Question about 1998 Nissan Altima
I saw your response to a Nissan sentra issue about a rough idle in drive without moving (sitting still). I went ahead and did everything already that you gave as advice and then some. I have my own OBD II reader and know that there are two codes a Knock Sensor (which i have replaced before-not really recently but within the last 2 or 3 years) and a cylinder 4 misfire. I was told that the cylinder has hardly any compression to it but of course I don't know any more than that. It is a '98 Nissan Altima and I already did the wires and plugs, had a new used trans put in back in the end of July so I know the fluid is new (not sure about the filter). Any ideas? I have to get it smogged and of course it failed due to the previous check engine light still being the system. I'm going to disconnect the battery and see if that resets the system before I have to re-smog it. Otherwise, I am SOL and have to get it fixed for who knows how much money on a removing the top block type of job.
It seems that you may have a dead clyinder. An engine compression test has to be preformed first to determine if this is in fact true. If you do have a weak or dead clyinder, it could be the cause of two failures. Braken or worn piston rings, or more commonly, burnt valve. Either one of these conditions will cause you to fail smog test.
Both of these jobs are also major repairs. I worked for Nissian/Datsun for many years rebuildng their engines.
Posted on Nov 23, 2008
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Posted on Jan 02, 2017
The term "flash" has to do with the on board OBD2 computer flash memory. New software updates or sometimes performance tuning will be programmed to "flash" this memory effectively changing certain preset values such as ignition timing and air/fuel tables. Most cases i have experience with are for the performance market but have been developed in accordance with factory guidlines.
Posted on May 03, 2009
Sounds like the O2 sensor. Post the smog test results (if you have it from the exhaust). When the O2 sensor fails the exhaust doesn't get recycled (reburned) so it goes out the exhaust. With more oxygen the fuel burns better,.
Posted on Jul 24, 2009
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