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Top Speed Limiter Delete: Solved


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Finally got rid of the top speed limiter on my 97 Outback. All I needed was the OEM ECU from a 97 Legacy GT.

 

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Wiring harness is the same between different models of the same year, so if I had a 98 Legacy Outback I would have used the ECU from a 98 Legacy GT, same for 99. Not sure about 95/96, they may be different but I didn't spend too much time looking at those wiring diagrams.

 

Some people on a different forum were guessing that you could cut the wire that goes from the speedometer to the ECU, since the vehicle speed sensor goes through the speedo before it gets to the ECU, so if there's a speed limiter that's definitely where the signal to cut the fuel comes from. But the thing is, all models have this wire and only some of them have speed limiters. Someone said something about that wire does something like tell the computer when send more power to the rear wheels, but that sounds like BS to me considering the AWD uses viscous couplings to determine how to distribute power to the wheels. What seems more likely is that even if it's not sending a signal to cut fuel it's completing the electrical circuit for the speedometer.

 

The only difference (in that circuit) between models that had a speed limiter and those that didn't is the ECU. Swap in the ECU from the same year GT and that should get rid of your top speed limiter. No need for a piggyback or standalone ECU, at least not for this.

 

Please note, I'm not going to get into whether or not it's "safe" to drive over the speed limit, or whether the Outback can handle speeds that high. Every driver should know their own limits and the limits of their vehicle, and sometimes you don't want other people telling you where that limit should be. But that's off topic for this thread.

 

The next step, and it's kind of unnecessary, is getting a speedometer that can display speeds over 120 mph. The 95/96 had speedometers that went to 140, and the driven gear inside the transmission has an one more tooth than the 97-99, but pretty much everything is the same. My hypothesis is that if you swap out the driven gear and the speedometer faceplate you could have a working speedometer that can display speeds up to 140 mph instead of 120. It's a ton of work, but it's been done with the transmission still in the car, details here: https://bbs.legacycentral.org/viewtopic.php?t=48090

 

I'll add for reference that I'm running a stock 97 EJ25D with A/C delete, CAI, and nothing else I can think of in the way of mods that actually add power. I can get up to 115 pretty easy (and I'm happy just being able to do that considering it used to have a governor at 113), but getting it up to 120 and beyond took some effort and a loooooot of distance.

 

Have fun out there, just don't come back here complaining to me that you wrecked your car driving too fast.

 

Edit: forgot to mention that you probably need a used ECU from your same year because there have been part # supercessions since then and I don't know if the new ones they sell do or don't have speed limiters. Altogether cost me $50 on eBay and about 10 minutes of my life.

Edited by Leggyobw97
used/new ECU part # supercessions
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