96 240sx se power loss

[husker240]

so i have a 96 s14 se automatic with a KA engine. when i am sitting at a red light, the rpms drop, the car almost stalls then kicks back up to the usual rpm. then when i am driving, it drops power (i can see the rpms dip every couple seconds by about 100-200 rpm. i have gone through 2 tanks of fuel and it is getting worse.

i have new spark plugs, wires, cap and rotor, and oil. no check engine lights or anything.

i am thinking it is the fuel pump going out, any other ideas?

[idlafie]

It's possible the fuel pump could be going bad. It could also be something else too. How many miles on your 96 S14? Ever replace your fuel filter? It's possible the Mass Air Flow Sensor could be going bad. Or an electrical short in the wiring harness leading to your Mass Air Flow Sensor. Ever clean the throttle body/combustion chamber/intake air control valve?? A can of throttle body cleaner or Seafoam ought to do. There's another sensor on the throttle body...can't recall the name at the moment....that you might want to check to make sure it's in specification. Download a FACTORY SERVICE MANUAL here from Zilvia. Use the SEARCH function to locate one for your car. Follow the procedures in the FSM on how to adjust that sensor. Also make sure your timing and idle adjust are set properly on your car. If you've got a lot of carbon buildup in your throttle body/combustion chamber it can cause your idle to fluctuate.

Anyhow, hope this helps...

ID

[Kingtal0n]

are you running an air filter? check that air from a fan is not blowing across the maf's hot wire.


could be fuel pump, but that is rare for them to be intermittent. And if there was a clog in the fuel filter bad enough to cause a miss at idle it would not drive well at all, ever.

The ignition Coil and ignition ground wires can cause that. So can a ECU ground or MAF ground, double check the wiring, was anything altered recently?

I would start with the cheapest items first. Coil/grounds/fuel pump/ you said you already did the other ignition components, thats good.

You need to figure out if the engine is lacking spark or fuel. If it's fuel related it must be fuel pump / ecu / wiring. A single injector would not cause the entire engine to stumble and miss at once.

If it's spark related the only thing you didnt change is the coil, and of course it could still be ecu / wiring related.

diagnostic tools that may help:
fuel pressure gauge that you can see while driving, Air/Fuel narrowband gauge to verify closed loop is occuring. You can also stick a voltmeter on the narrowband and verify the voltage swings from 0.02v-.997v while driving to verify closed loop.