fuel cut off at 4000rpm

[slideurride]

hi,

i did a search...got results...but no sure answer...and i didn't want to dig up dead threads.

so....my 89 240sx cuts off the fuel (feels like its hitting the rev limiter) at 4000 rpm in 4th and 5th gear (and sometimes 3rd). But, when in neutral the car revs fine. This is a serious problem when I am driving on the freeway and all the sudden my car stops accelerating ( i don't know what speed cuz my digital speedo doesnt work either.... but i'll save that for another thread). So i have to step on the clutch and rev the engine past 4000. When I let go of the clutch after I do this, the car is above 4000 rpm and everything is good again. But when I shift into the next gear... same problem again....

how do i fix this? when i did a search people suggested everything from a faulty fuel pump/fuel injectors to a clogged catalytic converter to a bunch of turbo related parts. from what i see from drifting from forum to forum, this is quite a common problem, yet I cannot find a definitive answer....

thanks in advance

-tim

p.s. my car is a 89 240sx sohc .... and stock engine(and please don't tell me to do search [because i did many times]...increase your post count in a more constructive manner)

[mys13240]

Hey,

Try fixing your speedometer. My car did the same thing when my speedometer wasnt working. When It worked the problem went away. So i got a speed sensor at the salvage yard, put it in and it fixed the problem. YOu loose alot of clutch fluid when you do this so you have to Fill it back up and rebleed the clutch, if you have a 5-speed.

[slideurride]

thanks for the help...

I was under the impression that my speedometer wasn't working due to a faulty capacitor in the gauge cluster.

Are all speed sensors the same for all 240s? (89-97)

[Redline2]

I think 4000 rpms is also where you can only rev to if the mafs is going bad. I could be wrong though, but check the connections on the mafs and clean it.