KA24D Misfire

[DCSportEJ1Civic]

A friend of my recently bought a 1990 240sx, it has the KA24D 5-speed. I'm trying to figure out what where to start looking to diagnose a driveablity problem, I'm just not very familiar with these cars. With the clutch in trying to take off from a stop the engine will randomly bog down sometimes. It does this with maybe %10 throttle, when it starts to bog it pours unburnt fuel out of the exhaust and sometimes it will die. When it dies it wont restart for around 10-15 minutes. It also idles around 1400rpm most of the time. I havent found any vacuum leaks and the only thing we've done so far was replace the fuel filter (problem started before that so i doubt it has anything to do with it). Any help here would be great because i dont know where to start or what the common problems with these motors are.

[Patarach]

so its a ka24de swap into a 90?

It sounds like you have multiple problems here, since your friend just bought the car I would suggest you go through the first part of the ef & ec section (idle speed and Ignition timing) in the 240sx FSM
240sx-fsm-full-service-manuals-s13-s14- ... 11075.html Thanks Nico

As far as the high idle adjust your idle as mentioned in the FSM and If the idle does not drop check try pinching you IACV hose and for vac leaks again they can be pretty hard to find sometimes with a DE manifold. And of course it could be your throttle cable or TB adjustment.

Assuming your right about the unburnt fuel coming out the exhaust (my experience with 240's bogging is typically due to going to lean) Just check you ignition assoc. components.

Does this car still have a CC and EGR?

[StryfeS13]

Make sure your TPS is adjusted correctly. Unplug your TPS and see if it still bogs. An unadjusted or incorrectly adjusted TPS will cause the car to idle high, and/or bog.

To test your TPS voltage, backprobe the middle wire of your tps connector with a volt meter, and touch the other probe to ground (valve cover bolt works) It should read .50, if it doesn't, adjust it till it does.

High idle could also be because the throttle plate screw is holding the throttle open. I don't know why people screw with that when they still have the IACV on there car, if the throttle plate screw is adjusted at all, re-adjust it until it is not holding the throttle open whatsoever. I had that issue once.

Also, try a tune-up. Change spark plugs, wires, oil, etc. Check grounds also.

[DCSportEJ1Civic]

yea it still has the cat and egr. and the throttle plate is correct. it doesnt idle high all the time. ill check the tps today. id also like to check the maf, which wire should i check on there??

[StryfeS13]

I don't remember exactly, but there's a page in the FSM that tells you how to test it.

There's .pdf files of the FSM on here.