engine buckin like a bull

[n2402s15]

aight, as of now i have the gay KA motor in my 92 240sx. just about a month ago, outta no where, everytime i hit about 5000-5500 rpm, my engine bucks like a bull. but sometimes, i can go past 5000 right to redline BUT, then when i shift, it always stalls. but i dont hit redline. it just had a full tune up done 6 months ago. i have no friggen i deer what it is. please gimme some i deuz?

[Touchdown038]

Sounds like your fuel cut is coming in too early for some reason. Check that.

BTW, be ready to be flamed about the "gay KA" comment. At least you didn't post it in the KAT forum.

[leper421]

If you have a manual transmission, unplug your 4th and 5th gear sensors. My car had a bad 5th gear sensor, and the ecu thought I was in 5th all the time even in neutral. The rev-limiter was kicking in at ~5000 rpm no matter what gear I was in.

[MikeMurphy]

Its normal to feel some extra pull at 5000. Well, that is, it happens to alot of people. I think someone associated it with a bad water temp. sensor. Could be a number of things though. Plug into your OBD port.

Do your KA a favor and give it to me If you think a 2.4L RWD engine with forged rods is "gay", then you dont know what your talkin about.

[n2402s15]

yea, sorry bout callin the KA gay, i meant my KA is being gay. but, ill try unpluggin the transmission senssor and see what happens.

[n2402s15]

ooo, 1 more thing, i read that if you unplug your 4th and 5th gear sensors, that the car wont work in those gears cause it doesnt know it has em? am i right, or just readin bull?

[Nismo_yo]

as far as i have read, if you unplug those sensors it stops reading your rpm's in those gears and you have no speed limiter/fuel cut, but i could be wrong since i havent try myself, anyone got first hand experience?

[leper421]

I've been driving with both unplugged for over a year. They are only there so the ECU know to limit the rpms.

[n2402s15]

well, got the 2 sensors unplugged, but wont be able to try it out till friday. thats when i get my alt back from repair. ill post how it goes.

[leper421]

Unless your battery is dead you should be able to start it and rev past 5000 with no alternator. Or you could use jumper cables.

[Touchdown038]

I wouldn't. Revving the engine to 5000 rpm while the engine is still cold is a bad thing, and you don't wanna run it without an alternator long enough to warm it up.

Just my .02 though.

[n2402s15]

k, alt is in. took it for a spin. no bucking. leper421 is right. it must have been the sensors. and all is good. thanks for your guys help.

[NismoRb20S13]

if your alt. was dying it could have been that too, as it ate up all the juice in your batt.

good to hear its running if it wasnt i was gonna suggest checking the fuel filter and pump, weird stuff happens when you neglect those.

try plugging them back in now and see what happens, or say screw it