S13 bad idle+lost power

[cheesyriceo4]

Hi i'm new to this forum en it's my first post [ obviously.. heheh :x ]. I've been forum jumping everywhere and searching EVERYWHERE! But everyone seems to have SIMILAR problems as me but i just can't find anything that exactly pertains to me... :\

I have a 91' 240SX coupe with a KA24DE, all stock, with just a K&N intake.

MY PROBLEM: I start my car, and it idles really, really rough. When you rev the engine it's fine and it smoothly spins back down to about 1500rpm. Then once it hits 1500rpm, the revs DROP to 700-800rpm and fluctuate from there. Also when i'm driving it doesn't have as much power as it had before and i basically have to rev the engine higher before i engage the clutch to get going or i'll stall. The car spits out black dirt [ gasoline + soot i believe? ] so i'm guessing it's running lean. REALLY lean. I guess the strong gas smell when the car is on also hints it. Another thing is when I drive on the freeway it feels as if nothing's wrong but as soon as im on the streets driving it starts to act up again.

I've cleaned the AIV, changed the spark plugs, spark plug wires, distributor, changed the fuel injector for the #2 cylinder [ because we thought it was the #2 cylinder that died ], got a new fuel pump, checked all of the fuel injectors, checked the fuel rail, did a compression check, checked the timing, checked the throttle body and it's still the same. when we cleaned the AIV it ran normally again for a good minute or two but the idle just got worse by the minute. now it's back to the same ol' putt putt sound. what do i do?? heeeellllp!!!

[fuzion]

I think there are a couple other things that can affect the idle.. My car used to be fine until I put the clutch in.. it would drop to 500 and sometimes die.. oneday it just started working ok

This is pasted from a thread in the 240SX Tech section [it's a sticky @ the top]

Idle Adjustment Screw - The IAS is located on the passanger side rear of the intake manifold. It looks like a large flathead screw. Turn it either way to bump idle rpms down or up to suit.

IACV - Air Regulator (Idle Air Control Valve)- The IACV is an air regulator valve. It's job is to provide your fast idle when the car is cold. The valve consists of either a wax or bi-metallic spring temp. sensing peice and a spring. When the engine is cold the valve is open and thus air bypasses to raise the idle. When the engine is warm the valve closes to drop the idle.

IACV - FICD - The IACV-FICD valve allows air into the motor when the a/c system is on to compensate for the added strain of turning the compressor. This will bump the idle up if working properly.

IACV - AAC - The IACV-AAC valve is an ECU controlled unit that runs off of a duty cycle set by the ECU. The valve operates in an ON/OFF/ON pattern. The greater the "ON" signal, the greater the amount of air that enters the valve (and a higher idle as a result).

* You can test the connectors for resistance to determine

I would check the above and see what the result is..

Hope this helps.. if not you can smack me

[NISTECH]

black soot and feul smell indicates its running RICH not lean. meaning it it getting way to much fuel. check your coolant temp sensor and its connector for corrosion. also check your air flow meter operation. too much oil on the K&N filter can build up on the airflow meter and cause serious run problems. I have posted how to check airflow operation a few times in here and in 240 technical. search for it.

Welcome to nico glad to have you on board.

[cheesyriceo4]

hmm thanks fuzion and nistech ill try that out. my dad knows a couple mechanics and they also said it could be one of the vacuum lines that could be bad, is that true?

EDIToh yeah sorry about that i meant RICH not LEAN.. oops ;x

[cheesyriceo4]

MY CAR IS FIXED.

we took it back to the dealer because we just couldn't figure out what was wrong with it... well, here was the problems

1) clogged fuel injector2) bad throttle body gasket

i hope this helps some future people who could be searching?