Mass Air Conversion Success!!
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Mass Air Conversion Success!!
hello all..i just completed the ford racing mass air conversion on my 87 f-150 4x4 5.0l. I cant believe the power difference it gives the truck. the only problem im having is when its cold it idles low and when i drop it in gear it struggles to stay running. when its warmed up its completely fine. the biggest performance gain ive noticed is when its completely warmed up. it used to have decent power when cold, but when it warmed up it was a dog...now it feels just as powerful at all operating temperatures. im now sold on sefi! it is defenately better. and call me crazy but i think it sounds better at all rpms (already had hedman headers, no cat, and single 2.5" through a flowmaster. most guys hear it and expect duals with chrome tips like everyone else, but it looks like completely factory exhaust, but sounds identical to a well built 5 litre mustang! also besides the idle problem, where can i get a chip for the pcm? its an A3M1 eec iv. thanks to all, sorry for the length im just really happy with it...hope this helps anyone pondering the conversion
Post Fiend
Joined: Nov 2001
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From: Topsfield, MA
Ya I'd check the TPS adjustment and clean out the IAC. You shouldn't have any idle problems like that if there isn't a problem with a sensor.
I did the conversion on my 302 a couple years ago and have to agree there is more power from SEFI. It makes sense, since the fuel is being sprayed when the intake valve is open and it has better atomization of the fuel.
One thing to be aware of - is that that kit splits the 1 oxygen sensor signal into 2. That computer you have (same as mine) is a reconditioned or whatever A9L computer (has the same programming). The A9L is the popular one from mustangs that people use for MAF conversions. This computer is setup for 2 oxygen sensors that monitor each bank. Your truck only has 1 oxygen sensor, so the FMS kit splits the signal to "fool" the computer. No biggy, but just be aware that that's how it's run.
The conversion kit he is speaking of isn't carb/efi - it's converting speed density EFI to sequenial mass air EFI.
I did the conversion on my 302 a couple years ago and have to agree there is more power from SEFI. It makes sense, since the fuel is being sprayed when the intake valve is open and it has better atomization of the fuel.
One thing to be aware of - is that that kit splits the 1 oxygen sensor signal into 2. That computer you have (same as mine) is a reconditioned or whatever A9L computer (has the same programming). The A9L is the popular one from mustangs that people use for MAF conversions. This computer is setup for 2 oxygen sensors that monitor each bank. Your truck only has 1 oxygen sensor, so the FMS kit splits the signal to "fool" the computer. No biggy, but just be aware that that's how it's run.
The conversion kit he is speaking of isn't carb/efi - it's converting speed density EFI to sequenial mass air EFI.
Last edited by MustangGT221; Dec 29, 2005 at 05:11 PM.
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From: Pittstown NJ
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Post Fiend
Joined: Nov 2001
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From: Topsfield, MA
You can buy the kit at any FMS dealer - it's about $600-$650.
I got mine used...
You can also do it yourself for cheaper (kit is kinda expensive). If I had to do it over again I'd of done it myself. You can check in the 87-96 forum with the search function to pull up MAF conversion topics, that topic has been beat like a dead horse.
Gas mileage will definitely improve - 1 or 2 pts or so.
I got mine used...
You can also do it yourself for cheaper (kit is kinda expensive). If I had to do it over again I'd of done it myself. You can check in the 87-96 forum with the search function to pull up MAF conversion topics, that topic has been beat like a dead horse.
Gas mileage will definitely improve - 1 or 2 pts or so.
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no i didnt have to modify the harness, i just unlplugged the old injectors, yanked them out and tied them up on the existing harness, and plugged my new overlay harness in. the new injector harness was even numbered for each cylinder. then i unplugged my pcm, yanked the old computer, installed the new one and plugged the adapter in, and then my origional harness into the adapter, mounted the new air intake, plugged in the maf, and fired it up. My wife got me the conversion for christmas on ebay, dont know how much she paid, and wont ask. one thing i did, is i changed the firing order at the distributor because i read that the new computer fires the injectors with the 5.0 HO order. it ran like crap, and then i changed my wires back to the truck firing order and it ran fine. I wonder if this could have caused a code to be stored and this is my idleing problem? tomorrow ill reset the pcm, fire it up, check again for any vaccum leaks, and if that dont help,,,ill pull codes....thanks for all the help
Lead Driver
Joined: Nov 2002
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From: Concord, NC
A quick note on the firing order: the actual firing order of your engine will not change unless you swap to a cam that has the 351/302HO firing order. Thus the spark plug wire order will not change either. The Ford motorsports conversion kit is setup for the stock truck 302 firing order, making it plug and play.
Post Fiend
Joined: Nov 2001
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From: Topsfield, MA
The conversion kit can be setup in either firing order...you can change the wiring on the connector to change it. I think you can actually buy the kit in either config.
I got confused about this too when I had mine...
The kit I have is wired for the 351/302HO firing order. My truck had the old 302 firing order. As stated, the cam determines the firing order, so you can't change the spark plug wires as your valve timing events will still be off. The kit determines injector firing order, since this is now sequential EFI instead of regular batch fire EFI, there is an injector firing order that follows the spark firing order. If the injector firing order is wrong, the engine will still run fine...it just means that some cylinders are not being injected at the right time, the intake valve is closed and it works just like the old EFI.
If you want the sequential injection to work properly, the injector firing order needs to match the cam firing order, and obviously the spark plugs need to follow that order as well.
When I said pts I meant MPG points, not %...
I got confused about this too when I had mine...
The kit I have is wired for the 351/302HO firing order. My truck had the old 302 firing order. As stated, the cam determines the firing order, so you can't change the spark plug wires as your valve timing events will still be off. The kit determines injector firing order, since this is now sequential EFI instead of regular batch fire EFI, there is an injector firing order that follows the spark firing order. If the injector firing order is wrong, the engine will still run fine...it just means that some cylinders are not being injected at the right time, the intake valve is closed and it works just like the old EFI.
If you want the sequential injection to work properly, the injector firing order needs to match the cam firing order, and obviously the spark plugs need to follow that order as well.
When I said pts I meant MPG points, not %...
Last edited by MustangGT221; Dec 31, 2005 at 11:03 AM.