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Discussion Starter · #1 ·
I'm considering swapping the fuel injection system off of a '84-'93 2.5l tbi s-10/s-15. These trucks are plentiful and cheap, and I think it'll be pretty straight forward. I'll have to make an adapter plate for the tbi, mounts for the sensors and put in a return line to the tank. I want to keep the toyota motor for reliabilty and light weight, but add simple/cheap injection. What do you think?
 

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The only difficulty I would see is in the ignition system. The EFI computer controls ignition timing and gets a signal from the magnetic pickup in the distributer for rpm and timing. It is certainly possible that the GM system will be able to "read" the signal from the pickup in the Toy electronic distributer and igniter. It depends on if they use the same style pickup and the "data rate" of the system.
Otherwise, the system will work O.K. given that the engine displacements are similar.
 

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I looked into this 6-7 yrs ago when I had a carb'd 22R and couldn't figure out what to do about the signal from the distributor. I found something years ago on the DIY-EFI board about possibly using a GM dist module that would convert the Toyota tach signal to what the GM computer was looking for.

EFI knowledge for the avg guy has come along way since then maybe someone can give you that piece of info. Besides that it's pretty straight forward: O2 Sensor, MAP sensor, TPS sensor and wire it up.

not sure if it wouldn't be simpler to put a 22RE intake and works in since it's been done quite often and is fairly well documented here. good luck with it though.

- jack
 

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Interesting.... One thing you are going to have problems with, fuel mapping. You might be able to pull it off if you can find somebody who can really tweek a custom prom. As for the reference to the ecm, that would be easy. Just use the a/c output off the dist to an ignition module off the same motor as the tbi. I can't see any reason why that would not work as the a/c outputs of both versions are pretty close to the same and I don't think the module would notice the difference..
 

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Discussion Starter · #5 ·
I'm wanting GM over Toyota is (1) simplicity, (2) availibilty and (3) price. Around here you can buy a whole s-10/s-15 for less than the price of a 22re with no electronics. And the GM's are far more plentiful. Thanks for the advice on triggering the module.
 

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Id vote on using a chrysler TBI setup. Shouldn't be all that hard to do. The wire harness can be made to a stand alone configuration pretty easy. Computers can be socketed and custom cals can be made too, but no ones dumped a TBI SMEC cal yet (im working on doing a cal but its for a the car)

only hard part of the swap would be too make a custom distributor or swap the guts into a toyota dist, which *might* be doable to
 

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crash said:
Interesting.... One thing you are going to have problems with, fuel mapping. You might be able to pull it off if you can find somebody who can really tweek a custom prom. As for the reference to the ecm, that would be easy. Just use the a/c output off the dist to an ignition module off the same motor as the tbi. I can't see any reason why that would not work as the a/c outputs of both versions are pretty close to the same and I don't think the module would notice the difference..
I think that since the displacements are similar, and the VE for each engine should be close enough that the EFI's adaptive stratagy should compensate. If after running the set up for awhile and the Long term fuel trims start getting up there (+-30%) You could compensate with an adjustable fuel pressure regulator.

As far as the ignition pickup is concerned, again, it depends on the data rate. If both the GM and Toyota distributers have four lobes passing a magnetic pickup, then you are O.K. If, howerever the EFI system you run is a High data rate system, there may be as many as 64 signals per revolution to moniter camshaft position and speed. These may also have a missing "tooth" to identify no. 1 position. There are also systems with a tin ring and windows that generate a square wave digital signal, using either an optical or magnetic sensor. Some systems also use a crankshaft position sensor to moniter crankshaft speed and rotation off of the crankshaft. I am not familiar with the GM system you want to use.
 

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zags said:


I think that since the displacements are similar, and the VE for each engine should be close enough that the EFI's adaptive stratagy should compensate. If after running the set up for awhile and the Long term fuel trims start getting up there (+-30%) You could compensate with an adjustable fuel pressure regulator.

As far as the ignition pickup is concerned, again, it depends on the data rate. If both the GM and Toyota distributers have four lobes passing a magnetic pickup, then you are O.K. If, howerever the EFI system you run is a High data rate system, there may be as many as 64 signals per revolution to moniter camshaft position and speed. These may also have a missing "tooth" to identify no. 1 position. There are also systems with a tin ring and windows that generate a square wave digital signal, using either an optical or magnetic sensor. Some systems also use a crankshaft position sensor to moniter crankshaft speed and rotation off of the crankshaft. I am not familiar with the GM system you want to use.
Ok you have confused me, high data rate? If you are talking about what I am thinking, you are refering to the newer genertation pcm's...

The early ecms are very poor with fuel adaptabilty and can only modify themselfs in very little amounts...

#1 position, no gm has ever had an indexing mark, that is done using a cam sensor, and you are refering to sequential injection, a more complex system...
 

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I guess I kinda confused things by adding too much info on other types of systems. I thought it might be helpful for others who are considering EFI swaps in general. Ford used High data rate systems back as far as the late eighties on some SEFI applications. like I said, I don't really have much experience with GM systems. I do know that all EFI systems that utilize O2 sensors have some type of ability to adjust fuel mixture adjustment to compensate for altitude, engine wear, malfunctions,ect. Every system I am familiar with (Mostly Toyota, Nissan, Mazda, and Ford) Can adjust at least 30%. Thats a lot. Even if the GM stuff only goes half of that, it should be enough with the stock software that you can dial it in by just adjusting fuel pressure.

One additional thought. If the EFI system you use does not use vacuum or mechanical advance in the distributer, you will need to lock that out in the Toyota one.
 

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Discussion Starter · #10 ·
Thanks for your responses so far. Please keep them coming. I know I'll have some kinks to work out. But, if I can get it right and it's cheap enough and easy enough, I'll do a full write up with pics. It could be a source for cheap injection for us 22r guys.
 

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I've been thinking about this too. You could probably use hall-effect sensors (crank trigger) if you had to do some serious adapting of the distributor signal - IE use signals from the crank.

I've also considered adapting one of the holly pro-jection units, but most provide too much fuel.. and the pro-jection doesn't get good reviews on normal installs.

I've decided that the best way to do it is the "DIY-EFI" way - IE, megasquirt. I know there is at least one person who has one it..

On a 22r, this would involve drilling/tapping the head for the 22re manifold (cheap and available) - most of the sensors could be used from that....

I'm considering doing megasquirt myself and might be willing to assemble the megasquirt (not install or program) for a fee while I'm doing my own (I've got an EE degree and now abit about electronics assembly). I know that base mappings for the 22r are available. Megasquirt does not control spark.

Cost for megasquirt is about $260 unassembled.
 

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dcg9381 said:
I've been thinking about this too. You could probably use hall-effect sensors (crank trigger) if you had to do some serious adapting of the distributor signal - IE use signals from the crank.


A crank trigger setup would not work on a stock system designed to get its signal from the cam or distributor. The crank turns twice as fast as the cam and distributor.
 

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FYI...I dug up some very preliminary notes Jack and I were starting to put together on doing a 2.5 TBI on a 22R. This was done 12/96 and was a first pass. For what it's worth.......
Jay

Went thru the schematic starting at the bottom of the ECM and going to the right. Then went left to right on the top of the ECM. Kinda hard for me to read some of numbers so some may be wrong and you can correct.


Part – Location - Wiring

Manifold air temp sensor – Intake - GM harness only

To A/C system (probably monitors when compressor is on so ECU can bump idle up, 2 wires?)

MAP sensor – Intake - GM harness only

TPS - TB unit - GM harness only

Coolant Temp sensor - Water area (neck?) - GM harness only

Oxygen sensor - Exhaust pipe - GM harness only

Idle air control - TB unit - GM harness only

Three wires at lower right of ECU ????

ECM A0 - (wire) - To Toy ignition switch

Fuel injector - TB unit - GM harness only

ECM C9 - (wire) - To Toy ignition switch

EGR solenoid (I think this is so the ECM can command the EGR solenoid open/close if so, you could leave unconnected)

ECM C15 & B1 - (wire) - To battery voltage

VSS (not applicable for 2.5L)

Fuel pump circuits

Looks like A2 is an ECM monitor line that watches the fuel pump voltage, not positive though. Would like to get some more info on this or see what they call the line. Looks like A1 drives the fuel pump relay, turning the pump on and off when needed. Looks like A12 may just provide voltage to the fuel pump relay or may be a monitor. Again, I need more info here.

Not quite sure about the fuel pump prime stuff.

Essentially the way the fuel circuits work is that they turn on the fuel pump for some x number of seconds when you first turn the key on. After this time, the ECM looks to see if you have oil pressure. If you do, it keeps the pump on. If no oil pressure, it cuts the pump off. This prevents gas from continuing to pump should the engine die for some reason. The one exception is that the pump is active anytime you turn the key to the 'start' position.

The fuel circuit shouldn't be hard to implement.

Idle air control (why two?) - TB unit - GM harness only

Battery, alternator, starter, clutch switch, ignition switch, etc. - Existing Toyota

Coil, Distributor (The distributor is still the tricky part. I see the four wires from it to the ECM, but I do not know what they are. These are the signals we have to figure out. I know basically what should be there, but I need all the specifics.)

 

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I still think the chrysler injection would be easier then a GM swap plus there is a 2.2 and a 2.5 liter cal
 

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dcg9381 said:
the pro-jection doesn't get good reviews on normal installs.

thats no joke, guys in my club use pro jection on jeeps and chevy's. whenever something goes to hell, they are down for a week or so waiting for parts from holley, not like going to the boneyard for some common s-10 parts.
 

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Colorado_bound said:
Thanks everybody, this info is greatly appreciated. Matt, any specific vehicles to look for?

anything TBI 2.2/ 2.5 from 87 - 95?
 
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