Fox Wiring Harness difference 93-94.

[jclose11]

I need some help. What is the difference between the wiring harness 1993 and 1994 mustang gt.. I just bought a megasquirt computer for up to a 1993 mustang , but I have a feeling its a 1994 wiring harness in my car the mass air plug is different then the stock fox mustangs I've had in the past. I'm hoping I can still use the Megasquirt in my car.

[excell]

Pretty unlikely - the 94+ harness and modules are different than the 93-, and a bunch of engine accessories are different. Check this out: https://www.stangnet.com/mustang-forums/threads/95-gt-harness-and-ecu-in-a-fox.883713/ https://www.sn95forums.com/threads/putting-sn95-motor-in-foxbody.27713/

Is the MAF on the car right now different than stock? What's more likely, is you have a newer MAF and someone cut the wiring and replaced with the newer pigtail. I have a pigtail for my Pro-M on my 89 here for just that reason, to get rid of the adapter I'm currently running. Got any pics? What year is the car? Was it a mass air car that got converted later?

[jclose11]

3158431583

[excell]

Yea -- can't tell exactly what MAF that is (looks like a Lighting MAF similar to https://lmr.com/item/M12579L54/Ford-Racing-Mustang-90mm-Mass-Air-Meter-MAF-96-04) but that is a 6 pin connector for MAF's with integrated IAT. You can see where it's been cut and soldered on. Here is the pigtail you need to go back to a 4-pin MAF https://lmr.com/item/LRS-8695MAFC/Mustang-MAF-Connector-Plug-86-95

What color are your injectors? Snap a pic. Good chance you have 24lb injectors I'd bet.

Also, take a pic of the TFI module on the distributor. Another dead giveaway on the harness, as the SN95 cars had the TFI relocated off the distributor.

[jclose11]

I don't have apic of the injectors on my phone will get one after work.


31593

[excell]

That MAF traces to a 2000 Mustang 4.6l. https://www.rockauto.com/en/catalog/ford,2000,mustang,4.6l+v8,1362743,exhaust+&+emission,mass+air+flow+sensor,5128 But no idea what sample tube is in it, I think the factory tube is a 24# but it could be changed/recalibrated. C&L I believe for a time sold these meters with whatever calibration, but don't quote me.

Regardless, I'd figure out what injectors you have, then put a 4-wire pigtail and MAF back on it, then wire up your Megasquirt and set it for the injectors you have -- if you want to use everything out of the box.

[jclose11]

3159431595

[excell]

Yep, those are 4.6L 24lb "Blue Top" injectors, so you have a factory 4.6l MAF which are calibrated to 24#.

The TFI module is factory as well. So, you certainly have a Fox harness with a 6-pin MAF pigtail. Cheers. :)

[Martin0660]

In the end, beside understanding what you have, you wont use the MAF with the squirt conversion going to speed density.

[jclose11]

I need schooled on this ECU what is it. . I just pulled the kick plate and saw this ECU.
31597

[excell]

Wow! I don't know anything about them, I'm sure others here will, but that's a Speedbrain -- it was a programmable ECU that had software to tune it. http://www.mustangandfords.com/how-to/engine/35638-speedbrain-computer-chip Check it out. Love the floppy disks. :)

[jclose11]

Well my last post was I found out my new project had a speedbrain ecu and car was running badly, So I have a MS2 I was planning to install this winter in the car, but that day came early. Today Was the day, I've been watching videos and reading on here. I think I have the settings set right, I started the auto tune and the car ran poorly for a little then after driving it seemed to be night and day difference ran really nice at the end. So I got home and stopped the autotune and saved it. I turned the car off(Did some BBQ grilling) and restarted it and its now surging and acts like it did before I started autotuning, When sitting there idling it dies after awhile. . I think I reloaded the saved software but not 100% . I hate messing with something like this when I don't fully understand it. Seems like a great program. just going to have a steep learning curve.

[Martin0660]

Auto tune - works wonderful, but you really can’t use it tuning in the idle or low RPM range.

does this car have a cam? Overlap in a cam at idle will screw with wideband readings. On my junk, with my cam, idle is indicated at 12:1 to idle clean and not surge. Best option is to manually add fuel in the idle range cells and set the lower limit in auto tune to something 3-400 rpm above where it idles so it won’t go there.

as a broad rule, surging is lean. If you look at your VE table you will see me meat ball going in a circle, likely going from where it has enough fuel to where it doesn’t. Timing can also help a bit, but usually fuel first.

i hate both the ideas that these folks sell Squirt packages as plug and play and auto tune. Those things get you to where it runs, but it takes some time to fine tune to good drivability close to an OEM setup. This is why most shops don’t like squirt solutions. You can tune WOT very good and fast on a dyno, but a lot of hours to get the drivability right. Pretty hard for them to charge shop rate to mess with it as much as it needs.

[jclose11]

I dunno, what the lift and all that is , but id say stock cam maybe a little over, I am not running a wideband yet, have one to put in just haven't had time and I wasn't planning on putting the MS in till winter, so I could learn more about it. The more I read and watch videos the more confused I become lol.

[Martin0660]

I will tell you that autotune has like ZERO change of getting the AFR dialed in without a wideband.

[Martin0660]

I guess to try and be helpful, Is you car set up speed density? I assume it is as that the logical method for Squirt. If not, no help, lol.

There are fundamentally 3 table that you should be looking at.

1) Ignition timing - self explanatory, its timing versus RPM.
2)AFR Table - This is nothing more than a static table that tells it what you want to target for AFR (when using autotune).
3) VE table - This is a confusing number, but VE is the amount of fuel you need versus the theoretical 100% of fuel. So a VE number like 70 means it's putting in 70% of 100% to get the desired AFR target. Autotune adjusts the VE table by looking at the Wideband reading versus the AFR table. If they match, good, if lean it adds VE numbers, if Rich it takes away VE numbers.

With a good base tune, you can basically only ever have to touch the VE table to "tune" your car.

[jclose11]

Yes i disconnected the MAF.