I am in the middle of swapping my 89 E150 from speed density to MAF. I am about 98% done with the wiring part of it, but I have run into a snag. I need to supply power and a ground to the mass air flow sensor, but the pins for this on my computer are already being used.

What is the preferred method of splicing in? Is there another pin I can use?

Thanks!

 

out of curiosity, what are those pins supplying? esp the +5v pin.

i am pretty sure you can use the ground by splicing into it. you just want all devices in the computer system to be at the same ground potential so i don't think there is any current restriction on adding to that ground other than the pins themselves.

 

These are the power and ground for the MAF sensor itself. All other wires are already plugged in and are happy. I have done more searching on the net and it appears I splice into the (+) and ground pins already running to the computer.

 

well you said:
" I need to supply power and a ground to the mass air flow sensor, but the pins for this on my computer are already being used."

so what you meant was that you don't have a dedicated source for the MAF +5 and grnd. correct? ok so i think what you have read is correct - although i would stay away from tying into the O2 sensor circuit. i don't believe the MAF demands a lot of current so you should be safe splicing in to 5v somewhere.

i was looking thru my collection of stuff on such a conversion and found this in some notes:
Mass air conversion from 95, 5.8 processor (processor number BIO0, last digit zero!) would require running 6 new wires for injectors. Pins 12, 13, 14 ,15 and 38, 39. 2 new wires for mass air sensor at pins 9 and 50. Other mass air sensor wires are power and ground. Pin 2 must be run to brake switch. Switch pin 28 to 18 and 19 to 9 (diagnostic wires).
so the implication is as you suspect - tie in somewhere.

 

OK, I guess I wasn't explaining myself clearly. There are other pins my wiring diagram indicates provide ground and power in my existing wiring harness. I was wondering if anyone was aware of any pins which provide ground and power that are not already used by the existing equipment.

I have already added the requisite wires for the injectors and shifted the pins around for the air pump items.

I think I will just be doing some careful splicing.

Thanks for the input.

By the way, I am converting my van from a speed-density 302 to a 351 HO out of an 84 van and a MAF injection system out of a 93 Mustang GT. The interesting this is that the Mustang only had one O2 sensor. I double checked the wiring harness from the car and there is no provision for the left hand O2 sensor. Odd, but convenient for my application.