I have a 99 Nissan Altima SE 4cyl, 5 spd with 80,000 miles. When the car is cold, it runs absolutely fine. Once it heats up though, it idles rough and it hesitates badly when you give it gas under load until it gets above 2500rpm. It runs fine above 2500rpm. So far I've only tried a little fuel injector cleaner and air filter. Any ideas?
Is the " check engine light" on? Has it been tuned up with OEM parts(fuel filter, plugs, wires, etc)? If the light is on it will have to be scanned to retrieve the trouble code or codes. Could be the Mass Airflow Meter, Coolant sensor, etc .
December, 27, 2006 AT 4:32 PM
No, the check engine light does not come on. It runs this way every time I drive it. Runs fine cold, bad warm. To my knowledge the plugs, wires, etc. Haven't been changed but why would this affect the way it runs based on temperature? I'll change the plugs and wires though justto see. Does anyone know where the fuel filter is located on a 99 Altima?
December, 27, 2006 AT 5:25 PM
When they are cold they run a little richer and then lean out with engine temp. This changes the load on the ignition system. Besides the mileage you are at it should probably be tuned up so that there arent any basic problems