2K Maxima stalls when warm

Hi guys,

I have searched and searched and seen a few people with symptoms like mine, but unfortunately, they never posted the cure...

My Maxima has been stalling at idle in drive, park, neutral, whatever, after the engine is warmed up. Problem began a couple months ago, and has gotten progressively worse so now it does it pretty regularly. You can drive fine until you get to a stoplight, and it will usually die after standing still for 10-20 seconds. You can start it right back up and it will run for a few more seconds, then die again if you don't give it gas. If you give it a little gas, it will run fine.

Second issue which may be related is that I have a 3500 rpm hesitation. It has good acceleration up to 3500, then feels like it loses 20% of the power.

I had it into a local shop yesterday, and they could not fix it. They checked the TPS, checked for a vacuum leak, cleaned the throttle body, but gave up when they did not find anything.

The check engine light has been on for years with a catalytic convertor below threshhold, and they told me it had an O2 sensor code, but did not think that could cause the stalling.

Help!

Thanks for your time,

Mark in Spokane, WA:icon16:

Having experenced multiple check engine light codes on my maxima I can say they lead to many engine performace problems especially if it has to do with the 02 sensors which provide input to the OBD system that controls many drivability functions. I would repair the system first beforre doing any other work.

TPS is used 'only' when cold.

MAF failure is known in 2k models and fits (also) your symptoms. Try self diag - also for mentioned O2. Autozone does(?) tests free, just dont buy but the test...

This or similar diag device is smtg wortwhile: http://www.scangauge.com/

Read/follow links in this page
http://www.cardomain.com/ride/748507/9

Well, I think I may have solved part of the problem. Since it had at some point given me an o2 code, and since it has 145K on the originals, I changed out the two upstream sensors. That seems to have improved the responsiveness, and low end torque, but it did not solve the stalling issue, or the 3500rpm and up reduction in power.

I then pulled out the maf and cleaned it with brake clean. It was clean to begin with, but I ran half a can through it anyway. Then I looked over all the vacuum hoses and connections. Didn't find any issues. Finally, I checked the intake manifold bolts and found that about half of them were loose. I did not know the torque value for them, but they were probably at less than one ft lb, so I torqued them all to around 10-12 ft lbs.

The maf cleaning and/or IM torquing seems to have solved my stalling issue, knock on wood, but the 3500 rpm power decline continues.

I can live with it now, but if you have thoughts on this I would love to hear them.

Thanks!

...but the 3500 rpm power decline continues. ...

O2 is not used cold & WOT.

Check Fuel pressure. Intake Air leaks. Coilpacks: disconnect one by one, test drive and try to chart if any behaves differently. If MAF is bad, only good one will help.

Start by checking charge voltage.