Bad ground?
Bad ground?
I've had problems getting my car to pass emissions...I was way over on the CO and about double the limit on the HCs. I replacedd the O2 sensor, spark plugs, and found an EGR hose that was cracked and replaced that too. I failed again and after checking various other things, decided to just take it to someone. They've worked on it for about a day and are telling me that everything is good except that there is a bad ground on the O2 sensor, or that the wiring is messed up somewhere. Is this common? I read in one post that Nissan has a problem with grounds, but it doesn't seem like he's taken enough time to know for sure that that's the problem. I'm afraid he is assuming that my car has the same problem as someone else with a 240 that came in recently. I asked him if he checked the MAF, Feul pressure reg., or coolant temp. sensor. He said, "Oh sure, all those things are fine." Do you think I'm getting jacked around here? Is an electical issue with the O2 sensor likely? Is it more likely one of the other things I mentioned? I don't want to pay this guy so he can turn around and screw me. I can get that for free.
the o2 sensor's only one wire...I reckon if it grounded, it'd ground through the exhaust manifold. Something sounds a bit fishy here. You'd probably be better off waiting for Nistech, he's the man when it comes to emissions. But until then, you might be better off posting the emissions numbers you got so he doesn't have to wait for em.
What he stated could be true. The wire for the O2 has a sheild around it up to the spade connector near the O2 sensor. It could be the sheild has shorted to the O2 signal wire[the wire running inside the sheild] We had one about a month ago that failed smog for the same problem. We found the short about 10inches up the wire from the spade terminal. We cut the wire there and put a new end with a regular wire to that point. problem solved numbers dropped drasticly.
sorry fire wall side. We were using a DSO watching the voltage reading while wiggeling the harness when we saw the voltage jump up to a normal range we new we found it. You could do the same test with an ohm meter. disconnect the ECM connector and the end plugged into the O2. place your black lead of your ohm meter on the intake manifold and your red lead on the spade connector of the engine harness connector for the O2. If its shorted to the sheild you should have continuity to ground. If you dont have continuity and it is an open circuit thats not your problem.
I didn't expect my mechanic to go ahead and fix the problem, but he did! I don't mind...he saved me the time. I retested the vehicle today and was very pleased.
HC: allowed - .8000 grams/mile , my car - .0386CO: allowed - 15.000 grams/mile , my car - .5071NOx: allowed - 2.000 grams/mile , my car - .1885
I'm so happy - it passed with flying colors!Man, those O2 sensors really make a difference (when they're working anyway) I'm sure my baby will get much better mileage too.
HC: allowed - .8000 grams/mile , my car - .0386CO: allowed - 15.000 grams/mile , my car - .5071NOx: allowed - 2.000 grams/mile , my car - .1885
I'm so happy - it passed with flying colors!Man, those O2 sensors really make a difference (when they're working anyway) I'm sure my baby will get much better mileage too.