SPS

I have a 94 Sl1 Saturn with a 94 Sl2 engine and trans swap.I want to know what to do with the VSS for racing.The car keeps shutting down when I hit 124 mph.Cann't win races with the engine shutting down.Unplugging causes problems with the PCM.They are racing Saturns so someone must have come up with something.Thanks for any help. Chris

I don't know what kind of racing you are doing, but if you are exceeding 122 mph in a Saturn, then you are kicking butt.

In all of the amateur road racing, autocrossing, and drag racing that I have done, I have never hit the speed limiter. Granted, the tracks that I've driven have been the relatively tight circuits in the OH/MI/IN area (Mid-Ohio, Grattan, Gingerman, IRP, Putnam). I've never made the trek to a big track like Elkhart Lake. James has. I don't know what James did with those long straightaways - probably stuck it in 5th gear and lumbered along at 120 mph, I'm guessing...

So I do not have any proven solutions for raising the speed limiter. Your best bet is to find someone like Mark Womac to reprogram the PCM to cut out at a different sensor voltage that corresponds to a higher speed. But very few people have the tools and knowledge to do this for you.

I have often wondered if you could wire in a voltage regulator between the sensor and the pcm. Theoretically, if you could deliver a steady stream of voltage to the pcm at a level that equates to somewhere between 0mph and 122mph, then the pcm would be tricked into thinking that you were going less than 122, right?

I am useing the MP 3 automatic trans.You are useing a standard trans which may not have a vehicle speed sensor.Most sensors use a 5 volt reference signal and the sensor governs the voltage back to the PCM.I would think it reaches 0 when the VSS is activated and cuts the ingnition off for the brief time it does it or till a voltage comes back which is 200 KM and the ingnition cuts back in at 180 km.I was thinking I could measure the voltage at the sensor at which time it cuts out and see what the voltage is at.I could introduce a 1 volt signal back to the PCM and fool it into thinking it has not reached the max. My other thought was to find the wire at the ignition and disable it so the PCM cann't kill the ingnition. Will keep you posted on which one works and how I did it.If not sucessful I will have to look at putting in a 5 speed manual trans.Wouldn't be any more work then I have put into the car with changing the SOHC engine to a DOHC engne.Thanks for the help.You got my mind working. Chris

Oh they ALL have a speed sensor and a speed limiter. They have to - otherwise, the vehicle tires could be pushed beyond their capability and fall apart with catastrophic consequences.

So the limits vary according to the stock tire spec. I forget the exact numbers, but it is something like:
122mph for the SC2
118mph for the SL2/SW2
I don't even have a guess for the SOHC models...

Good luck!

H rated tires or V rated tires would be better. HKS makes a SLD part# 4502-RA003 Speed Limit defencer for automatic trans as well as for manual trans.It may work on the Saturn.I was thinking if the PCM controls the speed limit by cutting fuel would I be able to cut the wire that goes to the fuel pump or over ride it with a seperate 12 volt wirer to a switch?

I would be hesitant to tamper with anything forward of the pcm because those controls may have dual purposes and thus bring unwanted consequences.

If it were me, I would limit my experiment to the path between the sensor and the pcm.

That HKS thingy sounds promising. Can you tell based upon the written product description, is it manipulating sensor voltage signals? If yes, is the output voltage adjustable in any way?