Mechanics

I30 P0171, P0174

2001 Infiniti J30

Engine Mechanical problem
2001 Infiniti J30 6 cyl Front Wheel Drive Automatic 120000 miles

I have an I30 2001, I had a bad coil pack which would cause missing, replaced pack, know I get P0171, P0174. When I start the car in cold weather the engine starts OK When the engine starts it goes to high idle (about 1500 rpm) after about 10 seconds it drops to 1100 rpm running a little rough, after about 15 seconds it goes back to high idle, this in neutral. After that the engine runs fine. The gas mileage is good, in fact on a long road trip I got about 30 mpg. While driving at highway speeds the check engine light goes on. When I check the error it is the P0171, P0174 error, I have changed the air filter, and cleaned the MAS with no difference. The car seems to run fine with or without the check engine light on or off. The car is never difficult to start. This missing problem only happens on a cold engine. I have 120,000 miles on the car. I cleared the code several time, and will return. Thanks for you help. Ron
AD
Avatar
Rmaytin
April 10, 2009.




Have you checked the front O2 sensors to see what they are doing. They may be bad.
AD

Racefan966
Apr 10, 2009.
Why would both be bad, and how can they be tested. Would they cause the rough idle for just 10 to 15 seconds?

Tiny
Rmaytin
Apr 10, 2009.
The codes that are there being that both are present indicate that both front O2's could be bad. You need to use a scanner that does a live screen scan so you can see what they are doing while running. Yes this can cause it to run to rich or lean making it miss.

Racefan966
Apr 10, 2009.

AD