Proximity sensor for speed sensor

I am using this on my ej22 swapped beetle chassis kelmark gt.

https://m.youtube.com/watch?v=JEtdtq4hWqk

It seems good up to 25 mph or so, and as long as I keep it below 4k or so rpm i have no issues. 

BUT... when i step on it, and it does not sense, it tosses a code and cuts the fuel for a bucking ride, at about 4k rpm. 

The video and site don't go into a lot of detail on the install.  It's been a while since I installed it, but I get the flashing led as shown, so I did something right. 

I have messes with its position a couple times, and when I think it's right its not.

Some have said put a pull up resistor in, but no details.  

Thoughts on this or others methods of getting a vss signal for the ej exam will be appreciated. 

Its hard to say if you need a pull up resistor or a pull down resistor, it depends on the prox that you used.  If you could provide the part number of the prox you would probably get the answer you seek.

In reply to Doc Brown :

Thanks. I will try and find the paperwork, or crawl undwr the car tonight. 

You'll want to look at the spec for speed for your particular sensor.  Not all of them are fast enough for what you're doing.

In reply to APEowner :

That may be the case.  I was thinking, how many vw buss guys are going to spin there engines past 4k.  They may never know there is an issue unless they check codes or are using it to drive their speedo. 

I am still using the vw cable to drive my speedo. The reason I know it drops after about 25 mph is due to me investigating the 4k cout off and watching the speedo in torque. 

In reply to Doc Brown :

So far, all I can tell is that it's a npn.  

hoping to get a pic of the part number with out getting all garage floor smutz stuck to me. Its 90 degrees and 90% humidity. 

Edit: Got it, took a couple shots from the ground and from above.
The Part number is LJ12A3-4-Z/BX.

Pull up/ Pull down, value ????  Thanks 

Looking up the data sheet its good for DC:0.5Hz AC:25Hz. 
I think its to slow. based on my tire size I have 793 rotations per mile, there are 6 CV bolt heads for sensing. If my chicken scratch garage math on scrap paper are right, I am thinking about 75hz at 60. The that would explain the 25 mph fall off.

Sill would like to try the resistor.

Thanks a million for the input

I used a similar set up to signal an automotive timing as a strobe light. Didn't work out of the box, but a capacitor on the signal input to the timing light fixed it.

As this may be to slow for what I need, I was thinking...never a good thing... can I use a cheap abs sensor in its place ?

Thoughts before I spend way to.much time over analyzing this ?