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Usually with converting you just add the maf wiring into the harness and move a couple wires for the map sensor. You shouldn't need to swap the harness. For me personally, anything that has a crimp connector would have the crimp connector removed and it would be soldered and marine grade heat shrinked on that harness if you use it.

The truck probably has a speed density stock ecu in it. If you have a decent sized cam, speed density won't idle without a tune. Once vacuum is affected SD computers can't control the engine properly.

Once you get the other ecu code I'll look up the wiring changes for that swap. It would also be a good idea to take that A9M apart and look at the capacitors. #1 issue you see with old Ford computers is leaking caps. They are extremely easy to replace or you can pay a local electronics shop to replace them if they are leaking.
 

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From my limited research it looks like the A9M is a 5 speed mass air ecu. Whether it can be used in this application I’m sure others would know better than I would.

You said it lost spark. What did you do to fix that?


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If I was in your shoes, and I don’t like to tell people how to spend their money, I’d get a stock f150 ecu and engine harness and start from scratch. Get another tune from someone that knows what they’re doing. Is the cam lumpy? Maf is the way to go. I’m a little weird lol I like speed density myself but I get it’s limitations with cams and more air. When it’s working it works well. I have a sd 302 in my 87 Grand Marquis, it just keeps going. Its never given me any problems in all the years I’ve owned it. Now if it was modded and had a bigger cam maf would be the way to go.


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Post a video of the engine running. Not a quick 5 second video either. Show us how it starts, walk around the engine bay, give us a shot of it idling for a solid 10 seconds and throw some revs in there.

Upload the video to Youtube and post the link
 

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Well it runs but will not idle.
somewhere in the mix of things I had it 180 out and its the 1-3-7 firing order, so it has a HO motor cam?
There's a lot going on here, but I've seen this before when someone tries to take a standard output 302 and convert it to MAF using a Mustang ECU.

The main issues. The wiring and firing order is different.

The 302 standard output ECU uses batch fire injection, while the Mustang MAF is using sequential injection which fires the injectors in sequence with the cam firing order. The wiring for the injectors is different between the batch fire SD ecu and the SEFI MAF ECU and two injectors need to be swapped. This can be done by swapping the pins at the ECU

First thing I would do is confirm the cam firing order. You would need to pull a valve cover and rotate the engine to observe valve events. yes it's a PITA but it will confirm what you actually have in there and then you can figure out your next course of action. Hopefully the cam does have a 1-3-7 firing order.

After that, you would need to confirm the injector wiring matches what should be correct for the A9L. There are a number of MAF ECU pinouts showing what injector goes to what pin, but i can provide one if needed. You need to test continity from injector to pin to make sure the injectors are wired in the correct 302HO/351 firing order.

Then, complete the MAF swap. skimming through some of the posts it looks like it was half done? This would be similar to the MAF conversion on a mustang where a few pins needs to be moved and added on the ECU connector.


I bet the cam and injector sequence is not matching up which is why it won't idle. You have two injectors firing at the wrong time. I would be those two cylinders are wet too.
 
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Discussion Starter · #50 ·
Last post didn't post, I'll try to get video later, seeing it won't idle I'll have to get the speaker wire out again to hold the throttle open.
Cylinder 2 plug is always just clean and wet. Every other plug is black and soaked.
The cam is pretty lumpy.
I do have a Gm ls motor, Trans, ecu sitting here but I'm trying to give this little motor a shot as it seems pretty healthy.
Thanks for all the help so far.
 

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The cam is pretty lumpy.
I've seen vacuum leaks and/or misfires make a stock HO cam sound like a pretty healthy cam. I wouldn't assume anything, but if you feel it is a performance cam with a 1-3-7- firing order, then I would ring out the injectors to see if they are pinned to the correct location on the ECU 60-pin connector.

I have a wiring diagram, but cannot post it until later tonight. You'll have to test continuity from injector plug on the motor to the pin on the ecu connector to make sure it's in the right spot.
 

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Discussion Starter · #52 ·
That would be great. It would clear up some things also so I know what needs to be done moving forward. Hopefully the long weekend I can have it sorted but I have all winter to tinker with it.
 

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Here’s the EEC pinout for a 1990.
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Discussion Starter · #54 ·
Here is some videos. Starts hard, idles high until it gets a little heat it in then drops down and dies.
FYI the tail pipes are probably 6in away from my garage door. It's 28 degrees out. I didn't want to open it. Lol
All these are in order, with very little time between. Total time from start to die is less than 5 minutes.
 

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I still think the timing is off.


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agreed. I would double check firing order by pulling the drivers valve cover as mentioned earlier.
 

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No idea, isn't #1 on the passenger side front?
I used the pencil to put in#1 cyl to ensure it was at tdc.
Yes. #1 is pass side front. #5 is driver's side front. 1-4 on pass side, 5-8 on drivers side.

Keep in mind, Cyl 1 goes to TDC twice during each cycle. Once on the compression stroke, and once on the exhaust stroke. The easiest way to tell TCD i've found is to remove the spark plug, and wad up a peice of paper towel and stuff it in the spark plug hole tight. Rotate the engine around and when the compression stroke is starting, the paper towel will pop out of the spark plug hole (last time i did it, mine made a very loud POP). Continue to rotate the crank slowly until 0 TDC aligns with the pointer. Stab the dist with the rotor pointing to Cyl1 and fire it up. Once it starts, you'll want to set the base timing to 10 BTDC as quickly as possible to avoid fouling plugs if the initial stab was slightly retarded (been there, done that).


Things i would have on my list to do.

#1 Verify the injector wiring matches up to the cylinders indicated a few posts up when running the Mass air ECU. This however will only work assuming the cam you have is a 1-3-7 firing order.

#2, based on the vids, i'm not sure if there is an aftermarket cam in that engine based on how it's running. Like said, i've seen stock 5.0 HO's with bad misfires idle similarly with that deep lope sound. I would still pull a valve cover to verify timing events. PITA i know, but need to be sure. Pass side would tell you the best.
 
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