Since there's no forum for this: Fuel Injection Gurus, see within...
01-22-2009, 11:23 PM
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Since there's no forum for this: Fuel Injection Gurus, see within... Alright so here we go 
Backstory:
97 Bravada came into my buddy's shop that needed a motor, and so they put in one and have the core left. Only money back for the core would've been $100 so my friend is keeping it instead since it just had a single spun bearing. Initial plan was to take the heads off an put them on his 89 S-10's 4.3 till we get the SBC in it, which as busy as they are may be a bit longer than we hope. He's since kind of changed his mind due to not wanting to have to drill either the heads bolt holes or the intake's, to work with each other. My initial idea was to use the bottom aluminum half of the intake (top is composite) and fab a top box to bolt down and mount the TBI unit on it. Well that seemed to be a bit more work than it's worth so I started thinking of other ideas...
The Plan:
So then I got to thinking... GMs sensors haven't changed ALL that much and there's a lot of different types of injection out there that I must be able to think of something. Then I did
What if a person was to take the WHOLE top half of the motor and transplant it onto the 89 4.3? I mean everything except the distributor! The heads, lower intake, upper composite, CPI and that LS style TB. The MAP, TPS and IAC would be a breeze to change over with just new pigtails. The CPI would be the "hard" part you'd think, but it's just 6 pairs or pins, 2 per 'injector' like a normal multi-port. With the exception of the CPI block looks like it's basically just 2 driver modules that pump out to the 3 nozzles per bank. So I figured it wouldn't be all that hard to wire it up like a TPI or 93 LT1 as Batch Fire off of the 2 TBI injector's wiring. The only thing I'd have to look into would be pulse width and if it's any different between the two. Then we took the Bravada for a test drive with his scanner hooked up, I went with just so I could monitor the pulse width, but I noticed that there isn't 6 injector pulses just "bank 1" and "bank 2" o_0 It's already batch fire!!
The Question:
Now I'm pretty sure that if I take the scanner into his 89 S-10 and drive around while monitoring the pulse width, it'll read the same as the Vortec CPI 4.3's. But since I haven't done that yet, I'd like to know if anyone here knows if they'd be the same and if the signal the TBI puts out will drive the CPI module? And insanity aside, if you think that this would work? I'd use the original plugin for the CPI unit and just solder in the TBI's injector wiring to the appropriate ones. I'd still be using all of the same sensors off the 89 as well as the computer, so the only real change would be going from 2 TBI injectors to 1 (or 2, however it's designed) injector(s) that is the CPI unit. I personally feel this should work seeing as we have access to wiring diagrams. It's really just the pulse width I'm concerned about about.
So there you have it, and yes I know I'm a bit crazy, but you'd have said that about both people who've now made working LS PCM LT1 setups had they ran it passed you first
Yet opinions are welcomed heh
Backstory:
97 Bravada came into my buddy's shop that needed a motor, and so they put in one and have the core left. Only money back for the core would've been $100 so my friend is keeping it instead since it just had a single spun bearing. Initial plan was to take the heads off an put them on his 89 S-10's 4.3 till we get the SBC in it, which as busy as they are may be a bit longer than we hope. He's since kind of changed his mind due to not wanting to have to drill either the heads bolt holes or the intake's, to work with each other. My initial idea was to use the bottom aluminum half of the intake (top is composite) and fab a top box to bolt down and mount the TBI unit on it. Well that seemed to be a bit more work than it's worth so I started thinking of other ideas...
The Plan:
So then I got to thinking... GMs sensors haven't changed ALL that much and there's a lot of different types of injection out there that I must be able to think of something. Then I did
What if a person was to take the WHOLE top half of the motor and transplant it onto the 89 4.3? I mean everything except the distributor! The heads, lower intake, upper composite, CPI and that LS style TB. The MAP, TPS and IAC would be a breeze to change over with just new pigtails. The CPI would be the "hard" part you'd think, but it's just 6 pairs or pins, 2 per 'injector' like a normal multi-port. With the exception of the CPI block looks like it's basically just 2 driver modules that pump out to the 3 nozzles per bank. So I figured it wouldn't be all that hard to wire it up like a TPI or 93 LT1 as Batch Fire off of the 2 TBI injector's wiring. The only thing I'd have to look into would be pulse width and if it's any different between the two. Then we took the Bravada for a test drive with his scanner hooked up, I went with just so I could monitor the pulse width, but I noticed that there isn't 6 injector pulses just "bank 1" and "bank 2" o_0 It's already batch fire!! The Question:
Now I'm pretty sure that if I take the scanner into his 89 S-10 and drive around while monitoring the pulse width, it'll read the same as the Vortec CPI 4.3's. But since I haven't done that yet, I'd like to know if anyone here knows if they'd be the same and if the signal the TBI puts out will drive the CPI module? And insanity aside, if you think that this would work? I'd use the original plugin for the CPI unit and just solder in the TBI's injector wiring to the appropriate ones. I'd still be using all of the same sensors off the 89 as well as the computer, so the only real change would be going from 2 TBI injectors to 1 (or 2, however it's designed) injector(s) that is the CPI unit. I personally feel this should work seeing as we have access to wiring diagrams. It's really just the pulse width I'm concerned about about.
So there you have it, and yes I know I'm a bit crazy, but you'd have said that about both people who've now made working LS PCM LT1 setups had they ran it passed you first
Yet opinions are welcomed heh Last edited by Formula350; 01-22-2009 at 11:29 PM.
01-23-2009, 08:05 AM
#2
I wouldn't use CPI injection / injector setup if that's what was in a 97.
I can't speak for the 97, but the 94 CPI intake manifold is okay if you want a long runner design (think TPI.) Due to warranty issues, GM had to service some CPI models with 6 injector setups; this assy. is still available to convert CPI to regular injectors. Since the CPI manifold lower has smaller openings than what an LT1 injector would fit in, I would think your injector options when using the CPI lower intake are more limited than other years.
I believe the 4.3L 2002 Van uses the same 12200411 PCM as the 5.7L 2002 Van.
So, heads & intake manifold, injection w/ the 12200411 and a 4.3L non-E-trans. tune and who knows what injectors... And when he's ready to go V8, you'll have to add 2 injectors and re-tune. I'd do that way before running the TBI ECM.
On the TBI ECM injector driver(s) driving the CPI module; it will depend on the ohms or other electrical properties of the injectors being used.
You're not crazy, but you're trying to re-use some bits that I wouldn't.
I really really really tried to convince my friend that his 91 needed a SBC but he stayed 60deg V6...
I can't speak for the 97, but the 94 CPI intake manifold is okay if you want a long runner design (think TPI.) Due to warranty issues, GM had to service some CPI models with 6 injector setups; this assy. is still available to convert CPI to regular injectors. Since the CPI manifold lower has smaller openings than what an LT1 injector would fit in, I would think your injector options when using the CPI lower intake are more limited than other years.
I believe the 4.3L 2002 Van uses the same 12200411 PCM as the 5.7L 2002 Van.
So, heads & intake manifold, injection w/ the 12200411 and a 4.3L non-E-trans. tune and who knows what injectors... And when he's ready to go V8, you'll have to add 2 injectors and re-tune. I'd do that way before running the TBI ECM.
On the TBI ECM injector driver(s) driving the CPI module; it will depend on the ohms or other electrical properties of the injectors being used.
You're not crazy, but you're trying to re-use some bits that I wouldn't.
I really really really tried to convince my friend that his 91 needed a SBC but he stayed 60deg V6...
01-23-2009, 11:12 AM
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I wouldn't use CPI injection / injector setup if that's what was in a 97.
I can't speak for the 97, but the 94 CPI intake manifold is okay if you want a long runner design (think TPI.) Due to warranty issues, GM had to service some CPI models with 6 injector setups; this assy. is still available to convert CPI to regular injectors. Since the CPI manifold lower has smaller openings than what an LT1 injector would fit in, I would think your injector options when using the CPI lower intake are more limited than other years.
I believe the 4.3L 2002 Van uses the same 12200411 PCM as the 5.7L 2002 Van.
So, heads & intake manifold, injection w/ the 12200411 and a 4.3L non-E-trans. tune and who knows what injectors... And when he's ready to go V8, you'll have to add 2 injectors and re-tune. I'd do that way before running the TBI ECM.
On the TBI ECM injector driver(s) driving the CPI module; it will depend on the ohms or other electrical properties of the injectors being used.
You're not crazy, but you're trying to re-use some bits that I wouldn't.
I really really really tried to convince my friend that his 91 needed a SBC but he stayed 60deg V6...
I can't speak for the 97, but the 94 CPI intake manifold is okay if you want a long runner design (think TPI.) Due to warranty issues, GM had to service some CPI models with 6 injector setups; this assy. is still available to convert CPI to regular injectors. Since the CPI manifold lower has smaller openings than what an LT1 injector would fit in, I would think your injector options when using the CPI lower intake are more limited than other years.
I believe the 4.3L 2002 Van uses the same 12200411 PCM as the 5.7L 2002 Van.
So, heads & intake manifold, injection w/ the 12200411 and a 4.3L non-E-trans. tune and who knows what injectors... And when he's ready to go V8, you'll have to add 2 injectors and re-tune. I'd do that way before running the TBI ECM.
On the TBI ECM injector driver(s) driving the CPI module; it will depend on the ohms or other electrical properties of the injectors being used.
You're not crazy, but you're trying to re-use some bits that I wouldn't.
I really really really tried to convince my friend that his 91 needed a SBC but he stayed 60deg V6...
01-23-2009, 06:17 PM
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Well, not that I really understood why the ohm of the injectors would matter from the computer firing one to the next (other than there being more resistance maybe) but the TBI injectors are about 1.3-1.45 and the CPI is 1.5-2.0. So if anything, and I had to increase the ohm, I'd think a resistor would do.
