My 93 240sx seems to be missing some power.

[Luke]

Well, it's not easy for me to explain, but my car has 95k miles and i just bought it at 92k. It seems like it's missing some power it should have. It doesn't pull very hard in first gear. The clutch seems to be a little worn (my next upgrade) but it doesn't seem like it's slipping. I'm going to try and remember what maintenance things 'ive done since i've got this and maybe you guys can tell me some other things I can do:- Oil and filter change- 300ZX fuel filter- NGK Spark plugs- Oxygen sensor- Cleaned throttle body and MAS sensor with carb cleaner- Carbon cleaned engine, oil and fuel w/ Seafoam(http://www.nissaninfiniticlub....=2312)- Tightened drive belt and a/c belts(they were a little loose)- Flushed coolant and filled with new- New cone air filter (it is an APC temporarily, it came with an injen intake and the filter was in bad shape)

What maintenance things can i do besides what i've already done so far. Like i said, i plan on getting an ACT clutch. I"m also going to change the transmission and diff oil. Also possible spark wires and dist.

The real reason why i believe im missing some power is that around 5000 RPMs, sometimes it will start pulling a lot harder than it did in the lower rpms, whether it's 1st, 2nd, 3rd, etc. This seems to happen coming from lower rpms instead of say hitting the throttle at 4k rpms. I know that the KA24DE has a pretty straight power curve and that it isn't supposed to do that hehe. I'm not all that smart when it comes to this, but im wondering if the carb cleaner could have hurt the sensor in the Mass air sensor? Would that make sense because the engine isn't seeing the increase in airflow and the engine runs lean? Then somehow it sees the air and gives it more fuel? or could it be injectors or fuel pump. Has anyone had similar problems? thanks for the help

[sab3460]

Have you found a solution to your problem? I have a 91 240SX 5 speed with 100k miles, that does the exact same thing. At about 5000 rpm, I get a great surge of power. So I think I am probably missing power at lower rpm. I have new plugs and clutch, but that is all.

One shop's opinion was that it was the catalytic converter, and that it is taking the pressure generated from the high rpm's to push through the restricted catalytic converter. It did pass TX emissions testing. I have not replaced it, as I hate throwing money at "it might fix it " parts.