Getting rid of the onboard computer

[itwasthedog]

Howdy -

I have a 97 sephia, 1.8L, 5-speed manual, use it for a commuter - it's a plain jane, but it's fairly comfortable for my 45 mile each way 5 day a week commute. It gets 32 - 36 mpg, it's no hot-rod, but it has plenty of power to pass when needed.

The only thing about the car that is making me mental is the on board computer. I'll be buzzing along, fat dumb & happy, then the thing will cut out for about 2 seconds, then back on for 2 seconds, then off, then on. I floor it and it takes off like a scalded cat - will pull hard clear to 100 mph+ (about then i get scared and back out of it), then it will cut in and out again at anything other than wide open throttle.

The current fix is to pull over, unhook the positive battery cable, ground it, count to 30, hook it back up and enjoy another 200 - 500 miles of trouble free motoring. The problem is that I'm afraid that some day, resetting the computer won't get me going again and I'll be calling a tow truck.

After looking at the intake manifold, I'm pretty sure I can take the upper portion off and build an aluminum adapter plate that I can bolt a carburetor to. The distributor - that's going to be problematic.

Back in the day when I was hot-rodding - engines were made of cast-iron, had 8 cylinders, and the distributors had contact points. The ignition timing was adjusted not by an on-board computer, but by a mechanical advance that would advance the timing as the RPM's increased, and by a vacuum advance system that would retard the timing as the intake manifold pressure increased (this would reduce the pre-ignition knock as the fuel mix leaned during hard acceleration). The contact points would supply a capacitive discharge to an EXTERNAL (can you believe it???) ignition coil each time a cylinder needed a spark. That's how we did it back when dinosaurs still roamed the earth, and velcro hadn't been invented yet.

I'm hoping that one of you young hot-rodders that know something about these new motors can give me some sound advice - I'd like to know if there's an earlier incantation of this Mazda engine that has a point style ignition that I can bolt onto this engine, or if someone makes an after market ignition computer that would adjust the spark timing based on engine RPM, manifold vacuum and engine knock (using the Kia's knock sensor or an after market knock sensor) that I can wire into this Bosch distributor. Or, does this Bosch distributor already have all that crap built into it?

I really hate black box technology. The idea that if the engine management system, O2 sensor, TP sensor - or any of that other crap goes south, you're stuck buying proprietary parts at inflated prices to fix it. And let's face it, repairing these things are well beyond the scope of the common car owner's capabilities.

Personally, I don't feel like getting screwed by my local friendly Kia repair man, so I would like to yank the computer, pitch it far into the back forty, and plow it under come spring. If someone knows how I can come up with a computer-less ignition system for this thing, please drop me a line.

Thanks.

[itwasthedog]

Come on! Doesn't anyone know anything about distributor interchange on these things? Surely there's a gearhead out there that is privy to the black art of de-computerizing a kia sephia! If not, I'll go trudging thru the U-Pull-It till I find something that looks like it will work. Is anyone even interested in de-teching their car to improve the reliability and reduce the maintenance costs?

[kiaracer]

looking for an old miata or protege would probably be your best bet. the bad thing is that they'll most likely be fuel injected too. if you wanna keep the fuel injection but would like to get rid of the stock ecu you could go with a megasquirt engine management computer. they're really easy to swap in and you can adjust the fuel maps, timing, etc with a computer. i'm not too familiar with the earlier mazda based sephias so i wouldn't know if there was any earlier mazda protege or miata 1.6 or 1.8L engine that were carburated or had distributors with points.

i don't think anyone is into getting rid of the fuel injection and puting on a carburetor because fuel injection is more efficient.

[itwasthedog]

Thanks for the info bud! I'll look at those distributors real close - my big plan is to build an adapter plate and put a carburetor on the engine. It's been a lot of years since I've seen one of those old B1800 pickup truck distributors (those had points - no computer) so I don't know if they had the same mounting as this current engine. I'd really like to get rid of all electronic engine control systems and make it as simple as possible. I remember that those old japanese engines were virtually unstoppable and very cheap to maintain. These current engines are of far superior design and there is no reason to have as many troubles with them as we have. The problem is obvious - the electronic control systems are so complex, with so many components and connections that they are quirky and temper-mental: This really makes me leery of driving more than comfortable walking distance from home.

An engine with a carburetor and a point style distributor will usually give you plenty of warning before you're shoe-bound. These dammit computer controlled engine management systems will leave you stranded at the drop of a hat. When that happens, you better have some franklins in your wallet to pay for a tow truck and the guy who will hang parts on your car until he stumbles upon the part (or loose connection) that is actually the problem child. And guess what? He will bill you for all the parts he hung that DIDN'T fix it too!

So - that's why I would really like to put a carburetor and point ignition on this little motor. I think the engine is a good design, and the car is comfortable enough for a commuter, but I'm way less than impressed with the electronic crap that runs it.

[kiaracer]

you just gotta know how to work on the complex stuff. being a kia tech, i have no problem working on them but i agree that a carburetor and points is simpler.

[itwasthedog]

Kiaracer - I hope I didn't get your dander up - didn't mean to insult you when I ranted about the expense of car repair. If you can figure these things out - hats off to you - you've obviously studied hard and have an honorable profession. I realize you gotta eat too, and you've probably got a small fortune tied up in tools and education - that's what makes you worth the money you charge. I'm just sniveling because I ain't got the brains to figure this new stuff out!

Anyhow, I've been doing some research on these Mazda engines - history, development, family groupings, etc... found all kinds of interesting stuff about them. (Please correct any of this that isn't right)

Apparently this is a B8 motor, an incantation of the Mazda B family that started as a 1138cc (1.1L) engine that was sold in little cars in Europe and Asia in the early 80's. The B8 was the first of the B family to have the increased block dimensions (they needed room for 1839cc displacement). So, we're looking at an engine family that has two entirely different blocks and a bunch of different head configurations - and who knows how many intake, ignition, and engine management systems that are proprietary from manufacturer to manufacturer. Yikes. It ain't like an older Cummins 350 that will be the same thing regardless if it's in a Pete, a KW or a Freightcrate.

I did find one interesting possibility - The B6D engine was sold in America in the Mercury Capri from 91-94, and the 94-96 Mazda MX-3 RS. On the engine in the Mercury, there was a distributor that had a dual chamber vacuum advance, a mechanical advance, and what appears to be a hall effect pickup and amplifier module of some sort. I looked at a lot of distributors on NAPA's shop online website, and the mounting looks like it will bolt on to the B8 motor that's in the Kia.

When the weather gets a little better, I'm going to cruise the U-Pull-Its and see if I can't get my hands on one of these. I'm going to see if it's something I can hook an aftermarket coil amplifier (like a MSD6? - got one in the shed - can't remember the part #) to the hall effect pickup and see if the base will actually bolt to the Kia's Mazda motor. Then all I gotta do is build an adapter plate to put a carburetor on the intake and presto - a motor that doesn't need a computer to run.

If you're interested in this perversion of automotive technology, I'll post as the project digresses. Either way, have fun - life's to short to do otherwise.

[itwasthedog]

I just gawked at the megasquirt sight - www dot megamanual dot com, Man, that is something!

I might have to crawl out of my cave and learn how the modern world works I guess. Thanks for the tip on that!