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I have a 03 Nissan Altima 2.5L SE . About a year ago it started idling rough when you put it in drive. It has not really gotten worse but now I have started smelling gas sometimes. The dealership cant find anything wrong. They have tested the throttle body, throttle position sensor. MAF sensor, Intake gasket, and just about everything else. Its not giving any codes. It just feels like timing doesn't advance when you put the car in drive. If you turn the air conditioner on it will smooth it out. Ive changed the plugs but have not changed the wires the dealership said they were fine. Also have checked the 3 way going to the converter and this is fine. The car has 75000 miles on it.

I cleaned the throttle body. Cleaned the MAF. Changed the air filter and spark plugs. I took it to the dealership they reprogrammed the ECU and ran diagnostics. The car runs good but you can tell it doesnt have the power it used to. It idles perfect in park and runs smooth all the way up to hwy speeds. You can tell its a little sluggish when you get on the gas. Its just when you put it in drive and sit idle it vibrates. Its not loping and skipping just seems like its idle is too low. When you turn on the air condition the idle goes up and it smooths out, but when you put it in drive its like it doesnt sense the extra load and the idle stays just a tad too low. Just recently I have noticed you can smell gas in the car when you are at red lights or just stopped. Its not strong but you can smell it. I thought this may help in the diagnosis. The motor mounts are like new also. So im stumped. Fuel pump or fuel filter ?? Maybe but would it run this long without getting worse ? Someone told me to replace the Crank position sensor because it can cause problems like this without giving a code. What do you think ?


Thanks in advance


Terry:confused::confused::confused:
 

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try this to test it out:

drive the car a bit.
when it starts shaking like you say...park it somewhere and pop the hood open.
now unscrew the cap that is on the radiator where antifreeze passes through (have a towel thrown on it before you twist the cap as the fluid is VERY hot).
if when you unscrew it and some fluid comes out and the car stops shaking. theres your answer.

may be a clog or possibly the coilpacks but you say you have changed that right?

in a wild shot it may be the IACV

its definately not anything major like engine or tranny though but is just as annoying and can even be dangerous i would say
 

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I have a 03 Nissan Altima 2.5L SE . About a year ago it started idling rough when you put it in drive. It has not really gotten worse but now I have started smelling gas sometimes. The dealership cant find anything wrong. They have tested the throttle body, throttle position sensor. MAF sensor, Intake gasket, and just about everything else. Its not giving any codes. It just feels like timing doesn't advance when you put the car in drive. If you turn the air conditioner on it will smooth it out. Ive changed the plugs but have not changed the wires the dealership said they were fine. Also have checked the 3 way going to the converter and this is fine. The car has 75000 miles on it.

I cleaned the throttle body. Cleaned the MAF. Changed the air filter and spark plugs. I took it to the dealership they reprogrammed the ECU and ran diagnostics. The car runs good but you can tell it doesnt have the power it used to. It idles perfect in park and runs smooth all the way up to hwy speeds. You can tell its a little sluggish when you get on the gas. Its just when you put it in drive and sit idle it vibrates. Its not loping and skipping just seems like its idle is too low. When you turn on the air condition the idle goes up and it smooths out, but when you put it in drive its like it doesnt sense the extra load and the idle stays just a tad too low. Just recently I have noticed you can smell gas in the car when you are at red lights or just stopped. Its not strong but you can smell it. I thought this may help in the diagnosis. The motor mounts are like new also. So im stumped. Fuel pump or fuel filter ?? Maybe but would it run this long without getting worse ? Someone told me to replace the Crank position sensor because it can cause problems like this without giving a code. What do you think ?


Thanks in advance


Terry:confused::confused::confused:
try this to test it out:

drive the car a bit.
when it starts shaking like you say...park it somewhere and pop the hood open.
now unscrew the cap that is on the radiator where antifreeze passes through (have a towel thrown on it before you twist the cap as the fluid is VERY hot).
if when you unscrew it and some fluid comes out and the car stops shaking. theres your answer.

may be a clog or possibly the coilpacks but you say you have changed that right?

in a wild shot it may be the IACV

its definately not anything major like engine or tranny though but is just as annoying and can even be dangerous i would say
try this to test it out:

drive the car a bit.
when it starts shaking like you say...park it somewhere and pop the hood open.
now unscrew the cap that is on the radiator where antifreeze passes through (have a towel thrown on it before you twist the cap as the fluid is VERY hot).
if when you unscrew it and some fluid comes out and the car stops shaking. theres your answer.

may be a clog or possibly the coilpacks but you say you have changed that right?

in a wild shot it may be the IACV

its definately not anything major like engine or tranny though but is just as annoying and can even be dangerous i would say
I have the exact same problem. Very little mid range power and runs rough at idle when in gear. If you have heard how to fix this problem please contact me at [email protected]
 

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I have a 03 Nissan Altima 2.5L SE . About a year ago it started idling rough when you put it in drive. It has not really gotten worse but now I have started smelling gas sometimes. The dealership cant find anything wrong. They have tested the throttle body, throttle position sensor. MAF sensor, Intake gasket, and just about everything else. Its not giving any codes. It just feels like timing doesn't advance when you put the car in drive. If you turn the air conditioner on it will smooth it out. Ive changed the plugs but have not changed the wires the dealership said they were fine. Also have checked the 3 way going to the converter and this is fine. The car has 75000 miles on it.

I cleaned the throttle body. Cleaned the MAF. Changed the air filter and spark plugs. I took it to the dealership they reprogrammed the ECU and ran diagnostics. The car runs good but you can tell it doesnt have the power it used to. It idles perfect in park and runs smooth all the way up to hwy speeds. You can tell its a little sluggish when you get on the gas. Its just when you put it in drive and sit idle it vibrates. Its not loping and skipping just seems like its idle is too low. When you turn on the air condition the idle goes up and it smooths out, but when you put it in drive its like it doesnt sense the extra load and the idle stays just a tad too low. Just recently I have noticed you can smell gas in the car when you are at red lights or just stopped. Its not strong but you can smell it. I thought this may help in the diagnosis. The motor mounts are like new also. So im stumped. Fuel pump or fuel filter ?? Maybe but would it run this long without getting worse ? Someone told me to replace the Crank position sensor because it can cause problems like this without giving a code. What do you think ?


Thanks in advance


Terry:confused::confused::confused:
Several things that could cause a rough idle:
  • What brand of spark plugs are you using? You should be using OEM NGK plugs; other brands such as Champion or Bosch many times cause driveability problems in Nissan engines.
  • The cam position sensor may be marginal.
  • Incorrect fuel pressure. Tee-in a temporary fuel pressure gauge between the fuel feed hose and the fuel rail. The readings at idle should be 51 psi.
  • There may be a major intake system vacuum leak. To check the intake system for a vacuum leak, attach a vacuum gauge to a full vacuum source. With the engine fully warmed up, the reading at idle should be 18 - 20 InHg. At 3,000 RPM, it should be 21 InHg. If readings are under 18 InHg, check the intake manifold nuts to make sure they are tight. The gasket may have failed; spray a water mist at the gasket to see if the gauge reading changes. Also check the intake plenum bellows at the throttle valve and at the MAF for cracks or loose clamps.
  • Dirty fuel injector(s). Run some good injection cleaner, like BG products 44K, through the system; give the cleaner about a week or two to do it's job.

With the engine fully warmed up and in "park", the idle speed should be 700 rpm. If it's too low, then you might need to have the dealership perform the following:
Perform "Accelerator Pedal Released Position Learning".
Perform "Throttle Valve Closed Position Learning".
Perform "Idle air volume learning".
 
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