Will not run with MAP sensor
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From: CT
Will not run with MAP sensor
I have a 302 in my 93 F150, with the map sensor hooked up the truck will start run then die. If it remove the vac. line from it and keep the sensor plugged in and plug the line the truck will fire up and run and keep running. If while it's runnig i plug the map sensor back in the engine will die. I used this same sensor on the MAF 393ci that was in the truck, although i was using it as a BP sensor the truck ran great. Time for a new map sensor? any other ideas?
Lead Driver
Joined: Nov 2002
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From: Concord, NC
Are you using the truck batch injection wiring harness or the sequential injection MAF harness you were using with the 393? Is that a mustang speed density computer? I would make sure all the pinouts and wiring connections are correct.
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From: CT
Fuel pressure was fine on the 393, not sure on the firing order, the pinout of the injectors is the same between the A9L and the ecu I have, the engine is from a late 80's crown vic. The engine will start pop and sputter if i feather the gas with the map all hooked up, too much throttle and it quits. And whats strange is, the map is still plugged in, just no vac input. with the engine running, and it runs just fine without it, upon hooking up the vac, it dies instanly like someone turned off the key.
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Lead Driver
Joined: Nov 2002
Posts: 9,555
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From: Concord, NC
That's really strange. I wish I knew something else to try, but it sounds like you already have a pretty good grasp on what's going on. Have you tried to pull codes? It probably won't tell you anything you don't already know, but you might get lucky.
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From: CT
tried 2 maps sensors, same deal, i tested the vac and im getting around 17" at idle.. I tried unhooking the map sensor and plugging the vac line, fired up the engine and slowly applied vac to the map sensor. The idle picked up slightly around 10" then ran for a few seconds and quit.
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From: CT
i wish i could remember what wires i had to change during the maf swap. I'm gonna try hooking the maf sensor back in and trying to start it with the A9L.. If that works it's gotta be wiring..
Fleet Owner
Joined: Aug 2005
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From: Easton,Ks
Sounds like you have a fuel problem. With the vacuum line off the computer thinks you have WOT goes full rich, when you plug the line back in it goes lean and that is not enough to keep it running. Could be the wrong tables in the computer for the injectors you have or low fuel pressure.
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From: CT
they are a tan off white color, defn. not yellow top, fuel pressure is fine. So ill take a shot at this, the ecu being from a mustang is giving the engine fuel as if they were 19lb injectors? found an ecu online, is there any way to decode it? E7SF-12A650-AC1C the one i have is E7SF-12A650-C1A
Last edited by FordPerf300; Dec 24, 2007 at 01:00 PM.