# 2001 Maxima Rough at startup code P0171



## twomoons (Dec 20, 2005)

I just bought my first Nissan, a 2001 Maxima. It runs and drives great except for about 2 minutes shortly after startup when it is cold. During that short period it will quit or almost quit and the only way to keep it running is to keep reving it up a little. 
I've read out the fault codes, reset them and they return after the next cold start. I get a P0171 AND a P0174 which indicates Bank 1 and Bank 2 (V6) are both running lean. I've checked for induction leaks, found none. I'm assuming that this lean condition is sensed by the Oxygen sensor(s). I am going to replace the O2 sensor 1 front and see what happens but I'm doubtful because that sensor is only on one bank of cylinders.

If anyone has any experience or new ideas, please let me know.


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## twomoons (Dec 20, 2005)

*Additional info*



twomoons said:


> I just bought my first Nissan, a 2001 Maxima. It runs and drives great except for about 2 minutes shortly after startup when it is cold. During that short period it will quit or almost quit and the only way to keep it running is to keep reving it up a little.
> I've read out the fault codes, reset them and they return after the next cold start. I get a P0171 AND a P0174 which indicates Bank 1 and Bank 2 (V6) are both running lean. I've checked for induction leaks, found none. I'm assuming that this lean condition is sensed by the Oxygen sensor(s). I am going to replace the O2 sensor 1 front and see what happens but I'm doubtful because that sensor is only on one bank of cylinders.
> 
> If anyone has any experience or new ideas, please let me know.


Well, I replaced the O2 Sensor 1 (front) for (Bank 2). I can't tell any difference in the symptoms. I haven't reset the codes or re-checked them.


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## bigern45 (Oct 25, 2005)

are you positive that there are no intake leaks? there are a couple more threads on this page that deal with leaking intake manifolds..... both o2 sensors go lean biased bad is very rare. they are just saying your system is not getting enough gas/ too much air, doesnt necessarily mean the o2s are bad. you could have bad fuel pump or fuel filter, bad mass air flow meter or bad intake gaskets, or another intake leak...


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## twomoons (Dec 20, 2005)

bigern45 said:


> are you positive that there are no intake leaks? there are a couple more threads on this page that deal with leaking intake manifolds..... both o2 sensors go lean biased bad is very rare. they are just saying your system is not getting enough gas/ too much air, doesnt necessarily mean the o2s are bad. you could have bad fuel pump or fuel filter, bad mass air flow meter or bad intake gaskets, or another intake leak...


I think it is very odd how this failure exhibits itself. As soon as you start the engine, it runs fine/smooth. In about 10 seconds it starts acting up and will quit if the accellerator isn't touched. As I understand what the computer is doing at each startup, a learning process is occuring and the I guess after the computer figures it out and adjusts the fuel volume needed it runs smooth. I will go back and start taking it apart and look for that air leak.


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## bigern45 (Oct 25, 2005)

if you dont hear vacuum leaks, it really sounds to me like a faulty mass air flow meter... let us know if you found any vacuum leaks..


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## smj999smj (Jan 1, 2006)

I once worked on a 2001 Maxima that wouldn't start, or would have difficulty in starting, every time it sat in 35 degree F. temperatures for 3 hours or more. Swapped a multitude of parts, lots of scan tool monitoring and lots of back and forth on the phone to Nissan's tech hotline. Once the car started, it would run like a top and subsequently restart fine until the "cold soak." As it turned out, it was the upper plenum gasket that was not sealing properly at very cold temps. You couldn't hear any vacuum leaking and I even sprayed the intake with carb cleaner to check for leaks. Apparantly, once the vehicle warmed up a few degrees, the gasket would seal and the problem would be eliminated. The upper plenum gasket had been updated at that point to promote better sealing but apparantly that information was never released to the tech hotline personel until this incident occured (which was about 4 years ago).


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## twomoons (Dec 20, 2005)

*I'm still diggin'*

Well, I've taken the intake apart and checked for leaks and bad fits but haven't found anything. I've decided to buy a new, (to me), Mass Airflow sensor. The problem is that I can't find one. Every auto parts store, including the chains is out of stock and can't get one. One even stated that the main warehouse had 80 or so on backorder. I really hate to check with a dealer. That's like giving up!

Before I do that I'd like to find out what the fuel pressure is but it looks like an adapter (T) is needed. Any ideas?


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## smj999smj (Jan 1, 2006)

There's no shraeder valve port for fuel pressure testing, so you'll need a "T" adapter.

Nissan MSRP is $488.19 for the MAS, but you can get one for around $385 if you go to http://www.parts.com and buy through one of the Nissan dealers there. It's still not cheap, but a hundred bucks cheaper ain't bad. I would also install a new Nissan air filter with it.


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## RLLOGY81 (Feb 1, 2006)

twomoons said:


> I just bought my first Nissan, a 2001 Maxima. It runs and drives great except for about 2 minutes shortly after startup when it is cold. During that short period it will quit or almost quit and the only way to keep it running is to keep reving it up a little.
> I've read out the fault codes, reset them and they return after the next cold start. I get a P0171 AND a P0174 which indicates Bank 1 and Bank 2 (V6) are both running lean. I've checked for induction leaks, found none. I'm assuming that this lean condition is sensed by the Oxygen sensor(s). I am going to replace the O2 sensor 1 front and see what happens but I'm doubtful because that sensor is only on one bank of cylinders.
> 
> If anyone has any experience or new ideas, please let me know.


i was having the same problem, did you have anyone test the ignition coils? i just had to have all six replaced, car runs very good now


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## DRUNKHORSE (Mar 6, 2005)

twomoons said:


> Well, I've taken the intake apart and checked for leaks and bad fits but haven't found anything. *I've decided to buy a new*, (to me), *Mass Airflow sensor*. The problem is that I can't find one. Every auto parts store, including the chains is out of stock and can't get one. One even stated that the main warehouse had 80 or so on backorder. I really hate to check with a dealer. That's like giving up!
> 
> Before I do that I'd like to find out what the fuel pressure is but it looks like an adapter (T) is needed. Any ideas?


I'm not sure if youre still having this problem, but have you tried inspecting the MAF sensor? if not, here's how to. I know it sais 93-98, but 2001 is similair

a common problem is the MAF's heated sensor causing this error code. The heated wire element gets dirty and causes the engine to run lean in one bank. It might have a coating of oily dirt. You gently clean the element with a Q tip and acholol. Then put a new filter in and reset the ecu. 


I was also wondering if when you pulled the intake, did you check the injectors while you were there?

if I were you, I would check the fuel system first. some auto parts stores sell a decent kit for 100 bucks or under. if you already delt with this issue then nm.


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## mleslie (Jun 12, 2010)

I know this forum was put up a long time ago but I am looking for help. I have the exact same problem you had with your car and I am hoping you can tell me what fixed your rough starts when cold.


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