converting from carb to EFI

[fordfreak300]

I do need a different distributor. I need one with the TFI hook up. That's $290.00 to add on to my costs. Looks like this will be come an expensive conversion. I will have to add the distributor after I have the car converted over. Hopefully I can find a stock distributor cheap.


Still looking for some tips on putting an 88+ mass air harness onto my existing 84 harness. Any help would be appreciated.

[GT5.0]

im collecting parts for my efi swap, im goining to use a 86 engine harness then do the maf swap.

i bought pretty much an entire 86 harness and then a buddy gave me another 86 engine harness.

so i could sell you one of my 86 engine harnesses if were to go that route

and also for the efi distributer, i got mine off ebay for 10 bucks
________
XSexyKittenX

[v8only]

I was going to say, Mark, just grab a $10 oem distributor. I've never had one go bad on me yet.

[v8only]

$1

http://cgi.ebay.com/ebaymotors/87-93...11848642QQrdZ1


CAN'T beat that!

[Dean_T]

Mark, if you need parts, PM me. I have a free '86 Mustang fuel tank Jeremy gave me I'll pass along to you. I'm keeping the fuel lines though, I'm going to cram them on a Fairmont...

Dean T

[v8only]

SWEET! I forgot about that tank. does it still have the sender in it?

[paul78zephyr]

Here is a general overview of the harnesses used in all EFI Mustangs:

1. Main underdash harness - connects to all other harnesses. Also connects steering wheel switches (ign, turn, wiper, etc), instrument cluster, radio, heater/AC controls, clutch sw (MT)

2. Main underhood harness - connects main underdash harness to front lighting, battery/alternator, starter relay, horn, wipers/washer

3. Rear harness - connects main underdash harness to rear lighting, FP relay (86-90), FP, tank level sender

4. Main EFI harness - connects to main underdash harness, engine harness, and O2 sensor harness. This harness has the connectors for the computer, EEC power relay, distributor (TFI), ign coil, MAP/BP sensor, AC WAC relay, MA sensor (89+), EVR and TAB/TAD solenoids (on pass side inner fender). Has connection (ring terminal) at starter relay 'B+' terminal for power, and connector that atttaches to the battery neg cable for ground.

5. Engine harness - connects to main EFI harness via two 10-pin connectors (salt and pepper connectors). Has connectors for ACT, ECT, TPS, ISC, CANP, INJ 1-8, and oil press and water temp senders (gauges).

6. O2 harness - connects to main EFI harness and O2 sensors.

7. Trans harness - connects to main underdash harness. Connects to neutral safety sw (AT) or NGS (MT), back-up lights sw, speed sensor.

You said your car may have a 86 'harness' but currenly was not EFI. You were looking for the 'computer connector'. Theoretically your car could have 86 wiring harnesses but without the main EFI, engine, or O2 harnesses. Then you would not find the computer connector - as its on the main EFI harness.

What most guys that are converting to EFI get hungup on is they go out and get the main, engine and O2 harnesses and then say 'where do I connect them into the rest of the car?' That is where you need to know that the key is that the main EFI harness plugs into connectors on the main underdash harness. However, in general, these harnesses (main EFI and main underdash) only 'plug and play' when they are from the same years from 86-93. There are some exceptions that Im certain of:

87-88 (SD) will fit 87-88 (SD)
91-93 (MA) will fit 91-93 (MA)

Although rewing and/or splicing MAY be minor Ive not heard of any direct plug and play between any year main EFI harness and any pre-86 underdash harness.

Also to make things more confusing some of the connectors between the main EFI harness and main underdash harness are located on the engine compartment side of the firewall and some are on the passenger compartment side. And their exact number vary by year.

Good news: Engine harnesses are compatible with main EFI harnesses across all years 86-93

Bad news: O2 harness are not only generally year specific to their matching main EFI harnesses, they are transmission specific (AT vs MT).

Also keep in mind that even if you splice a 86-90 main EFI harness into a non-compatible underdash harness you will have to 'hard wire' the circuit for the fuel pump relay and FP. Only 91-93 main EFI harness have the relay circuit built in.

Its not complicated, but it can be VERY confusing. Ive researched this for some time as I am converting the 89 5.0L in my 78 Zephyr back to EFI (I converted it to carb when I originlly installed it). Ive studed lots of schematics for all years 86-93, but schematics only tell part of the story. A schematic is only an electrical representation of the circuitry and most times does not tell you anything about harnesses and connectors. Ive also looked at lots of harnesses, but Ive not seen all years (or at least not in detail). Ford even made subtle changes to these harnesses - like on the main EFI harnesses for 89 and 90. They look identical - same exact connectors at all locations - but in several places they changed the pinouts at several connectors including the key ones between the main EFI and main underdash harnesses. So a 89 main EFI harness is NOT electrically compatible with a 90 underdash harness and visa versa - although everything will physically mate up.

Im actually using an 89 engine harness (came with the engine), and 90 main EFI and O2 harnesses. I heavily modified my main EFI harnes to add the needed FP/FP relay wiring and brought all other needed connections to the rest of the car to one large connector that is located on the passenger side of the firewall. Since Im connecting to a non-Mustang car I knew Id have to make many 'splice' connections from the main EFI harness to the rest of may car. This is actually quite common as 5.0L EFI installations in non-Fox Mustangs are quite popular. I try to tell anyone that is doing an EFI conversion on a Fox Mustang to either convert the entire car wiring to one year (86-93) or if you only want to install the main EFI/engine/O2 harness (and do some splicing) then try to get the 91-93 setup that includes the FP relay circuit.

I hope this helps. Yes it IS confusing.

Paul

[Dean_T]

SWEET! I forgot about that tank. does it still have the sender in it?

Um, no... You grabbed it first! LOL

Dean T

[fordfreak300]

Dean hold onto that tank for me for a bit. I live out by palmsprings so it may take a bit before I can get it from you. I definitely want it though. If you are at Jeremy's before I get it take it to him and have him hold it for me and I'll run over there and grab it.

[v8only]

Um, no... You grabbed it first! LOL

Dean T

it's been so long, I hardly remember, I think I grabbed it for a spare, knowing how hard they are to find.

mark, I "may" still have it, if I do, I'll give it to you.

surprisingly, they're not hard to find in the yards still, 1 or 2 weekends and you're bound to come across an 86 in the yards still

[fordfreak300]

Paul that does help to some degree. Now I am back to maybe I do have an 86 under dash wiring. My problem is I have no idea what to look for to be able to tell. I am kinda back to square one with what I have and what I actually need. Do you know how I could tell if my underdash harness is an 86 or not? I am not too worried about plug and play. I am fine with splicing anything I need to. I just really need to figure out what I have first. And that seems to be my biggest problem right now.

[paul78zephyr]

Paul that does help to some degree. Now I am back to maybe I do have an 86 under dash wiring. My problem is I have no idea what to look for to be able to tell. I am kinda back to square one with what I have and what I actually need. Do you know how I could tell if my underdash harness is an 86 or not? I am not too worried about plug and play. I am fine with splicing anything I need to. I just really need to figure out what I have first. And that seems to be my biggest problem right now.

Trying to tell what year underdash harness you have may be difficult, especially if you think it may have been changed - Im definately not an expert on identifying those. Im sure its not a 87+ as this would not match up with the 79-86 dash and instrument cluster. If it truly was an 86 underdash harness then - and if you currently do not have a main EFI harness - then it should have some connectors that dont seem to go to anything. These may be on the engine comp side of the firewall (probably near the brake booster area) and/or may be on the pass side of the firewall (probably on the far right/passenger side). Pre-86 will be difficult to tell apart. Perhaps you can find the part number band on it, but this can be difficult/impossible. Even if you found it the number can be deceiving. Say it has a E4 (84) number on it - it may actually be a 85 harness.

Paul

[fordfreak300]

I have extra connectors on both the driver side and passenger side.

[paul78zephyr]

I have extra connectors on both the driver side and passenger side.

Are the ones on the drivers side on the eng comp side and are they round with 8 pins each? Are they black and/or gray?

Is the one on the pasenger side under the dash and is it 8 pin rectagular and green?

Paul

[fordfreak300]

I should have the big salt and pepper shaker connectors or at least the wires cut off for them right?

[fordfreak300]

Pass side under dash is white and is a 6 pin connector with only 5 wires going to it. The driver side engine compartment has 2 black round with 4 wires each and are 4 pin connectors.

[fordfreak300]

I do have a grey 8 pin connector but it is pluged in on the driver side it is rectangle.

[fordfreak300]

i do not have any of the connctors you said. v8only even took pics for me and i do not have any of those connectors.

[Dean_T]

Okay, tank is yours, Mark. It's safe where it's at unless Jeremy has another BBQ then it goes back to his place - if he doesn't mind haha.

The FRPP M-12071-C302 Main Harness has those Salt and Pepper shaker connectors as well as the oval grommet and computer connector. The engine harness connects to the salt and pepper shaker connectors. Aren't the '88-'93 harnesses the same? This harness also has the connector to the Mass Air meter so isn't comparable to the '86 harness. It may be a stand alone unique aftermarket harness. But I thought it was the same as the one in my '89 Mustang.

Aren't the '89-'90 harnesses modular?

Dean T

[paul78zephyr]

I should have the big salt and pepper shaker connectors or at least the wires cut off for them right?

Not necessarily. Remember those connectors are on the main EFI and engine harnesses. We are assuming that you do not have those.

Based on the other connector descriptions Im still not sure what main underdash harness you have, but with all those unused connectors I would -guess- that you do have a 1986 underdash harness.

Look again at Rbuckleys pic of the '86 main EFI harness'. You can see two round black connectors that should connect to the main underdash harness. They are located near the left side of his picture just below where the fat harness becomes 'vertical' in his picture. In that area are the two round connectors (they both look black which matches yours), the pyramid shaped test connector, and what I believe is the connector (with two green wires) for the brake differential switch on the proportioning valve. If you have an 86 uunderdash harness thern those are the connectors that would mate with the black round connectors you are seeing. I do not see any connector in Rbuckleys picture near the computer/EEC power relay area. I know in later madel EFI harnesses there is a rectangular connetor there too that connects to the underdash harness - thats why I asked you to look. The white connector you saw could be for something else.

Paul

[paul78zephyr]

Okay, tank is yours, Mark. It's safe where it's at unless Jeremy has another BBQ then it goes back to his place - if he doesn't mind haha.

The FRPP M-12071-C302 Main Harness has those Salt and Pepper shaker connectors as well as the oval grommet and computer connector. The engine harness connects to the salt and pepper shaker connectors. Aren't the '88-'93 harnesses the same? This harness also has the connector to the Mass Air meter so isn't comparable to the '86 harness. It may be a stand alone unique aftermarket harness. But I thought it was the same as the one in my '89 Mustang.

Aren't the '89-'90 harnesses modular?

Dean T

The FRPP M-12071-C302 is nothing but a bone stock/production 92-93 Mustang main EFI harness.

No 88-93 harnesses are NOT the same.

86 SD is unique. 87-88 SD are the same. 89 MA is unique. 90 MA is unique. 91 MA may be unique - Ive read conflicting info - or may be same as 92-93. 92-93 MA are the same.

Not sure what you mean by 'modular' for 89 and 90.

Paul

[paul78zephyr]

fordfreak300,
I see you are also linking into to an old thread from 2004 (titled 'carbed to EFI?'). Much of the info there is correct, however some of it is wrong. The 89-93 EFI harnesses are NOT the same. The FRPP EFI harness is not the same as any 89-93, although it is the same as the factory 92-93 EFI harness. The brown connector they talk about is ONLY on the 91-93 EFI harnesses.

Paul

[fordfreak300]

I have plugs that look like they would be the mates to those plugs. What I need to know though is how many pins they each have mine are 4 pins a piece.

Rbuckley any way you can look at the 2 round connectors that are right next to the computer Check connector and count how many pins each one has?


Paul, you have been extremely helpful! Thank you Very MUCH!!!!!! You have really stuck in there to help me figure this out, and also to help me understand what I need to know. If I determine this is not an 86 underdash harness but is indeed an 84 harness I will get the 92-93 EFI harness so it has the brown connector then. I did find a part number on the part of the harness that is in the driver side kick panel and goes to the rear of the car before the plugs that attack it all. It started off with E4 then had 2 more numbers/letters.

I did compare some of the information I found on the other thread with things you have said recently such as what harnesses are the same and what not.

Dean thank you for holding onto the tank for me. I am pretty far from you, your in the Ventura area right? Jeremy is seeing if he has the sender that came out of the tank for me so that is a big plus if he has it.

I guess it is time to start collecting all of the parts. No matter which harness I have (and I am still determining this) I feel confident I can get the EFI engine harness hooked in.

I am also going to need to figure out how to wire in my MSD 6a box in this equation as I don't have duraspark anymore.

[fordfreak300]

Am I missng the salt and pepper shacker connections on Rbuckleys engine harness?

[paul78zephyr]

Am I missng the salt and pepper shacker connections on Rbuckleys engine harness?

Do you mean missing them in the picture? They are there, just hard to see - especially if you dont know what you are looking for. I assume you are zooming in (hi resolution) on the pic too - they are impossible to see at the low resolution.

Look where I told you the two round black connectors are - at the bottom of where the fat pasrt is 'vertical'. Now pan to the right a little and you see another thinner part of the harness that is also 'vertical'. If you follow that loom it actually looks like a 'C'. Look just to the right of the thin vertical, at the bottom inside of the 'C'. The black connector is a bit over the white one making it difficult to see. Also both the black and white connectors have a black 'cap' on them that makes the wires exit them at a right angle.

Paul