Secondary Injector Driver

[Double Phister]

Does a device exist that can drive two injectors from one (stock) ECU signal? As a thought experiment I want to ramp up a set of small injectors then add in a set of large injectors.

[sperry]

As a thought experiment, it's trivial: build a signal processor that listens to the IDC from the ECU, then drives its own set of injectors any way you want.

In reality, just get a standalone ECU.

[Double Phister]

Originally Posted by sperry

As a thought experiment, it's trivial: build a signal processor that listens to the IDC from the ECU, then drives its own set of injectors any way you want.

In reality, just get a standalone ECU.

Are there any stand alone ECUs that support OBDII?

[knucklesplitter]

There have been secondary injector drivers available since the early nineties. I know Aquamist makes one. There are others, but I can't think of the names. Some of the other meth/water injection companies may have them too, because the technology is similar. The good ones are programmable to bring on the secondary injectors as needed, for example - as boost increases.

[Kevin M]

Originally Posted by Double Phister

Are there any stand alone ECUs that support OBDII?

Is the new Hydra setup available yet? Phil has been talking about it a bit on Nasioc, but I'm not sure if it's available yet. Basically it is a pseudo-piggyback that tells the stock ECU what it needs to hear to make OBDII work is what I got from it, but I didn't pay much attention after I decided to go with an '05 ECU in the wagon instead of standalone.

[Double Phister]

Originally Posted by knucklesplitter

There have been secondary injector drivers available since the early nineties. I know Aquamist makes one. There are others, but I can't think of the names. Some of the other meth/water injection companies may have them too, because the technology is similar. The good ones are programmable to bring on the secondary injectors as needed, for example - as boost increases.

I want the amount of fuel delivered to be controlled by the ECU and not an external device. It's my understanding that the existing secondary injector drivers have their own look up tables and sensor inputs. That doesn't sound as ideal as an ECU that can drive the secondaries directly or indirectly.

The indirect approach would require the injector latencies in the ECU to move to the secondary controller.

I'd like to have stock or smaller than stock primary injectors with good blending control to huge injectors. To the ECU it would just look like there where massive injectors. But you'd have great fueling at low loads/RPM.


I'd go MOTEC if the check engine light and OBDII port worked the same (or close). I know I'd still have to worry about making 8 injectors look stock for a SMOG check.

[knucklesplitter]

Originally Posted by Double Phister

I want the amount of fuel delivered to be controlled by the ECU and not an external device. It's my understanding that the existing secondary injector drivers have their own look up tables and sensor inputs. That doesn't sound as ideal as an ECU that can drive the secondaries directly or indirectly.

The indirect approach would require the injector latencies in the ECU to move to the secondary controller.

I'd like to have stock or smaller than stock primary injectors with good blending control to huge injectors. To the ECU it would just look like there where massive injectors. But you'd have great fueling at low loads/RPM.


I'd go MOTEC if the check engine light and OBDII port worked the same (or close). I know I'd still have to worry about making 8 injectors look stock for a SMOG check.

There are a lot of people daily-driving 850cc injectors these days, and those idle fine at 900rpm or less, and they drive fine at low load. Unless you need more injector than that I don't think it is even worth the thought experiment.

Another option is to go standalone 11.5+ months out of the year and swap in the stock ECU for smog. It is a hassle, but I know many Cali folks do much more swapping than that just to pass smog.

[sperry]

Originally Posted by knucklesplitter

There are a lot of people daily-driving 850cc injectors these days, and those idle fine at 900rpm or less, and they drive fine at low load. Unless you need more injector than that I don't think it is even worth the thought experiment.

Another option is to go standalone 11.5+ months out of the year and swap in the stock ECU for smog. It is a hassle, but I know many Cali folks do much more swapping than that just to pass smog.

+1

I have a Hydra 2.5 and switch to the stock ECU for smog checks. In fact, they're both installed under the dash so swapping them is just a matter of opening the passenger airbag hatch (I've got no airbag of course) and just switching the plugs over.

But really, it sounds like your problem is your PE850's. Switch to some Deatchwerks and I bet your idle issues just evaporate. I was running the PE800 top feeds and their latency was like 1.6ms or something horrendous... and while the side-feed PE850's are way better, the DW's are that much better again apparently.

[Double Phister]

My PE850s are fine. I have stock idle and passed smog with them on pump gas. I will need to go larger for E85 and high boost. It's going to require me to redo my entire fuel system so I'm evaluating my options.

[sperry]

Originally Posted by Double Phister

My PE850s are fine. I have stock idle and passed smog with them on pump gas. I will need to go larger for E85 and high boost. It's going to require me to redo my entire fuel system so I'm evaluating my options.

I thought that going larger for E85 doesn't affect idle since you will need that much more E85 at idle. Injector-wise, everything should scale linearly based on the lower energy content of E85 vs. gasoline. The extra boost you get to run on E85 is because E85 is higher octane... you shouldn't have to add significant fuel for the added boost, should you? At least not to the point where you're running injectors so large it won't idle.

1000cc injectors on E85 idle the same as 850cc injectors on gas, don't they? Or are you planning on building an E85 capable fuel system, but also run gas on occasion with another map? I could see issues with idle/smog if you're trying to run a 91 octane map on 1000cc injectors. But really, I'd just stick to E85 all the time over trying to use some multi-injector system.

I dunno, I'm not up on the E85 stuff since it's such a huge PITA to get it in Reno I haven't even considered it. Are people having significant idle issues on E85? I'd think by now people would have solutions for this, and I've never heard of people using 8 injectors on an STi.

[Double Phister]

There's some work being done in romraider to give the ECU flex fuel capabilities. Just put whatever is available in the tank. So yes I might run 91 when I can't get E85 (like in Reno or Redding). I have APS TGVs that have provisions for additional top feed injectors.

[sedonabugeye]

As long as you are able to tune the larger injectors and have a decent knowledge of whatever computer system you're using you should be fine..I'm running the ID 2000's on e85 and idle is, should say was, right around 1000 rpm. I only run e85 in my WRX and havent had any issues w my fueling system at all. However I am on a aero motive fpr and I saw you want the ecu only to control fuel..

[Double Phister]

I'm looking for stock idle RPM on 91 octane for the low end and mid to upper 20's boost (whatever this turbo stops making good numbers at) on E85 on the high end.

The only change I currently make for smog is the downpipe. I hope to change that someday too.

Another idea I had was to use ID1000's and vary the base fuel pressure with boost via rising rate FPR (oh god this sounds like the Honda days before Hondata allowed us to sense boost) and have the ECU sense the pressure via an unused TGV input. The ECU would then need code to blend between new low and high versions of some fuel related tables. I'm not even sure the required output would be linear though.

I'd keep my walbro and use it as a lift pump into a surge tank. Then have a large pump do the hard work. But then I start thinking about the next issue of wanting to vary the speed of the pumps to keep from overrunning the FPR and unecessarily heating the fuel.

I know I'm overthinking this but that's part of the mod bug for me.