I started noticing a problem with what seemed to be my car running lean, after putting gas in at a station in Alabama. That night at the track, and on the way, I noticed that it felt like my car was not running right, especially under WOT.

The 1/4 runs confirmed my fear that the car was not running up to it's normal potential.

I checked everything on the outside,a nd everything is normal. I completed a dyno run tonight to check the A/F ratio, and my fears were confirmed. The car is running lean immediately upon WOT, and then the timing backs off, killing some of the power.

Ideas? I am having the tank pulled and checked with the fuel filler recall, so I will have the internal filter checked then. Other than that, this seems to be a hard to find issue. Sometimes it's worse than others, but it is never like it was.

Here is the video link, and the Wide Band graph.

http://www.dropshots.com/day.php?use...8&ctime=004542

 

Soemthing odd happens at 3500, even on my car. I jump in leanness too, but i'm running rich overall. 14.5 isn't 'lean' for NA..around 13.5-14 is good i think. did you really go to 8700RPM>

 

6,700.

It hit 14.6 all 3 times, which is too lean, even for N/A. You can feel the ECU retard the ignition, backing off on the power.

 

perhaps its just time that u need a flash.
Or i suppose it could be a clogged up fuel filter, but then the car would run like crap a lot and be bad on gas.

 

just jump to the UTEC bandwagon. I tested UTEC on my car and on I/E tune i gained 20whp lol. It was a nice change (cash for actual HP gain). I might be getting one this summer depending on how my mood is.

 

my car does that too. but it seems random, and i can pin point a cause. my a/f gauge slowly dips into the lean range to where the all the LED's turn off because of the lean spike. almost like when your going fast and let off the gas pedal and the gauges spikes towards the lean end. the car shifts sloppy and engine noise gets a little deeper. it does it at those same exact rpms too.

i'd like to know what possible causes could be since i have no way of knowing because no CEL codes are thrown.

 

I think the cam lobes on the intake side are staying open longer...that would attribute a more lean condition. Seeing as how the changes are almost instant, it very much could be that.. I havn't noticed this spike on revup motors either..

 

I've seen the lean A/F step shift on many, many VQ's. Its too lean and its not uncommon at all.

 

Well, oddly enough, the lean spot did not show itself in 32 miles of driving today.

I am going to have to give in and get the UTEC.

 

I hate how it does that.

Obviously, its not our engine. Its the VooDoo ECU connected to it.

 

stupid technology.....drive-by-wire....."super duper smart" ECUs...

gimmie some good old 5.0 pushrod technology anyday of the week

 

I don't mind the drive by wire per say, it’s the dependant and independent multidimensional algorithms they have changing values all over the place. It’s a mess.

There are so many variables moving around and recunched in a feedback loop (if it’s not in a tightly controlled setting) I'll bet Nissan can't even predict function at any moment in time.

Its reminiscent of the Windows operating system.

 

atleast yoru car doesn't crash all over the road because of it

 

ya my car is in a good mood this weak, but last week i was considering trading it in, due to how slow it was being.