Our 2005 Maxima has about 1000 miles on it and it has started having starting problems. It turns over quickly but it takes between 5-10 seconds to fire and start up. The motor runs great after that. We thought that maybe it was bad gas so we tried different gas stations and the problem still persists. We are using the bottom grade (87 Octane), which is what the book recommends. Any ideas of what the problem could be.

 

what do u mean by "turns over quickly "? also, try using 93 Octane. that's what I use and no prob with starting.

 

Why 87 Octane?

 

That's news to me about 87 octane. The 4th generation and the 5th generation Max requires 91+ octane. I'd double check.

 

If I remember right, the 6th gen manual said use "at least" 87 Octane, but when u look at the gas filler door, it says use premium gas for optimum performance. That's why I've been using 93 Octane ever since.

 

Premium fuel is required for this car. I forgot where I read it but it is recommended that you use 91+.

 

hey man, how's your case with your car?

 

By turning over quickly, I just meant to say that the battery is working fine. It tries to start as it did the day we picked it up, but the engine does not start running until after 5 or 10 seconds. We have been running 87 in it for a month now and it just started acting up. Do you think the 87 finally caught up with it?

 

93 here, no probs..................

 

uhmmm...maybe...? but better yet have it checked with ur dealership.

 

93 is highly reccomended by Nissan. lower grade are acceptable, the engine will adjust and run accordingly. switching grades will cause problems. the engine was designed to run on premium, therefore performs the best with it.

I only run 93. I would take it in to the dealer. But they may just say it's the 87.

 

Just run on 93 for a while and see what happens. If it's still messed up, reset the ECU. Final option is to go to the stealership.

 

I never have had this problem and I only use 93.
I would take it to the dealer and have them look at it. I'm not a mechanic but I can't it believe it would be the low octane that is causing your initial firing problem. Is there a way a dealer can determine if you used a lower grade without you telling them?

 

Could it be the fuel pump problem that some people have? TSB is here: http://maxima.theowensfamily.com/tsb/NTB04-021.pdf

 

I've run nothing but 87 the last several months. No problem here, nor have I noticed any loss in power.

 

required and recommended are two different things

Nissan recommends 91 octane, but they require at least an octane rating of 87. People living in higher elevations are exempt from this rule however.

 

I had a similar problem where the car wouldn't start in extreme cold temperatures. Later on a fuse burned out and it wouldn't start at all. It was likely a poorly made fuse that didn't contact properly in cold weather.

Definately not the octane you are using. I've used 87 with no troubles for long periods of time. I've used 94 octane for long periods of time too. My octane choice depends on the weather and price of gas.

Likely your issue is fuel pump related.

CM

 

Took the car to the dealer and they diagnosed it as an internal failure of the fuel pump. They replaced the pump and it is working fine now.

 

Glad to hear you got it all straightened out now. Pesky electric fuel pumps can be a real pain when they work intermittantly sometimes.

 

From what I read about hydrocarbons is that octane stablizes the gas (from the name it should be a simple single-bonded 8-carbon chain with 18 hydrogens off the carbons).

Anyway, the chemistry behind the idea is that octane helps lower the vapor pressure of gasolines. Lower vapor pressure results from lowered rate of evaporation (which equals less volatile gas).

Along with fuel injectors replacing carburators, octane is also supposed to help eliminate "knocking" (which is condition caused when the liquid gasoline vaporizes in the fuel lines before hitting the engine).

I believe the biggest difference between the ratings is the octane (I think that's why they call the numbers octane rating). Some of my students tell me that they put in premium gasoline because their parents told them that it is cleaner gas. Two reasons why the parents might have thought this: 1). Premium gas has detergents that help clean the engine 2). premium gas is the first distillate which is "purer" than the latter distillate of the distillation process.

None of the two are true. In the early to mid 80's I remember Amoco or Mobil advertising their gasoline and their motto was "drive your engine clean". This was because they were the only company that added detergents to clean the engine. I believe that in the late 80's, the government made it mandatory to add detergents to ALL gasolines.

So the question of 87 to 91+ difference is, I think purely percentage of octane added per volume of gas. higher octane gas would be more resistant to evaporation, meaning that while it travels through the gas lines and in the engine bay, it will stay liquid (hence denser, and more gasoline molecules per volume). Less octane gas will tend to vaporize bit and will be less liquid/some vapor by the time it hits the injectors.

The difference in volatility might also explain why the "MIL" light goes on when you leave the gas cap off the car? I am guessing that there is a pressure sensor that measures the vapor pressure of gas ABOVE the gasoline INSIDE the gas tank. If the pressure is really high, then that means the liquid gas is very volatile, telling the ECU that the gas is prone to evaporation so that ECU can make adjustments and use more gas than combustion stoichiometry suggests. If the tank vapor pressure is low, then it means that the gas is really stable (then ECU can "sip" the gas because it will be mostly liquid, thus more molecules of gasoline to burn). If the gas cap was left open, it would equilize vapor pressure with atomospheric pressure (which is always less). This will report an "infinitely stable" gasoline that seemly NEVER evaporates, confusing the ECU, causing it to throw the MIL light and going into "safe mode".

Nissan recommends that at least 87 is used but that you will not get the advertised full horsepower unless you use 91+ octane.

There are also stories of cars using up 87 gasoline faster than 91+ octane gasoline. If what I said about stability of 91 vs. 87 is true (and I didn't make that up), then the idea of 87 being used up faster makes perfect sense.

87 octane will vaporize. It's like hot, humid day in summer, where because of humidity (and temperature) there is less oxygen in the air. Makes you gasp for air (which is your body's way of trying to get more volume of air into your lungs). I am not sure how many folks have tested this, but I swear that when I run 87, I get less mileage than 91+.

Anyway, all this is just ramblings of a scientist. If anyone disagrees, comments are welcome. At least the male students seem interested in stoichiometry, vapor pressure and in general, chemistry when I tell this to them...

 

It is a question of octane, which affects the ability of gasoline to burn rapidly, thus avoiding knocking. The engine can accept lower octane gasoline (87 octane, for instance), but that forces the ECU to retard the spark timing to compensate.

Retarded timing will reduce engine efficiency, both in terms of output (the power you feel) and fuel economy. The reason is that the retarded timing - which is necessary to delay the flamefront propagation, and thus the knocking - fires the sparkplug later in the combustion cycle and combustion is less complete. That just means some unburned gasoline exits via the tailpipe. At the same time, more accelerator has to be used to make up for the lost performance and that means more gas used to get from point A to point B.

Mike

 

This thread is giving me a headache.



Too much thinking going on here. I do enough of that at work.

 

That's a really BIG Avatar there.

 

I never put anything lower than Premium in my cars. If I have to put the lesser gas in it I feel physically ill since I know that the car isn't gonna work as well as it could. You may want to put some better gas in it and some octane booster to get it working at 100% again. Worse comes to worse take it to the dealership and don't tell then you were using the poopy gas. That way they will actually look at it, there may be another underlying problem.

 

Correct me if I am wrong but aren't these high compression motors? Personally, I use Premium grade Chevron fuel. No problems starting up or with power. The cars seriously require premium to run "great" so I would just spend the extra 3-4 dollars a tank and fill up with Premium...

 

It says on the fuel door to use high octane for best performance. My Porsche says on the fuel door nothing lower than 93 octane.
Automon