DDEC IV ECM may require removing the auto transmission programming.   
Have you established what is causing your no-start?  The DDEC unit could be ruled out.  They are easy to blame, but often are not the source of the fault. 
If it has failed, why?  The DDEC is powered by a separate 12V system, and often isn't damaged by 24V faults.

JR 

[busguy01]

Well all, please know that allison does make an electric version of the 740 - it is called a 741 and works quite well with DDII. If you have a four speed AND a push button selector I think you have a 741, complete with atec.

[Ace]

What I have is a gear selector. No push button!

Ace