So you've successfully been able to turn DOD/AFM on (auto) and off? What about being able to enable/engage DOD/AFM (4 cylinder mode)?

 

Yes, I am able to put it in either Auto or Off with a switch.
I can't actually tell it to turn it on, cause that relies on a whole lot of variables. I think you would have to tweak a bunch of settings in Hptuners to have it on more.

 

So, are you getting a code again, or was the DTC turned off?

 

Haven't gotten a code since I got everything hooked up right. I am fabbing a mount for the switch as we speak (type).

 

I'm calling this mod done. I am happy with the way it works for now, it does what I wanted it to.
I can work on a writeup if anyone is interested. I think I have under $10 invested, but I already had some things to work with.

See the final install pic.

 

i would be interested in a write up sir.

 

Hey

What was the value of the variable resistor you used?


Cheers

Mike

 

Write-up please!

 

Good to see that this worked out for you.

 

Write up please. With a catless downpipe and a cutout this is a MUST! I always daydreamed of having a switch for DOD. Props to taking charge and coming up with a solution!

 

Write up would be sweet

 

omg I just drooled on my keyboard.. x10000 on that write-up. I'd be willing to pay-pal you some $$ for your R&D efforts too!!

 

Thank you for your hard work.

I'd really be interested in truly fooling DOD/AFM. Could you look into getting this to work? Maybe some sort of logic board (maybe I'm pushing it) that fabricates the right amount of variables to fool the vehicle?

 

GXP25

It is a 15 turn 10k ohm pot, .75 watt I think. I didn't measure it after I got it dialed in, but I think I may been able to fine tune better with a 5k. I made a lot of turns on it before the voltage started coming down.

The problem I see here, is that if you take one of the variables neccesary for DoD to enable (say throttle position), and modify its input to the ECM, the ECM is going to also adjust timing/mixture to try and satisfy it. The only reason this particular mod worked, is because I don't think there is anything the ECM can control (other than DoD) that would create more vacuum.
Here I think I would side with using HP tuners to adjust the parameters more to your liking, and also having the switch to turn it off.
Not saying it can't be done, but that I don't know how

I will start working on a write-up.

 

You are the man.. PM me your paypal addy and I'll send you some $$

 

Well thank you, but it wouldn't feel right!

It should be known that this mod requires a bit of a learning curve to use without getting a CEL. Since we are basically putting the ECM into a fault mode, you have to follow some rules to keep from setting it off.

On the plus side for some of you, once you get this CEL the DoD will no longer engage at all until you clear the code. So if you don't mind the light, and you just want DoD off, you could just stop there.

I am still learning, so I don't know all the rules, but here is what I try to do.
DoD is left on for the majority of the time. It is on when I turn the car off, and on when I start the car.

When I do use it, I try to limit to around 10 minutes, then turn it back on and allow DoD to come on, then turn it back off for another 10.
There was one time where I had it off for around 20 minutes, when I tried to turn it back on (on the highway), it didn't come on for close to 10 minutes afterwards. It may have set the light had I shut the engine off in this time period. Limiting it to 10 minutes at a time seems to prevent this.

Also, if I am using it on my way home, I turn it back on before I get home and try to get at least one cycle out of it before I shut it off.

Not sure how much of this is neccesary, like I said I am still learning, but be forewarned, its not for your average driver to use.

If I get the light, I just pull the fuse for a bit and try again.

 

Great, thanks for the info.

If you could put an Ohms meter across the VR and take a reading, we could dump the VR and go with just a straight resistor.

My nickle bet is 5K.

Cheers

Mike

 

If I could get to it I could, but readings wouldn't be entirely accurate since it is hardwired in.
I may be able to tonight, something went wrong with my final install, I must have shorted something out.
single resistor would be much simpler. Only problem is I would have to assume that the threshold voltage is set the same for all LS4's.

 

844 ohms! I sure hope I remembered that right, should have written it down. pretty sure it was .844k and not 844k lol. Makes sense though, as many turns as I had to do to get it down.

BTW, a hairline solder bridge was shorting things out. should be good to go now.

 

Mines an 06 with a different ECM, so good point about potentially different values on different LS4 revisions.

I will plug in a 10K radial and dial to suit. Post my results here when they are available.

884 or 8.8 K? We cant calculate the voltage drop without knowing the current flowing thru the resistor. 1K seems reasonable to spoof the ECM, however 10K would probably appear as an open to the ecm. If you leave it totally open does it toss a code? Is the resistor totally needed to prevent it from setting a code?

Just thinking out loud.

We shall see.

Interesting stuff. Thanks.

Cheers

Mike.