my carburettor seeks freedom from its computer control (electronic enslavement)

I own a faded blue 87 GL sedan. It has the electronic feedback carburettor (slap the engineer that thought THAT was a good idea). Its a little low on the options list, it doesn't even have power steering....or power windows, or power locks....but it DOES have power mirrors!! woohoo!! Anyway, it does the basic transportation bit pretty well, and has even survived a few off road excursions (or as I prefer to call it, "prairie surfing"). This car has run solid for the 3+ years that I have owned it, except for some annoying issues with the computer-controlled part of the intake system.

The car had no muffler when I bought it (rusted up and fell off). So I put on a simple flow-through glasspack muffler. Wasn't loud anymore, but you could still hear a good tone, and I figured it was a good idea for the exhaust pipe to exit behind the car, not under the back seat. Every so often, the car would adopt a rough idle, back-fire more, and the ECS (emissions control system) light would come on. This meant that the poor computer could no longer adequately "fix" the imperfect air/fuel ratio from the carburettor (probably crap built up in the "duty solenoids" that mess around with the carb). Blast some carb cleaner through it, drive it a bit, and it would clear right up.

Everything was fine...until a few days ago, when little pieces of my catalytic converter came flying out my tailpipe. Then big pieces, and the more pieces that came flying out, the louder the car got! It now has quite a rumble at idle and roar at full-tilt-boogie (WOT). Anyway, i'm not complaining, i rather like it loud (haven't listened to radio since....just roll down the window and listen to the "engine music").

Yesterday, the ECS light started coming on again. Now, the only reason the computer was screwing with the air/fuel ratio was to keep the Catyl'verter happy (whole lot 'o' good THAT did). With no more 'kitty-Cat', whats the point? I think the car would run stronger (and be simpler) without all the computerized shenanigans going on in the intake manifold. The plan is to: (A). either remove all extraneous solenoids and valves from intake manifold and plug the holes, or swap the carb onto an efi manifold. (B). Remove ECS light (C). Tell the computer to go to hell.

If anyone's done this and has wisdom to share (or is simply smart enough to know something I don't already) please let me know. Don't tell me not to bother, I shall not be swayed...so don't bother. If you think I'm crazy for undertaking this project, you don't know the half of it. After the carburetor is liberated from its electronic restraints, I plan to mount it at the mouth of a turbo.....draw-through style! But that's a project for another day. One step at a time....

p.s. i realize that driving a car with no cat and removed/disabled emission controls is illegal...it will be for OFF-ROAD USE.

I would convert it to fuel injection. Even a batch fire system such as Megasquirt would be easier and cheeper than trying to fuck with that carb system.

the subaru carbs had major problems. Even when the entire system was stock, they can be very hard to get to pass emissions, they like running rich at cruise. I've never bothered disecting why exactly, because I don't "do" carbs....I just diagnose problems.

Your goal of removing the feedback portion of the system isn't worth while. What you need is a better carberator (or fuel metering system in general). Your problem is, I doubt you have a whole lot of bolt-on options that are cheap. You could, of course, swap out the entire engine with a more modern EFI setup. Not cheap. You could convert to megasquirt. Not only would it require a decent chunk of money, but requires quite a bit of learning, knowledge and fabrication.

If it was me, and I was being a cheap bastard, I would bastardize it to accept a better carb. Maybe a CV carb off of a Vtwin motorcycle. Plenty of carberation for your car, already downdraft config, and would take hardly any fabrication to make it work. Simply need a round tube to mate it to. Tuning it would require a little trial and error....but that would be a given no matter what you went with.

and...you could completely remove all the emissions crap these cars are infested with (I absolutely hate feed back carb systems too)

But then, I'm also very familiar with tuning carbs, and bike carbs....so thats the first angle I look at. Its probably not a very practical suggestion for most people....but I'd bet it could be made to work well if someone had the time to kill.

Is this car an 97 Subaru Leone???


As for feed back carb systems the one in my 89 Honda works very well, its not quite as good as proper programed fuel injection, but its better than a mechanical fuel injection system.

As for feed back carb systems the one in my 89 Honda works very well, its not quite as good as proper programed fuel injection, but its better than a mechanical fuel injection system.
until something goes wrong.

Trying to find the source of a problem on a honda feed back system is a nightmare! Must be 30 vacuum lines, at least 10 vacuum valves, meters etc....and nothing is easy to get to, or easy to find info on.

I did like the short-lived prelude twin carb setup, because they used Mikuni CV carbs right off a Honda motorcycle....until they added all the feed back stuff anyway :screwy:

I did like the short-lived prelude twin carb setup, because they used Mikuni CV carbs right off a Honda motorcycle....until they added all the feed back stuff anyway :screwy:

Now I know why they sound so good on a cold winters morning :)
The mass of vacuum lines does look bad, but if you take a logical approach to it, and read the diagram on the lid of the control box, it's actualy quite simple to understand and trouble shoot.
Iv never had to do it on my car, but Iv done it a few times on others.

I have a question for "TheSilentChamber": How is converting to a completely different Fuel Injection System (megasquirt or otherwise) "easier and cheeper [sic]" than tweaking the system already in place? Me turning wrenches is free; buying new systems, adapting them to work in this application, probably a little custom fab involved.....definitely not free. maybe i'm just not following your logic; care to elaborate?

UncleBob, I realize that my carb might not be all that great, but it seems as though it could work better without all the emissions carp. Besides, the Carburettor Liberation Movement is only the beginning. And yes, I do have "the time to kill."

Moppie, where did 97 Leone come from? look at the top of the page....the post that started it all, i believe it says: "faded blue 87 GL sedan". which is indeed the car in question.

Feedback systems suck...this we know. Removing "all that crap under the hood that doesn't make it go any faster" won't necessarily fix all the problems, but carb diagnosis and adjustment will be much easier without "all that crap" constantly changing settings and messing things up. And it'll look alot prettier. I might actually be able to see the engine; without tubes, hoses and "vacuum solenoids" blocking the view.

It will also simplify the conversion process to A: a different carb, B: an EFI or throttle body setup, or C: a turbocharged form of induction (draw-thru carb, blow-thru carb, EFI, Throttle Body, or otherwise)

p.s. don't worry, this isn't my daily driver...it's the car i wrench on when i'm bored.

if i wanted to poke around an engine bay crammed with a myriad assortment of vaccuum lines, i'd buy a twin-turbo RX-7....well, i want to buy one anyway, they're just a bit pricey (especially on a 20-something's insurance). and its getting harder to find examples that someone hasn't blown up.

whatever i do to my Suby, be it custom-fabbing, carb-swapping, or just carb-fixing, that feedback carp is coming out.

I have a question for "TheSilentChamber": How is converting to a completely different Fuel Injection System (megasquirt or otherwise) "easier and cheeper [sic]" than tweaking the system already in place? Me turning wrenches is free; buying new systems, adapting them to work in this application, probably a little custom fab involved.....definitely not free. maybe i'm just not following your logic; care to elaborate?



I'm not sure if what your wanting to do is a matter of tweaking rather than an act of reconstructive surgury. Logic behind my responce was if you replace the carb with one thats not electronically controled, your looking at probably $200, and you still have a carb (I have a profound hate for carborators, but thats a differnt story). Now say you wanted to do a megasquirt system, thats $100ish, plus say $50 in parts from the junk yard- intake manifold, fuel rail, injectors, and a few sensors. Now you have a fuel injection system (primative, but still fuel injection) that is alot more tuneable than that carb, and easier to tune once you turbo. Draw through turbo has allways been a bad idea in my mind, your mixing air and fuel, adding heat and compression... if something goes wrong you have a whole charge pipe thats essentually now a pipe bomb.

Moppie, where did 97 Leone come from? look at the top of the page....the post that started it all, i believe it says: "faded blue 87 GL sedan". which is indeed the car in question.



Faded Blue 87 GL dosn't tell me shit about what sort of car it is.
In 1987 I can think of half a dozen manufactors who used the GL tag any number of their different models.

Uncle bob said something about it being a Subaru, but you have a Nissan listed in your profile, and a photo of a Nissan Pulsar EXA (one of the worst cars ever made) in your Avatar.

If its a US spec small 1600 or 1800 Subaru then it was sold else where in the world as a Leone, and I might have some ideas, as my brother used to own one.
If its a US spec Nissan Pulsar EXA then I deffinitly know how to solve your problem.

Sorry Moppie, I had originally posted this in the Subaru/Nonspecific category...(which received few views and no response) I then reposted it here without specifying it's Subaru nature. The car is a blue US-market (California spec) 1986 Subaru GL sedan, which in later years was called the Loyale, and my service manual mentions the 1600, 1800 name. My other car is a US-market 1987 Nissan Pulsar NX SE which appears identical to my profile pic (stolen from nissanexa.com or somewhere...i don't remember) which is immaterial to this discussion. I realize now the confusion potential of having a car-picture for my Avatar and asking automotive questions without exactly specifying which car I have. oops. my bad.

SilentChamber, my intentions at present (they may change without notice) are to keep the current carb and to simply remove or disable all who would seek to hinder its operation (all the valves and hoses and crap that masquerade as an emmissions control system). Where I go from there all depends on when I get there, and how much money is in my wallet then.

Realze that that stuff doesnt just hinder its operation, it makes it operate.

TSC is right, with out all the extra crap the carb won't function correctly.
This means replacing the carb.

Fortunatly, I happen to know the Japanese market version of that car didn't have a feed back system on it, like wise the NZ market version.
So if your clever you maybe able to get hold of a carb from overseas, here from a wrecker here in NZ, or Japan, and then retro fit it.

Or, since Subaru are very good at useing everyone elses parts, and building very few of thier own, find out what brand of carb it is, and see if a replacement is easily obtained.
What I think you will find however is the carb thats on there bolts to a manifold with a standard choke size and bolt pattern. Likly to be the same as used by Webber and Dellortto etc.
This makes it really easy to find a replacement, and your biggest cost will be a little time on a dyno getting it tuned.

I like how this thread has gone full circle :licka:

TSC, I'd like to see you build a MS system with $150.....Thats one very mighty friendly junkyard you go to that has a really awesome selection of parts! And where are you getting the MS for that cheap??

draw thru's do suck....no reason you have to do it that way though. Blow thru carb systems work very well.

And not that its all that important, the avenue I was suggesting would probably cost around $50. Maybe $100. Depends on Ebay.

Realze that that stuff doesnt just hinder its operation, it makes it operate.

this is very true. Its the biggest reason I wouldn't use the carb. You will not get it tuned properly without doing some pretty serious modifications to it. IE, re-engineering it.

Granted, it'll run without the feedback stuff. But not nearly as well as it could.

Yeah, your right, price on the mega squirt kits (even version 1) have about trippled sence last time I looked at them. You used to be able to get the kit for less than $100.

Wow, this thread is pretty interesting, makes me want to get a little tinker-car (like an 80's civic or something with a carb).

anyways i think the simplicity of a carb would be good for what you want to do. efi would be more difficult to tune and everything. hell, you might be able (and that's a decent sized MIGHT) to do a quad carb system since this is a fun car to play around with, i think it might be a little fun project, it won't give you any real improvements if you get a turbo though. the problem with carbs is that they are very very difficult to tune for a turbocharger and dont give you the performance that an efi system would. I would opt for going for a later model's efi system if it's available. if there are some, go to a junkyard, pick up a bunch of stuff, enough that you could "forget" to show some stuff and they wouldn't notice that you took some extra becauuse you're already claiming quite a few things. so if there's something small, just stick it in your toolbox. most places like these don't have any kind of survailance so they won't even notice.

also, if you get some stuff you don't need, just come back later and tell them that it didn't work or whatever and ask if you can get your money back if you go put them back on the vehicle.

Dont steal from the junk yard, most are just family owned operations trying to earn an honest buck.

shame on you Mr. (beef_bouri)T(o) !!

I like the fine folks at my Automotive Dismantling and Salvage yard*, they've given me lots of little pieces for free (small hoses, electrical connectors, etc.) Or they say: "eh, don't worry about...we know you'll be back...catch ya then" They're cool like that. I'm sorry if you think that stealing parts is the only way to get a good deal. Perhaps your flawed logic is the reason for your skewed perception of the world (in relation to honesty in business relations, that is).

I do recommend getting a tinker car, its so much more fun to have pieces of your car's engine spread all over the garage when you don't have to put it all back together before morning so you can drive to work and get money to pour into your insane automotive project! But don't steal from junkyards*!! I'd laugh if "bad car-ma" catches you and your project car of stolen junkyard* parts gets stolen and parted out to junkyards*. Could you really be mad? It'd be going "full circle"

UncleBob, "draw-thru's do suck"....of course, duh! where do you think the name came from? the turbo is sucking on the carb....he he he...i know it's not the "Best System EVER!!!" but I want to try it. just cuz. if it "sucks" as bad as everyone says, i'll "re-engineer it." But I want to try it first! "It won't work" is like "I triple dog dare you" with me...

As for the carb not working without the stuff, I unplugged everything yesterday, and it ran like a champ! when i plugged the solenoid valves back in, the engine sputtered, almost died, then settled into a lumpy, "i really don't want to idle" kind of idle. whereas just before, with it all unplugged, it would idle smoothly, almost purring. and it "feels" smoother and maybe a bit more powerful when the stuff was unplugged. But I want to simplify the underhood system, and I am still convinced that it is a worthwhile endeavor.

Quick question....has anyone ACTUALLY removed the feedback systems from the carburettor on an otherwise well running car? I hear a lot of "It needs that stuff" and "You'll never get it right" but I'm not hearing the "I did it and here's what happened" which is what I was really asking for in my original post. I don't need "It won't work"...but if you can tell me why it didn't work for you, then we're getting somewhere.

* junkyard is a slang term for an Automotive Dismantling and Salvage yard. Unless they have a crusher. then the term fits rather neatly. (In My Humble Opinion....)

I think all the different feed back systems used all work quite differently.

I know if you disable it on my Prelude it won't work.
However, I also know there are some settings that set mechanicly on the carb, and then overridden, or controled by the ECM.
For example idle speed is set mechanicaly, but over ridden when its cold so it runs faster and richer.
Removing the feed back system would remove the choke control, making the car impossible to start when cold. However, if you warmed the car up, then removed only that part of it, it would still run very well.

Its possible the Subaru system is a lot simpler than the Honda system (which wouldnt surprise me, the Honda system is an excerise in complexity) and it may only over ride machanical settings when it thinks something needs changing.
Its quite possible the carb, set mechanicaly, works very well, and the feed back system only works to make it a little more efficient, or in this case works to make it a little more in-effcient.

It is my understanding of the Subaru system from reading the manual, looking at the engine, tracing hoses, minor disassembly, and from my mechanical intuition, that the carb is self contained, and the feedback system hangs parasitically off various parts of the manifold. And though it at times interferes, it has no direct mechanical control over any carb settings.

Also, my carb has an electric choke that is completely independant of the "shenanigans" going on elsewhere. I do not intend to remove the choke. it gets cold here. that would be a bad move. I believe the carb is up to the task of mixing fuel and air, then feeding said mixture into the engine. The feedback system was necessary to sell the carb-equipped car in California in 1986. I live in a part of Colorado which does not require emissions testing. And I get the feeling that the feedback system doesn't work quite as well as it did 200,000 miles ago. Therefore, I wish to evaluate the carb's performance without the system (requiring the system's removal). We'll see where I go from there.

As for recommendations and preferances toward other systems, methodologies, feel free to rant on your own thread.... that's what the "start new thread" button is for.

Then rip that evil parsitic sucker off the carb and see what happens. :D

If you unhooked everything and it ran fine, what was the point of this thread?

I think it was to ask a question so he could not like anyone's suggestions that didn't follow his original preference :screwy:

I think you should convert it to propane :icon16:

the problem with carbs is that they are very very difficult to tune for a turbocharger and dont give you the performance that an efi system would.

this is plain bull. You have two choices. you can jump into unknown waters, where people have never gone before, and it might be simple, and it might not be....but this greatly depends on the person doing the experimenting. Or you can take a tried and true system, where someone has already done all the research for you. Let me tell you there are dozens and dozens of carb blow thru systems than have been tried and tested that you can copy to a 'T" that will get you very good results.

They may not be as EASY to tune as a fancy EFI system....but lets get this straight. Too many people think that a EFI system with a FMU is better than a carb'ed system. There is many different flavors of carbs and EFI, and there is definitely worse situations with EFI than there is carb'd, depending on the examples. FMU's are one of them.

But then, if you know what you're doing in the beginning, you don't need a perfect step-by-step instruction for a given circumstances....This is where one or the other gets a bad name...its from people making an attempt at it and they don't know what they are doing. Good recipe for someone to get frustrated and quit. But then they don't say "I don't know what I was doing, therefore I suck". No, they say instead "blow thru carbs are too difficult to tune".

You have to read between the lines.

UncleBob, "draw-thru's do suck"....of course, duh! where do you think the name came from? the turbo is sucking on the carb....he he he...i know it's not the "Best System EVER!!!" but I want to try it. just cuz. if it "sucks" as bad as everyone says, i'll "re-engineer it." But I want to try it first! "It won't work" is like "I triple dog dare you" with me...


Its not a question of it "working"....it can work OK, but the design of it, it will not idle well, it will not have low-throttle response that is good. Its also, IMO, harder to tune.

I wont' tell you not to try it, because it has been done many times in history with decent "success". But....and this is a big but....if you want a fun street vehicle with good idle quality and stock-like drivability, a draw-thru is definitely not the correct direction to go.

You will find die-hard draw-thru' users if you look for them, and they will tell you its "easy".....and maybe if you follow their suggestions perfectly, you will be happy. But I tell you this, every draw thru system I've had personal contact with has had the same issues no matter what they said on the net. They didn't idle well, and they had low throttle response issues. Even if they said otherwise.....

Blowthru on the other hand....not a problem

sorry, i didn't write what i wanted to write. what i meant to say is that they usually won't give you the performance you want because they're more difficult to tune and if you don't do it right, it'll suck. with efi it's more forgiving when it comes to small mistakes.

Am I the only person that reads posts from the beginning?

My original question, and "the purpose of this thread" was to see if anyone had removed or otherwise disabled a feedback control system on a "computer/carburetted" car. Some of the responses have actually shared useful insight. I believe I'm entitled to ignore the others, because A: they sought to answer a question that was never asked, and B: they were immaterial to the question that WAS asked. If that offends you, I do not apologize. Your preference may be for a different system, a different method, or for leaving the car "as it was when it rolled out the factory door". That's great, and I'm proud of you for standing up for what you believe in.

My car has a carburettor and it works fine! ...when the computer doesn't interfere. From research, and some online feedback, I became convinced that the feedback system could be removed, so I tried simply unplugging everything (which still leaves a lot of crap under the hood, so is not a full solution). I had not disconnected those wires until just then when I posted that I had done so! The car idles and runs much better now. I am going to dive into taking the system completely out, as soon as I can set aside the time (and floorspace in the garage).

As for all the systems touted and slammed by various posters, let's hear some stories! I'd love to hear about what did or didn't work for you. But vague generalizations and repetitious babblings are a waste of my time. Thank you, but no.

(the following is a little hypothetical game)

I walk into the grocery store and ask where the bananas are, and the clerk tells me : "bananas suck. you need apples, aisle 5." "Um...okay. but where are the bananas?" "I'm telling you man, bananas are bad. I mean, you're really better off going with apples. aisle 5, bro." I happen to know that I like bananas. To me, bananas are good. I'm asking for banana information, and all this guy wants to do is sell apples!! How frustrating would that be?!? not just for me, but also for apple-guy. He can't convince me of his perspective, because it's counter to my own. And I can't convince him, for the same reason. Sound familiar? Now, to recap: I walked in and asked where the bananas are. Don't accuse me of asking which is better, then rejecting the answer. That's not the question I asked. Fruit preference is not in question here.

BANANAS, %^*&@$&*#@&@!!!

And when I finish this project and get it all running, you're welcome to come over to my house. we'll go for a drive while you reiterate all the reasons it wouldn't work and i shouldn't have done it. it'll be fun.

Cars drive down the road, cars start, run, and operate at differnt rpm levels. Cars require percision.

Taiste cant be measured, bananas grow in a tree, get cut off the tree, and sit on a shelf. You cant measure the performance of a banana and compair how this banana will taiste comapired to another banana.

Obviously the lesson of the story is; never trust someoen who cant find produce on their own.

psychopathicdude You gave some general info, and asked some general questions, mixed in with some details, looking for detailed answers.

In reply you received a variety of general and detailed opinions, which is exactly what Internet forums are great at.
I don't see what the problem is.

you won't get any better info unless you find someone who has played with your particular carb in this fashion. I have disabled all sorts of feedback stuff on carbs thru the years....with varying success.

But, its a good thing your cat is already gone. Because this type of "playing" is a good way to start fires. Since you don't seem to have any data collection to watch how what you do changes what, as far as drivability goes, you're basically taking a big huge guess on many of the component changes.

So here's a very detailed answer that would help greatly: get a wbo2 :wink:

I know I "asked some general questions". And I may have overdone it a bit with the bananas. I've a small problem when it comes to asking a specific question. If you've not seen from my posts, I'll use 100 words when 10 would suffice. (My brother says me posting a question/response is akin to "writing a book"). And it's often mostly filler. Not necessarily pertinent information. Therefore, I suppose I ought expect the wind to blow some chaff my way along the wheat. Especially so great a wind as the Internet. As stated by Moppie, that's "exactly what Internet forums are great at." I also may have responded a bit too personally at times. I'm new at this. I could've/should've let some things slide rather than striking back. Plenty of good ideas, I needn't be quite so selective in what I consider, 'least not so vocally.

Thank you all for an informative and educational discussion.
When I dive in, and get my damn bananas, I'll let you all know.
I expect it to be a delicious success.
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To get rid of the computer control means you'll have to re-jet the carb. I've drilled out jets to get bigger, and soldered and redrilled to get them smaller. You can buy a bunch of spark plugs to read how your mixture is (just 1 new plug at a time)
Or you can put an older non-computer carb on. I've used a chunk of mahogany to build an adapter plate. It's a dimensionally stable wood so it won't wrap / leak when you're done. You might need an asbestos-type insulator gasket. Since all carbs give an idle circuit, and tried for a proper mixture, just get one close to the right CFMs, and it will work OK. It's easier to get a slightly smaller carb to work than a carb that's too big. I find getting the linkages to work the biggest problem.
Good luck