So I own a 2003 Maxima SE automatic (Get you're licks in now.. lol) I have added an Injen cold air intake system while using OEM MAF, also upgraded exhaust system from stock size to I believe 2.5" using Magnaflow as the muffler. I have about 96,000 miles on my Max. I changed the spark plugs around 94,000 using NGK Iridium, just replaced the fuel filter and collector today at 96,000. Questions begin here... Having done those upgrades to allow more air flow my ECU is set to OEM parts probably does not see the aftermarket upgrades I made. I am floating between 21.6 to 21.9 MPG while running high octane always (Sunoco only). I feel like the car could use a tune up maybe by reprogramming the ECU or on a DYNO, if I do this will I notice better fuel economy and more horsepower from the ECU reprogram? Any help will greatly be appreciated

 

so youre getting normal mpg...yet youre complaining? that doesnt make sense.

MPG rating is: 20 Combined, 17 City, 24 Highway

Not trying to be a d*ck, but these cars arent known for the good gas mileage

 

2003 SE auto myself. Approximately 20-21 mixed (depending on driving habits) and 24-25 all interstate/trips.

If you're looking to "free" up some power, lose the intake choker and go SRI, check motor and torque mounts and lower control arm bushings...replace as needed. Actually, just replace that craptastic electric motor mounts with ones for a manual.

Did you just replace the muffler or the entire catback? Did a shop do it? Is it mandrel bent or crush bent? Big difference and crush bends chock exhaust flow regardless of the muffler. The stock resonator section is the biggest chocking point on the exhaust, I assume that was replaced with the system?

But understand HP and fuel economy are not linear. Increasing one does not inherently increase the other. The plugs and fuel filter are the only two things I saw that might help improve efficiency. To gain fuel economy, you need to install light weight rims, eliminate bulky sound system if you have one....stick with a single sub in box, and for the most part, just lose weight and drive like a granny.

Other helpful suggestions would include making sure your ebrake cable is not dragging and keeping pad pressure on either rear brake. Check tire pressure, check belt tension on drive belts (people often disregard this one), and perhaps try running ethanol free gas if you have it available. I'm sure there are things I've missed, but this is a start.

 

Not complaining at all here, just wanting more performace from the mods I have done. I feel like if I set the cars' tune with my mods I will see better performance such as overall power etc.. As I stated the ECU does not know I have upgraded to a cold air intake and opened the exhaust so I am thinking about buying a tuner to plug into OBD2. I have done research on those but still not sure which one to buy that can give me the ability to adapt the ECU with PRE-SET settings.

 

 

Ok so not in on the acronyms, "Intake Chocker and SRI?" Motor mounts might be too advanced for a DIY job without any directions. Muffler is from cat-back with high flow cat. Shop did the job, will check with them to see if it is mandrel bent or crush bent, also not sure on the stock resonator will have them check tomorrow all in one shot. I may just remove the resonator altogether that would allow for better air flow correct? Stock rims, no system just original Bose that came stock. As stated just replace fuel filter and fuel collector today, only drove a few miles but noticable throttle response. Always monitor oil level and tire air pressure. Not sure how to check belt tension on drive belts also, I can follow a set of directions with no problems though.

 

I believe he meant Intake Choker (Stock intake/air cleaner housing). SRI = Short Ram Intake.
Motor mounts are actually a very simple job. There are instructions somewhere around here. Do a search for it.

 

Turn that injen into a short ram or route it to the fender.

 

Thank you man, is this a job that requires additional parts?
Hey, my Injen does run all the way down to fender. No more stock at all expect the MAF.

 

30mpg for the 3.0l is good mpg's. 3.5 FTW for everything else.

 

Here's the problem. You have an automatic. The automatic has at least one, maybe both, electronic motor mounts. The inserts from Energy Suspension (which is what you want) will not fit in these motor mounts. You need to find mounts from a junkyard for an 02-03 MANUAL. Then you take those mounts to shop and have them press out the old inserts and press in the new ones from ES.
Then it's just a matter of jacking up the car, unbolting the mounts from the engine, and unbolting the cross member that runs under the engine. Once it's off, swap in your manual mounts. Start your engine mount bolts (do not tighten yet) and then bolt up the cross member. Torque everything to spec.

 

Re: resonator comment. The resonator itself is not a restriction and you and/or your neighbors will likely despise your car if you simply remove it. The restriction in the stock section lies in the exhaust pipe before and after the resonator in that section.

I suggest before you do anything else you spend several weeks just reading and searching on this forum. Then ask any lingering questions. Then decide where you want to go. Your goals may change or find they are out of reach depending on what you currently expect to accomplish.

 

I have an auto too, and if i could find mounts for an 02-03 manual, i would grab them, and the manual trans for a swap. speakin on the subject, you guys in the states are lucky with max's in the wreckers.. I've owned my max for 2 years and work in a bodyshop in Vancouver BC and search at least once a week on our used autoparts search and only found one 5th gen ever!! And sadly it was an auto...

 

eBay sir, new manual trans mounts are on there all day long for the cheap. I think you can buy good quality mounts (all 4) new for less or around $100. I think just the two engine mounts cost roughly $50-60 shipped. Not sure about what you'd need for a full manual tranny swap though, you'd have to eBay that one yourself! LOL!!

eBay: online wholesaleparts - front and rear manual mounts $58.40 shipped. Canada likely more, but there's you're mounts, just the two anyway.

 

Ebay is definitely the way to go. Here's the front, rear, and right mount for ~96.00$C http://www.ebay.ca/itm/2002-2003-NIS...75c68b&vxp=mtr

 

It sits in front of the radiator, that's bad. Move it away from there.

 

to me to do a dyno tune on a car with just intake and catback exhaust is a waste considering how much money you'll spend just on a tuning option. You can get a cheap fuel controller and adjust fuel but it wont make THAT big of a difference. You'll really need something that can adjust ignition timing AND fuel. Now you talking about in the $1000 hp range. Did you get a y-pipe at least? That will make a noticable difference. I had a y-pipe and injen CAI on my old AUTO 4th gen and it was worlds different than stock. I never did a tune and it did about 22-25mpg depending on my driving habits. I would not go tuning route unless you get headers and y-pipe with full catback exhaust. just a catback and intake not going to make that much of a difference...

 

http://www.stillen.com/ http://www.cattman.com/ is all i have to say u want to go fast then do it the right way then go for for a tune dont do it your self

 

So are you suggesting to use a tuning chip that connects in OBD2 port or nothing like that at all. I do not have a Y-Pipe just original style exhaust fitting only upgraded to stainless steel and opened it to 2.5". The Y-Pipe will allow less air restriction, what type of gains should I expect from that? Also once I save the money I will add a pair of headers which should increase HP to a noticable difference, would you agree? I also posted the location of my Injen CAI and this is down in the drivers side fender where the front bumber has some open areas to allow cold air in as I am driving, someone made a comment about the intake sitting behind the radiator which is not correct, just want to clear that up.

 

Also, don't forget those front/rear engine mounts. You won't believe how much difference it makes in reducing wheel hop and getting that power on the ground.

 

see above

 

NA Tuning w/ all that $ invested in standalones and whatever will ONLY net about 30 to 40HP on the dyno and even that is being generous.

 

Which brings me back to the comment I made that increased HP does NOT = increased fuel economy, which is the OP's primary issue......as I understood it anyway.

In fact, OP....you start to do things to increase HP, you will likely see a decrease in fuel economy. Why? Simply back to the age old issue of driving habits. I don't even recall seeing a post indicating whether you do mixed or primarily city driving...which makes a huge difference. So you need to consider if you do all city, you are going to hit a glass ceiling on fuel consumption.

To address something else you stated in your post, your ecu doesn't need to "see" your mods. It is designed to operate the engine efficiently based of pre-programed parameters. Many mods create horsepower simply by freeing up barries created by the design of components such as intake, headers, Y, exhaust. "Performance" parts don't so much create horsepower as they allow you to recollect what is already there but robbed by the barriers of stock components and design. Sure, an AFC makes sure you see better HP output by better taking advantage of these mods.....but.......

Which brings us back to the original issue you posted about....better fuel economy. I understand you don't mind the side effect of extra HP, and increased HP does mean the engine works less to do the same amount of work. But gains in fuel economy are going to be minimal given you will have to make significant horsepower increases to reduce the overall HP to weight ratio while also ensuring you are at least maintaining the engine efficiency you currently have (or better yet, improving efficiency). Inherent problem in all this is still going to be driving habits. Tendancy is that with increased modifications, a driver will accelerate faster, speed more, brake later....just a couple of factors which drastically decrease fuel economy. Lets look at what Ford did with their new 305 HP V6 Mustang. Took it to a track and set strict standards for driving/ acceleration/ braking/ speed and resulted in significant fuel economy. IIRC, stipulations were no more than 1/4 throttle, speed limit of 45, and coasting well in advance before stop/braking.

I appreciate your desire to ask questions, but you really need to read up on some things. Clearly you either don't know quite a bit or have been given bad information. Please research and put together what you're goals are. Really, doing so helps us help you. Right now, not sure what else we can offer you. I get the feeling we need to fall back a few yards and punt.

Maybe need to ask some different questions:
Driving habits? Speed demon?
Driving environment? (City/hwy/mixed)
Run A/C or defroster often? Leave car running when stopped/waiting/ long morning warm up period?
Is fuel economy primary goal or are you looking for increased HP and fuel?
Is it about increasing fuel economy or lowering fuel costs?

 

Ok going back to square one here... This car is my everday driver to start. I enjoy adding mods that can give it an aggressive ride when I want to smash on the gas. I do concern about ride comfort as well which my MAX is smooth there. Honestly I am on the forums here to gain knowledge from the EXPERTS rather than going around to local dealers or friends who don't know much about my MAX to the T, where as some of you do So moving forward.. I do mostly highway driving 15 miles one way to work..for now until company relocates lol. No more A/C only heaters/ defroster now I live in a small town close to Pittsburgh, PA. Moving forward I will hit 100 mph plus two to four times a week. Typical driving is 70 to 80mph, with minimal breaking (try to at least). I drive very conservitive through city, unless I am tested. So that is basic background on my driving style. As mentioned I am a just beyond a ROOKIE when it comes to adding mods that will improve certain areas of performance. I understand what I read on here as far as advice goes. Therefore I am going for a blend of fuel effeciency and raw power. My question about the ECU chip was because I know my car needs a TUNE to compensate the CAI and CATBACK exhaust, or at least that is what I am being told. Other major plans as stated above are HEADERS, possible 3" exhaust pipe from 2.5", front & rear strut tower braces, then general maintence as needed. Here's and example; brake upgrade when rotors are worn down will go to SLOTTED with dots or drilled. So I am here to help others with knowledge I do have and also gain from those with more experience.

 

You don't really need a "tune" because the stock ECU can accommodate for some of the mods. Now we're not talking about a +100hp turbo kit or an S/C kit where you must get tuned. A tune will only try to squeeze out whatever small % of gains from the cai/exhaust etc.

Perhaps these examples will help you, if you are looking for HUGE power you won't find it on an NA platform, get boosted for those kind of gains.

http://www.importtuner.com/powerpage..._infiniti_g35/
G35 - VQ35 engine + mods

http://www.importtuner.com/powerpage...z_power_pages/
350Z

 

Thank you man, that does put the mods into an exact perspective I was looking for. SO a DYNO will squeeze any "remaining HP" from the mods I have done...right?

 

A DYNO will tell you where you are at HP wise, a TUNE will squeeze every last drop of "HP" from your mods.

Dynos - $75 for 3 runs (no tuning)

Tuning w/ a standalone - $100 per hour at whatever shop

Those are the average prices

 

Right I understand, but will those OBD2 "Tuners" work like a professional tune? This is where I have done reasearch but still mixed, because in order to tune the car it has to be done from a DYNO to see where you are then into the tune which I still don't know how to set the tune, in other words how it is done. I would think the best time to tune a car is right after a DYNO run.

 

OBD2 Tuners work? Yes, kind of but w/o a standalone on a dyno it's hard to fine tune. The OBD2 tuners will do like a "good enough" tune and leave it at that.

The best time to tune a car is when it's on the Dyno, you make changes on the fly to the standalone ECU and run it until the tuner sees that it's safe and reliable and at the power level you want.

Check out Nistune, but it's not available for 03 Maxima. (not yet anyway)
http://www.nistune.com/

My 300zx was tuned with Nistune, they burned the EPROM on the spot w/ the tune and installed it in my ECU. I asked them to tune it for 400hp as a conservative tune at 16psi. I could go up to say 500hp at say 22psi but that's really pushing the turbos I have.

 

If you want better fuel economy, this is your problem. I believe i drive aggressively and get roughly the fuel economy you get and I don't drive as near as aggressive as you do. You would see easily 2 mpg gains per mile by resolving this area.