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Not that it really bothers me, I really never go this fast, but the other day I decided to just slam on the gas and see what my car could do with 195K. Well I noticed that under WOT it has a little miss (my plugs need to be changed). As it got up to speed it passed the 106 mark and climbed passed it. What the heck happened?? Could the miss be causing this.
 

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From what I've seen posted here before, the speed limiter is not based on mph, but rather on rpm's. Therefore, if you have different tires, different gears, etc., (other than stock for that car) then the limiter will be working at a different mph.


EDITED for clarity
 

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Did you get past the 111 mark? What the speed limiter is set at varies on different years, but my 94 cougar would shut down at 111 before I had a tune. I say take it for another ride and see when it shuts down. If you can get up to 120, then the speed limiter has been disabled. If it shuts you down before that, you know what speed your car is limited to.

Mike
 

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MadMikeyL said:
Did you get past the 111 mark? What the speed limiter is set at varies on different years, but my 94 cougar would shut down at 111 before I had a tune. I say take it for another ride and see when it shuts down. If you can get up to 120, then the speed limiter has been disabled. If it shuts you down before that, you know what speed your car is limited to.

Mike
yeah go ahead ..There is always a trooper waiting to tell you exactly how fast you were going:D
 

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Rolling-Thunder said:
From what I've seen posted here before, the speed limiter is not based on mph, but rather on rpm's. Therefore, if you have different tires, different gears, etc., (other than stock for that car) then the limiter will be working at a different mph.


EDITED for clarity
That makes sense because I remember cruising around with Jesse (Fubarian), he was telling me that his 96 mark8 was maxed out at a certain lower speed because he didn't get it tuned yet. I think it was around 80mph with 373 gears.

That was actually a fun time, we were driving around in columbus after a snowfall in his mark with 373 gears and summer tires on it. Haha.
 

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My car is all done at 95 with the 3.73 gears and 225/60/15 tires, or rather, 4000rpms in top gear.
 

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I'd be surprised to see top speed limited by rpm because my 95 used to reach it's top limited speed in Drive or Overdrive. I think it was around 100mph.

If you didn't correct for a gear ratio change OR a tire diameter change the computer will not know the difference.

Let's say you are limited to 100mph and you are actually going 100mph.
Now you change to a taller tire. Your computer will still limit at 100mph, your speedometer will show 100mph but your actual speed will be higher than 100mph.
Same if you take a stock Tbird, install some deep low gears like 4.10. Now your top speed will be reached earlier because your computer will see 100mph way before you are actually reaching 100.
 

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jfsram said:
I'd be surprised to see top speed limited by rpm because my 95 used to reach it's top limited speed in Drive or Overdrive. I think it was around 100mph.

If you didn't correct for a gear ratio change OR a tire diameter change the computer will not know the difference.

Let's say you are limited to 100mph and you are actually going 100mph.
Now you change to a taller tire. Your computer will still limit at 100mph, your speedometer will show 100mph but your actual speed will be higher than 100mph.
Same if you take a stock Tbird, install some deep low gears like 4.10. Now your top speed will be reached earlier because your computer will see 100mph way before you are actually reaching 100.
By RPM-they're referring to driveshaft RPM.
JL
 

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I’m pretty sure mine topped out at 110. That’s with 3.08 gears. The main reason for the limiter is the driveshaft can only handle so much rpm, so if u had 3.27 factory gears, your top speed will be lower then 3.08's.
 

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mines got stock open diff with 3.27s and ive hit between 115 and 120, dont know exactly what i hit cuz i was looking at the road
 

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when i had the aod in with 3.73's out back the speedo read 108 same as the aod and 3.08's, with the m5r2 with 3.73's also said 108 but only about 60ish. but as of now i got 3.08's with the m5r2 and i get about 125mph. the drive shaft rmp would make sense but how would the car know the drive shaft rpms? keep in mind i used the 3.08 speedo gear with the 3.73's
 

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My 3.8 definately stops at 105, nasty limiter. Driveline is all stock.
 

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Both my cougars act the same...

With stock tires/gears they shutdown at 105...But neither shut down in 3rd...I've had both over 120...

Changing the tires/rear end will make a difference; it also messes up the shift schedule for the tranny.

Before removing the speed limiter, you need to update the tires to proper rating, replace the driveshaft with aluminum or racing design.

For high speed shifts, esp the 3-4, there are transmission parts that need upgrading, and if you have the stock plastic intake manifold, that needs to go; I broke one with 5k rpm shifts. The stock torque converter is only good for 5krpm, upgrade it before raising the rev limit.
 

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dwinthrup said:
how would the car know the drive shaft rpms
OSS="output shaft speed" sensor
 

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thats not how i meant it. how dose it know if you change the speedo gear out that would change what the car thinks about the drive shaft rpms. how is it possible to go from a 3.73 at 108mph to a 3.73 at 128mph useing the same speedo gear to the car it would be the same pick up signal right
 

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"Output Shaft Speed" sensor is not the same as a "Vehicle Speed Sensor".

Two seperate sensors.
 

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for both of my 93 cars, about 113 they would shut down. It didn't matter if you hit the governer in 3rd gear or 4th they would shut down at 113. RPM's didn't have anything to do with it. My 5.0 thunderbird stock gears had a little bit longer legs then the v-6lx and it still hit the governor at 113mph just the same. I did this all the time when I was younger, never got pulled over at that high of speed luckily.
 
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