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Hi everyone.. First of all im new.

Ok well I have a 97 altima and its been good to me these past 2 years. I received the altima a couple months after my 16th birthday (im 17 almost 18 now) after my mom had bought a new maxima. I recently took it to get the state inspection sticker, and I was surprised to find out there was a couple things wrong with it, considering none of the check engine lights came on. Of course I failed the state inspection and I cant get the sicker until I fix everthing,and I don’t know when that’s going to happen cuz im busy with school. There was a knock sensor 1 circuit malfunction, a cylinder 4 misfire, and it also said system too lean. I know what the cylinder 4 misfire is…but what are the other two??A couple of my uncles have seen it and all of them also said that the intake gasket needs to be replaced. What is an intake gasket and how much does it cost to fix?

thanx
 

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What county do you live in? A friend of mine in Charlotte, NC was told an unbelievable amount of things needed to be fixed on his Camry before it would pass. All were false, so make sure you get a second opinion if you don't trust the mechanic. Why would you have to have all of these things fixed? Does the car not pass emissions because of these problems?
 

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star_struck_tx said:
There was a knock sensor 1 circuit malfunction, a cylinder 4 misfire, and it also said system too lean.
Since your car did not have the Check Engine light on, these malfunctions were detected some time in the past and are not currently happening. The computer stores malfunctions for a fairly long time after they go away.

Go to an auto parts store like Auto Zone and ask them to check your computer for faults (it is free). They can read them out and reset the computer to remove the stored ones. After it is reset, you will have to drive a while for the readiness tests to be set by the computer. There is no indication whether they are set or not, so you should go back to Auto Zone and have the computer checked before you get it inspected again.

The knock sensor is a microphone attached to the engine which listens for detonation. If it detects detonation the computer retards the timing to make the detonation stop. The circuit malfunction means either the connector to the knock sensor is faulty or the sensor is. I would guess it was the connector.

The cylinder 4 misfire is usually tripped if a spark plug or plug wire is bad. Change the spark plugs.

The system too lean is usually caused by one of the vacuum hoses leaking because it is old and cracked. You can buy hose at an auto parts store, cut it to length, and replace any questionable hoses yourself.

Lew
 

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Biru O' Kudasai
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The intake manifold gasket can leak and cause all three of these codes but it could also be a problem with an injector or the fuel filter, a problem with the EGR valve.
First spray a can of carb cleaner around where the intake manifold attaches to the engine with a spray pattern from end to end. If the engine increases RPM on it's own then try to isolate it a little more by spraying, listening, and observing for the exact place the leak is occuring. It is possible to have vacuum hose cracked or broken which could cause this problem but can be isolated with the spray.
A clogged fuel filter can restrict the flow of fuel which can cause a lean condition as well so if it has been more than 15k miles or a year since replacing the fuel filter I recommend doing that now as well. If possible after replacing that hook up fuel pressure gauge between the filter and the fuel rail to check for adequate fuel pressure for the injectors to pulse correctly. The fuel injector can be checked by placing the metal end of a large flat screwdriver on each injector and then placing your ear against the butt end of the handle this will give you an indication when the car is running that the injector is firing mechanically. If one sounds drastically different than the others or nothing is heard that particular one may have a problem. The injector should have an ohm reading of between 10 and 14 if you want to check it electrically for a problem. If they all sound ok then usually I will add or recommend 44K from BG with a full tank of premium fuel and this typically cleans out a dirty or clogged injector.
Also I would replace the spark plugs with new NGK if they are over 15k miles / 1 year old and just to eliminate those as a problem.

Troy
 

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In all the posts I have read on Nissan cars, I have never had someone find their problem was due to a leaking intake manifold gasket. Perhaps if the car has massively overheated this might happen, or it was removed and replaced incorrectly.

When the air filter is clogged, the car usually runs rich because there is not enough air drawn in for the amount of fuel delivered. Since the engine management system measures the mass of air taken into the engine, it will adjust for this. The symptom would be a loss of power since it would be like the butterfly valve not opening all the way.

With a clogged fuel filter, the engine cannot get enough fuel under certain conditions, and again the computer will adjust the mixture to compensate. This will also lead to a loss of power because of the inability to get fuel.

When there is a bad injector, the engine will run rough since one cylinder is not making as much power as the others.

Another possibility of measuring a lean mixture is if there is a leak in the exhaust system. This lets unmetered air into the exhaust system where the oxygen sensor is, and it erroneously reads the air/fuel mixture as being lean.

Lew
 

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Biru O' Kudasai
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Lew, the KA24DE in the U13 Altima occassionally has a problem with the intake manifold gasket leaking but it can cause this condition and if bad enough it will not run. If you have never heard of this check with your local Nissan dealer's service department.
I didn't say anything about the air filter because the problem is a lean condition which is either too much air or not enough fuel. I only suggested the fuel filter and injector(s) but no the computer cannot adjust for or detect restricted or low fuel pressure. The computer is programmed to work within set perameters to adjust injector pulse timing so the fuel pressure is supposed to be a constant. And it will not necessarily run rough.
The exhaust leak is certainly an additional possibility but it wasn't said to be louder than normal so I didn't say anything about that; however, it is the same principal of introduced unmetered air into the system, although I am suggesting on the intake side.
I didn't say anything about the knock sensor because it is working normally in detecting a knock instant when it had the no. 4 misfire so I would say it is working fine.

Also I am going through the same diagnostic procedure as the service manual and the technician would utilize. If you want I'm sure that I can scan the manual pages in and email them to you. Although I have not been a Nissan dealer tech for several years, I still know what I'm talking about being a certified technician for the past 18 years though. I would appreciate it if you would not try to get in a pissing contest with me because I did conceded to your valid points, Thanks...

Troy
 
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