Help us help you. By posting the year, make, model and engine near the beginning of your help request, followed by the symptoms (no start, high idle, misfire etc.) Along with any prevalent Diagnostic Trouble Codes, aka DTCs, other forum members will be able to help you get to a solution more quickly and easily!
Hello! I'm working on a 2011 Nissan Altima 3.5L engine. This car sets a p0171 pretty consistently. Trims indicate a lean condition on both banks although bank 1 shows a slightly worse lean condition. For example: Bank 1 will read 128 n Bank 2 125. Trims get a little better @ 2500 rpms but not much @ all. A/F ratio sensors seem to be reading accurately(I can add fuel and they move rich, voltages look good) I've replaced MAF thinking it was skewed, no help. Smoked intake, checked for vacuum leaks. Ran off different fuel supply. Fuel pressure is good at 51 psi. Performed injector balance test(they're good). While driving today p0171 did not set but once it idled in the shop a bit then it did. Any thoughts would be appreciated. Sorry if I'm not clear on something...ask n I'll try to clear it up. Thanks
It really sounds like a vacuum leak they can be devils to find especially on a V engine. Check not only the manifold and air duct after the MAF but check the air duct to the air filter.
" We're trying to plug a hole in the universe, what are you doing ?. "
(Walter Bishop Fringe TV show)
As long as the air filter and its' case are intact I would think it would be Okay, but I always keep in mind any change to the induction can throw the MAF calibration off.
" We're trying to plug a hole in the universe, what are you doing ?. "
(Walter Bishop Fringe TV show)
How many miles on this vehicle? On my 08 Odyssey I had some lean conditions that, while not bad enough to throw a code, turned out to be skewed O2 sensors (AF sensors upstream and regular O2's downstream.) Vehicle had 170K and four new O2's finally solved the problem and it runs like a new car.
I guess the missing tube is possibly throwing the MAF off... But, that tube is well ahead of the filter, correct? Unless there's something in the filter that's screwing with laminar airflow across the sensor.
I see that you smoked the intake with no luck. Have you happened to try carb/brake cleaner? I usually hate using those to find leaks, but it may be worthwhile in this case. There's a vacuum canister on the front of the intake that's part of an intake butterfly system. There's a check valve in the hoses that'll prevent smoke from showing the leak, but can be found with spray.
I saw one if Paul's videos where a missing air box caused a lean condition. That might not be the same though. Could it be missing a screen in front of the maf sensor?
