Engine MAF Conversion Help

88foxbodyowner · Jul 5, 2019

I just completed doing the swap to the A9P computer on my 88 mustang. I ordered the conversion harness from lmr and also got a bbk MAF sensor. I put everything back together but when I started it up it was a little rough at idle but never died out. It stayed somewhere about 600rpms I would say. I could tell it was definitely lower than usual. Is this a sign of anything or will I just have to play with the idle air control?

General karthief · Jul 5, 2019

There is a thing with the conversion, there is a vacuum line that needs to be removed from a sensor (map) on the firewall, you leave the port open and plug the vacuum line. The speed density system looks at vacuum (map) at this location and maf system does not (baro). Leave the harness hooked to this sensor,
I've seen this step skipped on several occasions.

88foxbodyowner · Jul 5, 2019

I did plug that line when I first did it and I went back to check if I plugged it well and it is still idling weird. This afternoon I did a cold start and it died out once but then remained around 600 but still seems to dip down or go up in RPMs at some points. Does the computer just need to learn since its a different engine to it?

Mustang5L5 · Jul 6, 2019

Let's get some background first.

1988, original AOD car?

Mass air swap with a9p. The mass air meter is cLibrated for stock 19# injectors correct?

Any mods on the engine?

Can you double check your wiring?

When I swapped my '88 to mass air, it started up and idled perfectly on first crank

Steel1 · Jul 6, 2019

Never had to do a maf conversion but wouldn't a base idle reset be in order,
just thinking out loud.

88foxbodyowner · Jul 6, 2019

Stock AOD using a A9P computer
I have a msd box, electric fan, upgraded 130 alternator, bbk cold air intake now with a 75mm mass air flow with it calibrated for 19lb injectors

New issue that is key information
I started the car and unplugged the mass air meter to check if it was bad and it didn’t shut off. It went back to the normal rpms

Now shouldn’t if I unplugged it the engine should shut off? Could that just mean a bad mass air meter or even my wire is bad
But I am 100% certain I spliced the correct wires, relocated the correct two wires and put in the two new wire

Blown88GT · Jul 6, 2019

No, unplugging maf tells ECU to use "limp home" fuel map.

Engine MAF Conversion Help

88foxbodyowner

New Member

General karthief

wonder how much it would cost to ship you a pair

88foxbodyowner

New Member

Mustang5L5

That is…until I whipped out my Bissell

Steel1

Mustang Master

88foxbodyowner

New Member

Blown88GT

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Engine MAF Conversion Help

88foxbodyowner

New Member

General karthief

wonder how much it would cost to ship you a pair

88foxbodyowner

New Member

Mustang5L5

That is…until I whipped out my Bissell

Steel1

Mustang Master

88foxbodyowner

New Member

Blown88GT

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