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Guest Message by DevFuse

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CIS Fuel Injection Conversion - Write-Up with Pictures!!

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39 replies to this topic

#26 Guest_Russ Hill_*

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Posted 07 June 2003 - 10:14 PM

Good Job!
I always liked the CIS system. It's very simple and there are a ton of them in the wrecking yards.
Nice going. :)

#27 Guest_hodakarider_*

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Posted 10 June 2003 - 04:06 PM

Yep, the carat had the GLI/GTI engine. Nice peppy car. I had it lowered a little for better handling, too (the GLI came with better suspension to start with).

#28 Guest_PHATBRAT_*

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Posted 10 June 2003 - 08:48 PM

So, Overall, In english, what is to be Gained/Lost from this? Is it worth the trouble? Only want to hear from the one who did it.

#29 Guest_bushbasher_*

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Posted 10 June 2003 - 09:02 PM

my mom's '78 vw bus has CIS on a 2 litre motor (the latest aircooled model made, with hydraulic lifters etc, and that thing goes like stink for a bus, outran an earlier mr2!

#30 Guest_OH Noah_*

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Posted 10 June 2003 - 10:13 PM

Honestly this is a really bad car to be judging Gains and Losses from. I knew going into this that it'd be hard to be sure what did what when I got done. Here's why.

In addition to adding CIS, I also:
-switched to MPFI heads
-did a DIY P&P to those heads
-switched to "spider" intake manifold
-switched to MPFI distributor
-changed spark plugs
-removed entire A/C system

With all these variables, it's hard to conclusively say what caused the changes I'm experiencing. On top of that, I have a crappy 3spd automatic that makes it really hard to tell what the engine is doing in the first place. I also haven't fine tuned my ignition timing yet.

Disclaimers aside, I <span style="text-decoration:underline">have</span> noticed more power. It's not much faster than before, but it doesn't sound strained anymore. I guess you could say that it now takes less effort to do the same job as before.

Right now I have a hesitation when coming off idle. I'm hoping that it's not something the P&P caused. I think that it'll be faster once I fix the timing. I'm also planning to uncork the exhaust some.

I think it'll be easier to see the pros/cons when I try this on my EA81, but that might not be until next summer.

#31 Guest_Snowman_*

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Posted 11 June 2003 - 01:37 AM

Even if there are no actual power gains, that system is much simpler than subaru EFI systems, and hence less likely to malfunction, easier to fix, etc. (and personally I hate computers in cars). It would also be advantagious over a carb because "drivability" would be increased on extreme angles and such.

Just my $.02

#32 Guest_LostWater_*

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Posted 19 June 2003 - 09:56 AM

Can someone make this a sticky?
It sure woudl be nice for this post to be made accessible. It has such good info and makes very good reading.

Christiansburg, VA

#33 Guest_turboroo_*

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Posted 19 June 2003 - 11:51 AM

I have owned my share of cis vw's and while yes they run well most of the time. but when the cis has a problem it is a bit dificult to pin down. this is just my opinion. I have to disagree with snowman as to the complexity of the cis vs efi. take a look at a brake down of the cis fuel distributer espicaly on later models. lots of little mechanical parts inside. efi gives codes and can be easily checked if you know what is normal and what is not.
I assume there are 2 fuel pumps running this system? vs a single pump on most efi cars.

I have doubts about how "easy" this is for most people wanting to convert fuel injection. when I changed my toyota pu too fuel injection I chose to go with a efi manifold and a programable controler from SDS. it was a long process and that was more or less a bolt on.

dont get me wrong I fully respect the inovation that must have gone into this and a lot of work. I just want to point out that a stock system would be a good deal easyer to install and troubleshoot. or a aftermarket efi system.

my cousin is a volvo turbo guy and says that to bring thier cars up to the next level they are going to efi from cis. go figure.

#34 Guest_OH Noah_*

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Posted 20 June 2003 - 12:42 AM

I agree with alot of what Turboroo said.

For maximum performance, you can't beat programmable EFI. Of course, that usually costs at least $1000 and requires programming. From what I've seen, programming often involves a laptop and/or dyno to do it right. CIS only cost me about $50 and worked right away.

Factory MPFI systems seem pretty nightmarish to me. I'd definitely want to have an entire parts car before attempting such a swap. Even then, they are set up for a single configuration which includes many emissions controls, so they often don't adapt well to changes (such as increased boost). CIS exists on many different cars while using mostly the exact same parts, and any emissions controls are external to the system. Not to mention, it's as easy to wire up as a basic stereo system.

As for the complexity issue, I think it really depends on your view of complex. EFI is by its nature more electrically complex, while CIS by its nature is more mechanically complex. In either case, the most complex parts are hidden and need not be messed with. Yes, CIS problems can sometimes be difficult to figure out, kinda like a carburetor, but once again it only cost me $50.

#35 Guest_turboroo_*

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Posted 20 June 2003 - 09:08 AM

noah I appreciate your good attitude.:D

Im glad we mostly agree on this. I would like to use that spider manifold set up on my RX. of course it would be efi for me.:lol: you are close about the cost of programable efi. the SDS system was about 800 dollars without injectors or pump. but it comes with a control pad to program the system.
I guess im just trying to say that the gains from converting a mpfi car to csi would be minimal if any.
you are correct about turbo charging. stock N/A cars efi cannot maintain fuel control without dodads like adjustable fuel pressure regulators.

keep on building crazy subes, this is good stuff I like it.8o

#36 Guest_OH Noah_*

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Posted 20 June 2003 - 01:29 PM

I agree that swapping CIS onto a car that already has n/a MPFI would be kinda pointless. I was thinking of it more as an easier way to put a MPFI or turbo engine into a car that originally had a carb or SPFI. I also thought that it might be beneficial for turbo owners who have modified their engines or boost levels, but I've never had a turbo car so I'm just guessing here.

I've had experience with the $800 SDS system. My VW buddy had that on his Scirocco, and I helped him program it. It was a little bit of a pain without a dyno, as he had to drive on the freeway while holding both the brake and gas while I watched the mixture meter. He opted to stick with CIS on his latest VW project because the SDS (without O2 sensor) reduced normal driveability too much. I will say that I did like the SDS system. If I were going to put aftermarket EFI on one of my cars, I'd probably choose one of their closed-loop systems, but I'd want to do the initial tuning on a dyno.

Rest assured, there will be plenty more crazy Soobs to come! (I just bought a EA81T engine for my 2wd Hatchback!!!)

#37 Guest_x silvershad0w x_*

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Posted 20 June 2003 - 02:29 PM

Firstoff I'd like to congradulate Noah on a job well done, this is a awesome project and pioneering as well, probably the first CIS system on a Subaru of this or any era, and if not, doesn't matter, because he was first to bring it into public eye and make it a fully reproducable project from start to finish, and I respect that a lot.

Secondly, I had to jump into the whole CIS-EFI debate and put in my two cents. Since I work with EFI quite a bit anymore and obviously biased myself towards that end, I don't want anyone thinking that you should pick one over the other all the time, this is going to depend totally on the individual and the project at hand - my main goal is really to show benefits of FI, either CIS or EFI over carbys, which are outdated and I really think that -anyone- considering a fuel delivery system upgrade should look into FI as the best alternative.

Main things that keep people away from FI are cost and charting new territory, and it may seem more (too) complex to make it worth bothering with. Aftermarket FI has been beaten like a dead horse, there are so many companies doing it - Haltech, SDS, Holly, Edelbrock, etc etc etc, at least 10 more names in there. They each have a target market, all trying to provide 'bolt-on' fuel injection, at a price.

The point I try to make, and I think it's in line with Noah's ideas, is that not a lot of us here are going to spend that much money for fuel injection on our cars, especially when I can spend half what a SDS system costs bare bones and get a Weber that is proven to give my ride a good kick in the pants. I of course, have been working with this MegaSquirt for a while now in my spare time, tinkering here and there seeing what works and what doesn't, playing with costs, etc etc. and I've come up with a pretty solid way to get you a fully tunable EFI bolt on that will cost less than a weber and give better performance, tuneability, driveability, you know, the way FI is supposed to work. My goal is to make it easy enough and and attractive enough so that it's just as easy or easier for Joe-Blo to bolt it on as it is to do a Weber upgrade.

My First published work will be with changing a carby EA82 over to SPFI w/ megasquirt. Now this is just the fuel side, and i think it's a good start and about the most basic and easy conversion. Once I tune it up I can get all the baseline numbers and post them, making everyone else's tuning that much easier, because you can start with a baseline and work from there.

I am moving on to other things, distributorless ignition, MPFI converted over to MS (just as easy as SPFI), adding a turbo to any of these setups, etc etc etc. If there is much interest in this once I actually get off my butt and write all this stuff up, I might make junkyard runs and start making ready to use wiring harnesses and everything, if people are interested.

One last little jaunt, when you plan on a FI system, there area lot more 'hidden' little costs than just a simple carb upgrade. For instance you buy just the baseline SDS system, expensive enough already, you are no where near ready to FI a previously carbbed car - you will come to find all sort of extra features you want and need that they happily charge more for to add it on for you. You can avoid all of that and keep the cost very reasonable, and that is what I hope to pioneer, if ya'll have interest by the time I get around to it. :)

#38 Guest_OH Noah_*

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Posted 21 June 2003 - 10:16 AM


I briefly looked at MegaSquirt a few months ago after Skip had mentioned it. It reminded me alot of Linux with its open code, etc. It looked like something that would certainly work on our cars, but would take alot of effort from some pioneering person to try it first. I just don't have time or the facilities to be that person, so I'm glad to see that someone else can be.

Everybody seems to think that my CIS conversion took alot of work. In reality, the vast majority of my time on this project was consumed by the task of putting the MPFI heads on the engine. After that, I probably only spent one full day on the mounting and connecting of the CIS components, including the wiring. Of course, I had already put a fair amount of time into research and planning, but hopefully I can shorten that part of the process for the next person.

I know that SubaruJunkie is planning to give CIS a try, and I'd love to see someone else try it out. If anyone has any questions, don't hesitate to post here or email me.

#39 Guest_jon61484_*

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Posted 02 July 2003 - 12:22 PM

I'd love to convert my carbed EA81 to MPFI. Say I worked the heads/intake from an MPFI or SPFI, would this be a good way to do the electronics?

#40 Guest_ShawnW_*

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Posted 07 July 2003 - 02:32 PM

Archiving now. Anybody has any questions regarding CIS just start a new post.

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