And what is that upper intake manifold from?

 

Look, there are Ford OBD-1 testers out there. Look on Amazon for one. You should have that weird connectors guys have shown to do the blinking light test. The decent testers are like less than $50 for this. Get it, test it, follow the directions carefully. I’ve even seen them at Autozone. Let us know what codes you find. The user manual with most are excellent.

 

The ECM if stock and not reprogrammed is a 93 Mass air flow with sequential efi.

Is there a MAF on intake inlet?
I couldn’t see one from the posted pictures.

 

Thanks for the info - did you decode the numbers on the ECM to get that?

Yes, it has a MAF in the intake, here’s a pic.

Also I think someone said the color of the injectors can show what they are, so here’s a pic of one. They are grey.

 

I think that electrical fitting on the metal tube on the intake is the MAF you're looking for. He needs to locate the test port so we can get helpful codes. Otherwise, we’re all guessing.

 

The connector in picture appears (at least to me) it might be the Air temp sensor for ECM.

The foxbody MAF had an oval 4 wire connector.

It was common to read in magazines where the Air temp sensor was relocated to the intake tract to fool computer that the air was cooler…for more power of course.

The factory location was on the #5 runner on the lower intake just behind the distributor.

Retrieving error codes would be a good first step.

 

Some people have posted their very good 5.0 efi mileage. A couple have posted mileage I don’t believe. I’ll post my real in-town, not-perfect-engine, city-only, short-drive mileage: 13 mpg. Still a 50% jump from what you are seeing.

Check codes, check the brakes, make sure your odometer is right. You’ll find it.

 

Some people have posted their very good 5.0 efi mileage. A couple have posted mileage I don’t believe. I’ll post my real in-town, not-perfect-engine, city-only, short-drive mileage: 13 mpg. Still a 50% jump from what you are seeing.

Check codes, check the brakes, make sure your odometer is right. You’ll find it.

My 65 289 is around 16-18 around town 22 on the road if i can keep my foot out of it.
If i am really having a good time it is around 10

 

Just adding two thoughts not already covered.

• Based upon you description of odor in the garage after starting, you may be way rich during cold running. Like having a chock that doesn't open as quickly as it should. This would really affect mpg for short trips but would be good once warmed up.
• Check the timing as retarded timing can result in poor mpg but often not adversely affect how the engine runs. Not sure how to do that with your engine but be sure to disconnect the vacuum advance if you have it (check online on how to time your engine).

Good luck and let us know what you find.

 

If you want additional help, Stang.net has helpful folks, and one specific site for issues with 5.0’s from your donor year:

https://stangnet.com/mustang-forums/forums/fox-5-0-mustang/

I have found this a good source for problem solving as I have an 87 donor 5.0 in my 73 Stang. Good luck.

 

I might be off base. But I believe the E4OD or AODE would require a separate aftermarket controller from the ECU. And that controller might have an LED display that could be set to display MPH. If you don't have a trans controller, you might have an AOD.

 

There’s great information here for future reference.

https://www.vintage-mustang.com/threads/foxbody-5-0-in-a-classic.1215135/#post-10839701

I performed my swap back in 2018…yours may have been done much earlier.

 

A bit late to the game but 9 mpg in around-town driving, with the propensity for a bit of "lead-footing" is around what I'd expect from his combo.... The E4OD, while being particularly "stout" is, like it's C6 predecessor, big, heavy and a parasitic horsepower hog. My old F-150 didn't fare much better than that unless I got a chance to cruise the open road.

 

I think until you put a OBD unit on this, anything else doesn’t give you the basic info you need to proceed. .

 

+1. We need some of the results of the suggested checks and tests, or we're stuck in neutral here.

E4OD, you sure? That is a truck trans and a cramped fit in a '66. Even the AODE from a Fox body is a bit snug in there. I only mention, as a truck trans on a Fox C3W PCM is unlikely, or would be less-than stellar performance or economy without some expensive reprogramming. Back to checks and tests for answers.

 

It's going to take us some time to do the diagnostics suggested. It is my son's car and we need to do it together as a learning experience. And since a lot of this is custom we're going to have to search for the connection point to pull the diagnostics.

Am I sure its E4OD? No. That's what the car was advertised as having, but I don't know one Ford auto transmission from another. The car came with an appraisal from 2010 that listed the transmission as a 5 spd auto, which I believe is wrong. I can post some pics of it and perhaps folks with more knowledge that I can tell me what it is. There's enough inconsistencies in that appraisal that I don't rely on it to be accurate.

"Window sticker" from when the car was being sold. I don't think the rear end is 9", pretty sure it's 8".

Transmission pics

 

The EFI system used on the fox body is a great fairly simple system. I'd take it over Sniper etc. I've daily driven 90s F150s since they were new and still do with the same system.

Appears to be stock 19# injectors. But my first thought was oversized injectors.

Check the fuel pressure. Should be about 30-35 PSI. Also check that it holds pressure after being shutdown for a while. If it bleeds down quickly its dirty leaky injectors. Remove the vacuum line from the fuel pressure regulator and see if it smells like gas, if so it's bad.

An Innova 3145 can be had from Oreillys Amazon Summit etc for about 30 bucks. Its the only way I'll read codes on EECIV. Counting Morse Code beep and flashes is nonsense.

Can't be an E40D. It wouldn't fit. Likely 4R70W or AOD.

What rear gearing? Or What RPM at 65-70?

 

Thanks. I replied above about the transmission. IDK for sure what it is, just what was reporting to me.

The rear gearing is reported by the last owner as 3.55. He did the rebuilt on the rear end so I'm reasonably confident in that info. No tach installed so can't state RPMs.

 

Here's another older version of the tester you can get to read the codes. This one, you count flashes. I gotta get one like tx65coupe pictured. Counting Morse code is a POA. The key is to find that plug. It's usually on the driver's side of the harness in an OEM harness. Sometimes has a dust cover with EEC Tester embossed on it. Often these have be lost though. A single separate grey plug is also nearby. If the PO stripped this from the harness, they shot us all in the foot. The codes are just the start and point you in the direction of diagnostic routines. Great suggestions by tx65coupe. I'm leaning fuel system as well. Too much fuel can ruin O2 sensors compounding the problem. I thought your spark plug looked pretty good though. Check the rest though.

 

Very helpful, thanks. We're going to have have to search for the plug; having a starting point and a good visual is key!

 

Looks like a AODE

 

I'd check the codes and see if it displays anything but I'm in the camp that 9mpg isn't out of the realm of normal for a kid driving an auto. My EFI'ed 64 Falcon with a 5spd and 3.25 gears does about 18mpg on the highway at 70mph which I attribute a lot of that to the aerodynamics being similar to a brick. I've never bothered to check the city but I'm sure its not great.

 

Add 2.80(early listings) and 2.79 (later) to the list of common Ford 8" diff gears.

 

Couple updates.

We looked for the diagnostic port yesterday. No dice so far, haven't found it in the engine bay or under the dash. Possible it's closer to the ECU, which is hidden above the heater box meaning the glove box has to come out to check. A bit frustrating. Right now wishing I had thought to look at this when we replaced the heater box 2 months ago...

Injectors. Cleaned some grime off of one to check the color and wow! It went from grey-brown to bright orange! I knew the engine bay needed a cleaning but it was surprising. Anyway, confirms the injectors are 19lb type.

 

I doubt it would be there. When I installed one using the stock harness, I seem to recall it ending up near the hood hinge. (Maybe I missed what harness you are using). Throw a wideband on it (has that been discussed?).

 

I would not have expected it to be behind the glove box either, but can't find it anywhere else. No idea what harness was used - swap was done by a PO.

What's a wideband?

 

Ah hah! Found it! Went out with a brighter flashlight and found the port attached to the driver side shock tower, hidden under a bundle of wire looming.

 

Good find on the test connector!

Someone else also mentioned this, but I'm curious about that upper intake. From a Thunderbird maybe? The Mustang HO intakes were more squared off.

 

I've been trying to do some research into the intake and what it is. It does actually have "5.0 Mustang HO" cast into it, so I think it's safe to say its not from a Thunderbird.

Although, that plate is bolted onto the intake so I suppose it's possible that it was a custom addition or swap.

 

Mitchell will have the factory service manual for that year donor. Codes, diagnostics, etc. It’s $19 for a month, $40 a year. Until you get codes you may as well be playing parts darts.

 

Update: @b_arrington and I pulled the codes and compared to the manual’s chart:

54O - “Intake Air charge temperature sensor circuit open; vane air flow sensor out of range”
79O - “Air Conditioner ‘On’ during Self-Test / defrost on”
81O - “Air diverter solenoid fault, intake air control circuit fault / air injection diverter”
82O - “Air diverter solenoid circuit fault or supercharger bypass circuit fault” / “Integrated relay control module”
22C - “Manifold Absolute Pressure or BARO sensor out of range”
54C - Same as 54O (“Intake Air charge temperature sensor circuit open; vane air flow sensor out of range”)

 

I'll note that as might be expected this car does not have factory air, but uses aftermarket Classic Auto Air that's not connected to the ECU.

 

did you ck the fuel pressure

 

Haven't gotten to it yet.