Removing Top Speed Limiter
As for removing the speed limiter, I highly doubt the dealer is willing to help you out
with this one. I actually just completed the task last week.It's not too difficult to do
yourself as long as you have the ability toramp or lift the front of your car up enough to
get to the transmission. Here's the procedure. First you must disconnect two sensors
(presumably RPM limiters?) from the tranny. One is the fourth gear sensor, while the other
is the fifth gear sensor. If you look at the transmission under the car there are
supposedly four (4) sensors (I only saw three, but the fourth one is somewhere under
there), the ones that need to be disconnected are the middle two (2). The electrical
connections are simple snap lock configured so not cutting is required. Once the two
connections are disconnected, I recommend you thoroughly tape over the ends of the
connectors to prevent moisture from entering within.
By doing this step the ECU doesn't know your 4th or 5th gear RPMs, therefore it won't limit you. Note: If you have faith in placing your car on jack stands (some members have done this) you can test the limiter for each gear before and after each step. What you'll find is that the ECU limits the top end RPM for 4th and 5th gear before you disconnect anything. Afterwards, the skies the limit.
The last step is to disconnect a control wire that comes from the tranny area and passes by the passenger side of the starter in the engine compartment. You'll find another simple electrical connection (looks like a tube style fuse holder) with small gauge wire. Unhook this connection and then drive your car and you'll notice the speedometer doesn't work, nor do the number onyour odometer change. What you've disconnected is the sensor that transmits the speed to the ECU and the display. Now the computer tries to watch your speed to make sure you don't go past 115mph (S13 model, S14 may vary higher), but never cuts off your fuel since it doesn't have a clue how fast you're traveling.
Since most of us don't cruise over 115mph you may want to wire a switch into the speedo connection just mentioned. I used a simple red rocker switch and installed it into the blank Nissan console plate located to the right of my
rear window washer/wiper control buttons.
Disclaimer: This method may vary for automatics and S14 models. Drive safely and
Super page! I have owned a 1991 240sx and an 1989. My latest venture is an 89 SCCA ITA racer. I just recently got the car built and its first test day and race. I did not have time to get a chip (also not legal, :-o) to remove the speed limiter. I missed pole in my class by .233 of a second and I was losing more than that on the straight because of the limiter. Therefore I took [email protected] advise under Speed Govenor/Rev Limiter in your FAQ section to remove my speedo and limiter. Well.... ....at the start of the race, in third gear, I pass two cars and go to fourth, NOTHING!, I try fifth, NOTHING!, I go back to third and redline! Try 4 & 5 again, NOTHING! After almost getting rear ended I packed it up after one lap. Apparently the computer could not read 4th & 5th, after disconnecting the harnesses!? I know your are not directly responsible for the info on your page and I am ultimately the one responsible for what I do to my car. I emailed Turbo240, (nicely) and no response. The main reason I write to you is to remove or at least fix the incorrect info that cost me my first DNF in four years. And I was bragging to all my Rotary friends that my 240 would be just as dependable as our RX-7's. :-p... Well, enough rambling, I was still wired from this weekend. Again nice page! I hope to contribute soon.
Juan D. (Racer X)
How do you remove the speed limiter?
After reading the first solution I looked into finding a simpler solution. Best of all, everything can be done at the computer. My car is a 89 with a 96 ka24de, but all the wiring and computer is 92. On my computer, there is a yellow wire with green stripe, 8th one over from right on harness. This is the vehicle speed sensor signal. Cut that wire. That is it. If you have a California car I think it will trigger a code, but for the rest of us, it is an easy trick. Your speedometer will still work because the signal comes from the tranny, goes to the gauges, THEN feeds the computer. I had to find a solution because my car comes very close to the speed limiter at the end of the 1/4. If anyone can beat the revlimiter let me know. I'm working on it.
Name: Steve Kovacs
Email: [email protected]
How do I remove the speed limiter from the 240?
If your willing to spend the extra cash head over to http://www.superchips.com/240.htm and take a look at a super chip. They claim that it brings your HP and torque up 10-15% in mid revs. Price as of late 1999 - 395.00 american.
The Dixie Flatline
Email: [email protected]
I don't know how many people have run into a problem with your rev limiter, but I've
noticed the 240's rev limiter is quite harsh. It is bad emough to stall the engine
sometimes, especially if you hit it in the middle of a speedshift. Although I have no
solution for the rev limiter aside from getting a reprogrammed computer, If your engine
dies because of the speedlimiter, it won't start right back up. I don't know how
many times I had to pull over and try to figure out what to do. I used to just wait
10 minutes and start it up again with no probs, but I did find an easier way. I did hit
the rev limiter on the freeway in morning rush hour and stalled the engine. Frantically I
tried to get the engine restarted while I was still rolling to a stop. I then found
out by turning the key back to at least the acc. position(I wouldn't recommend turning it
back all the way as your steering wheel may lock), you can then start the car right back
up! It took me 1.5 years to find this out, and it probably the best discovery I have
made about this car. Saved me from getting flipped off and yelled at from passers-by. I
thought this might be helpful, if not at least interesting.
Hi Shawn I am a longtime fan of you website. I own a black1992 240sx five speed coupe. I read something on the faq part of the web site about the speed limiter. I was wondering if you have tried any of the solutions on your car or gotten any feedback on them. The one I speak of in particular, is cutting the green and yellow wire on the computer. I would very much appreciate it if you would give me the heads up on this. Thank you in advance for your assistance in this matter.
Thanks for responding Shawn, I researched this at the dealer and I had one of the techs verify it in on the schematic. It works like a charm. It is the 8 wire down on the left #32 in the computer (yellow/green strip) the rev limiter can be by passed by removing the tachometer cable from the tranny.(although I haven't tried that one yet). Thanks again.