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Sedans Nissan Altima Nissan Altima Engine Failures
497 messages, Last post on Nov 21, 2009 at 8:01 PM
You are in the Nissan Altima Forum. Your Hosts are pat & karens
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Replying to: ndiboy (Aug 01, 2008 12:41 am) Oxygen Sensor, don't cut the wires! You need the O2 sensor working, because that is the main component that the computer uses to regulate the amount of fuel injected into the cylinders. The signals to the fuel injector are called "Pulse Width Modulated" signals. That means a pulse of voltage is sent to each fuel injector, a short pulse opens the fuel injector to only open for a short time, allowing only a small amount of fuel to enter the cylinder. A longer pulse allows more fuel to enter. The computer varies the lengths of the pulse according to the output of the oxygen sensor. If the O2 sensor reads rich, the computer tells the fuel injectors to go lean, If the O2 sensor reads lean, the computer tells the fuel injectors to go rich. It is always in a varying state, according to the reading of the O2 sensor. Now if you cut the wires, that will put the computer in the "default" state or "Open Loop" state, which just runs on a set of predetermined values that are not fuel efficient. Fuel consumption will increase, the engine will use more gas and not run as clean. Try to maintain the computer system and sensors. If you can't, then do the best that you can. You must have internet access to get to this forum, so try using Google to find the information that I previously told you about, it will explain all that I have said and much more. My Daughters 2002 Altima 2.5S is performing very well. I did a Sevice, oil change & filter change last weekend. It is using about 1 quart of motor oil in about 2,400 miles, which is OK. I change the oil and filter every 5,000 miles, using only Mobil One 10W-30 Synthetic Motor oil and Purolator Pure One Synthetic oil filter. I was noticing some vibration on the serpentine belt, I may have to change the belt tensioner soon. Other than needing some new tires, it is doing great. Thanks for the vote of confidence, but not needed, as I said before, I have done this type of work all my life, rebuilt many engines and transmissions. I retired from that work, but I still do it if needed, and my daugther really needed the help, so Dad had to help her out. I hope most of your questions are answered now. Good Luck E.D. ISF
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Replying to: electricdesign (Jan 27, 2008 9:10 pm) However, mine only misfires upon start up and shortly after. Never while driving. Swapped coils and checked plugs and still misfired #3. Oh, it also idles slightly higher...at almost 1500 sometimes, but doesnn't surge. I'm thinking maybe the #3 injector is not closing completely at idle or upon engine shutdown....thus loading up the cylinder with fuel. Sound possible??? Thanks for any info you may have, Rick
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Replying to: krzy10boomr (Aug 02, 2008 7:13 am) One thing to check first - Do you loose any coolant from the radiator coolant tank, or do you have to add any coolant, and if so, how much and how often? The symptom sounds like a small amount of coolant leaks into the cylinder when the engine is shut off. Later when the engine is cooled down and restarted, the small amount of coolant in the cylinder causes the spark plug to missfire for a minute or less, until the coolant is all blown out, then the engine runs normally. The high idle may be related to the above or not. Check the PCV valve and check for vacuum leaks. Look for unplugged, loose, or cracked vacuum hoses. Check to be sure the upper and lower intake manifold bolts are all tight. Check to be sure the the O-Rings at each injector is not leaking or sucking air. Squirt oil on these things and listen to see if the speed of the engine changes. Connect a vacuum gauge to the intake plenum and see if the vacuum is good and steady. Fuel injector #3 might be the problem, but not as likely. Do you use a fuel system cleaner or additive? You should add a fuel cleaner additive to the gas tank at least every oil change, to keep the injectors clean. If you have not added any, try adding some and give it time to work. Use an STP type or Seafoam. Another problem that may cause the high idle could be the throttle body, Try carefully cleaning it with throttle body cleaner. Be sure the air filter is clean and that the air intake tube is not cracked or leaking anywhere. Sometimes, the Mass Airflow sensor needs to be cleaned, but they don't usually give problems on these vehicles, unless they are allowed to get dirty. Good Luck, E.D. ISF |
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Replying to: electricdesign (Aug 01, 2008 6:49 pm) The serpentine belt you mentioned just made me remember something.Is it the same thing as the fan belt? and what is the tensioner? The belt in my Altima (right side of the engine) wobbles and it appears its the lowest pulley holding the belt that does that and causes some vibration when I put on the A/C. I think I need some help with regards to this.Does the pulley get damaged and does the wobbling affect the function? Thanks, Chuma.
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Replying to: ndiboy (Aug 04, 2008 5:02 am) Good Luck, E.D. ISF
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Replying to: electricdesign (Aug 04, 2008 6:46 pm) 'GROOVED pulleys are on the INSIDE of the belt loop, and SMOOTH pulleys are on the OUTSIDE of the belt loop'. This is not clear to me.Which one is the autotensioner? Is it the pulley above and just behind the compressor pulley? Thats the one that wobbles a bit when the engine is idling.The compressor pulley is grooved while the one I am referring to, next to it is smooth and on the outside(just went to examine them). Is this the meaning of the statement above? that is the grooved pulleys get the rough part of the belt while the smooth ones get the smooth part of the belt which is on the outside. Thanks, Chuma. Is the autotensioner one of the smooth pulleys
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Replying to: ndiboy (Aug 05, 2008 2:34 am) Smooth pullys are outside the belt loop, the back of the belt rides on the smooth pullys. The pully that you see bouncing (not wobbling), is the autotensioner. Good Luck, E.D. ISF
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Replying to: electricdesign (Aug 05, 2008 11:00 am) Thanks, Chuma. |
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| How hard is it to replace the crank sensor on my 02 nissan altima?? My car keeps stalling and is hard to start. | |
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Replying to: acevedo669 (Aug 18, 2008 6:35 am)
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