Juki5536

iTrader: (1)

My car has been running like crap for a while now, so I got it diagnosed at the local Nissan Stealership (complimentary 100-point checkup). Bittersweet news...my alternater was replaced under recall, but I've got a couple of codes:
1) Multiple Misfire
2) Bad knock sensor
3) Bad O2 sensor

Now...I think first off I will replace the coil-packs for the misfire. The Nissan mechanic told me that the sensor problems may be from the misfire. Should I go ahead and order the sensors also, or change the coil-packs and hope everything goes back to normal. Any advice would be appreciated. Car has very rough idle when warming-up, chokes off when revved, and no pick-up on the road. Thanks.

izzydig

I'd check ur 02 meter first. ****ty mixture can cause lean/rich conditions which cause sputter, and cause knock/and or misfire.

If you're unsure, volt out the 02 sensor. it should read i think .45-.55V whilst car is running....all 02 sensors are universal in output. If the voltage is excessive one way or another, either ur 02 is messed up, or your ECU isn't reading ur 02 right. Tho, my $.02 (get it? 02, .02 eh? eh? funny right? hilarious! fantastic funny mumble!) might be a "foot in mouth.".

I shall lay off the booze now.

guido32

Multiple misfires?Unless you have a misfire code for every cylinder, only replace the coil packs on the misfiring cylinders. If you are unsure, I believe there is some way to test them to see if they are bad. I would say take care of the coil problem first because, as the Nissan mechanic told you, misfires could cause sensor codes. This could occur because the outgoing exhaust content would be way off normal, since all the air/fuel mixture isn't being burned correctly. Also, alot of misfiring could cause the engine to "knock" excessively, causing the KS to go crazy and code.

Are you running premium gas? If not, try running that first. Low octane or crappy gas could easily cause these codes as well, not to mention destroy your engine. When was your last tune up? Bad plugs could be a culpret as well.

Good luck

Juki5536

iTrader: (1)

Thanks. I will check my coil packs as soon as I can. I've seen the write-up on how to do it. You're going to have to explain how to check the O2 meter though....I don't know how to do that...and I always run premium....in every car I have. Thanks for the suggestions/comments, keep em coming. The car is still running like crap. Idle fluctuates while car is warming up between (500-1000 RPM); if I drive with car cold, it bucks like crazy. Huge loss of power, and bad gas mileage too....soo many problems...