• Mustang Forums
  • 1979 - 1995 (Fox, SN95.0, & 2.3L) -General/Talk-

Fox ECU for 351w swap w/out EFI?

  • Thread starter Thread starter Dxn
  • Start date Start date Jun 20, 2023

Dxn

Member
Jun 10, 2023
5
4
13
ALABAMA
Jun 20, 2023
#1
  • Jun 20, 2023
  • #1
Have an 85 hatch I am thinking about 351w swapping. My 85GT has the 302HO, being said both have the same firing order so can I just reuse this ECU? Are there any other standalone ECUs that are more benefitial without the complete swap to EFI? Please share your experiences with this swap and other obstacles with the solutions you have found. Thanks all!
 
Last edited: Jun 20, 2023

AeroCoupe

lube between the nut and the face. I know my lubes
Founding Member
Oct 28, 2001
5,886
4,010
183
Claremore, OK
Jun 20, 2023
#2
  • Jun 20, 2023
  • #2
So I thought ‘85 GT’s were carbureted I.e. no ECU?
 
Reactions: Noobz347

General karthief

wonder how much it would cost to ship you a pair
20+ Year Stangneter
Aug 25, 2016
27,926
10,572
203
polk county florida
Jun 20, 2023
#3
  • Jun 20, 2023
  • #3
I think the 85 may be a Duraspark type ignition system if carbed,
 
Reactions: Noobz347

AeroCoupe

lube between the nut and the face. I know my lubes
Founding Member
Oct 28, 2001
5,886
4,010
183
Claremore, OK
Jun 20, 2023
#4
  • Jun 20, 2023
  • #4
Which if paired with the correct dizzy from a truck 351 will work for his project.

I used and MSD dizzy and box and called it a day.
 
Reactions: General karthief

General karthief

wonder how much it would cost to ship you a pair
20+ Year Stangneter
Aug 25, 2016
27,926
10,572
203
polk county florida
Jun 20, 2023
#5
  • Jun 20, 2023
  • #5
AeroCoupe said:
Which if paired with the correct dizzy from a truck 351 will work for his project.

I used and MSD dizzy and box and called it a day.
Click to expand...
That's what the MSD type box was made for
 

85GTStangGuy

5 Year Member
May 19, 2021
1,001
625
133
Jax, Florida
Jun 20, 2023
#6
  • Jun 20, 2023
  • #6
AeroCoupe said:
So I thought ‘85 GT’s were carbureted I.e. no ECU?
Click to expand...
Only the ones with manual transmissions..... automatics were efi.
 

limp

wrap a little cheese around it and its a done
5 Year Member
Oct 4, 2020
5,466
2,899
173
Florida
Jun 21, 2023
#7
  • Jun 21, 2023
  • #7
85GTStangGuy said:
Only the ones with manual transmissions..... automatics were efi.
Click to expand...
I would disagree as my EX wife and looked at these when they were new.... Last year of Carb, was a big selling feature to me....
Of course I was ONLY looking at manual transmissions...... So you could be correct........
 

Dxn

Member
Jun 10, 2023
5
4
13
ALABAMA
Jun 21, 2023
#8
  • Jun 21, 2023
  • #8
AeroCoupe said:
So I thought ‘85 GT’s were carbureted I.e. no ECU?
Click to expand...
Oh I didnt even know I thought the ECU still would have controled the timing/coil. Thanks for this haha!
 

AeroCoupe

lube between the nut and the face. I know my lubes
Founding Member
Oct 28, 2001
5,886
4,010
183
Claremore, OK
Jun 21, 2023
#9
  • Jun 21, 2023
  • #9
So were the ‘85 autos CFI with an EEC-III?
 

Noobz347

Stangnet Facilities Maint Tech... Er... Janitor
Admin Dude
Jan 4, 1985
43,093
21,276
234
Box behind Walmart
Jun 21, 2023
#10
  • Jun 21, 2023
  • #10
AeroCoupe said:
So were the ‘85 autos CFI with an EEC-III?
Click to expand...
Nope. Just carbureted that I'm aware of.
 

AeroCoupe

lube between the nut and the face. I know my lubes
Founding Member
Oct 28, 2001
5,886
4,010
183
Claremore, OK
Jun 21, 2023
#11
  • Jun 21, 2023
  • #11
Some are saying the auto cars were injected hence my question.
 

Noobz347

Stangnet Facilities Maint Tech... Er... Janitor
Admin Dude
Jan 4, 1985
43,093
21,276
234
Box behind Walmart
Jun 21, 2023
#12
  • Jun 21, 2023
  • #12
AeroCoupe said:
Some are saying the auto cars were injected hence my question.
Click to expand...
I vaguely recall something of that nature and if it was relegated to Auto cars, I think it might also have been relegated to California cars.
 

Noobz347

Stangnet Facilities Maint Tech... Er... Janitor
Admin Dude
Jan 4, 1985
43,093
21,276
234
Box behind Walmart
Jun 21, 2023
#13
  • Jun 21, 2023
  • #13
I found this:







What I don't see is the who, what, when, where, and why for the "F Code" cars.

Most threads concerning CFI cars are about how to convert [away] from the restrictive 2 bbl CFI.

I also saw some discussion about the CFI cars being non-roller but I don't know if that's true.
 

General karthief

wonder how much it would cost to ship you a pair
20+ Year Stangneter
Aug 25, 2016
27,926
10,572
203
polk county florida
Jun 21, 2023
#14
  • Jun 21, 2023
  • #14
Let's get @FoxChasis in on this, he may be able to shed some light on this, I think the question may be what ignition control was used on the CFI model
 

85GTStangGuy

5 Year Member
May 19, 2021
1,001
625
133
Jax, Florida
Jun 22, 2023
#15
  • Jun 22, 2023
  • #15
General karthief said:
I think the 85 may be a Duraspark type ignition system if carbed,
Click to expand...
That is correct.... a DuraSpark II system. Again, that is on carb'ed cars only though.

AeroCoupe said:
So were the ‘85 autos CFI with an EEC-III?
Click to expand...
No. '85's with slushboxes, which used the 2 barrel CFI, came with an EEC-IV managed DuraSpark III system.

An interesting side note is that the intake manifold on those CFI cars was the same manifold used on 1979's two-barrel carbureted 5.0 Mustang motor.

Noobz347 said:
I vaguely recall something of that nature and if it was relegated to Auto cars, I think it might also have been relegated to California cars.
Click to expand...
Yes, that's correct about the CFI being relegated to AOD cars only. But it had nothing to do with Cali versus 49-state cars.

Noobz347 said:
I found this:







What I don't see is the who, what, when, where, and why for the "F Code" cars.

Most threads concerning CFI cars are about how to convert [away] from the restrictive 2 bbl CFI.

I also saw some discussion about the CFI cars being non-roller but I don't know if that's true.
Click to expand...
The "F" Code engines were for the AOD equipped cars. The bottom "M" Code engine was for the T-5 manual cars. The middle "M" Code (EFI) engine listed there was never used in the '85 Mustang.

That's true about the CFI/AOD cars not being roller cammed, at least for 1985. In 1986, all combos went to the roller cam motor.

Also, the '85 CFI cars, which initially came out as 165 hp (the "F" Code motor above), had a mid-to-late model year upgrade which upped them to 180 hp. That was done by using the carb'ed motor's exhaust system (ss tube headers vs cast iron manifolds, lower restriction cats, the whole pseudo-dual exhaust setup, and other tweaks) in place of the originally carried-over '84 exhaust.
 
Reactions: Noobz347
F

FoxChasis

20+ Year Stangneter
Dec 23, 2003
589
276
93
Jun 22, 2023
#16
  • Jun 22, 2023
  • #16
85GTStangGuy is correct on all counts, except the "F" engine code. Both 1984, the first year for 5.0L with CFI in the Capri/Mustang, and 1985 model years were engine code "M" for either the CFI/AOD or the 4V/T-5 combo. Last year for the "F" engine code was 1983.
 
Reactions: 85GTStangGuy

Noobz347

Stangnet Facilities Maint Tech... Er... Janitor
Admin Dude
Jan 4, 1985
43,093
21,276
234
Box behind Walmart
Jun 22, 2023
#17
  • Jun 22, 2023
  • #17
FoxChasis said:
85GTStangGuy is correct on all counts, except the "F" engine code. Both 1984, the first year for 5.0L with CFI in the Capri/Mustang, and 1985 model years were engine code "M" for either the CFI/AOD or the 4V/T-5 combo. Last year for the "F" engine code was 1983.
Click to expand...
Question: If the last "F" engine code was 1983, why do I see multiple references to a 1985 "F" code?


The table that I posted above is from here: https://www.mustangspecs.com/1985-mustang-engine-302-v8/

Is this incorrect?
 
F

FoxChasis

20+ Year Stangneter
Dec 23, 2003
589
276
93
Jun 22, 2023
#18
  • Jun 22, 2023
  • #18
That is incorrect, for the Capri/Mustang anyway. I just went through a bunch of those pages, not just engine specs, but VIN codes, and there is some bad info on every one of them. I left several replies but I'm not confident anything will get corrected.

1979-93 Mustang (and 1979-86 Capri) 5.0L engines...

1979 = F
1982* = F
1983* = F
1984* = M (4V or CFI)
1985* = M (4V or CFI)
1986* = M
1987* = E
1989* = E
1989* = E
1990* = E
1991* = E
1992* = E
1993* = D (SVT Cobra) and E (GT, LX 5.0L)

* High Output (H.O.)
 
Last edited: Jun 22, 2023
Reactions: Noobz347, 85GTStangGuy and General karthief

85GTStangGuy

5 Year Member
May 19, 2021
1,001
625
133
Jax, Florida
Jun 22, 2023
#19
  • Jun 22, 2023
  • #19
FoxChasis said:
85GTStangGuy is correct on all counts, except the "F" engine code. Both 1984, the first year for 5.0L with CFI in the Capri/Mustang, and 1985 model years were engine code "M" for either the CFI/AOD or the 4V/T-5 combo. Last year for the "F" engine code was 1983.
Click to expand...
Thanks for the clarification/correction on that.

I guess it's one of those errors that was made somewhere along the way and then just kept getting repeated by others.... many others. Like @Noobz347 pointed out, I've seen it in multiple publications/websites. And also at quite a few parts sites, when it makes me do the drill down to a specific car model, one of the last specs is for the motor/transmission combo, and it always identifies the 4bbl/T-5 as an "M" Code and the CFI/AOD as an "F" Code. So, while FoxChasis is very much technically correct, there are times when one needs to identify (albeit incorrectly) their CFI/AOD car as an "F" Coded car in order to get the right parts.
 
Reactions: General karthief
You must log in or register to reply here.

Similar threads

D
Foxbody Misfire 5.0 Swap
  • DPORTER0729
  • May 2, 2025
  • Fox 5.0 Mustang Tech
Replies
7
Views
621
Fox 5.0 Mustang Tech Jul 13, 2025
90sickfox
Engine HELP - 351W Based Build Under Stock Hood
  • thinkfaster
  • Oct 17, 2024
  • Fox 5.0 Mustang Tech
Replies
13
Views
2K
Fox 5.0 Mustang Tech Dec 31, 2025
Qtrhrse23
Q
For Sale 94 Cobra 408w AOD Project For Sale
  • Labora
  • Oct 11, 2024
  • SN95 Mustangs For Sale (1994-04)
Replies
1
Views
1K
SN95 Mustangs For Sale (1994-04) Apr 7, 2025
Labora
P
New to StangNET
  • Popeye1790
  • Apr 19, 2024
  • The Welcome Wagon
Replies
2
Views
907
The Welcome Wagon Apr 19, 2024
Popeye1790
P
Electrical Use a 94 engine with 89 GT wiring and A9L ECU in non-Ford chassis?
  • Wallyman
  • Apr 8, 2024
  • Fox Engine Swaparoo
Replies
11
Views
2K
Fox Engine Swaparoo Apr 25, 2024
AeroCoupe
Share:
Bluesky Email Share Link
  • Mustang Forums
  • 1979 - 1995 (Fox, SN95.0, & 2.3L) -General/Talk-
Menu
Log in

Register

  • Forums
  • What's new
  • Media
  • Resources
  • Contact
  • Sponsor
X

Privacy & Transparency

We use cookies and similar technologies for the following purposes:

  • Personalized ads and content
  • Content measurement and audience insights

Do you accept cookies and these technologies?

X

Privacy & Transparency

We use cookies and similar technologies for the following purposes:

  • Personalized ads and content
  • Content measurement and audience insights

Do you accept cookies and these technologies?