Need help identifying MAF sensor plug and MAF issue

acmemopars · Jul 31, 2018

I need to buy a MAF sensor and pigtail but (first) need help identifying the correct plug.
Here's my dilemma....

I bought a 68 Mustang with a known bad motor (Fox 5.0L). It did run and drive but it had a cracked head and tons of water in the oil so I swapped it out.
The donor engine block is a 306ci with AFR 1472 heads and a Wolverine 1087 cam with a ported GT40 intake and a 70m throttle body.

I dropped the engine in the hole, hooked it up and it starts and runs pretty good.... but not perfect. I noticed that the Throttle body was running open without a MAF sensor...and I remembered that the old engine also did not have a MAF sensor attached.

I'm assuming that it's probably running on the default fuel/air tables and is in limp mode...and needs a MAF sensor.

--> In order to find the right MAF sensor and pigtail connector, I need to know what the MAF harness plug looks like. (NOT THE PLUG THAT PLUGS INTO THE SENSOR...but the end of the harness that th pigtail plugs into).

OLD ENGINE:
I was told (unconfirmed) that this engine harness and the old motor came from a 1988 / 1989 Fox Mustang so that should be the harness I'm trying to connect to.

1.) I found 2 unused plugs on top of the lower intake but would like to know if anyone can identity these plugs and what they go to.

2.) If I buy a MAF sensor for a 5.0L (1994 cobra for example) can I splice that pigtail into this engine harness and would it work ?

3.) If not, what is my best option ?

The photo is below:

Thanks for any help,

Mike Nelson
Denison, Tx

Mustang5L5 · Jul 31, 2018

Important question. What ECU are you running. If the donor engine is possibly from an '88, then it could be a speed density setup which doesn't use a MAF sensor. 1989 does use a MAF. The wiring will be different between those two years as well.

If you are running a speed density ECU, then that brings us to the problem. Speed density doesn't play well with aftermarket camshafts.

Steel1 · Jul 31, 2018

I agree with Mustang5L5, If it is speed density might be easier to go
with a MAP based aftermarket ECU.

Blown88GT · Jul 31, 2018

acmemopars said:
...--> In order to find the right MAF sensor and pigtail connector, I need to know what the MAF harness plug looks like. (NOT THE PLUG THAT PLUGS INTO THE SENSOR...but the end of the harness that th pigtail plugs into)...

This statement makes no sense to me.
The MAF harness plug IS the plug that plugs into the sensor. There is no MAF pigtail.

Mustang5L5 · Jul 31, 2018

Blown88GT said:
This statement makes no sense to me.
The MAF harness plug IS the plug that plugs into the sensor. There is no MAF pigtail.

I thing he's assuming he's missing a subharnnes (which doesn't exist) which plugs into one of the two plugs he's holding in his hand (one of which is the charcoal canister plug)

acmemopars · Jul 31, 2018

Mustang5L5 said:
Important question. What ECU are you running. If the donor engine is possibly from an '88, then it could be a speed density setup which doesn't use a MAF sensor. 1989 does use a MAF. The wiring will be different between those two years as well.

If you are running a speed density ECU, then that brings us to the problem. Speed density doesn't play well with aftermarket camshafts.

Here is the ECU: EEC-IV
I do not see a connector on the harness that will fit the MAF sensor. If this is in fact, setup for speed density, then I assume it will not be there.

Would I be better off buying a 1990 - 1994 ECU and engine harness ?
Is there a better option ?

Thanks in advance
Mike

Mustang5L5 · Jul 31, 2018

DK1 is the relevant code here. Trying to look up now what that corresponds too. It's not a standard mustang ECU.

But it is a speed density ECU (says SFI-SDI), which means no mass air meter. That's a problem with aftermarket cams, and larger size injectors (if you equipped your motor with it)

Do you still have the old motor? It's possibke that motor was never a 5.0 HO to begin with

acmemopars · Jul 31, 2018

Mustang5L5 said:
DK1 is the relevant code here. Trying to look up now what that corresponds too. It's not a standard mustang ECU.

But it is a speed density ECU (says SFI-SDI), which means no mass air meter. That's a problem with aftermarket cams, and larger size injectors (if you equipped your motor with it)

Do you still have the old motor? It's possibke that motor was never a 5.0 HO to begin with

Thank You for identifying the ECU as a speed density model, that helps !

To answer your question: Yes it is very possible that the old motor was not a 5.0 HO.
The new motor is definitely a 5.0 HO and runs great and with the mods, it really needs an updated ECU and a harness with a MAF plug.

Any suggestions as to the best way forward ?
Do I buy an updated (90-94 ECU for example) plus an engine harness ?
Or would I be better off going with an after market solution ?

My objective is not to RACE the car, but I would like to see the engine benefit from these mods and run good, so I'm looking for the cheapest and easiest way to (not cut corners....but make this right.

Thanks in advance
Mike

Mustang5L5 · Jul 31, 2018

In theory yes, you can buy an A9P/A9L and mass air conversion and wire it up and call it a day.

In practice, you should ideally identify what you had as the non mustang ECUs tend to be batch fire injection vs sequenctial like the Mustang. You could also run into issues with pin 30/46 and how that's wired up with the unknown harness as it could fry your brand new $300 A9L ECU, and we certainly don't want that.

Steel1 · Jul 31, 2018

Seems like the best way would be to get a new/used harness.
Even if you get an 89-93 harness w/MAF wiring you could still
choose to run a SD aftermarket ECU and fine tune your set-up or run a stock ECU w/MAF
and some form of tune.
Some aftermarket ECUs come with their own specific harness..i.e.ProM , Holley and would
probably run you around $2k or so.
You could also go the MS route like Stinger Pimp or Megasquirt PNP, I believe they both
offer a replacement Fox harness and would run you around $1500 w/harness.
Not sure if you have experience tuning these ECUs but if not factor in how much time you
want to spend learning.
You could always spend more $ and find a tuner to tune it for you.

General karthief · Jul 31, 2018

I'm a little confused, which is nothing new, but you say it runs great, so whats the problem?

acmemopars · Jul 31, 2018

General karthief said:
I'm a little confused, which is nothing new, but you say it runs great, so whats the problem?

Good point.
More accurate to say that it runs ok.
Higher RPMs and under power it pops and spits a little... you can tell that something is just not right.
The posts I've been reading say that with large camshafts and high flow heads, etc... it could possibly cause damage to the engine if it does not self tune, so that's the reason for wanting to make it right.
I don't want to spend $1500 for a few HP, but if I can get the right ECU and harness for a few hundred, then I'll do it.

THanks
Mike

Mustang5L5 · Aug 1, 2018

I can't find any info on what a DK1 ECU is out of. I've found one for sale, but no word on application.

Steel1 · Aug 1, 2018

Just for reference:
https://www.americanmuscle.com/frpp-efi-harness-8693.html
I see A9l and A9p ECUs for sale on Corral quite frequently for around $200.
I'm sure you could get a reman unit for around the same.
Still need to verify what the engine came out of, post more pics if need be, there
are some really smart people on this site (not me) willing to help.

Blown88GT · Aug 4, 2018

Mustang5L5 said:
I can't find any info on what a DK1 ECU is out of. I've found one for sale, but no word on application.

I can't find it either. I still have my original DA1 (speed density), not used in 25 years. I would consider selling it.
http://web.archive.org/web/20131229165710/http://oldfuelinjection.com/?p=17

Need help identifying MAF sensor plug and MAF issue

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wonder how much it would cost to ship you a pair

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