2009 Nissan Altima WAI ABA testing

[itjstagame]

Ok, I've been driving the family 2009 Nissan Altima for commuting this week and decided it had way too much cooling up front so completely blocked off the lower grill openning.

Then I decided since that is done I should look at HAI, the first obviously being just removing the part of the intake that pulls cold air over from under the hood and to the filter box and the next being to get tubing and hook the box to around the cat (which hangs jut off of the exhaust manifold (vertically) on these cars to get and keep temps up quickly).

Here are some things I noticed on the commute:

OEM (stock):
Outside F          IAT F             Speed/Notes
55		    65	              65MPH
57		    78	              Stop and Go traffic (so pulsing to 15-20MPH and gliding to stop)

With the stock tubing removed:
57		   108	               60MPH
65		   122-133	       Stop and Go

With tubing pointing between exhaust manifold and cat:
60		   133-155	       all conditions

Other interesting things, regardless of intake config my cruising (that is light pedal to maintain speed) timing advance hovers between 38-40 deg and at idle it's 3 deg and during DFCO its either -10 or -5 deg.

I find the high advance interesting, I wish I had a wideband to know what it was really doing. I never P&G this car, its very hard to get the CVT to stay where you want though I can typically get it to stay at 1200rpm during accel from a stop in an almost lug state but whenever you pulse, even the slightest pedal increase severly drops MPG. For instance I can maintain a light cruise at 55mph and instant MPG is about 40, but if I want to raise this slowly, even say 2MPH per min, barely touching the pedal more drops me to 20MPG. I understand the theory of going for 15-20MPG pulses and infinite glides but I can never get much out of my glides (CVT likes to hold you at speed on DFCO) so try to stay in that light pedal sweet spot. I think the car tries to lower gearing as power need increases rather than increasing throttle, no matter how slightly. Very strange but amazing the control it has.



EXPERIMENT:
Ok, so I have only been driving the car for 4 days on the commute (100mi total daily), the first day felt about 30MPG and the next 2 with WAI and HAI respectively felt closer to 32MPG. I could see where my average slowly crept to 31MPG on the tank or would drop to 30MPG on accel, etc, so it felt like I was getting just above 31MPG to maintain that average over the tank.

Feeling an improvement I set up a test to verify, I do not have very level ground anywhere near me, its mostly long sweeping curves up a steady, minimal grade followed by slow drops with occassional steep grades (nothing you'd ever have to down shift for but certainly you'd hit 60-70% throttle to maintain speed).

Anyway, not having that and having only the OEM fuel gauge I decided the best thing I can do is just drive a longer distance, so I did 2 16mile legs per setup (there and back) holding cruise at 56MPH and letting it go. I thought this would be pretty ok because it'll show how the setups compare in multiple throttle positions and load requirements and even though the OEM gauge may not be terribly accurate, it feels pretty accurate to .5MPG or so, so if we can see a confirmed 2MPG change that should be significant. Maybe expecting a 1-2MPG difference was too much, but with sustained 150F IAT I thought that should help, I would have liked to hit 200F, if I find a way to maybe I'll test again.
It was a slightly breezy and rainy/misty night but conditions and temperatures stayed the same throughout the test (about 1.5-2 hours).

				Outside F	IAT	     Leg1 MPG/MPH	Leg2 MPG/MPH	      After leg2 idle in park stats
HAI 				56	      145-155	      30.5/56.4	          39.7/56.1	         27.1 load %/ .501gph maf / 133 IAT
(tube pointed at cat/mani)

OEM				56		70            32.4/56.7	          40.6/56.1	         22.4 load %/ .358gph maf / 77 IAT

HAI 				56	      125-135	      32.2/56.6	          39.9/56.8	         23.5 load %/ .400gph maf / 130 IAT
(tube pointed at cat/mani)

I'm really not sure what caused the differences in the idle numbers or if they're even significant but they are interesting. I'm also not sure why leg1 was so bad the first time, it was a bit windier perhaps, but marginally, and the car was fully warmed up (had just commuted home). If anything it might have been extra heat soaked, it really started at about 160F IAT around town and dropped as I drove (and rose again on hills). I also think the last test I must have positioned the tube in a different location to get the slightly less temps, it doesn't really 'fit' snug all THAT well and I was burning myself on the manifold in the dark so settled with where it would fit.

Lastly, I would have REALLY liked to do another OEM test to see if I could get a confirmed, but marginal increase but at this point it was 10pm and I was beyond exhausted and had been in the car for 3 hours.


The results imho, say I should stick with my OEM for now. I do want to compare OEM to WAI (no tube) because I think the warm up would be beneficial in winter. For now though I left the intake as OEM and during the drive to work today sustained over 35MPG where previously it had to be less than that the days before, to only hover the average around 31. Looking back I think I know the reason too, when I removed the stock intake part, I saw leaves completely blocking (tightly packed) sticking out of the hole on the front of the air filter box, so I openned it up and there was a fairly solid brick of about 2"x4"x6" of leaves very tightly packed. It stayed together after emptying it from the box too. Very odd and I looked forward to the improvement but I bet that was the main reason for my improvements the last couple days and the OEM intake without leaves is better overall. Although clearly fall has only just started so I have no idea how it snarfed so many leaves... I'll have to watch it.


Anyway, I just wanted to post my week of interesting numbers as I've been driving and watching my code scanner because I didn't see that many numbers out there for the newer Altimas. Please ask any questions you want and let me know if you see ways I could improve my experiment or if you think cruise on a windy, mountainy road could never yield any significant data (ie. the test was flawed), or especially if you can think of an easier way to test mods that doesn't require driving 96 miles (6*16). I'm about to bring my SW2 online and will not hold back on mods for that but would really like to have a progression of proven data as I go.