car running too lean

[9524tee]

i have a 95 240sx it is running to lean not too  much but just enough to make it misfire a bit at low rpms , how can i richin it out a little bit , for not alot of money ? any ideas ? and how much money would i be looking at spending on those ideas ...

[240racer]

Are you sure that it is running lean?  If that's the case, check the fuel injectors, O2 sensor and MAF sensor.  I would guess that it is probably something else.  I would check timing, it should be at 20 btdc, the instructions for setting timing can be found at 240sx.org faq.  Let me know why you think it's running lean, thanks

[9524tee]

i know it is running lean because i had it diagnosed at a nearby shop and watched the machine , the o2 sensor is working fine they said they said the mafs is also and i have perfect fuel pressure ... they said it was a lean misfire at 2200 rpms and at 3800 rpms ...

[9524tee]

and the fuel injectors are clean as can be ... and i just had my timing done cuz they thought that was it ... so how can i add more fuel?

[240racer]

I don't know, of course you could get the S-AFC and tune it with that, but it's $260 or so.  Then you would have to run it on the dyno too.  I would ask that shop what they think, they are the ones that told you it's lean, ask them why.  Also, what did they use to measure the air fuel ratio?  Make sure they are using a wideband O2 sensor, then you know what the a/f ratio actually is, rather then just lean or rich.

[AKADriver]

If this is a stock or near-stock engine then this is not a question of tuning.  There's something broken, and if it's not the MAF or O2 Sensor, then it's something else less obvious.

Have you ever checked your fuel filter?  They do eventually get clogged.  If the fuel filter is okay, next check the condition of the fuel pump and the electrical connections to the fuel pump.