ssrogers

I am wanting to use a 5.3 with Drive-by-wire with my 700R4. Now, I have my reasons for wanting to stay with drive by wire. My question is, if I make something that attaches to the gas pedal and pulls the TV cable in its correct sweep exactly like it would if it was on a carb or TBI, then what would be the problem? It is an honest question. I Want someone to reply with something I have not thought of. Please note, I am not just going to attach the cable to the pedal arm. I plan to attach a rod to the pedal that rotates a small arm to mimic a carb's throttle, moving the TV cable in the exact radius and pull length as originally mounted. I have an engineering degree, I am quite certain I can make this work, as far as pulling the cable. However, information about the TV cable seems to be little more than "make sure it's right" and "it's not Just a kick-down".

Thank you,
Steven

novaderrik

the only problem is that the engine ecm doesn't move the throttle blade directly proportional to the throttle input- it senses what you want it to do by how far you push the pedal, then adjusts the operation of the throttle blade, injectors, and ignition system accordingly. so the engine might not immediately go to WFO just because you put the throttle to WFO.. it might work, but it might not..

ssrogers

Wow, yes, that's a very good point.

I will have no traction control or cruise control. So, if I floor the pedal, would there be any reason that the throttle would not eventually reach full? I would think that delay would always be only a fraction of a second. I wish I knew how quickly the throttle valve of the transmission reacts. I'm hoping that to the transmission the difference between the delay of the dbw would be the same as an engine that just simply doesn't respond to the throttle as quickly, like a much lower hp engine might.

jmd

iTrader: (4)

If you haven't driven a late model vehicle with (very) obvious DBW pedal tip-in and throttle body opening differentiation, then you might not be aware how different they can be. And I can't put it in numbers for you such as percentages. But mileage is driven by stability. Emissions are too. Many engines can get awesome mileage at a clean burn if they're driven at a steady rpm. Accel requires rich, decel lends itself to lean conditions. Either one will screw with emissions, accel will hamper mileage.

It's no exaggeration that several seconds pass before I feel the WOT of the throttle body in a household DBW vehicle match the pedal position.

I'm going off on a rant and well... consider your time and money. Can you get a good used 4L60-E for $x.xx and offset the cost with the sale of your 700-R4 for $x.xx? yeah.

If you want 100% matched pedal to TB, put it in the tune. If you want to leave some factory tip-in delay for mileage, put/leave it in the tune. Having these controls in the PCM allows also for things like spark retard at shifts for transmission life and a fairly infinitely variable ramping up of shift firmness. Granny shift for daily use, kapow tire barking for 3/4 throttle? Again, in the tune.

The TV cable isn't complicated. The TV needs opened 100% at 100% pedal travel. That's just bellcrank math you can work on if you wish. But, the 100% TV opening with the engine doing something else (in rpm, timing advance etc.) is what could be very detrimental to this working properly.

Long story short? Leave the DBW throttle response delay basically zero (there are still curved ramp-up schedules,) and do what you want to do. And hope that it works to what you think it should / will do.

Or, give yourself more options, save time, spend a few bucks and just join the -E crew.

ssrogers

So much to respond to.

I have a 2008 Corvette Z51 manual and even with traction control off you can still tell that there is some computer modulation of the throttle.

Emissions and mileage will be better than the current engine.

What is a household DBW, a Tahoe? Yes, it is very obvious on those type vehicles. Being that that's where this engine will come from, it will almost certainly need the throttle tuned.

The reason I don't want to go 4L60E is because I intend to eventually go manual. Being that the engine that I'm getting is stand-alone, it is actually going to be more work and money to convert it to a T56 from the current 700R4, than it will be to go from TBI 305 to LM7. I am just trying to take this in steps instead of both at the same time.

ssrogers

I guess my question now is, is there any harm in the trans going to 100% while the engine throttle goes from 90 to 100%? What do turbo people do? Because when you floor it on a turbo car there would be a small delay before it would hit.

jmd

iTrader: (4)

Too much TV pressure allowance is better than too little.


BTW:



google "FroJoe DBW"

ssrogers

Thank you for the picture. I have literally been looking for Weeks for a picture example of what I was talking about doing. I have only been able to find people talking about it, like me.

Ozz1967

iTrader: (4)

I didn't even know this was a thing! Better than mounted to the throttle body?

cosmick

I've considered this before, but for different reasons. I never wanted DBW, nor will I ever run it where DBC is possible, even if fabrication and reprogramming are required. Plus there are linkage kits to run a TV cable off early LS1 TBs.
And even if you go DBW, it would be better to run the TV cable off the other, non-motorized side of the TB.

Ozz1967

iTrader: (4)

Would it be possible to do this on a normal cable pedal as well?

cosmick

I've seen a TV cable arm spot-welded to the right / passenger side of an LM7 TB, seems to work, not as pretty as the expensive kit from BTO, but the BTO kit requires the early LS1 78 mm TB, so if you want to go to a 90 mm TB, you're on your own. I guess you could make it pretty with enough work.

Ozz1967

iTrader: (4)

In this instance, I'm going to go with the 78mm throttle body to use the 700R4 for the BTO set up and later on when I do swap to a 4L60E, when I can afford to build one properly, I will look at a bigger throttle body set up.