5k rpms is my rev limiter? Only sometimes!

[S13_RB25]

Hey guys i recently ran into a problem that i've searched for and have come up empty handed. The car is 93 S13, rebuilt motor, around 2k miles and was running fine before this thus! When i left my college i got on it and took it up to 5k rpms and it just start to bounce back and fourth, like it does on the rev limiter. It still does it, mostly when im driving, and sometimes not all the time but also when im standing in neutral. Could it be signs of the fuel pump going bad or a clogged up fuel pump filter??

Thanks in advance nico!!

[simmode1]

First thing I'd check is to make sure all the speed sensors are properly plugged into the transmission.

[S13_RB25]

The only sensors im using are the speed sensor and the reverse lights. There both working fine.

[Chris28]

Your 5th gear sensor is closed. It's a speed limiter, when you hit 5k rpm in 5th there is a rev limiter.

Check your wiring and make sure the 5th gear switch isn't creating a closed circuit.

[costa_rican13]

i have this same problem, never could figure out what it was, and its at random, like it can happen then i shut the car off then immediately turn it back then i can red line normal at 6500 again. and it wont happen for a while like days, weeks, then do it again.

[Chris28]

It's the wires heading to the 5th gear switch shorting out intermittently. Even if you unplug the switch if the wires are grounding out anywhere in the harness the ecu will think you're in 5th and limit you at 5k.

[costa_rican13]

oh really? could this be because the guy who i bought my car from, did a 5 speed swap? and what if i just cut the wires? is there any way to get rid of the limiter in 5th? thus wouldn't that do away with the limiter?

[S13_RB25]

Wow this is amazing, even when you don't plug s*** in, it still comes back to bite you in the azz lol. But im also wondering the same as costa_rican, would cutting the wires help?? Oh also it was after i removed the extra ground i had in the engine bay, i guess ill put that ground back! Thanks nico.

[Chris28]

It all depends on where you cut the wires. If you cut them after the short it doesn't make a difference, and it's possible that if you leave them unshielded after cutting them they could short out. Your best bet is to follow your 5th gear sensor wiring back up the harness and checking for shorts. I'm not sure where the wires go to after joining the body harness, my ecu has the speed limiter removed so I haven't been running a 5th gear sensor for quite some time now.

[costa_rican13]

well then what would happen if you just take off the 5th gear sensor chris?

[Chris28]

If the short is happening before the sensor it doesn't matter what you do with it. I should have said I've had mine unplugged not i don't have one, I think it's still in there. If you took it out you'd have a hole in the side of the transmission, so yeah don't take it out.

[spank044]

Don't quote me on this. But I think pin 108 on the ecu is the input for the sensor. If you cut it then you no longer have that rpm limit or a speed limit. If you do that then you don't need to find the short in the wiring harness. If you did just cut the wires, then corrosion or moisture ay be making the connection.

Read this from the old articles. It has info that will help you with your problem and give you ideas.
http://www.240sx.org/faq/articles/spdgov.htm

[Painter92p]

did you guys ever fix your guys 5k limiter problem i got it now it only happens once i go in to 5 gear and stays on in all the gears after that then goes away at times