I recently picked up a 94 Altima as a daily driver. It is high mileage. It runs horribly. Starts up fine and stays running. But at a stop it surges and almost feels like it is about to staul (but never does). Has extreme power loss. Feels like a sensor maybe. Any ideas would be very helpful.

 

do a major tune-up

 

O2 sensor, check tps voltage, check timing. Change fuel filter and check fuel pressure under power conditions to check for pressure drop to indicate bad pump. I guaruntee its something really stupid.

 

I had the same problem as far as power loss, turned out to just be an 02 sensor. My idle still dips down every now and then, but not enough to worry me so im not concerned with fixing it.

 

check the air inlet after the MAF to the throttle body, see if it is off or has a crack. check for vac leaks. check your fuel pressure. 02 wont cause a no idle condtion on that setup, the car is in open loop for idle anyway.

check the basics first.

 

It could be an EVAP problem, are there any codes?

 

no cel

 

pre OBDII has a very primitive evap system, it is rarely an issue with driveability.

 

Yea that's true, but keep in mind that if 1 percent of the total intake air is composed of fuel vapors from the charcoal canister the air/fuel ratio can change by as much as 20 percent. If the purge is stuck shut and the PCM is expecting fuel vapor from the canister it will start leaning it out, and if the fuel vapors aren't there you'll have problems.

It's probably not the problem but if you've checked everything else it's worth looking for a lean code just to rule it out.

 

true, but on that system, purge isnt used at idle, mainly on a cruise. it is a remote possibility, but unlikely. now on most of the 97+ cars that use a PWM purge setup even at idle...that shit irritates me.


making me buy a fucking 2800 dollar smoke machine so i can test shit.....