my buddie has a 89 240sx all stock and around 4 thous.rpm the motor just cutts out and wont start to go until 3 thous.rmp we replaced the fuel filter and still no luck so if anyone has any ideas plez help me out thanks... tia

 

Sounds like limp mode.
Pull the main fuse and wait for a few minutes, reinstall and see how she runs.

 

this seems to be a pretty common issue. try searching and see what you find. I seem to recall there being a few of these topics pretty recently
it could be a number of things, start with the main fuse (or disconnet the bettery) and see what changes.
have you checked the ECU to see if it is throwing any codes. sometimes the light doesn't come on, but there are still codes in the ECU.

 

Just throwing it out there..had any problems with the knock sensor lately?
and yeah..check for any codes off the ECU

 

Dont worry about the knock sensor. Although it is a code registered and stored by the ECM it will not throw a Check engine light or MIL, you woulde have to count blinks or in some cases uses an OBDI connector. Anywho the knock sensor will not cause the ECM to enter limp mode.

 

Have you replaced coolant temp sensor?

 

check the teeth on the dizzy