Speed Cut (Speed Limiter)

Hello,

I have generated a lust for high speed but I have running into a brick wall for some time now. I am currently using Hondata Flashpro on the car, and for those who know the software it is very user friendly. If you go into the Rev Limits tab you should be able to just change the speed limiter rpm and the speed limiter speed to values above what you could normally reach to disable them right? Wrong.

The car is a later model one and uses a drive by wire throttle body. The factory speed limiter kicks in about 124 Mph or 200 Kph. With your foot to the floor the throttle pedal reads 98-100% but regardless of what you set the rev limit parameters to it starts to "shut down" the throttle plate. This reduces engine power so that the car can no longer accelerate which is not the goal here.

This problem has persisted sense I bought the car. Some time early 2017 I was being E Tuned before I knew about HPA. The guy tuning it looked at my datalogs and told me that it might just be the throttle body or something... Jeez Thanks!

I have Manual Swapped the car between now and then which means now the car has a new ecu, wiring harness, interior fuse box, exterior fuse box, power-steering control module, new engine, new transmission (Obviously) and a different throttle body from the donor car. Pretty much everything was ripped out and replaced so I'll spare you the details.

The car is turbo charged right now. This doesn't effect the speed limiter what so ever, it's just as happy to slow down the car N/A or Turbo charged.

So far I have not had any results and i'm not sure what my next course of action should be. I could switch to a aftermarket ecu and completely rewire the entire car, but it's kind of silly to do that just to go through 5th gear.

What are everyones thoughts because I am stumped.

Cable Throttle?

No, Its an E- Throttle or electronic throttle body. I forgot to put in there that the car is a 2012 Honda Civic Lx using Hondata flashpro. It does the same speed cut thing completely stock v.s. modified so the mods should not matter. If anyone wants details, datalogs, ill post them here if it helps. Thank you for anyone who has read this far. Just having eyes on the problem can make all the difference!

Have you tried asking Hondata or posting on their forum? My feeling is it probably needs input from someone more closely involved with their system. Speed limiting would not typically be done via throttle so I dont think it is a speed limiter. I would be leaning more towards something like a torque reduction request coming from the stability control system or similar.

I was suggesting you switch to a cable throttle. That way it will be open when you want it open. No factory Nanny speed limiters.

Adam@linkecu, No I have not yet posted on their forum. I will defiantly be in contact with them per your advice and hopefully get a fix asap.

David Ferguson, I don't want to open that can of worms right now. Although, after doing that the engine would have no choice but to do as it's told!

I am thinking about disconnecting the wheel speed sensors later tonight just to see how the car would react. I still need to see what the hondata team says but if it allows the car to keep accelerating it could be a viable option. I'm sure this is going to cause lots of problems and is less than ideal but curiosity killed the cat.

Looks like there is a vehicle speed limiter (that can be changed) according to this help page:

https://www.hondata.com/help/flashpro/index.html?rev_limit_parameters.htm

After posting my situation on the hondata forum the Hondata admin sent me a reply and asked if he could take a look at the calibration. Hoping to hear back soon.

I didn't bother unhooking the wheel speed sensors for anyone wondering. Big pain in the butt to get to and it's not worth all the trouble codes to be quite frank.

I'll keep everyone updated as things unfold.

I saw your posting on the hondata forum, with an unreasonable value for the speed limit. I would not be surprised if that value was stored as a 1-byte value in the ECU, meaning the maximum value that would work would be 255 km/h or 159 mph. Have you tried setting to to something like that?

No I don’t believe I have tried a lower value like that. Let’s see what happens, I’ll post the results later tonight.

Well that didn't work but it was a good effort.

Hondata got back to me and said no guarantees but they're going to add something to the next "release" for me to test out. (I assume that means the next update).

Thanks for keeping up with the thread David and Adam as well as everyone who has been following along. I am going to wait for the next update and see what happens. If any substantial progress is made I'll post it to let you guys in on it. It would be awesome to see this post resolved in the future, until next time!