mas air conversion

[dj6991]

Please help. my friend has an 86 fullsize that he tried to convert to mas air. needless to say it doesnt run right which is why it got dumped in my lap. it has the bronco motor and small cam, 6al box and probillet dist, jegs sheet metal upper intake mustang lower intake, painless mustang wiring harness, aem ecm, stock bronco injectors. starts and runs but idle fluctuates between 600 and 1200 rpms then runs fine from 1500-3000 then falls on its face. it is at a speed shop now and they cant figure it out but im kinda doubting their ability. i am an ase certified tech but im scratching my head. any help would be great thanx.

 

[BLADE262US]

Too many changes at one time best bet would be to remove all the wires from the engine controls and verify that everything is connected correctly where its supposed to go especially if its someone elses project that got dumped in your lap . Go to ford fuel injection .com and learn all you can about the mass air EFI . Did they put an oxygen sensor on it when they did this conversion ? Did thios ECM require 1 or 2 ? Lots of variables there . /emoticons/[email protected] 2x" width="20" height="20" />

 

[BroncoJoe19]

Too many changes at one time best bet would be to remove all the wires from the engine controls and verify that everything is connected correctly where its supposed to go especially if its someone elses project that got dumped in your lap . Go to ford fuel injection .com and learn all you can about the mass air EFI . Did they put an oxygen sensor on it when they did this conversion ? Did thios ECM require 1 or 2 ? Lots of variables there . /emoticons/[email protected] 2x" width="20" height="20" />

Blade262US knows WAY more about these conversions than me, and since I am not sure of a lot of the abbreviations that you listed above, all I can offer at this time is this:

On a non-modified '86 efi a surging idle could be a vacuum leak, IAC, MAP or TPS.

Considering that you have a top end issue as well as idle, would that point more to a faulty TPS?

Certainly with a significant vacuum leak, even if you sucessuffuly converted to MAF, couldn't it give you MAF like symptoms?

I don't know if you changed the computer, but if you did, would it be helpful to pull Diag Troubleshooting codes?

IF so... as a certified tech, you may already know how, but here is a refresher for you.

http://broncozone.com/forums/index.php?s=&...ost&p=74581

Good luck!

It is often more difficult picking up in the middle of a project than it is to start fresh yourself.

joe

 

[madmaysey]

i know converting to efi from carb your supposed to use a fuel filter accumulator.....not sure if you knew that or what the symptoms would be if you didn't have one

it goes right before your high presure fuel pump and its purpose is to prevent the EFI fuel rail from ever being starved of fuel....