# ideas for DIY Additional Injector controller (for CIS)



## EuroVeeDub (Nov 16, 2001)

Well, I am getting closer and closer to my turbo install on my GTi (83 1.8 CIS) http://****************.com/smile/emthup.gif 
I already have a Audi 5000 turbo WUR for extra fueling (obviously I need a little more though







)and a dual-port distributor for timing issues under boost








I was just wondering if anybody had any ideas for a *DIY* injector controller








Im really lookin' for someone with some schematics or a link to some, pics would also be nice. 
A while back I posted a link to a $25 DIY AIC, but I cant seem to find the stupid website again








Thanks








-Drew


[Modified by EuroVeeDub, 12:26 PM 8-14-2002]


----------



## rocco2nr (Aug 24, 2000)

*Re: ideas for DIY Additional Injector controller (EuroVeeDub)*

a hobbes switch and your cold-start valve? wouldnt atomize very well though. sticking the injector before the throttle body would probably work better.


----------



## EuroVeeDub (Nov 16, 2001)

*Re: ideas for DIY Additional Injector controller (rocco2nr)*

I've heard of using a Hobbes switch before...but I don't know anything about it. Got any more info about it? Like a website or something that I could order one from








BTW: I really like your sig








-Drew


----------



## rocco2nr (Aug 24, 2000)

*Re: ideas for DIY Additional Injector controller (EuroVeeDub)*

that quote has inadvertently become my entire philosophy. "my car's working great, i should mod it so it stuff starts breaking!"
http://www.dawesdevices.com/switches.html
its a switch that turns on at a certain boost pressure. pretty cool shiznit.


----------



## EuroVeeDub (Nov 16, 2001)

*Re: ideas for DIY Additional Injector controller (rocco2nr)*

So....you're saying I could use this switch in conjunction with my cold-start injector? So basically, under boost, this switch would trigger my cold-start injector.....hmmm it's all becoming clear now








This sounds like a *very* simple solution (and you and I both know that when it comes to VW's....the simpler the better







). Do you know of anybody who has used it successfully?
quote:[HR][/HR]"my car's working great, i should mod it so it stuff starts breaking!".[HR][/HR]​HaHa, yeah, I just got the bunny running good again and now I'm gonna force-feed it...hopefully it won't get the sh!ts















Thanks for the info BTW http://****************.com/smile/emthup.gif http://****************.com/smile/emthup.gif


----------



## killa (Nov 26, 2000)

*Re: ideas for DIY Additional Injector controller (EuroVeeDub)*

how bout an aic and have good driveability since it has a map sensor?


----------



## Stephen Webb (Apr 12, 2001)

*Re: ideas for DIY Additional Injector controller (EuroVeeDub)*

I'm going to weigh in. I'm not claiming to be an expert, but I've done a fair amount of research on this subject (as have many other people). 
1. The cold start injector is poorly placed to be used as an additional injector - you won't get even fuel distribution.
2. The cold start injector doesn't atomize fuel well enough to be used as an additional injector.
Most books I have read that talk about the cold start injector say this. I haven't tested it beyond looking at where the CS injector is, and watching the spray pattern. It was designed to get a cold engine to start easier. This doesn't mean per se that it won't work as an additional injector, but if you look at the placement and fuel spray pattern, it starts to look less and less appealing. 
As far as I can tell, there are two basic ways to use extra injectors to aid in fueling on a turbocharged car. The first way, and the only way in my opinion, is to use the extra injector to supplement your car's fuel system throughout the powerband. Your stock fuel system never "runs out" of fuel. The second way is to try to compensate for a stock system that can't deliver enough fuel by itself. Maybe it maxes out at 5000 RPM, and the extra injector is supposed to add the "right amount" of fuel to take up the slack. Time for larger injectors.
If you are using CIS, I say you should adjust the fuel flow with a control pressure regulator (boost sensitive) or by messing with the frequency valve. The CIS pressures are probably too high for a "normal" EFI injector, the CS injector isn't well placed or designed for adding extra fuel under boost, and there doesn't seem to be a great place to mount an additional injector. You can probably get the etra fuel you "need" by messing with the frequency valve duty cycle. Keep in mind that Volvo uses ONLY the frequency valve duty cycle for enrichment - they run 10.5 psi. With the "terminal 11" trick (for the Volvos at least) you get higher duty cycle, and can safely run higher boost, so they say. 
An EIC hooked to the frequency valve may be the best option (Peter?) for controlling the additional fuel under boost. The frequency valve is more or less a fuel injector - it's about 3-4 ohm impedance(on mine, anyway), and the factory control unit has a 10 ohm current limiting resistor in series with it. I would think the EIC should have this resistor too, otherwise you will be running currents 3x normal through the frequency valve -- can it take it? maybe, maybe not.
Also, I don't know how much it matters, but the frequency valve normally operates at about 70 Hz. I'm not sure how EICs work, but they may try to drive it too fast or too slow, but you may have complete control over this, too. Not sure.

If you want a circuit for driving an extra injector, I think there was one floating around somewhere that was triggered by the coil signal(is this the one you were talking about?), and had an adjustable duration pulse going to the injector. This sounds pretty reasonable to me. It should be pretty easy to build. If you really want to build one, I could help. Go learn about the 555 timer, in particular the "monostable" mode and you'll be halfway there. (there is plenty of information on the web about the 555)
-Steve
EDIT: clarity


[Modified by Stephen Webb, 12:57 PM 8-14-2002]


----------



## EuroVeeDub (Nov 16, 2001)

*Re: ideas for DIY Additional Injector controller (Stephen Webb)*

Steve, thanks for the super explanation http://****************.com/smile/emthup.gif








quote:[HR][/HR]
If you want a circuit for driving an extra injector, I think there was one floating around somewhere that was triggered by the coil signal, and had an adjustable pulse going to the injector. This sounds pretty reasonable to me. It should be pretty easy to build. If you really want to build one, I could help. Go learn all about the 555 timer, and in particular the "monostable" mode and you'll be halfway there.
-Steve[HR][/HR]​That sounds like a good idea, it seems more or less independant from the rest of the fuel system right? I have *very* basic knowledge of electronic circuts and such, but I'll see what I can try to learn about the 555 timer on my own and maybe we can put our heads togeather and come up with a good idea http://****************.com/smile/emthup.gif 
Im assuming that the 555 timer would take the tach signal from the coil and use that to progressively flow more fuel to the extra injector? does that sound right








As for the mounting of the injector... do you agree that before the TB would be best?
Thanks for all your insight http://****************.com/smile/emthup.gif 
-Drew


----------



## EuroVeeDub (Nov 16, 2001)

*Re: ideas for DIY Additional Injector controller (Stephen Webb)*

Oh yeah, one more thing...
Is there another option for the CS injector? Maybe a different injector, with a better flow pattern, could be used in its place








Then you could easily block off the old CS injector port and drill a new hole for it at a different location... like right after the TB or something.
Do you think that might work?


----------



## Stephen Webb (Apr 12, 2001)

*Re: ideas for DIY Additional Injector controller (EuroVeeDub)*

quote:[HR][/HR]
Im assuming that the 555 timer would take the tach signal from the coil and use that to progressively flow more fuel to the extra injector? does that sound right








[HR][/HR]​The idea is that your fuel system is providing very nearly the correct amount of fuel, and just needs a little bit of help to run rich (like turbo engines tend to like). It's true that you need more fuel per second as the revs climb, but *per revolution* the amount of "extra" fuel injected should more or less be the same. 
The duration that the injector is open is controlled by the 555 timer (and the resistor and capacitor that you use). This pulse duration may be adjustable, but once it's set, the injector gets the same duration of pules every revolution (as long as you are under boost, or full throttle, or whatever)
So each time the coil fires, the injector opens for a specified amount of time. As the revs climb, the injector is triggered more often, but still stays open for the same amount of time. 
This is by no means an optimal solution, just something that will probably work pretty well as long as your stock fuel system is doing a good job delivering the right amount of fuel.
-Steve


----------



## EuroVeeDub (Nov 16, 2001)

*Re: ideas for DIY Additional Injector controller (Stephen Webb)*

So what do you think about the idea of relocating the CS injector and maybe replacing (or modifying) the stock injector with one with a better spray pattern?


----------



## mrkrad (Nov 9, 2000)

*Re: ideas for DIY Additional Injector controller (EuroVeeDub)*

Digi-1







sounds like a lot less DIY and lot more reliability.


----------



## psi (Oct 18, 2001)

*Re: ideas for DIY Additional Injector controller (mrkrad)*

I'm with Sam http://****************.com/smile/emthup.gif 
If you want to use the coldstart set up,use the 4cyl audi 4k intake manifold.The CS injector is right behind the TB on those.


----------



## EuroVeeDub (Nov 16, 2001)

*Re: ideas for DIY Additional Injector controller (mrkrad)*

Yeah, but that takes away from the fun of trying to figure all this out







(although I am lookin' to trade my NOS kit for a Digi I setup anyway...







)


[Modified by EuroVeeDub, 10:16 AM 8-17-2002]


----------



## Bicycle019 (Mar 30, 2001)

*Re: ideas for DIY Additional Injector controller (psi)*

quote:[HR][/HR]I'm with Sam http://****************.com/smile/emthup.gif 
If you want to use the coldstart set up,use the 4cyl audi 4k intake manifold.The CS injector is right behind the TB on those.[HR][/HR]​You beat me to it. I was about to suggest the same thing. The injector location is MUCH better for use in FI setups as it's on an angle shooting right into the runners from right behind the TB. You could even drill and tap the end of the manifold for your cold start injector (basicly mounting it in the stock location) and then use the stock Audi injector location for your extra injector. 
I've got one of these manifolds outside and have been contemplating it for a little while now...


----------



## EuroVeeDub (Nov 16, 2001)

*Re: ideas for DIY Additional Injector controller (Bicycle019)*

can yuo post a pic of the manifold for me?


----------



## Bicycle019 (Mar 30, 2001)

*Re: ideas for DIY Additional Injector controller (EuroVeeDub)*

Give me a day and I'll see what I can do about a pic.


----------



## dredward (Nov 11, 2001)

*Re: ideas for DIY Additional Injector controller (Bicycle019)*

What yr Audi 4k is this manifold from/for.


----------



## vwvixen (Sep 2, 2001)

*Re: ideas for DIY Additional Injector controller (dredward)*

now this a little diffrent since i am using it on a 98 2.0 but i used a boost sensitive switch and a cold start injector from a toyota celica. and i get perfect plug readings after every test run. i mounted it just after the TB. the thing with the toyato CSI it sprays from 2 180 deg sides so it get fuel to more cylinders. i have used it for over a year and a half now with now problems.


----------



## RavenGTi (Dec 12, 2000)

*Re: ideas for DIY Additional Injector controller (vwvixen)*

if you end up mounting another injector (CS or whatever), and you are worried about equal distribution and atomitization, you could aim it opposite the airflow. the air will still push it where you want it, but because its doubling back, it will be more evenly distributed.


----------

