Converting from DBW Throttle body to Drive by cable, Will it work? - Hemi Truck Club
 
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Old 12-17-2020, 10:52 PM   #1
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Converting from DBW Throttle body to Drive by cable, Will it work?

Hey, i have always been curious as to if the DBW system can be converted to drive-by-cable.
I recently received a stock throttle body which was donated bu Bada44 ( thanks once again) the goal is to see if the blade motor can be taken out of the equation and have the throttle blade be actuated by a cable instead.
In case you are wondering why would i want to do this is because i still have some surging while driving. The truck has a tendency to accelerate more than what my foot is inputting. Keith has helped improv the sensitivity of the throttle thru his tuning, but it seems that the more i drive the truck, after doing a throttle re-learn, the worst the problem gets. It happens gradually, as if the computer is “learning” to do it.
Anyways, let me show you what i have done so far:
I opened the cover, cut the middle plastic gear off. Doing that disconnected the motor from the throttle blade pulley. I was then able to drill and tap the throttle shaft. I used a m6x1 tap and a m6 shoulder bolt that measures 8mm in the shoulder area. The idea is to use the bolt to attach a throttle body cam. I drilled the throttle circuitry cover to 5/16 to allow the bolt to go thru it, i chose to drill a 5/16 as it is slightly smaller than 8mm for a snug fit so i can keep water out of the TB once reassembled.
Before i continue, I want install this “modded” TB to see how the system reacts. If i see there is potential, i will then fabricate a throttle cam (pulley) as well as throttle cable bracket. For pedal, i will use one out of a 3.8/4.7L.

I know the DBW system also takes into consideration input from the electronic pedal, i just dont k ow how much input and if it affect anything besides the TB motor. i have read from 2 guys that have done something similar when swapping hemis into older model vehicles and it has worked for them. Will it work on my application? we will soon find out 😄
It may be a few days before i test because it snowed a lot in my area and it is also very cold.
I will update soon.
Your input is appreciated
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Old 12-18-2020, 09:48 PM   #2
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Temperatures did not cooperate today either. It was just a little too cold to work outside. So while inside, I took a bit of time thinking how to “re-seal” the throttle body. I had a few ideal which involved some tig welding, but i just wanted something much simpler.
I know it may look a little ghetto 😀😀, but it works perfect!
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Old 12-19-2020, 09:33 PM   #3
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I haven't messed with that circuit for some time. But I seem to remember the TPS is involved. There is also two APPS signals generated by the pedal. You need these when using a 545rfe trans otherwise you'll get a limp mode.
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Old 12-20-2020, 12:04 AM   #4
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I haven't messed with that circuit for some time. But I seem to remember the TPS is involved. There is also two APPS signals generated by the pedal. You need these when using a 545rfe trans otherwise you'll get a limp mode.
Hello Greg, thanks for the feedback. I no longer have the 545rfe. The truck has a 518/46rh with manual valve body.
Everything electronic will stay intact in the throttle body, even the motor that actuates the throttle blade will stay connected, it is just that there will be no mechanical connection between the motor and the throttle blade since i removed the gear that connects them. Instead a cable will be opening the blade. I assume the TPS in the throttle body should generate its signal with no problem (unless there is something i am overlooking).
The thing I do not know is if the PCM compares the position of the electronic throttle pedal to the position of the TPS and uses that to have the engine run properly. If that is the case, i may have a possible solution, but i will cross that bridge when i get there.
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Old 12-20-2020, 10:59 AM   #5
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I bet that is a fun truck to drive with the turbo/ 46re... I think you can make this work. I was trying to use a 545rfe when I was using the drive by cable tb. And the trans wouldn't play nice.. I plugged in the oem tb and hung it to the side, then used a LSX tb to run the engine on megasquirt. Engine ran fine but the trans would go into limp mode occassionally.. Don't umderstand why you are having trouble with over run. But enjoy reading about what you are doing to fix it. Good luck.. extra question.. do you use 1st gear when driving normal?
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Old 12-20-2020, 11:56 AM   #6
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.... extra question.. do you use 1st gear when driving normal?
I do, every time I come to a stop (red light, stop sign, etc) I go back to into first.

As for the electronic pedal, if it is needed to keep the truck running right I have to think of a way to piggy back electronics from the pedal onto the mechanical throttle pedal so they would both move as one. How? I dont know yet, but if it ends up being needed, I will figure out how.
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Old 12-20-2020, 05:27 PM   #7
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Max what year is your truck? Does it have the 03 remote APPS? If it does it is easy to piggyback the manual cable to the manual cable that goes to the APPS.
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Old 12-20-2020, 07:04 PM   #8
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Max what year is your truck? Does it have the 03 remote APPS? If it does it is easy to piggyback the manual cable to the manual cable that goes to the APPS.
No, the truck is a 05
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Old 12-22-2020, 07:54 PM   #9
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Go into my trans swap thread and you can see where I made my electronic pedal pull a TV cable. That can be hooked to a throttle body also and do what you need. Your much better at fabrication side of things than I am so my idea will be a base starting point.
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Old 12-22-2020, 08:04 PM   #10
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Go into my trans swap thread and you can see where I made my electronic pedal pull a TV cable. That can be hooked to a throttle body also and do what you need. Your much better at fabrication side of things than I am so my idea will be a base starting point.
that's what I had in mind, adding some sort of an "extension" to the factory electric pedal to pull the cable. I will go thru your thread and look for that picture. Thanks for the feedback, it is much appreciated!
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