pats37 Posted August 12, 2004 Report Share Posted August 12, 2004 When I bought my STS off the lot in '98 the salesman told me that top speed with 'H' rated tires was 130mph and with 'Z' rated tires 150mph. How is this determined? By a different chip or reprogramming. According to dealer they have no listing for speed chips. Link to comment Share on other sites More sharing options...
bigfoo Posted August 12, 2004 Report Share Posted August 12, 2004 It's determined by the VIN placed into the PCM. Mine is H rated and I had it at 130 and i think a few higher and it didn't cut me off or maybe it did i'm not sure because I let off the gas right there heh. 130 is fast, especially not in a straight line. Link to comment Share on other sites More sharing options...
pats37 Posted August 12, 2004 Author Report Share Posted August 12, 2004 bigfoo, So the top speed is determined at the factory. I'm assuming then that it cant be changed if you were to put 'Z' rated tires on later. I have never had it up to 130mph even on a straight road and dont have a burning desire to test its limits either, was just curious. I did, however, outrun a cop about 3 years ago but never went past 119mph. I exited quickly and took backroads home. Love that Stabilitrak! Pat Link to comment Share on other sites More sharing options...
bigfoo Posted August 12, 2004 Report Share Posted August 12, 2004 Haha.. yea, the PCM knows the VIN and the only way to change the top speed is to reprogram the pcm with another VIN , or have someone reprogram the whole thing which is something i'm working on for more power and such the newer ones such as mine and yours are using a pcm that has a lot of different chips so in order for someone to make a programmer for it they would have to support many different chip types which is a real pain in the butt. the older one used almost all the same one, plus they used removable proms. Link to comment Share on other sites More sharing options...
cad98 Posted August 13, 2004 Report Share Posted August 13, 2004 Cadi can change it with their computer but will only do it to the rating on the tires and it does cost a bit. Link to comment Share on other sites More sharing options...
Greg P. Posted August 13, 2004 Report Share Posted August 13, 2004 Cadi can change it with their computer but will only do it to the rating on the tires and it does cost a bit. I have never heard of any dealer who was actually willing to change the speed limiter. While I suppose it is possible, most dealers would be afraid of any liability associated with this action. Link to comment Share on other sites More sharing options...
cad98 Posted August 14, 2004 Report Share Posted August 14, 2004 Well mine is set at 150 but they would not touch it till i put z rated tires on it that hit me in the pocket book then cadi hit my pocket book too Link to comment Share on other sites More sharing options...
Hud Posted August 14, 2004 Report Share Posted August 14, 2004 Several years ago, I purchased a Hypertech Power Programmer from Hypertech and reprogarmmed my 94 Trans Am. Was able to change many of the settings including the top speed. I'm not sure if they make a chip or programmer for the Cadillac. I have had my DTS to 130 in the Mojave Desert when the limiter kicked-in. Link to comment Share on other sites More sharing options...
JasonA Posted August 14, 2004 Report Share Posted August 14, 2004 I'm not sure if they make a chip or programmer for the Cadillac. For OBD-II and later Cadillacs, that's a big negative, unfortunately. XMS can't even release their supercharger because they can't figure out the Cadillac computer code, allegedly. Jason(2001 STS, White Diamond) "When you turn your car on...does it return the favor?" Link to comment Share on other sites More sharing options...
bigfoo Posted August 14, 2004 Report Share Posted August 14, 2004 The code is relatively simple, it's the flash programming of the PCM that is the hard part. There is no standardization on the method to do this and many cars have different pcms. THe problem is that you could fry the flash and not get it back if you don't do it right so you have to have the specs of every single pcm for all the models and years and be able to detect that before you flash it or it could render it unusable. It's the hardware that is the problem, not really the code.. If I was going to put in a supercharger, i'd be willing to go with a stand alone pcm to control only the engine. Maybe someone can make an inline pcm that sends good signals to the factory one (just so you don't get a ton of codes) and then does all the control itself. Link to comment Share on other sites More sharing options...
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