Fuel Injection Options for 3A?

[Mad_Marx]

I've been looking for a reasonable (not ridiculously expensive) fuel injection set up for the 3A motor, and can't seem to find anything. Weber makes a kit for the VW Air Cooled engines that looks like it could be converted, but at close to $2,000.00 it doesn't look like a viable experimental build. There are some Single Fuel Injector throttle bodies for BMW in the 44 to 55mm range that look like they might work, and there's the Old Rochester 700 unit (cheap and easy to source). But that still leaves me not knowing much about the control systems that would have to be mated to the Tercel... Assuming an electric fuel pump, and some sort of pressure regulator would have to be installed, the 02 sensor would have to be in the loop for feedback, then addressing ignition timing, and a temp sensor for cold start control. Oh how I wish Holley made a Projection kit small enough.... Has anyone here documented a fuel injection conversion?

I looked through repair guides and searched the forum as best I could, but couldn't find anything. Ideas? Resources outside the forum?

Thanks in advance

M_M

[dlb]

i think teranfirbt came up with something but am not sure. search his posts and you should find it.

[Petros]

there is a very old thread where someone adapted (fairly easy) a throttle body injector out of a Suzuki Swift/geo metro. It is self contained with all the necessary sensors within the throttle body. find one at a wrecking yard.

Someone not too long ago got a motorcycle carb set up to work, with 4 small one barrel carbs (off of a popularl bike that owners like to up grade, so there are lots of these used carbs around). He had to mess around with the jetting to get the economy up, but the 4 one barrel side draft carbs look really cool and the next best thing to multi port injection.

If you are willing to cut and weld you can make up your own manifold and adapt any EFI system with enough messing around with it. But before you do that I would consder just doing either a head swap, or just a whole engine swap with the fuel injected 4AFE or 4AGE, both engines will bolt into the tercel with some fabbing of parts (there are threads on both these topics). Than you not only eliminate that troublesome old carb, but also replace that obsolete (and crappy) 8 valve head with a more modern 16 valve EFI head. Most of the parts you need you can get from a wrecking yard, or from Craig's list from people parting out EFI Corolas. The only big job is you have to make an exhaust header that will fit in the Tercel since the twin cam heads exhaust out the other side as the 3a single cam head.

[teranfirbt]

Until a couple of months ago I was running CBR600 throttles on Megasquirt with Ford coil packs for wasted spark. It ran well, but was a bear to tune since I couldn't do speed density, cold running was awful but it ran nice once everything was good and warm.

Current I'm working on a 5AFE swap (1.5 liter 4AFE) that will end up with custom intake, exhaust, cooling pipes, Ford coil packs, and Megasquirt.


For the fuel system on the 3A I built a small surge tank that was installed in the engine bay filled with the 3A carb fuel pump. I fed an EFI pump also mounted in the engine bay to get 40 PSI behind the injectors. For the 5A I've got an electric carb pump back by the tank with an added 5/16" pickup feeding the same surge tank and EFI pump.
I'll be getting a bunch of pictures up when everything is buttoned up and running, a lot of it is still in flux from a design standpoint.

Btw, none of that is the easy route. A lot of custom parts that require access to machine tools and welders. The easiest way is going to be to adapt some kind of factory TBI system with a surge tank and an efi fuel pump, surge tanks are 30 bucks on fleabay and factory fuel pumps are cheap on Rockauto. Could realistically be running EFI for 500 bucks using Megasquirt, I wouldn't want a factory system from a completely different engine.

[Petros]

Teranfirbt points out the difficulty developing a fuel injection system for an engine that never was feul injected. A lot of special made parts, adapters and trial and error solving drivablity issues.

That is why it is far easier, faster and cheaper just to do an engine swap with an engine that already has a fuel injection system designed for it. The factory already sorted it all out, all you need to do is get the parts, used from a wrecking yard or craig's list, and find a way to install them in the Tercel. The only challenge is purtly making it fit, such as an exhaust header (which is a straightforward cut and weld project for you or a muffler/custom header shop), and a few other relativity easy problems to solve. None of which would be drivalblity since you will be using the whole factory set up from the other car.

[teranfirbt]

In terms of factory EFI engines, 4AGE head on a 4AFE bottom end (or just crank really...) is the easiest since north/south intake manifolds are already available and the 4AFE crank has the correct number of holes for the Tercel flywheel (Which is unique to the T4WD).

I've seen 4AFE's in the T4WD with the factory manifold and some shenanigans out of the throttle for an air filter, but mine ended up with only ~1" of clearance between the throttle and the firewall, so I decided to just make my own intake so I can actually have an air filter... To me the whole project is for fun, and I have another car that I can daily drive. Any EFI conversion is going to end up taking more time than ever planned, and it's not guaranteed to work out of the box if you haven't done that kind of conversion before, so don't plan on trying to swap in EFI in a weekend and drive the car to work on Monday.

That being said, if you do the conversion you'll learn a ton about how engines and fuel injection systems operate, which makes diagnosis of problems easier.

[dlb]

i like teranfirbt's point. i agree that any complex engine swap should be done for fun more than any supposed upgrading since it is so much time, money, and effort. the cost vs benefit ratio is completely imbalanced.

[Mad_Marx]

Thanks for all the food for thought! The engine currently in the car is still very fresh. I have about 8,000 miles on it since the rebuild, I don't want to start another engine build/swap at this point. A TBI set up that could be adapted to fit(and look) stock parts would be ideal, I'll keep my eyes peeled for a small TBI at the local pick n pull.

[teranfirbt]

If you do fuel inject, I can't recommend enough to *not* use the stock computer that comes in the donor car, it just won't be set up correctly. You can pick up Megasquirt 1 kits (get the V3 board) for 200 buck, and a wideband setup for another 200. Using the factory Tercel distributor for spark you can get fuel only MS running and tuned pretty quick.
Let me know if you have any questions, I've done 3 different engines with Megasquirt that all ran great and returned better than factory mileage and power.

[Mad_Marx]

I looked through the Megasquirt site, so much information! Thanks again. Is there a way to tune it without a laptop? Like the Holley Projectionunit with tune knobs built in. Once you get it where you want it tunes itself. I think Edelbrock has a self learning/tuning set up. I'm concerned about passing smog. They aren't super strict here as long as it falls within sniffer parameters, but in the event it runs rich or something, I'd like to be able to fettle it.

[splatterdog]

Look up Hornbeam! I think it was a Suzuki tbi setup.

[dlb]

here is some stuff on the suzuki TBI stuff. more links within the thread.

viewtopic.php?f=6&t=6844

[teranfirbt]

I looked through the Megasquirt site, so much information! Thanks again. Is there a way to tune it without a laptop? Like the Holley Projectionunit with tune knobs built in. Once you get it where you want it tunes itself. I think Edelbrock has a self learning/tuning set up. I'm concerned about passing smog. They aren't super strict here as long as it falls within sniffer parameters, but in the event it runs rich or something, I'd like to be able to fettle it.

You'll need a laptop for tuning. You can get decent used IBM X120e for ~100 bucks on fleabay, it's got more power than a typical netbook but fits on the passenger seat better than most normal laptops. You'll want to invest in the full TunerStudio software, it has a powerful auto-tuning function built in.