5.2 EFI last piece

Posted By: ralphie361

5.2 EFI last piece - 05/28/11 02:08 AM

Does anyone know of an 8 pulse per revolution hall effect speed sensor with a pass thru for a speedo cable? I have a 16 pulse autometer one in the car now, and it cuts off fuel at 55 mph with the stock pcm. Had to borrow the mp computer out of my dakota, wich has no speed cut out. The system is a 95 dakota 5.2EFI in a 68 fury, the build was on the forum a couple months ago. This last piece is driving me nuts!

Posted By: hooziewhatsit

Re: 5.2 EFI last piece - 05/28/11 02:58 AM

All I have found before is this one: (16 pulse pass through)
http://www.summitracing.com/parts/SUM-G2887-1/

A divide by 2 counter is pretty straightforward, and wouldn't take long to make

http://www.electronics-tutorials.ws/counter/count_1.html

Posted By: gdonovan

Re: 5.2 EFI last piece - 05/28/11 12:23 PM

Quote:

Does anyone know of an 8 pulse per revolution hall effect speed sensor with a pass thru for a speedo cable? I have a 16 pulse autometer one in the car now, and it cuts off fuel at 55 mph with the stock pcm. Had to borrow the mp computer out of my dakota, wich has no speed cut out. The system is a 95 dakota 5.2EFI in a 68 fury, the build was on the forum a couple months ago. This last piece is driving me nuts!

Just disconnect the speed sensor.

Posted By: ralphie361

Re: 5.2 EFI last piece - 05/28/11 02:49 PM

I actually ran it without one to start because I didnt think I needed one, but the pcm uses it with brake pedal sense to adjust the idle speed. The car ran ok, but on closed throttle decel it would stall intermittently, without brake pedal sense it kind of thought it was doing a stall speed test all of the time! This is my first efi swap so I am learning as I go.

Posted By: gdonovan

Re: 5.2 EFI last piece - 05/28/11 07:09 PM

Quote:

I actually ran it without one to start because I didnt think I needed one, but the pcm uses it with brake pedal sense to adjust the idle speed. The car ran ok, but on closed throttle decel it would stall intermittently, without brake pedal sense it kind of thought it was doing a stall speed test all of the time! This is my first efi swap so I am learning as I go.

The PCM on some car looks for a reduction of speed along with the brake pedal input to see if the car is slowing down.

When it sees these two events it starts raising the idle speed to prevent the car from "flaming out" when coming to a stop.

You can get around it to some degree by raising the base idle speed (usally hiding under an anti-tamper cap) a half turn or so.

This will cause more air to come in at idle around the blades rather than the AIS motor passage and help the problem.

Posted By: FuryUs

Re: 5.2 EFI last piece - 05/28/11 07:32 PM

Can you take it apart and grind off every other tooth?

Posted By: ralphie361

Re: 5.2 EFI last piece - 05/29/11 01:13 AM

I took it apart and there are no teeth on it, just a round disc magnet, must be a +/- pole deal? Got me. I was expecting a reluctor wheel like a distributor. Come to think of it...it might be worth fabbing something to hold a pertronix or something. I also like the idea of splitting the signal like hooziewhatzit said, although Ill have to do some research on where/how big/how expensive those things are, I have no experience with that! I might turn up the base idle a hair to get me by, Thanks everyone for the ideas!

Posted By: 1_WILD_RT

Re: 5.2 EFI last piece - 05/29/11 02:18 AM

you can find an 8-pole vss on 84-90 YJs and 87-91 Wagoneers

Just found this chart, the PPR spec is pulses per revolution..

http://www.magsensors.com/vssapps.html

Posted By: hooziewhatsit

Re: 5.2 EFI last piece - 05/29/11 07:40 AM

Come to think of it, when I get around to my EFI swap, I think I may need a divider as well

If you can't find another solution, let me know and I can probably put one together pretty quick.