Will my A4 shift correctly?

[EyeOutThere]

To make a long story short:
Say I was ripping down the highway at 100mph, if for some reason the computer suddenly thought I was going 50mph (yet I was actually going 100) would the tranny unwittingly downshift?

To make a short story long:
I am trying to make a device that will bypass the speed limiter.
My first idea is to simply make a circuit that will intercept the signal from the VSS and replace I with a 111htz square wave. Thus making the computer think the car was going 100mph. I would simply turn the circuit on when I hit 100mph.
The problem is that I wont know how fast I am going.

So I came up with a circuit that would simply divide the VSS signal in half using a flip-flop. Now, I know the car would not accelerate correctly if I had the circuit engaged from a stop; but if I only turned it on when the car hit 100mph (in 3rd and WOT), would the tranny down shift when it sees the 50mph?

Feel free to volunteer any information, Thanks,
Jason

[Andy]

This soounds kind of like the project I am working on. I am trying to remove the speed limiter and fit the car with a 155 mph speedo. I had a friend give me some parts and this is the idea that I came up with.

As I read more into how the guage works I am seeing more obsticales. I was hoping that I would be able to simply fit the line with a voltage divider but that doesnt look possible now. The gauge operates off a 4000pulse per mile output. So for now I am looking into finding out who makes these gauge needle "thingys" and if I can find one that would operate on a higher range so the speed displayed would be correct.

So what if you made a little logic unit that counted the pulses and when the total was greater than 100, it bypassed the source and continued feeding the sensor the same ppm(100 mph). Wouldnt that get the result you needed. I have had some experience in this area. Let me know if you think this might work.

[strange_trp]

careful guys... vss information is sent to ebtcm for abs operation.... you may loose abs ability when you turn this device on...

[EyeOutThere]

I turned off my ABS. [img]smile.gif[/img] but your right, with the unit engaged, if we hit the brakes at 120mph, the ABS probably wouldn’t work (or it would be confused). I could make the circuit shut off when I hit the brakes though. :rolleyes:

Anyway…
It wouldn’t be that hard to make a circuit that could stop the pulses at 100mph. (just a couple strategically wired 555 timers and a logic circuit.)
However I still wouldn’t know how fast I was going after 100mph.

I would fix this by:
-Making a digital speedometer. All I would need is a counter, a 555, a shift register or something to hold the count, and 3 7segmnt displays with drivers. I would wire the 7 segment displays backwards, so I could set the display on the dash and have the image reflect off (or projected onto) the windshield. Cool. 8)

-dividing the speed in half.

-or simply bypassing the PCM. This would be accomplished by sending a 100mph signal to the PCM, while rerouting the actual speed to the Speedometer. According to the literature I have, the signal going to the Speedometer is the same 4000puls-per-mile that is sent from the VSS (after is is ran through the computer). However I have yet to confirm this.


I am trying to buy an oscilloscope to help me on my endeavor. But they are not cheep. (I have a 110 outlet in my car so I don’t need a portable one)

Edit: spelling

[ March 05, 2002: Message edited by: EyeOutThere ]</p>

[strange_trp]

fluke makes a good *cough* cheap *cough* scope
[img]smile.gif[/img]