palric

iTrader: (1)

Back in '92 I had an '88 Formula WS6 TBI man was it slow. So I started doing a performance buildup that lasted about 2 years and $7500 in total. Then the wife got pregnant and I had to sell the Firebird (old story eh ?).
The performance buildup really killed my credit card dumb move that was but I SURE had fun while I was at it, so much fun that last summer (10 years later) I bought another Formula, this time a '91 WS6 G92 TPI).

Back in '92 I did the Holley 670 with Weiand 7525, installed an '84 T/A cold-air unit, did the pulleys, did the Jacobs system, swapped out the drum rear for disk and 3.73s (never did get the speedo right after that), did headers with MANDRELL bend 3 inch front to back (mondo $$$), put in a set of comp cams 1.6 roller tip rockers and an Isky roller cam. The setup would have been great if not for the poor selection of cam, 217/225 @.050 and .475/.505 lift (try the math on that with the 1.6 rockers). The car never did run right after the cam, couldn't get more than 11 inches vacuum at idle so the map went bananas. But the 305 TBI did manage to regularily pull 6400rpms and dusted off more than a few 5.0s.

I've checked out the TBI forum and it sounds like since then some people have figured out how to deal with some of these issues that back in '92 were virtually unresolvable (like what to do with too much intake lobe duration on a MAP driven system) because no one had done it before. Remember there were no 'forums' back then either and perf tuning a TBI was considered somewhere between pathfinding and folly.

There was one mod I always wanted to try -- the dual TBI system. Has anyone out there in 3rd gen land pulled this one off ? It is really simple in concept. All you need is a dual 4 low rise intake with an EGR and Edelbrock has just the ticket. The secondary TBI would work by piggy backing off the primary for signal and throttle, just like a dual 4 barrel setup. In fact Turbo City (CA) used to sell pre-fabbed setups for a princely sum back in the early '90s.

Anyone out there tried this yet ?

RP.




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'91 Formula Firebird G92,WS6,5-speed,3.42 a ton of fun to drive.

Tas

I had a link to a writeup but it disapeared a couple months ago. you used a 7525 on a 305? I'm looking at the 7547.

------------------
-Tas
'89 Formula WS.6

Got Beach?


[This message has been edited by Tas (edited October 15, 2001).]

Duke

I should have kept my tech write up on this. I might still have it somewhere, dunno.

My 427 had duel TBI, it was a PITA to burn chips for, but it had an awesome power range.

ChevelleCLM

I am building one up for a 7747 computer. It already has the 4 injector drivers, and the IAC should be no problem. If you just paralell them. I have heard everythign form resistors inline to only using 1. All they are is stepper motors, and as long as they get the same pulses it's all cool. This is how the Crossfire tbi's are setup. I have all the parts, but am lacking a dual quad intake to put it to the test.

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69 Chevelle 2dr hardtop blue, bench seats, 12 bolt w/3.73's muncie 4 speed. TBI w/custom harness and prom best 14.5@90

JPrevost

Where were you guys, I NEED help. I posted about a week ago about the 4 injectors problem with TBI and stock ecm. I got an e-mail from turbo-city and they don't have anything that'll help me since they stopped producing the kit
Duke, how do I control the injectors?
ChevelleCLM, how do you have 4 injector drivers on a 7747? You've confused me, stock 7747 ecm is only 2 drivers!
I want to run a 4 injector pro-jection unit, the 700cfm on my motor for many reasons. One being more power potential and the other is hood clearance (get to dump the stupid 1' adaptor plate). PLEASE PLEASE help me with this project. I want to run 4 injectors but have had little help from the diy_eprom board.
If you have any information let me know. I'm going to compile a website of information about this project and if you guys can help with ANYTHING be it a link, phone number, whatever, I'd greatly appreciate it.

------------------
, Jon (350 TBI!)
91 Red My website

Tas

hey jon, the TBI that you want is on ebay right now 700 CFM 4 barrel. Do a search on "Dan W" he has a 4barrel TBI. I don't think I needed to tell you, but just just in case, fyi.

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-Tas
'89 Formula WS.6

Got Beach?



[This message has been edited by Tas (edited October 15, 2001).]

soulbounder

Well, I'll be doing the dual TBI to the extreme really. When I begin on the engine, I'm planning for an aluminum 427 small block, dual TBI setup (snuf's new throttle bodies), and a Gale Banks twin turbo system. The only thing I'm not sure about is if the injector pod will cause too much turbulence for the boost to even make a difference. I don't believe it will. It will be relatively low anyway.

snflupigus

this is why i want to make the 2.25" 2bbl tbi. Just spent some more $$ on the 69, bought a bed and a new computer, What the hell im in debt, might as well build a tbi right? hehe, i think im gona spring a couple hundi on a drill press and build one myself. for fun. anyway....... all in time my friends. all in time.

90rsMustangkiller

When i got my new, cam, heads, intake, and tbi i had to buy a computer chip so it would would flow the right about of air, but anyway when i had the custom chip programed my ecm would not take it so i had to get one off a tpi car. so buy one for tbi, it can be used on up to 8 injectors and i got mine used for 150 bucks.

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90 RS 305 tbi, 4 3/4" cowl Hood, Crane roller cam, comp roller rockers, vortec heads/intake, ported tbi, w/new injectors, 1 inch tbi spacer, air foil, 14x4 k&n flat base air cleaner, Rebuilt 700r4 w/ B&M shift kit, B&M Megashifter, 3.23 posi, 2 12 RF's with mtx amp, top of line alpine cd player, soon to have 90-91 gfx, z-28 wing, new paintjob, rims, and all new lowered suspension

lonsal

iTrader: (2)

You mean like this one?
http://www.turbocity.com/EFIDualDtail.htm

------------------
90 RS Convertible
Owner: Top-Down Solutions
(626)369-0040

http://www.sc3gfb.org/members/lonsal.html
http://www.taskerinc.com/gs3/profiles/Lon_profile.htm

fast_broker

iTrader: (1)

Turbo City stopped making that one... Too many problems/returns, I heard...

ChevelleCLM

I emailed turbocity with a tech question and they treated me like an idiot. I would never purchase anything from them.

The 7747 just has 4 injector drivers. haha I dont remember where I saw it at, but it does. The computer puleses ground to the injectors, and they are wired solidly to the positive terminal. I believe the extra drivers are on 2 unused pins in the ECU. but as far as normal 7747 injector outputs there are only 2 and they are negativly pulsed. check out this url
ftp://ftp.diy-efi.org/pub/gmecm/manuals/1227747/747ecm6.jpg

see that the 2 drivers are wired in paralell?

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69 Chevelle 2dr hardtop blue, bench seats, 12 bolt w/3.73's muncie 4 speed. TBI w/custom harness and prom best 14.5@90

fast_broker

iTrader: (1)

I didn't check the link but are you saying that there are two UNUSED injector drivers in the 7747 ECU??? I knew that the two that are used are alternating, but to have two more would be ideal???


Is THAT what Edelbrock does (ie, use all 4 drivers) with their MPFI conversion OR do they just use the two drivers to run the 8 injectors???

EDIT: Just checked it out... All 4 are used/wired-up in a 350 while only two are wired-up in a 305???... Using all 4 drivers must make them more powerful for 350/454 injector duty??? I bet... So, if you have a 350/454 harness, I bet you could run 8 MPFI high impedance injectors??? I bet the 305 harness just isn't wired for all 4 drivers and the ECU pins are naked???

Or, to the topic starters intent, just run two separate TB's with 305 sized injectors, which should be plenty for a pretty healthy V8. Bigger injectors may HURT the single driver per injector???



[This message has been edited by fast_broker (edited October 17, 2001).]

Tas

somone should buy the edebrock MPFI, download the chip and return it !!

------------------
-Tas
'89 Formula WS.6

Got Beach?

fast_broker

iTrader: (1)

I can get that BIN. You want it??? I kinda do, anyway... I know people...

EDIT: While am asking favors of Vic's employees, I might just as well ask them how they wire up the MPFI conversion kit and if they specify that all four injector drivers must be used, ie, 350/454 harness. and exactly what the electrical specs of the injectors must be.

Any other questions you guys want me to ask Edelbrock????? Last chance to list them HERE before I call Edelbrock Thursday afternoon!!!!

I really want to use an MPFI conversion with the 7747 ECU, can you tell? Still need a REALLY good diag too and cable, though. Working on that, too.


I sense a fast, relatively inexpensive, reliable, emmissions friendly Winter project in development.

Anybody get me a deal on Weiand MPFI manifold for Vortec heads and the associated rail/regulator kit??? (about $225 and $170 from Summit, resp, I believe)

[This message has been edited by fast_broker (edited October 17, 2001).]

ChevelleCLM

Absolutly you could use the 7747 on a TPI intake if you want to. it would be batchfire just like a tpi, but thats no big deal. I am sure that some the 8 tpi injectors are just as much of a load as the 2 350 injectors.
"thanks for letting us in on this Curtis" hahahah JK. The 7747 does not care what intake it is on. Just as long as it gets it's required inputs it is all good.
for the dual tbi you would use the 2 extra injector drivers that pulse ground, and use 4 305 injectors. That should be enough for any small block up to say 10krpm, and probbally a big block up to 6500 or so hahaha
wire the IAC's in paralell as they are stepper motors, and dont care about the cooexhistance of each other. everything elese is the same. We need to find out the PN's for some little small injectors in like a lumina or something that are a little bigger than half a 305 or 350 injector, and then use 4 of them on a stock motor. Then you could swap in your 4 big 350 injectors, for use on a 502 700HP beast, all with stock chevy parts (except the actual dual quad intake) and that is what I like having. Junkyard parts that perform like New performance stuff for 1/82 the price!
I will put this to test on my chevelle as soon as I can get an intake for cheap. help!
EDIT " So, if you have a 350/454 harness, I bet you could run 8 MPFI high impedance injectors??? I bet the 305 harness just isn't wired for all 4 drivers and the ECU pins are naked???"
This statment is totally true, and I have verified it. I actually have a 4.3 ltr harness with 350 injectors, and it is not hurting at all. the extra injector pines in the harness are naked. I just cant believe that you guys did not know about this

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69 Chevelle 2dr hardtop blue, bench seats, 12 bolt w/3.73's muncie 4 speed. TBI w/custom harness and prom best 14.5@90

[This message has been edited by ChevelleCLM (edited October 17, 2001).]

JPrevost

You must be joking. Let me make it clear that some trucks came with the 8746 ecm and they had the Lo5! I believe it was 89-90 vin "K" that had the ecm. So are you telling me that the 8746 ecm ALSO has 4 injector drivers? How the heck do you guys know for sure that these are injector drivers?
What doesn't make any sence is that you're saying 305 injectors are "easy" to operate compared to 350 injectors. That's bull! They both require the same power to hold except the larger injectors have a slightly larger internals. They are all the same ohm rating.
Another thing that doesn't make any sense is how the 7747 and 8746 were never used with 4 injectors so what are you guys talking about? Oh yeah, and if you want larger injectors go for the crossfire injectors. They are 67# but require a little machine work to get to work (very little machine work). Something about a locating pin needs to be ground off.
Okay, so lets make a few things clear. HOW do you know the 7747 and 8746 have 4 injector drivers? Doesn't the Edelbrock MPFI kit just plug into the stock wiring harness? It doesn't go plug into the ecm does it?
fastbroker, yes, please send me a copy of the bin file when you get it, my e-mail is in my sig, Thanks.
Any updates on this topic?

------------------
, Jon (350 TBI!)
91 Red My website

fast_broker

iTrader: (1)

Someone posted a link to the GM Manual schematic that shows the 4 drivers, I happen to have it the whole time in hard print and never even noticed it... Or knew what to notice, I guess...

Another question: Are all 4 drivers firing all the time in all 7747 ECU and PROM combos??? Are all 4 drivers in all the ECU's, even if they are not to be used??? Ie, are there driver number differences between 7747 ecu's, 2 vs 4, based upon engine size??? Also, can you open the ECU and "see" the drivers, ie 4 or 2?

I don't mind using "batch" fire for MPFI, but it would be half-batch, as the two drivers are on alternating periods. Ie, the first, then the other, then the first again, etc. That is what the Edelbrock ProFlo serious MPFI kits use and it worked just fine. I guess there would be an ideal cylindernumber-to-driver scenario, but who cares? ie, 1,8,4,3 to one driver, 6,5,7,2 to the other driver? Or is some other combo beneficial? I would think you'd want one bank on one driver for ease of wiring/neatness????

I still plan to talk to Edelbrock today, although I may not get all the answers I need immediately and I am sure the BIN will take a couple days to get. Usually does from them.

I'm even going to ask for a 8-injectors harness, while I am at it...


[This message has been edited by fast_broker (edited October 18, 2001).]

Kyle F

an it must be nice to have all that money. LOL
Though heres the problem with your idea, air pressure excerts force in all directions and will mess up you injectors flow rates because they will have to overcome the boost pressure to spray fuel.
Like say you run 19psi out of each Turbo for a total of 20psi of boost.
Not a lot but enought boost to put a 3.8 into the low 12s.
OK now thats a lot of pressure on the pod itself, dont worry about the turbulance compressive flow wont be bothered by it that much, but the p[ressure on the fuel injector tip will be incredible.
Making a bad spray pattern and not getting the full squirt.
That is why most succesful turbo systems work on a venturi(Carb set Up that picks up fuel based on the speed of the air flowing by it,pressure drop) on Port fuel systems that introduce fuel just before the intake vavle so once again the pressure is lower here and the injector is pointint the fuel in the direction of the flow.
No Im not saying its not going to work, but just a bitch to tune and I thought I would share with you a few concerns so you could plan accordingly.


------------------
89 Trans Am Turbo 3.8L All stock 43,000 miles #1053 of 1555

Past Thirdgen:
86 Trans Am w/ built 355TPI with SLP goodies and too much other stuff to List. One sweet *** car, wish I would have had a good enough Job to pay insurance on three cars so I could keep it, but for a 89 Turbo Trans Am w/ Low miles, I think I made the right choice!

ChevelleCLM

WHOAH I never said anything about any other ECU than the 7747. I have no idea about any other ones as I have never looked. Go check out my link up there and see for yourself man. How about the 454 injectors? what duty rating are they? GM must have had some reason to use those extra drivers.
ftp://ftp.diy-efi.org/pub/gmecm/manuals/1227747/747ecm6.jpg

As for bigger injectors? I would want to use injectors that were half as big so I could use 4 of them on a relativly stock motor.

On a note to Mr Broker, the injectors fire alternally just like on a stock setup. I am sure all the drivers are in the ECU's but maybe not the proms.
This is great brainstorming!

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69 Chevelle 2dr hardtop blue, bench seats, 12 bolt w/3.73's muncie 4 speed. TBI w/custom harness and prom best 14.5@90

fast_broker

iTrader: (1)

So the PROM tells which drivers to fire, when to fire and how long to fire??? Or are all four injectors fired even though they may not all be connected??? I bet Grumpy knows this stuff.

snflupigus

Grumpy has to know this, he knows everything there is to know about gm ecms. I would MORE than bet he knows. so... Hey grumpy. please respond .

Grumpy

The 747 uses 2 injector drivers.
The estra wiring is for redundancy, ther aren't 4 drivers in there, Just like the 165s and 730s the use the extra wiring for lessening the electrical load on the PCB traces etc.

There is no way to fire 4 low impedance P+H injectors with any oem GMECM.

There are 2 types of P+H injectors 1.2 ohm (TBI), and 2.4 ohm TPI. Then all your saturated are 16-18 but can be as little as 12 but those are rare.

The guys that were doing the 4 brl ones finally figured out the just won't work right without an external driver board (using a gm ecm).

The Edelbrock 747 TPI is happy running 8 SATURATED injectors, and they used to just change the AE stuff.

ChevelleCLM

OK anyone got an actual schematic for a 7747? I got 3 spares, and I will hack one apart if necessary. I am really curious about this.
http://www.tupics.com/members/Cmartz/4driver.jpg Here is a pic I took of one of my 3 7747 computers. All of them look like this.
I am assuming these transistors are the drivers as they are heat sunk to the case and nothing elese is. That would be the logical thing to do as they are the most constant duty thing in there? I am looking up the #'s on the transistors now to see their application

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69 Chevelle 2dr hardtop blue, bench seats, 12 bolt w/3.73's muncie 4 speed. TBI w/custom harness and prom best 14.5@90

[This message has been edited by ChevelleCLM (edited October 18, 2001).]

JPrevost

This is the 7747 ecm print out. Notice it doesn't label the injector drivers! Notice that they are wired in parallel maybe because that was how they were designed for all the injectors of low impendance (305, 454, it don't matter).

This is the 8746, notice it labels them 1 and 2. I guess that answers THAT question.


Now for the big yippie, I might have figured out how to drive more than two injectors. I'm still figuring out the circuit but I have a good feeling about it and I'll let everybody know once I have figured it out.


------------------
, Jon (350 TBI!)
91 Red My website

ChevelleCLM

How about just putting 2 more M8790 transistors in a 7747 computer? and using them to drive the extra injectors? I bet that would work well. You could even use 2 of the unused pins and run yourself some new wires, along in the harness.
JPrevost if you want to email me and talk this out in person w/out the cumbersome UBB that would be cool. I am curious as to what you are thinking?

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69 Chevelle 2dr hardtop blue, bench seats, 12 bolt w/3.73's muncie 4 speed. TBI w/custom harness and prom best 14.5@90

soulbounder

Kyle F, I see what you are saying. Do you remember the picture of the Gale Banks setup they had on the power adder board a while back? It appears that they have both turbos going into a "plenum" type box sitting on top of carbs if I'm not mistaken. Now, if the carbs are replaced with throttle bodies and each turbo is running about 8-10psi of boost, that would be too much stress and pressure for the injector pods? I know I still have a lot of research to do about this, I just wanted to combine two of my favorite things, TBI and twin turbos.

And yes, it's nice to have money, but money ain't everything.

JPrevost

ChevelleCLM, I'm really busy with school work right now. I have homework due at 6am but after that I should be free as a bird until Sunday (more homework, yuck). E-mail me with your AIM name and I'll try and get a hold of you this weekend.
Now let me put some input towards the supercharged/turbo TBI. It's been done. A supercharger is the same thing as a turbo on the intake side. Both have wastegates and pressurize the air. Let's get a few things straight before we dip into this. Pressure with make fuel condense, no fine mist! This why the most efficent superchargers are the roots style. The fuel air mixture is compressed and so the air velocity at the carb is VERY fast (great atomization). You can think of it this way: When you snap open the throttle blades at WOT you need a pump/accelerator shot of fuel, this fuel is extra fuel because at the instant you went WOT the pressure difference went from a vacuum to near altitude pressure and that causes the fuel to grab onto the walls of the intake. Keep in mind I'm only talking about wet flow! Dry flow is a different story. This is why most people with wetflow agree that roots is much better than the centerfuge style. Don't get me wrong though, the ceterfuges can work also. Take a look at the following page: http://w1.605.telia.com/~u60505093/index.htm
That's a blown TBI vette. It's crossfire but it's still TBI! The injectors will work but they will be a restriction. Now if you think about it, what does it matter how the intake looks on a supercharger/turbo? It's pressurized air, it WILL go into the engine no question about it. The normal naturally aspirated engines make more power when the intake is less restrictive. Why? Well because it's like me putting my hand over an actual vacuum, ever notice how hard the motor works when you are making it breath through a straw! But notice the velocity of that air is very high. You basically have a very unhappy vacuum motor. Smooth out the flow and you'll make a happy motor. Is everybody getting this? As for the injectors, Kyle, I don't think it would matter where the injectors are. As long as the fuel pressure has a greater force than the pressurized air I think it'll work fine. This is why I like the roots blower better on a TBI/carb setup. The fuel is being sucked in faster and THEN pressurized.
Let me correct myself, this isn't the most efficient supercharger until you start making BIG POWER. Okay, now that I've corrected myself on that little piece, let's look at the injectors themselves. There is basically no difference between 2 low impedance injectors on TBI and 8 high impedance injectors on TPI. Both have an equal force on the fuel. If one had more force and more power then that EFI system would run richer than the other. This is why I think if TPI can do it, so can TBI. They are both able to overcome the pressure of a supercharger/turbo setup.
If it were me and I was going with a twin turbo setup I would go with a dryflow EFI system. No point in going old school (carb and TBI). This is where I think TPI is better for supercharging and I won't get into the details because this has already turned in to a lengthy reply.

------------------
, Jon (350 TBI!)
91 Red My website

fast_broker

iTrader: (1)

So Grumpy, if I have eight injectors, how do I know if they are of the SATURTED type or of the P+H type???

Also, are you saying if I measure the resistance, and it is high enough (how high is "good"?) that I can use them in a custom MPFI conversion with a 7747 ECU?

If so, HOW DO YOU WIRE THEM UP???? Series, parallel or some other method/combo???


[This message has been edited by fast_broker (edited October 19, 2001).]

jwscab

The datasheet for the LM1949 might make things clearer, look at www.national.com, and search on the LM1949. This describes the operation of peak and hold injectors, with an example of a typical TBI injector. If the peak and hold part is confusing, just focus on the peak part, and you can understand why driving more than one injector is a bad thing for long term durability. A key here is the the input for the drive is digital, and high impedance, which means you can drive more than one driver with the same digital signal. If you can find all the parts, this circuitry is pretty low cost. Also, cherry and OnSemi make a CS453 which is alot like the LM1949, but is all contained within one part, which makes DIY driver boards that much easier. You will have to make a driver for each injector that you have, but going from 2 to four isn't that bad, just four drivers, 2 and 2 for each injector signal. Hope this helps.

palric

iTrader: (1)

Hmmmm... I can see that I opened a can of worms -- or brought up a subject that has some degree of notoriety ?

There is a guy in my neighborhood selling a low mileage '87 T/A with TBI for cheap $$$ and I was going to pick it up off him pretty much for the purpose of trying the dual TBI mod. I have a TPI car now but the dual TBI appeals to the instinctual hot-rodder in me.

Now you guys are getting into alot of technical issues on the ECM and such which surprises me -- so I obviously I have a few things to learn about it ?

On the other hand back in the early '90s when we were first doing this kind of thing no one talked about or was doing alterations to the ECM which was pretty much left alone.

The dual TBI setup consisted of a dual 4 bbl intake (with EGR, never forget emissions tests ...) and two 305 TBIs on it. I think the sum total was 1050 cfm ? What made it work on sbc's was the O2 sensor otherwise it would be too much cfm. The 'driver' TBI was the rear and the front TBI was 'jumpered' off the rear's signal. What Turbo City offered was a wiring kit to piggy back the signal for the IAC and injectors off the primary (TPS not neccessary) to the secondary. But this harness would not be too hard to fabricate on your own. The units that I saw were running very well as daily drivers and in most cases off the factory chip & ECM. They also made outrageous power I might add. I remember they also seemed to advance the rate of decay or failure of O2 sensors. (Anyone have any idea why ?).

Well, ECM debates or otherwise I am hoping to try this mod sometime this winter after picking up the right car. It should be relatively inexpensive -- TBIs are a dime a dozen at the wreckers and the 2x4 intake I can find for under $200 used. Your thoughts ?

Thx, RP.


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'91 Formula Firebird G92,WS6,5-speed,3.42 a ton of fun to drive.

Grumpy

Go ahead do it, I was just trying to min the time you waste. Fire up an 747 ecm on the bench and you can hear things go biserk when you try to fire 4 TBI injectors (at about 3K).

You can also dig out lots of GM training manuals that state that they alternate injector groups of firing on the 165, Again not all that you read is true.

soulbounder

JPrevost, thanks for the excellent explanation. I thought that the dry-flow system was always better for turbos but really like TBI. Roots blowers are nice but personally I don't want one sticking out of my hood and I definitely don't want a cowl hood. (But say if I had a 76 Stingray' a blown block with the supercharger and scoop through the hood would be just fine. ) So, while you say it is possible for it to work I think I will go ahead and abandon my idea of putting twin turbos on a dual TBI setup. Besides, I've always liked going N/A anyway. A 427 small block with dual throttle bodies, AFR heads, and "the works" should make decent power alone. You're right, definitely no reason going old school with new technology. Guess I'll have to build up two cars huh? lol

ChevelleCLM

Grumpy How about my idea of just putting 2 more (injector drivers)identical transistors on the board paralelled with the exhisting 2? I dont see why the 7747 would think there was anything different.

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69 Chevelle 2dr hardtop blue, bench seats, 12 bolt w/3.73's muncie 4 speed. TBI w/custom harness and prom best 14.5@90

9177

would putting a 1.2 ohm resistor in parallel with each injector then running the injectors in series work giving what the drivers see a 1.2 ohm load work? I haven't done much ECM or chip work but just wondering if this would help or even work

[This message has been edited by 9177 (edited October 19, 2001).]

JPrevost

What kind of reply is that? HELLO! I didn't say I was going to hookup 4 injectors to the current drivers! Where did you get that?
I said I think I know a way to hookup 4 injector drivers to the current two. Like somebody just posted, the signal to the current drivers is digital and high impedance, this means I can tap into that line and just install 4 drivers (might be able to use the two built onto the ecm).
It's basically a switching transistor from a power supply. The powersupply might need to be made external but it might not, I don't know how strong the built on power supply is. I have a few circuits that I'm looking at and I need to study the ecm a little more before I can be sure that this will work. Seriously though, the signal from the ecm to the drivers should be able to be spliced into, if not, then we 'might' have a problem. I'll keep you all updated but do some research yourselves. Search for peak and hold, TBI, EFI, injector drivers, ICs, etc. There are a lot of good websites that descripe this stuff in detail. Too bad most of them aren't specific enough to our application.


------------------
, Jon (350 TBI!)
91 Red My website