AFM (aka DOD) functionality after swap

[Jeff7]

Hey guys so I did some looking around and couldn't really find the answer to this question. Everyone always says with a Gen IV motor you can remove the AFM when getting it flashed/tuned, but what if you want to keep it? I've got a 98 K1500 with the 5.7L and I'm looking at doing a swap to get better performance (cheaper to swap a new engine into my perfectly fine truck than buying a whole new truck) but I would like to get a Gen IV so I could put that AFM to use. Is there a reason everyone says to just delete it, or would it work after the swap?

And related to that, although I might have a hard time finding a decently priced motor, does anyone have experience swapping in a Gen V motor if that were to be available to me? They seem to have all around better performance so that seems like a good choice, but I have no idea what sort of new complications that would involve.

Thanks for the advice.

[Nak]

I'm keeping DOD and VVT in my swap. Unfortunately, the harness I'm using is rather spendy. I have no idea if this has changed, but when I started Motech-- www.LSwrangler.com -- was the only outfit I could find that ran DOD, VVT, a BCM with stock cruise control and stock tap shifting for the 6L80. I researched all of this, and DOD seemed pretty elusive to keep active after a swap. I did find several threads around the internet where guys were trying to get DOD working. At least three guys did, but i couldn't find the details of how they got it to run. There's a whole laundry list of things that will inhibit DOD. It just seemed that I could pound my head against the wall trying to get all of this working--I think I would have eventually--or pay someone who had the knowledge and save myself a lot of time.

I plan on adding more functionality over time with the BCM. First on the list will be "Tow Mode".

A Gen V swap would be very cool, but you'd be more of a pioneer. There's a lot less information available than the Gen IIIs and IVs.

[Jeff7]

Yea I kinda figured with the Gen V, I likely won't be doing this swap for another year, so maybe there will be more info then.

And as for the DOD/VVT I kinda figured, I've asked pretty much this same question on multiple forums and this is the first reply. That's good know that it is possible though. I guess my next step would be to talk to some guys at shops that do this and see what there opinion is, what it would cost to get them to do some work in order in to get DOD/VVT (and tow mode would be great too) functioning. I'll post whatever I find out. Thanks for the info Nak.

[Nak]

Tow mode requires a BCM in the loop. If you want DOD, VVT and tap shifting, that also requires a BCM. Guys are using a Corvette tune to get tap shifting without a BCM, but that kills DOD and VVT. BTW, VVT is killer to have, just look at the torque curves of the motors with it. DOD would be nice to have as well. It's not all that hard to get the BCM in the mix if you wire your own harness. There seems to be some trick to get DOD to work though. The Motech harness does it all, but I just found a problem with their basic harness. The ECM plugs are wired about two feet too short to use on our rig with the ECM on the fenderwell, and the fuse box is about one foot too short. If you get a Motech harness have them do it custom and get those lengthened. BTW, the Motech accelerator bracket is easily modified to use in our trucks. Absolutely use one if you go with DBW. See my swap thread for pictures.

[Jeff7]

Ah ok sweet. I'm in the middle of moving right now but in a couple days I'll definitely give it a look through. So just so I'm understanding this correctly, you have done the swap and have VVT and Tow working, or you're still not done yet because if those harness length problems? Just trying to get straight exactly what you have functioning so far. Thanks for the info.

[Blasphemy]

I've been reading about cam companies making moves to develop more a/m parts for the part of the market that has no plans of deleting the vvt/afm/dod systems. It's possible to make respectable gains in torque and hp while maintaining streetable manners and fuel mileage. When the factories are pumping out vehicles, they are under strict guidelines to adhere to the federal epa standards as sanctioned by each states environmental needs. Therefore, making each truck, suv, and car with a ton of power aren't their first priority. Obviously this concept isn't new to the guys in the car/truck scene. Since I was kid my dad has been ripping and tearing at every emission part attached to his vehicle in order to free up the motor of the power lost. But now we can achieve awesome power capabilities while keeping fuel economy and the environment in mind.

[chvy=power]

Tow mode requires a BCM in the loop. If you want DOD, VVT and tap shifting, that also requires a BCM. Guys are using a Corvette tune to get tap shifting without a BCM, but that kills DOD and VVT. BTW, VVT is killer to have, just look at the torque curves of the motors with it. DOD would be nice to have as well. It's not all that hard to get the BCM in the mix if you wire your own harness. There seems to be some trick to get DOD to work though. The Motech harness does it all, but I just found a problem with their basic harness. The ECM plugs are wired about two feet too short to use on our rig with the ECM on the fenderwell, and the fuse box is about one foot too short. If you get a Motech harness have them do it custom and get those lengthened. BTW, the Motech accelerator bracket is easily modified to use in our trucks. Absolutely use one if you go with DBW. See my swap thread for pictures.

Do you have any links or dyno graphs showing a vvt motor with a better torque curve than a non vvt motor? Iv never been impressed with vvt as far as performance or driveablity. Iv talked to several guys, one being Geoff skinner of engine power systems, who claims that the vvt is purely gm's way of trying to pick up fuel economy and has no effect on performance.

On a stock motor I can see trying to keep it, but if it's performance your after...in my opinion it's a waste of time trying to keep it

[Nak]

Do you have any links or dyno graphs showing a vvt motor with a better torque curve than a non vvt motor? Iv never been impressed with vvt as far as performance or driveablity. Iv talked to several guys, one being Geoff skinner of engine power systems, who claims that the vvt is purely gm's way of trying to pick up fuel economy and has no effect on performance.

On a stock motor I can see trying to keep it, but if it's performance your after...in my opinion it's a waste of time trying to keep it

Built 454ss dyno.jpgL94 Torque Curve.jpg

I guess it depends on your definition of "performance". For the track, sure you'r better off with the extra RPM available without VVT. For day to day driving and towing? Around 300 Lb-Ft just off an idle with a stock engine and torque converter is damn nice to have. Look at the graphs, a built 454 has higher peak torque, but nowhere near the area under the curve that the L94 with VVT has. If my 6.2 ends up anywhere near as nice as my buddy's totally stock Denali I'll be thrilled to death. Quiet, great gas mileage, reliable, loads of torque from idle to redline and 0-60 in the mid 5's. No need whatsoever for a high stall speed torque converter. Yeah, I'll take VVT for a daily driver, for a tow rig, for the kind of off roading I do, for manageable on road traction in winter conditions.

Everyone's needs are different. For some, VVT is not the way to go. I'll easily agree that if you're looking for minimum 1/4 mile times, skip the VVT. But the truck that does great at 1/4 miles is not going to do as well towing in 6th gear at 60 MPH. Again, it all depends on what your definition of performance is.

That's just my opinion of course.

Just looked at your build thread, very nice! It totally sucks you had to lose the blower... Anyways, from the feel of your thread I'd agree that what you're after is better achieved without VVT or DOD. What I'm after in my build I believe is better with the VVT and DOD. (At least I'm hoping that my precautions will prevent the issues associated with DOD.)