Mass Air Swap, Quick ?'s

[sick88tbird]

The best thing you can do is use the 70mm MAF housing with the center bar cut out(obviously leave the sampling tube intact) and use fox-mustang electronics...I got one of the housings for $3 at the local junkyard and figured I'd give it a try...car ran so great afterwards, it extended my usable rpm range and more power through the curve...no idle issues, great off-idle response and a/f was nearly identical. I've heard a lot of people say that the stock mustang 55mm maf will peg at 5v before it becomes a restriction...that is definitely b/s.

I've also seen mustang guys cut out the center bar of the 70mm housings and try to use the stock F2VF electronics and it never works...has to be mustang stuff...(looking for the 3rd digit in the part number to be "Z").

[gadget73]

when you mod the housing, ot screws up the transfer function. Unless you can map a new transfer function and then program that into the ECM, modifying the MAF housing is a bad idea.

[pantera77]

Mass air = ass hair, at least for me

Alright, my A9M came in early today, so I decided to go ahead and do this. Went to the junkyard and grabbed 2 maf's, both out of 92 panthers. Found something interesting though. Bastard block 4.6's use (what I assume to be) a 55mm maf, and the other 92-95 4.6's use a 70mm maf.

Re-pinned the connector following the LoL article, http://www.lincolnsonline.com/tech/00077.html

Everything was going smoothly up into the point I tried to start it. First, fuel pump never shuts off. I'm assuming the pink w/ black stripe wire behind the left kick panel on panthers isn't the right wire.

Next, at first it wouldn't even start. After trying for a long time it would at least run for a few seconds, with the idle non-existing before stalling out. I can somewhat keep it running by nursing it but hardly. Unplugging the MAF connector makes no difference in how it runs. Neither the 55mm or 70mm Maf seem to have any affect, with or without an airfilter. Just to be 100% I didn't get 2 bum Maf's I tired the know good one off my 92, which again made no difference.

I've double, triple, quadruple checked I've moved all the pins to the right spots. My DVOM is at work, but I checked for continuity between all the pins at the maf connector, and all the pins at the ecm connector. All were fine. The maf is getting ground and power like it should as well.

I'm completely stumped on what the problem is. The only thing I didn't do was remove any of the cruise control pins, because I think the only pins that even existed on mine were 39 and 50. And I can't imagine that the always on fuel pump is the problem (although it certainly is a problem). The computer seems to be working fine, as it is controlling the engine, and I can rev it up all the way somewhat as I'm assuming it's using some base tables. But none of the Maf's I've tried have had any effect on the engine.

Thought's?

[gadget73]

pull the cruise wires just to be safe. I dont know what those pins may do on a MAF computer, but having stuff there probably won't help it. On the other hand, it may do absolutely zip and not matter at all.

If the MAF is bad or unplugged, it will run without it. Not terribly well, but it will run. If its got the wrong signal, you'll get a code for a hard fault, and another for the MAF with a KOEO. I don't believe it will allow you to do a KOER test if its got a hard fault set.

[pantera77]

pull the cruise wires just to be safe. I dont know what those pins may do on a MAF computer, but having stuff there probably won't help it. On the other hand, it may do absolutely zip and not matter at all.

If the MAF is bad or unplugged, it will run without it. Not terribly well, but it will run. If its got the wrong signal, you'll get a code for a hard fault, and another for the MAF with a KOEO. I don't believe it will allow you to do a KOER test if its got a hard fault set.

I know it should run, but it really can't. It makes an effort, but it can't even idle well enough to stay running for more than a few seconds.

The thing is though, plugging in any of the Maf's I've tried make no difference. Unplugged, plugged in, it's all the same. It's like the computer is completely ignoring whatever is there. But I know all the wires and pins for the Maf are correct.

The only things that may not be correct are the 2 cruise wires that I left in, and the fuel pump run monitor wire that didn't work at all. Neither of those I could imagine are causing my issues unfortunately hence my stumptness.

[gadget73]

pull the cruise wires. It may not affect it, but its probably not helping it either.

cruise control wiring:

50 & 39 - to the buttons
35, 38, 41 - to the servo

not sure which wire is correct for the fuel pump monitor, but it ought to be the fat one that has no power with the relay not engaged. It will work fine without that wire even hooked up, so just disconnect it if its a concern for now. It throws some code about the fuel pump secondary circuit but it doesn't affect anything.

[pantera77]

pull the cruise wires. It may not affect it, but its probably not helping it either.

cruise control wiring:

50 & 39 - to the buttons
35, 38, 41 - to the servo

not sure which wire is correct for the fuel pump monitor, but it ought to be the fat one that has no power with the relay not engaged. It will work fine without that wire even hooked up, so just disconnect it if its a concern for now. It throws some code about the fuel pump secondary circuit but it doesn't affect anything.

Never mind on the cruise wires, they aren't even a concern, because pin 38 is where you have to move the Thermactor Air Bypass Solenoid wire, pin 50 is where you put the Mass Air Signal, and I didn't have anything in 2, 35, 39, or 41.

[pantera77]

Ok something is seriously fuxed on this thing. Went to do a self test, nothing. Ok, maybe there's no bulb in the engine light, IDK. Hooked up a test light to the Self Test Output, and grounded the STI, this is where things get odd. The light glowed dimly, this is with the maf unplugged, key off. Turn the key on, it gets bright, and never blinks or anything. Just stays bright. With the key back off, the light stays dim, and plugging in the maf makes it slightly brighter. Unplugging it again takes it to it's dim state. I am completely lost right now. If this computer is fucked fuck this thing it can go sit in the back of the barn till the end of time.

[88grandmarq]

I would double and triple check your ECM power and ground wires. also check all the engine and chassis grounds. the bullet connector on the battery ground cable, hear the starter solenoid is the dedicated ECM ground, make sure its not crusty/corroded. make sure all the ECM harness pin connectors are locked in the harness clip and not sliding out when you plug them up to make connection.


Might also want to check the ECM and fuel pump relay and connectors.

[pantera77]

I have triple, quadruple, quintuple, sextuple, septuple, octuple, nonuple every connection and any pins I've moved. I've checked all the pins on both the ecm and the connector. I even took the computer apart, and besides for being dusty looked fine inside. All the pins were tight as well. Every pin on the connector is tight and clean too.

Still, the computer acts as if the MAF isn't there. Plugged in or not makes absolutely no difference. The computer tries to run the engine, but I don't think whatever base tables it's using are wide enough to cover how modded the engine is. It can't idle for more than a few seconds, and runs like absolute garbage as you rev it up. Still, it does run.


The only thing I can imagine is the problem is the MAF or computer.
The computer makes some effort to control the engine though, so I don't think it's that.
I've tried 3 different MAF's, including 1 know good one, so I don't think they are the problem either.

Unless the comp., just doesn't like either 55mm or 70mm MAF's. But still, I would think they would make at least some difference when they are plugged in.

[sick88tbird]

when you mod the housing, ot screws up the transfer function. Unless you can map a new transfer function and then program that into the ECM, modifying the MAF housing is a bad idea.

That's true when using the electronics that came in that particular housing...no tuning or re-mapping of anything required when using that modded housing with '89-'93 mustang electronics, air/fuel remained nearly identical through the entire rpm range.

As for the current issue...you're not still running a vac hose to the MAP sensor are you? MAP sensor becomes a BAP sensor with MAF swap. I've also heard of O2 harnesses plugged in to the opposite sensors and apparently that causes some serious idle/performance issues as well.

Good luck,
Don

[pantera77]

Nothing makes any difference. MAP with vacuum or not, plugged in or not, it doesn't seem to care. Hell just for shits and giggles I swapped the 55mm maf guts into the 70mm, and again it didn't care. It doesn't seem to care about anything.

[GM_Guy]

Do you know if the ecm was functional before you got it?

Alex.

[pantera77]

Do you know if the ecm was functional before you got it?

Alex.

Well it's from eGay, so not really, besides for the fact the seller said it did.

That said, it is doing it's job in running the engine (well attempting too), it just doesn't seem to like receiving input from the MAF.

[pantera77]

I gave up. If I can't figure it out tomorrow back to SD it goes. I admit defeat. Worst Mass air swap evar.