power loss...kinda?

OddyseusDSM · Aug 25th, 2003, 02:49 PM

ok, i feel pretty comfortable with cars but this is just puzzling. my car has a pretty good feel in the low end but the power seems to drop off kinda. some days it'll work like a dream for a little bit, it'll just run perfect. sometimes it feels like the clutch is slipping or something. no doubt the clutch is probly not grabbing completely but it wont rev and not accelerate at all, it'll also lose power between 2-3K rpms OR 3-4K rpms (thats as its warming up at a slow acceleration). but anyway...

when i accelerate i can never floor it, on a good day i can get it to about 75-80% throttle and itll accelerate, but if i go any more it'll feel like the engine is under heavy load like i'm drivin' up a hill. also if i floor it (100%) and bring it back a little the car will buck slightly and then start accelerating a bit. now, i've replaced the fuel filter, O2 sensor (car was running hella rich and i think the problem started occuring then), air filter, and removed the tube to the airbox. it felt better after each thing was replaced but it doesnt feel like when i first got it. all oil changes were done on time, spark plugs have been changed twice, wires done. i wonder if the fuel pump is going, or the distributer is going, or is it a matter of resetting the ECU. any other ideas are welcome (i tend to overlook things) i just cant figure it out.

niky · Aug 25th, 2003, 05:48 PM

well, if you think it's your ECU, that's pretty easy to check... just disconnect your battery for a while and leave it out long enough to make sure there's no charge left in the system and then reconnect it... sounds like a pump problem... i've been going through the same thing.

95 SentraB13 · Aug 25th, 2003, 06:00 PM

This is directly from a 1994 Nissan Sentra FSM(Factory Service Manual) - GA engine section

MASS AIR FLOW SENSOR MALFUNCTION

If the mass air flow sensor output voltage is above or below the specified value, the ECM senses a mass air flow sensor malfunction. In case of a malfunction, the throttle position sensor substitutes for the mass air flow sensor.
Though mass air flow sensor is malfunctioning, it is possible to drive the vehicle and start the engine. But engine speed will not rise more than 2,400 rpm in order to inform the driver of a fail-safe system operation while driving.

-----------------------------------------

THROTTLE POSITION SENSOR MALFUNCTION

When the output signal of throttle position sensor is abnormal the ECM judges it as a malfunctioning of throttle position sensor.
The ECM does not use the throttle position sensor signal, but judges the idle position by the amount of fuel injected and the engine speed.

Operation of Malfunctioning Throttle Position Sensor:

When engine is idling - Normal
When accelerating - Poor acceleration

I never said it was well worded

but either of these could be a potential problem.

OddyseusDSM · Aug 26th, 2003, 08:04 PM

thanks, i think i'll look into the fuel pump, but if anybody has any other ideas or suggestions....greatly appriciated

i also stall sometimes while comming to a stop with the clutch in, i think my TOB is bad but wonder if this brings up anything

OddyseusDSM · Sep 14th, 2003, 05:16 PM

today when i left work it felt like i hit a fuel cut around 2K then it happened again in 2nd gear. i had been driving around for like 2 minutes prior and lust left a light. the car was half way warmed up. im stumped. its gotta be fuel related. i dont have to much $$ to play with so i wanna nail this first shot although my gut says its the distributor AND the fuel pump. i got this car with most of the origional stuff on there. i think the fuel filter was origional too.

scrub brush · Sep 15th, 2003, 11:26 AM

Don't know if this helps or not, but on min, my car would not accelerate at all. Barely let the clutch out and give it a lot of gas and it still stalled. It turned out that the wiring from the MAF sensor was damaged, the prior owner attempted a hack patch job, and it came apart. Once I fixed the wiring, it was fine.