3.8L EFI swap questions

I'm planning to buy the parts to do the swap on my 84 but have a small problem. Over 15 years ago my dad did the DSII conversion on my truck, and threw away all of the stock parts. Now I need to know what I will need of the stock ignition system I will need to make this work.

FWIW the factory engine wiring harness was hacked off at the firewall so none of it is usable, but I'm not afraid of running new wires. I will also be keeping the Offy intake on the motor and using a 2bbl to 4 bbl adapter plate to mount the CFI unit. If I could find the 2bbl upper half for this intake I'd use that over an adapter but I don't believe it can be found anymore.

I will have to get my hands on a TFI distributor, hopefully without buying a new one. Also have to get the TFI coil, but aside from those I don't know what I need. Help!

On the fuel supply could I install an inline fuel pump rather than trying to proceure a 2.9 pump and tank? I will be installing a fuel cell in the bed floor down the road, so buy the 2.9 stuff and throw it out or buy an inline pump and use it with the fuel cell.

The tech. forum has a write up on this. Im doing the samething as you are doing. Im going to be using factory pumps (need 44psi to make the TBI work my truck already has them). You should be able to run an inline fuel pump dont see why not. You need the factory harness, computer, the sensors, TBI unit, air cleaner, wiring diagram. Dont cut wires like my dad did (later we found out what they did). Label everything from the vehicle you get the TBI setup from plus take picktures. My dad used the ranger coil and it worked fine. But his only problem was he was using a fuel pump that was running to much fuel pressure and the motor would run but very rich and die if you gave it gas. He didn't have the money for a fuel regulator so he gave the system to me to put on my 2.8 (when I put the motor in). But I think that you will still need a fuel regulator (not sure though) because the computer doesnt know that its feeding fuel to a 2.8 liter and not a 3.8 liter. You will need to run a return line from the TBI unit back into the fuel tank (we used aluminum brake line for most of this, much cheaper). As for the ignition system you will need the rangers factory distributor, and coil. The plug from the 3.8 harness will plug into the 2.8 distributor, all the computer needs is the pulses from the distributor to know when to open the injectors. The only part that sucked the most was the vacuum lines for the emissions system and fining out where they go. Im going to be making a build thread when I start on my truck (hopefully soon). BTW why are you getting rid of the Duraspark II system? Thats what I want to do but the TBI system was given to me so ill try it first. Peolpe say putting the TBI on a 2.8 motor wakes it up plus gives it great fuel mileage (which is a big plus the way fuel prices are). If you have any other questions, ask...ive most likely been there and done that when it comes to putting the TBI on a 2.8 liter. Like I said the only thing that stop us was the lack of money for a fuel regulator to get it to work for him. I think I even have the wiring diagram on my computer for the 3.8 liter TBI unit (got it from the library, it is very detailed, tells all).

I'm not really wanting to get away from Duraspark it's a great, reliable system. What I'm wanting to get away from is a 390 cfm Holley. You see I'm no good at tuning a Holley, even if I were TBI would be a better choice. Regardless of how well the Holley is tuned it can't match a properly working fuel injection system. By installing the EFI I will get better fuel mileage and most likely not loose any performance (maybe even gain some), and I won't have to keep trying to figure out how to tune it. Unfortunately for me the 3.8 CFI system requires a signal from the TFI module on the stock distributor.

Installing the TBI or CFI unit from a 3.8 onto a 2.8 is like going from a 280cfm to 350 cfm...big difference. Make sure the TFI module on the stock distributor is good....could mess with you if it is bad. The bad part about the TBI swap is all the emissions things it needs to run properly. Hopefully I will have my vintage motorbike sold tomorrow so I can start work on my truck. Btw how do you get a speeding ticket in a ranger?

Emissions, that's another thing I have to check into. I nolonger have the EGR system on my truck, so I have to check to see if I can delete that part of the EFI system. I have seen an EGR adapter plate for 4BBL intakes somewhere if I can find it again.

Look into the no EGR part. The computer controls its opening and closing, so without it you may be running in a 'limp home' mode. Generally, all items need to balance when computer controlled.

I've done some reading on a t-bird/cougar forum and it appears that the only thing the computer does concerning the EGR is to adjust the fuel tables according to the position of the EGR valve. From what I've read I can buy an EGR eliminator form RJM Injection Technologies that will tell the computer that the EGR valve is closed. This should take care of the limp home problem you mentioned.

Great site - Thanks!

So is all I need of the original Ignition system the Distributor w/TFI module, and the Coil?


For the fuel system I know I will have to have a return line and regulator. Could I use a one way check valve in the tank end of the return line then, rather than return the fuel to the tank, have it dump back into the fuel supply line just before the pre-pump filter?

As for the ignition system thats all you need. What Im doing is attaching the return line to the gas tank filer hose. A set up like this is avalible but im going to do it myself. As for the EGR eliminator setup you talk about, does this system allow me to completely remove my EGR from my engine and put a block off plate in its place (i can make one of those), and do you think it would work on a 84 Thuinder bird TBI set up (that the year of the set up I own)? I dont have any of the emission stuff for the TBI setup and Im wondering if I need any of it to have it run properly other then the EGR eliminator? Any help would be great, I dont own the original fuel set up for the 2.8 and the 3.8 TBI set up is all I have.

Thx

That might work as well. I'm actually thinking about using a factory 2.9 fuel pump/sender unit now though. I though I would have to have the 2.9 tank but from looking in LMC Truck it appears that all the first gen tank were the same, only differences appear to be the filler neck material. Since I believe my sender is messed up and the output signal should be the same for all first gen Rangers this would knock two two birds with one stone. If I do this I think the 2.9 may have a return line but I'm not sure about that. Got to do some more checking and decide which would be my best route.

What I know about the EGR eliminator. I took the information that I gleaned from the RJM Injection Technologies siteabout the year model mustangs it is applicable to. I went to Summit Racing and I looked up the EGR position sensor (what the eliminator eliminates) and cross checked that to the 3.8 CFI cars that I know of and the same sensor was used on those. With this information I believe that the Eliminator will work on any 3.8 CFI system.

As for the setup working properly without the EGR aside from the eliminator. The EGR system is going to dump hot exhaust gasses back into your intake. These exhaust gasses will give no benefit as the O2 had been burned and there would only be trace amounts of fuel left in the exhaust. What it does do is to warm up your intake charge. Seems to me that we don't want a warmer intake charge, but a cooler one. Colder air will support the burning of more fuel and in turn produce more power. IMHO not having the EGR will not hurt the running of the engine, and in fact may give you better power and performance.

As for the air injection system to burn unused gasses in the exhaust, won't hurt your engine or TBI system. Your emissions will be a little higher than they would be with the system, but still probably lower that what they are now.

Only part of the emissions related component I would recommend keeping is the Cats. They seem to make the biggest difference and with the high flow cats available now they will not hurt performance.

FWIW, my dad is wanting me to give the carb a second chance. At the moment I'm up in the air as to which way to go. If I go EFI and manage it make it work right I'll have a better system, probably no less power than was available from the carb, and much better gas mileage. If it doesn't work for me that's a couple hundred I've spent that I'll be throwing away, only to be buying parts for the carb. If I go the route of carbed I'll be spending a few hundred in order to get it tuned and running right. (I'll need a few sizes of jets, a secondary metering block conversion kit, an AFR meter, and the carb needs a new baseplate) I'll have to be adjusting it often and will never get that good of gas mileage.

There is a differance between the 2.8 and 2.9 sending units.... the 2.9 sending unit is bigger on top meaning it wont work on the 2.8 tank. Does anybody know what the Eliminator acutally does meaning does it just connect the two wires on the EGR valve together to get the 0.5volt reading or does it do a little more then that? If thats the case ill save myself some money and just solider the two wires together. But ya im keeping the Cat....the exhuast system has a limited life time warrenty on it (ya its made for the 2.3 liter) but its only 5 years old.

To sum it all up from what ive read and been told here all the 3.8 TBI comupter needs is the 0.5 volt reading from the EGR and the signal from the TFI module on the factory distributor and of courses power to the computer to function the system. Everything else im good without having.

BTW a 390cfm carb. sounds like a bit to much for the 2.8. Try a 350cfm carb. or Motorcraft 2150 carb.

Well then I guess I'll be using an external pump.

The CFI unti doesn't touch the EGR valve itself, instead it gets it's information from the ERG position sensor. I believe that this sensor acts like a potentiometer, meaning that the computer supplies X volts, the sensor acts as a resistor to only allow a certian voltage through depending on the position. So yes you could just connect the two if it is only providing you 0.5 volts. I do not believe this would be the case, but the only way to find out is a volt meter and check the wire. I think that Eliminator device contains the resistors to cut the voltage down to 0.5 volts.

You may even be able to get away without having the reading for the EGR there period, I don't know. Worst case scenario the fuel tables would be off and you would have to to fix it or live with it then. On the other hand the computer may be programed to detect that it isn't there. I've heard some say one way and I've heard some say the other.

BTW a 390cfm carb. sounds like a bit to much for the 2.8. Try a 350cfm carb. or Motorcraft 2150 carb.

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You'd be suprised. Back in the day dad had the 390 cfm double pumper on this thing, we're talking about a nascar prepared carb, and the thing ran great with it. Unfortunatly, due to abuse and neglect over years that it was in someone elses hands the carb wore out beyond repair. Well now they no longer make a 390 double pumper with a choke tower, and the one they do have is over $600 (was when I was looking anyway). So I setteled for the Vacuum secondary carb, it hasn't run right since.

If I should decide to stick with a carb (not likely to happen) I will spend some money on a AFR meter and attempt to do more tuning on the 390 I have. If that doesn't work I'll pull the old double pumper off the shelf and send it off for a professional rebuild. Once that sucker is put back on I know we can get it right. Of course I'll never be able to mention the words gas mileage again, and MPG will become GPM. Granted the blame for that would lie solely on my foot, which would also be carrying me into the courthouse to pay speeding tickets a lot more often.

I would just buy the 3.8 TBI unit. Grand total cost for the computer, wiring harness, sensors, TBI unit, air cleaner, (and anything else attached to it all that I cant remember),........$100. Now I know your costs may be higher to do this set up because you need the factory disributor, ignition system, and a fuel pump but all that should be less then $600.<<<<<< ouch!!!! I could get a 4.0 liter and its tranny for that price!

As for the Eliminator thing I can save myself 20 bucks and make the thing myself (and help from my dad he was an electronics expert, knows this stuff). But Ill get everything hooked up and see what the voltage is before I start doing stuff to the EGR sensor.

But thx for all the information you have helped me out a bunch and made me more confident to do this swap. I hope you do it too.

BTW how would you think a 2.8 liter would look in Daytona yellow paint....A hint of things to come.

I read your post on the t-bird cougar forum and about the O2 sensor, I think (this is what we did with my dads and what ive been told to do) is just hook both of the wires to the one O2 sensor. But if you want to use two O2 sensors then I guess that couldnt hurt either.

And from what they say no EGR and smog pump it sould run fine.

I do wonder though if there is a difference between the 5.0 and 3.8 TBI units other then the injectors...Ill have to look into it. I have a 5.0 TBI unit outside (given to me off a 84 crown victoria). Ill post if there are any differences or not other then emissions stuff and looks.