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EFI conversion

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Old Sep 19, 2011 | 10:14 PM
  #1  
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EFI conversion

I have an '86 300, I'm interested in converting it to EFI. Has anyone tried it before? Is it best to just pull and ECU and pig tail from an EFI truck and make your own harness? Is the factory harness integrated into the body? I have a '92 4.9L with all the EFI components on it.

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Old Sep 19, 2011 | 11:38 PM
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The ECU has like 66 pins on it, connectors along would be expensive. On the motor prepare to change everything but the block, the head and everything must be changed, along with intake egr, air pump, charcoal canister, dizzy, sensorsand the complete wiring harness from the donor truck and then mount the ecm. Whats wrong with the carb?
 
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Old Sep 20, 2011 | 08:38 AM
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Originally Posted by 84-6.9L
The ECU has like 66 pins on it, connectors along would be expensive. On the motor prepare to change everything but the block, the head and everything must be changed, along with intake egr, air pump, charcoal canister, dizzy, sensorsand the complete wiring harness from the donor truck and then mount the ecm. Whats wrong with the carb?
I'd like more reliability. I have the harness from the motor. Just not the harness from the truck side. Maybe I'll make a trip to the junkyard today if I have time and pull some parts.
 
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Old Sep 20, 2011 | 08:40 AM
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BTW I grew up working on EFI only. This is the only thing I've ever owned with a carb. It never used to idle then after it sat for a year gas started leaking out of the seals. I took it apart and rebuilt it. Now it runs, but pig rich, and starts awful. I usually need 30 seconds or starting fluid. It's that bad.
 
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Old Sep 20, 2011 | 09:01 AM
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Dont forget the fuel supply components. the OE system wont push enough pressure. At least the later model tanks will bolt in, but youll need thel ines and everything.
 
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Old Sep 20, 2011 | 09:47 AM
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It will be less work to just fix the carburated system, it will run great and start easily if there isn't anything wrong with it.
 
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Old Sep 20, 2011 | 10:20 AM
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In my opinion, if you're wanting to convert from carb to EFI, then some sort of aftermarket EFI setup e.g. Holley Projection would be the way to go.

As you're seeing, converting to a factory OEM-style installation is something of a Big Deal.™

I grew up with carbs and the claim of "looking for increased reliability" by changing to 20-yo EFI components based on pre-Y2K technology doesn't fly with me.

Not trying to sound demeaning or insulting, but something is screwed up on your carb and/or its installation, IMO you'd probably do best to merely exchange it for one that's been professionally rebuilt.

Carburetor technology has been in use for something around 100 years, it's had plenty of time to be developed & refined.

Detroit first started venturing into EFI on a semi-large scale I believe in the mid-1970s with some Cadillac models.

Modern multi-port EFI rocks in my opinion but 40 years has elapsed and technology has evolved considerably during this time.

Installing used components that are already 20 years old and looking for "increased reliability" by doing that is a conflict in terms.
 
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Old Sep 20, 2011 | 02:05 PM
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X2 what ctubutis said.
I thought about doing the same thing when I got my truck. But after talking to a friend that owns a junkyard here decided against it. He basically had the same argument and the "bang for the buck" just wasn't there. So decided if I was going to do it I'd go with a aftermarket intake and late model TBI setup. But yes it can be done. Just depends on how much work and money you want to put into 20+ year old technology, JMO
 
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Old Sep 20, 2011 | 06:43 PM
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Originally Posted by Archion
Dont forget the fuel supply components. the OE system wont push enough pressure. At least the later model tanks will bolt in, but youll need thel ines and everything.
Yep. The fuel system is completely different. As long as I use the ON power to a relay I can power up the fuel pump so that's all easy. Running the lines will prove to be a pain. I guess I might just be able to pull them off another truck.
 
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Old Sep 20, 2011 | 06:46 PM
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I pulled out an ECU out of a 1994 F-150 with a stick. I have the pigtail/harness as well.

 
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Old Sep 20, 2011 | 06:47 PM
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Originally Posted by Sw1tchfoot
It will be less work to just fix the carburated system, it will run great and start easily if there isn't anything wrong with it.
True. But I want to go forced induction, so a carb isn't really on the list.
 
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Old Sep 20, 2011 | 06:51 PM
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Originally Posted by ctubutis
In my opinion, if you're wanting to convert from carb to EFI, then some sort of aftermarket EFI setup e.g. Holley Projection would be the way to go.

As you're seeing, converting to a factory OEM-style installation is something of a Big Deal.™

I grew up with carbs and the claim of "looking for increased reliability" by changing to 20-yo EFI components based on pre-Y2K technology doesn't fly with me.

Not trying to sound demeaning or insulting, but something is screwed up on your carb and/or its installation, IMO you'd probably do best to merely exchange it for one that's been professionally rebuilt.

Carburetor technology has been in use for something around 100 years, it's had plenty of time to be developed & refined.

Detroit first started venturing into EFI on a semi-large scale I believe in the mid-1970s with some Cadillac models.

Modern multi-port EFI rocks in my opinion but 40 years has elapsed and technology has evolved considerably during this time.

Installing used components that are already 20 years old and looking for "increased reliability" by doing that is a conflict in terms.
Oh, I guarantee the carb isn't put together correctly. I don't care to put any more time into it. I wired a 20 valve, ITB'd, variable cam timing engine from Japan into a US Corolla GT-S. I also worked for SPX (they build the Genisys and Pegisys scan tools) building ECU trays as well. This would be a breeze compared to the Corolla.

I'm also planning on forced induction, and I really don't want to go with a blow through carb.
 
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Old Sep 20, 2011 | 06:56 PM
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Originally Posted by kedwinh
X2 what ctubutis said.
I thought about doing the same thing when I got my truck. But after talking to a friend that owns a junkyard here decided against it. He basically had the same argument and the "bang for the buck" just wasn't there. So decided if I was going to do it I'd go with a aftermarket intake and late model TBI setup. But yes it can be done. Just depends on how much work and money you want to put into 20+ year old technology, JMO
My complete EFI motor with all the components was $50. The ECU, harness, throttle cable, and airbox was $22. Now I need the fuel pump. That's going to be the tough part. The turbo manifold, tubing to be bent and welded, and exhaust will be the expensive components.
 
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Old Sep 20, 2011 | 07:16 PM
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Originally Posted by Blue86
Oh, I guarantee the carb isn't put together correctly. I don't care to put any more time into it. I wired a 20 valve, ITB'd, variable cam timing engine from Japan into a US Corolla GT-S. I also worked for SPX (they build the Genisys and Pegisys scan tools) building ECU trays as well. This would be a breeze compared to the Corolla.

I'm also planning on forced induction, and I really don't want to go with a blow through carb.
Since you seem to be aware of the technical aspect, maybe you would want the system to be completely customisable and easier to wire? You could take a look at this if interested, I found it in another thread and found it quite interesting.
MegaSquirt - Electronic Fuel Injection Computer by Bowling and Grippo ©2010

How simple the wiring is on a 5.0, it will work on an i6 too:
 
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Old Sep 20, 2011 | 10:23 PM
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It being an 86 I'm guessing it has the feedback system, anyway you can use a carb on forced induction. Just put the carb on the intake side of the turbo.
Oh and keep in mind that your efi system will probably have to be tuned to work with a turbo, I don't know what sources you have for diong that but that might be a big road block.
 
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