I have a 88 pathfinder 3L throttle body fuel injection. My car willnot pass DEQ emmission test. Car has been tuned, fresh filters, oil, new sparky parts. Runs and starts great. Has a fuel odor after driving. Failed test because of rich mixture, high on the CO and Hydorcarbons. Any Ideas on what to check? How to get the fuel consumption down.
Could be several things but I would start with the cheapest solutions first. First make sure the car is hot, (running for at least 30 minutes), at the time of the test. By doing this you are more likely to burn off the nastys instead of sending them to the tailpipe sensor. Two- use premium gas or better yet low emissions premium gas. The later can be found in most major cities but usually in the summer time. I would advise using a full tank of it and running it for the above mentioned time before testing. Third- check the PVC valve. If the car is running rich often replacing the PCV valve solves the problem. And last but not least, replace the catalytic converter. I did all of the above for two years of inspections but it finally took replacing the converter at about 210,000 miles. I purchased mine online from Summit Racing at a very competitive price. Word to the wise though. It took the better part of two weeks before it got delivered.
Best of Luck,
Thanks for writing, long story short, I did several things but it never made a difference. So I took it to a dealer and request a diagnostic for failing to meet DEQ, I was supprised when they called me up to say the car was ready, $55.00 labor and no parts, and he took it to the testing station and it passed, another $21.00 for that. I had to ask the 30 year nissan technician what he did, he said, he tricked the computer into resetting itself. And I asked how and he told me, very simple solution to a pain in the neck problem.