Actual best way to dpmi

Rob09msport

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I have been researching meth injection and on other platforms and even early on with ours people have tapped into the direct injector harness and ran it to a secondary mosfet usually one per bank. This outs no load on dme or injector and allows the port injection to follow the dme without any controller. My idea is one step further tap every injector and use like the fuel it or any other plate or intake manifold with injectors and hobbs switch but now we have no risk of melting a piston because dme shuts injector their is 0 delay safest way possible and i would assume smoothest as long as the hobbs switch is at a low enough boost and you have a custom tune dialed in. The only other necessary provision would be a basic pump controller or something to trigger limp or wastegates in the case of pump failure. Or could always run a jb4 so that it would still have the standard meth safeties and just setup as if charge pipe injection . Anyone have any thoughts or reason that i shouldnt pursue this style setup cause on stock turbos i feel either this or if not just chargepipe for cooling and valve cleaning benefits but nothing agressive is the only options i feel good about.
 
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Tuppidsay

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Aug 3, 2017
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Just off the top of my head it seems this would work on a port injected car for a second set of injectors. Don't know if the timing would be right for a direct Injected car.

It also seems you would lose the adjustability of injector duty cycle mid pull and would be relying on A static amount of meth and have to tune around it. Which seems like an awful lot of trial and error to end up In The same place as the basic direct port nozzle systems we have now.

Any adjustability would come with pwm to the pump which is unreliable.

I have misfired with the jb4 and it kicks you out to map4. With a bms injector controller for the injectors, that should shut the meth off and reduce the chances of a serious lean condition.

The type of setup and theory is the dream of secondary fuel guys. A true mpi system that is synced to the engine would be great. I think most people have written it off to something that has to be done at the dme level. Either with some serious work to the factory computer or an aftermarket stand alone. If you can come up with something that works that leave the factory dme un molested, you have one hell of a product on your hands. For meth and e85 secondary fuelling.
 

MoreBoost

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Jul 27, 2017
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I suppose scaling might be a challenge.
I take it you intend to run injectors for the meth. Presumably the meth injectors would fire when the DIs do, but would they also have to fire at the same PWM as the fuel injectors? I'd assume so as it's the same signal. Too much meth might be sprayed.
If the DME then scales back the DIs, it will also be scaling back the meth injectors as they are linked. Not sure if you could have something in between the DIs and the meth injectors to adjust the signal but by that point things might get complicated.
Not sure also if the long term trims values and learning routines might be confused by how much fuel is being injected by PWM for scenarios when meth injectors are on and not on.

Just some initial thoughts.

It would be great to have everything run off the DME. The wiring might be quite cumbersome once everything is in place.
 

Rob09msport

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The timing would not be an issue as it would be port injection for the meth or e85, it is just using the duty cycle for the volume. Also it would be completely variable based on engine load so the dme would adjust trims to hit target afr. You would size your injectors to your goals but basically if you size for 20 percent at peak hp you would have just that a 20 percent increase in headroom and you would adjust scalar in flash so is dialed in better but the dme would be able to fine tune flow.
 
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Rob09msport

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I suppose scaling might be a challenge.
I take it you intend to run injectors for the meth. Presumably the meth injectors would fire when the DIs do, but would they also have to fire at the same PWM as the fuel injectors? I'd assume so as it's the same signal. Too much meth might be sprayed.
If the DME then scales back the DIs, it will also be scaling back the meth injectors as they are linked. Not sure if you could have something in between the DIs and the meth injectors to adjust the signal but by that point things might get complicated.
Not sure also if the long term trims values and learning routines might be confused by how much fuel is being injected by PWM for scenarios when meth injectors are on and not on.

Just some initial thoughts.

It would be great to have everything run off the DME. The wiring might be quite cumbersome once everything is in place.
That is reason i would want a low pressure hobbs switch so as soon as come into boost meth flows and it stays gradual. Also this is where sizing injectors properly is important and or being able to regulate pressure to some degree if necessary.
 

dyezak

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May 4, 2017
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Instead of doing this blind why not hook up an ossilliscope to an injector and get ready to surprise yourself. If things were as easy as you make them out to be there would already be three or four vendors selling this arguing about who is better. Heck, if it were this easy someone who was, I don’t know, an electrical engineer and developed a whole standalone controller for this for our cars would have already done it...burger...
 

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Captain
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Nov 7, 2016
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It wasn't mentioned in any of the flex fuel posts because it will not be available in "OTS" fashion, but the flex fuel code also supports progressive meth / meth safety. If your meth controller has a 0-5V style output, you can format your bin for FF and just wire up the meth controller output to the same DME pin used for the FF ECA. Then as your meth starts flowing, it will seamlessly interpolate to your higher boost / timing tables, and can also safety fallback to the "no meth" tables if it stops flowing for whatever reason.
 

V8bait

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Nov 2, 2016
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Jake has changed the code so that when you misfire the coil disables along with the DI injector, which effectively fixes the issue for all practical purposes.
 
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Rob09msport

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Instead of doing this blind why not hook up an ossilliscope to an injector and get ready to surprise yourself. If things were as easy as you make them out to be there would already be three or four vendors selling this arguing about who is better. Heck, if it were this easy someone who was, I don’t know, an electrical engineer and developed a whole standalone controller for this for our cars would have already done it...burger...
It has been done but was off one injector.
However with what v8bait and Jake just said i think the flex fuel logic would be the way to go.
No one would market what i described because it's too easily ripped off, would need connectors made look at the whole bl coil issue and would still need tuning support so only mhd or jb4 could attempt to package and sell it. I know Terry would never package 10 dollars in mosfets and sell for some bmw markup and don't know anyone involved in mhd that would do that either if shiv was around we would have openmethbox 2.0 intro 399
 

Rob09msport

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Jake has changed the code so that when you misfire the coil disables along with the DI injector, which effectively fixes the issue for all practical purposes.
Right now your busy and i am so i just want do max effort 93 tune that's safe to daily but what jake just described is what my end goal would be ,just not aggressive but maybe run to ragged edge of 93 with good iat but not fully use the octane from meth for power, more just for cushion
 

Rob09msport

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WAIT A MINUTE this just clicked . You guys are telling me you found out how to change logic so can cut spark like does that mean instead of torque reduction by timing or fuel on shift can cut spark? Hence amazing shift farts all over the place lmao. That would be the most amazing thing.i tried burble for ten min but felt like a poser but shift farts would be key.
 
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Captain
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WAIT A MINUTE this just clicked . You guys are telling me you found out how to change logic so can cut spark like does that mean instead of torque reduction by timing or fuel on shift can cut spark? Hence amazing shift farts all over the place lmao. That would be the most amazing thing.i tried burble for ten min but felt like a poser but shift farts would be key.

No. What I did is when the DME shuts off an injector due to a misfire, fuel-cut, etc, that corresponding coil is also now shutoff.
 

Torgus

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Nov 6, 2016
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WAIT A MINUTE this just clicked . You guys are telling me you found out how to change logic so can cut spark like does that mean instead of torque reduction by timing or fuel on shift can cut spark? Hence amazing shift farts all over the place lmao. That would be the most amazing thing.i tried burble for ten min but felt like a poser but shift farts would be key.

idle farts, shift farts, throttle burble overrun farts. MHD is going to just add a fart button at this point ;)
 

Rob09msport

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No. What I did is when the DME shuts off an injector due to a misfire, fuel-cut, etc, that corresponding coil is also now shutoff.
Any chance i could bribe you to use spark cut like some n55 or does dct n54 use spark cut i would think that would make easier?
 

doublespaces

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That shift gurgle/fart you're thinking about might actually be the vanos. On some N55 and B58 they don't have a bov and the intake and exhaust valves are simply held open allowing the boost to go straight out the tail pipe.

Don't quote me but it works something like this.