I agree, most of the data we have to go off on this site (and most any other site) is butt dynos and heresay. There is typically very little factual data to support claims. What we need is a Nissan tech that writes the code

Here's my experience with my 96 Maxima with the VQ30DE and ECU resetting adjusting along with some information about the newer VQ35 Maximas. I know, I know, "The Maxima IS NOT A G35, Dave!!!!!!!". Just read what I have to say then you call me what you want.

I owned my Maxima for 6 years and did quite a few mods. I found out that when I truely cleared the ECU (removed it's power source), the intake got substainially quieter, the engine was less responsive below 4500rpms, MPGs were worse by 2-3mpg, though pure WOT felt about the same. After a few days, the car was back to running what I'd call "normal". The intake wailed like a banshee, the engine was far more responsive, and MPGs improved. It was clear to me that when the ECU is cleared, the ECU takes some time to learn the operating efficency of the motor. The ECU will initially run the engine rich and possibly retard timing a bite until it finds the efficent and "safe" A/F/timing preprogrammed tables. I verified the timing and air flow with my OBDII scanner. I was personally told by a local Nissan tech it will typically take about 30-40 runs for the ECU to find it's optimal setting after it's been fully reset. There was one Maxima owner that actually put the ECU resetting to the test on the dyno. One ECU had been in the car for weeks and the other would be installed after two dyno runs. The dyno results were there was no real measurable difference at WOT between "learned ECU" and the cleared ECU.

The 95-99 Maximas have 16 bit processor ECUs are ODB-II. The 99.5s+ started running 32 bit processor units and are also ODB-II. The VQ35DE used in the 02-05 Maximas is basicially the same engine except for the intake manifold. The cars have the same sensors (knock, 02, EGR, coolant, etc) and sensor location because the engines are basically identical except for drivetrain layout. It could probably be assumed that the overall tuning of the VQ35s in the Maxima/Altima/G35/M35/FX35/350Z are pretty similiar. There are some slight power differences (5-15whp/wtq), but overall tuning should be similiar. The sensor locations on the older VQ30s is also basically the same as is the operation. All the ECU does in any of these cars is read the sensor values and determine the optimal and safe parameters. It is very true that late model ECUs (96+ ODB-II) do adjust. They adjust for atmospheric conditions, knock (detonation), A/F ratios, coolant temps, etc.

What I find interesting is that VQ35 Maxima crowd doesn't do the ECU reset/clear in an effort to find more power. The only time it's mentioned is when someone gets a CEL they want to clear. I don't think I've ever read about the ECU reset to unlock power on the 350Z site either. On this site it seems to be some sort of normal operating procedure you're suppose to do Why do the G guys think this works and the Maxima guys don't and the 350Z don't seem to care? The motor overall is the same.

I know a lot of guys in here say their G performs better with the reset. They notice things like more throttle response, harder shifts, chirping tires, etc. I'm a firm believer in the power of suggestion. Couldn't it be possible that some of this released power is being noticed simply because the engine has been cooled downed and these guys are beating the engines when they're not fully warmed up? I can tell you that going WOT with an auto with tranny fluid that isn't fully warmed is going to shifter harder. That's just the nature of autos. Throttle response and overall acceleration is also better because the engine isn't heat soaked. Depending on my driving style, my G can be docile and shift smoothly. If I want to get naughty, it doesn't hestitate to shift pretty hard, chirp the 1-2 on occasion, easily do power oversteer on slow speed turns, spin the tires on a roll through 1st, etc.

Maybe I'll datalog my G before and after an ECU reset. Make that can give us some actual data.

 

I've owned my G35 automatic for 2 years now and I've performed the ECU resets over the years with noticeable performance afterwards. My true frustration is that I have to perform this "ritual" AT ALL! I mean, for the price I paid for this loaded - G, I've been a bit disappointed in this. Otherwise, I enjoy making the payments on this car. Why, if EVERYONE seems to be aware of diminished performance after "baby-city driving", isn't a more permenant ECU FIX being researched??

 

I couldn't agree more. No one on Altimas.net ever reset their VQ35-equipped Altima either that I can recall except, as you pointed out, to clear the MIL, fix an ECU hiccup or add an intake modification. Resetting one's ECU on an unchanged and otherwise healthy engine and then "feeling" a smoother surge to redline, a crisper shift, more power, etc. on the butt dyno is one of those power-of-suggestion things that I find dubious. I mean, let's be honest: We've all read posts from the less-mechanically-informed on all sorts of car-related websites with helpful tips such as, "I changed my oil and my car is definitely faster." Trying to convince the guy he's mistaken is like arguing with someone from the Flat Earth Society that, in fact, you won't fall off the planet if you row past Aruba.

Believe what you want to believe regarding the ECU reset, but until I see dyno or strip numbers, put me in there with the skeptics.

 

If you do a search you will find many tests were done. A dyno was done before and after a ECU reset, no cool down time. The car gained 5 rwhp. Nissan has switched ECU manufactures since your Maxima days. The G35 doesn't use the same manufacture ECU as your 95-96 Maxima did. The ecu acts differently. IMHO you need to stop comparing your maxima to the G35 because these cars are completely different animals.

Like I have said it before and will say it again. It's in the Service manual on how the ECU learns.

 

Maybe the reason you don't see it on altimas.net or Maxima.org is because people who drive infinities usually are a bit smarter and make more money. Either they are engineers, or know their stuff much better. I mean we look at Maxima site or Altima site, what do we see? A bunch of kids with riced up cars (not all but a good handful of them). Here we see a bunch of nice cars with much more older crowd.

I will recommend both you guys go do a search learn from the site, and learn from the veterans. You might get more respect doing that instead of making assumptions that the ECU reset just can't happen when the other cars don't do it either.

FYI, my350z.com the ecu reset is just as bad as here....they do it very often as well.

 

You're making my point exactly. Until I read it for myself, I'm not buying it.

If Nissan has developed a 'thinking' CPU (ECU), then Intel and AMD need to get on board. If a CPU on a fileserver could be conditioned to process data a specific way (read faster) with no change in its architecture, and then the same CPU could be optimized for rendering graphics simply by the user showing a tendency toward that practice, it would be a revelation.

If there is text in the service manual and someone has an e-copy, please cut and paste it here. I'd really like to read it.

For the record, I'm not one who goes by the saying "It must be true, I read it on the Internet" veteran or not.

As for learning from the 'veterans' I'm all for it. No offense to anyone here, but define 'veteran.' Join date? Post count? What?

Being a 'veteran member' or not being a member at but reading hundreds of posts and abusing the search likely amount to about the same level of knowledge - PMs aside. I've been reading here since 2003, but didn't join until I owned the car, 2005. I've probably read more data on this site than some who have been here since day one.

But anyway.

 

Sad to see people obviously don't want to see the facts or read the service manual.

It has been posted in the past, do a search for crying out loud.

 

Good link here with some info on how the ECU works..

http://www.my350z.com/forum/showthre...ight=ecu+reset

 

copied from my350z.com

This is something I've noticed from Chesbosto's updates with the TechnoSquare ECU threads. This might be some interesting info for you guys.

4-29-03

We have a good idea on how to tune the 350Z, but we need to do a 'heavy' mod so that it triggers the ECU to do something major to the numbers so we can find those key values, and base the tuning off what changes...... Its stock right now, we believe we can knock about 5-7rwhp more in stock form on premium pump gas...91 octane. You know how everyone is slapping on intakes and the car first gains power but then the hp goes away? Its due to a feedback control loop the ECU has for Fuel and Ignition timing... this is a new system Nissan has in all its New (2003+) cars... this number is a preset value which will tell the car to go back to its original state when it senses changes... well we just, prevent that from happening by altering this feedback number to a lower value so that the ECU cant adjust as much back.. we're testing the waters with slightly lower values and will keep on doing so until we reach a safe limit of where it dont adversely affect any safety measures pre-programmed into the ECU to prevent knocking.. but so far the preliminary results are pretty good... Ingition mapping is complete, the fuel curveis also nearly mapped out..

and

4-21-03

Dyno of the car resulted at 278 at the crank. It's from a Bosch dyno so it's not a regular dyno jet or dyno pack. It's an older dyno style that gives results in k/w... used for tuning purposes most of the time... Anyways, the ECU was re-flash with the stock program and went back and re-dyno and it was the same 278. Interesting note, if you disconnect the battery after a mod for example... you gain a few HP [3-5], but then then the computer re-learns and it brings the curve down a bit.

Sorry for the copy and paste. But the ECU isn't new to the New Nissans that Chezbosto's wrote in his thread. It's actually old. The 350z uses an OBDII (On Board Diagnostic) type II ecu. As well as every car made after 1996. (Which was the last year of the 300zx. interesting) Car's prior to that year used the OBDI type ecu.

The purpose of the EPA-mandated OBD standard was to provide a means for which factory engine controls could diagnose engine control malfunctions and identify to the driver (and subsequently the repair shop) that there was a problem. The OBD2 standard, mandated for all 1996 and up vehicles, required that the OBD interface be standardized across all makes and models, as well as monitoring emissions components performance and proper operation. This means that for 1996 and newer vehicles with OBD2 that if you remove the catalytic converter or EGR valve that the ECU will eventually identify that these components are no longer working and flag a check engine light (CEL) and OBD2 code.

What is known to the tuning world from dyno plots and tuning is that the ECU on OBD2- equipped vehicles will eventually "detune" modifications that alter cam timing, ignition timing, and air/fuel delivery. This includes common breathing modifications (intake/header/exhaust and port work). What this means for the average tuner is that when you bolt on i/h/e, do manifold or head (port) work, change injectors or fuel pressure, or just about any other engine-related mod, the ECU will detect the change in emissions and alter the timing and fuel maps to compensate. This has been dyno proven on multiple occasions with multiple different performance mods. It also happens that this is especially true for air/fuel controllers (AFCs).

The Fix
There are several ways to fix this problem. The first would be to do an OBD1 "conversion" where you replace the stock ECU with an older Nissan. This has its own drawbacks, requiring you to find/buy an ECU, a conversion harness (or making your own), etc. Even more expensive and time consuming would be to switch to a standalone system from Motech, AEM/GEMS, Haltech, etc.

While any of these would certainly be desireable and provide you with other options (such as programmability), there is a much cheaper and easier solution. Knowing that the OBD2 ECU will eventually learn and "detune" what you are working to achieve, the real objective here is to insure that your computer doesn't learn, or more accurately, "forgets" what it learns. What we will cover here is interrupting the backup power to the ECU to make sure that it does not retain it's memory while the car is off. It will "detune" while you are driving but go back to a clean slate every time you shut the engine off. Also, since the EGR and catalytic converter malfunctions are stored and only "flagged" as a problem after multiple driving cycles, these will be reset each time you start the car. This means you can install a test pipe (provided the second O2 sensor is still installed) or block off the EGR valve (or remove it) and not have to worry about a CEL. Not a perfect method, but a LOT cheaper, easier, and almost as effective as any other option.

I, personally don't have a 350z to do this. I'm just an avid 350z fan. I plan to get one by this winter. But if one of you guys wanna try to find the backup power to the ECU and put a toggle switch (On/Off) This method should work.

This mod is effectively the same as pulling the 7.5A CLOCK/RADIO fuse from the under-hood fuse panel, or removing the battery cable (all of which reset the ECU). The beauty of this mod is that you don't have to pull a fuse each time you shut the car down, If you are VERY worried about tearing into the stock wiring, you may want to just pull the fuse weekly, which is about as "fast" as the ECU learns (a few hundred miles).

Pretty much any switch will work, provided you know how to wire it as SPST. For most switches whichever end the toggle is flipped towards, those contacts are OPEN. The other contacts (facing away) will be shorted (ON). Flipping the switch alters the on/off state of each of the sets of contacts. Pick two contacts and wire them to the ECU- just be sure you know when they are shorted and when they are not, based on the position of the toggle!

This will setup will allow you to keep the switch OFF (open the backup power circuit) to keep the ECU from "remembering" anything. If you get a CEL, throw the switch back to the ON position and then it will remember the code. Just be sure you mark or know what's ON and OFF for your particular switch and wiring. By hiding the switch, this should also allow you to return the car to the dealer "acting normal." Most dealers don't like it when they can't retrieve diagnostics info!

Also the downside of this is that it voids the factory warranty (that's if the dealership can find the switch. hehe.)

This is called the OBDII workaround. Very familiar in Honda Tuning. Probably some of you people heard of this mod. This method should effectively work with the 350z as well since they use the OBDII ecu, just a different harness.

For as long as I've seen this done. I've heard of no reported problems on different forums. and so far there have been no reported issues with fuel economy or other problems. (if work-around is done on stock ecu with no modification of course.) There is no need to let your car idle for any period of time or anything else- just get in your car and drive off. It will act like normal and drive like normal, you will never know the switch is there or on or off.

 

It must be true, I read it on the internet.

What I read above is that the ECU senses (not learns) changes and adjusts itself accordingly. Nothing revolutionary there.

As long as the 'change' is present (read mod) then the 'adjustment' will remain in effect. This reads like a way to allow your mod to remain intact without doing a full ECU re-flash (read hard adjustment in what your ECU sees as normal).

In the case above, as the ECU senses the changes, it adjusts the functions of your car to remain as close to what it considers 'normal' as possible - thus negating the mod. Resetting the ECU just resets the process. It isn't 'learning' anything. It's compensating for what it sees as an abnormality.

I see nothing above that says your car 'learns' your driving style and adjusts the ECU to better match it. I'm a firm believer that the ECU adjusts itself based on the demands of your right foot on a given day.

Using this 'learning' theory, if I drove my car *****-to-the-wall for 29 days, then on the 30th day I drove sedately, I'd see no difference in my gas mileage because the car would have adjusted to my heavy right foot and only a ECU reset would make it 'forget.' That just isn't the case.

Still waiting on a legitimate source to convince me. Modders from 350Z.com fall a bit short. ECU work-around tips from some guy I don't know from Adam doesn't do it for me.

I have done quite an extensive search and have found nothing more than 'he-said, she-said' from average Joes. As for the dyno, you can dyno the same car on the same day on the same dyno and get different numbers. Could be ECU reset (not likely) or could be a coincidence (pretty likely).

If you want me to believe an ECU reset might temporarily restore the effects of a modification as a way to compensate for a lack of ECU reflash (read hard change in ECU processing 'norms') then I can agree.

If you want me to believe the ECU 'learns' your style, adjusts its 'norms' on its own, and then requires a reset to 'forget' then I'm still on the fence.

 

That post was to show you how it works. But the SM shows how it learns and goes from that for future settings. If you add mods, it won't change those settings without resetting the ECU. But if your WOT Open Loop, it won't matter anyways most of the time. But for closed loop operation for a better car, its good to reset the ECU from time to time.

Well, one car in our family really shows the learn feature. Our 2001 Altima (the style before the new body) is owned by a 60 year old father and is driven like a old person on a daily basis. I mean 5 mph under the speed limit, slow accels, coasting way before a stop. The car feels like a dog. If myself or my mother drive the car for a week, we can tell its a extreme dog, but after a few days of driving it, the car comes alive, and really is peppy again. It's kinda funny because once my father gets back in the car he really notices it and asks what we did. We tell him, we just drove it harder. lol. The ECU learns somehow, someway it does per drive to make the car work its best for that driver.

Edit: One other thing I thought I mention too. He gets way over 30 mpg in the city with this Altima. lol.

 

Strange quote #1:Uh, no. If anything, the opposite is true. Most of the folks on this site are relative laypeople when it comes to cars -- hands-on automotive maintenance is for the less fortunate, you know -- whereas the groups with which I've been involved before were more of a hard-core group that included real technical savviness. Being smarter and having more money does not mean you know a thing about cars; more than a few folks on this site illustrate this point on a daily basis. There's nothing wrong with that. But your point is way off the mark here and couldn't be farther from the truth.

Odd quote #2:What's been posted in the past? Oh, the little anecdote from some guy I don't know whose writings you've included that do nothing to support your position that resetting the ECU on a stock G35 miraculously provides an extra five horsepower at the rear wheels? Is that the one?

The argument this guy makes, which may well be true and with which I won't argue, is that the ECU in the VQ35 compensates for unknown variables such as aftermarket air intakes by de-tuning itself over time back to stock performance levels. I can buy that, Zotz. But don't try to sell me your theory that resetting the ECU in my stock VQ will miraculously gain me horsepower over where the thing was ten minutes earlier. Is it possible that the ECU running in closed-loop mode as it "learns" environmental, operational and electronic parameters and applies code to them might make a few more horses for a few minutes? I suppose. Could happen. But I think you're mistaken if you believe that resetting the ECU will magically provide you that extra performance over any length of time.

Not only that, but what kind of feedback system did Nissan design that requires a reboot every few hours/days/weeks to maintain peak performance? Let's give the engineers a little more credit than that. (Insert your own cheap Microsoft joke here.)

Last unusual quote:
Yes, I feel disrespected, and that concerns me. My tender feelings have been bruised.

Russell, searching and learning from the veterans is a useless waste of time if they don't know what the heck they're talking about. I've said it before, and GeeWillikers also apparently subscribes to the following axiom as well: Posting a theory on the Internet does not make it law. Applied here, what I'm saying this this: I'll give you a pass on the reset concerning moderately to heavily modded VQ35s, but I think the long-term (i.e., more than a few days) benefits of resetting the ECU on a stock VQ35 in any U.S.-sold Nissan or Infiniti is marginal at best. (One reason why: I've done it. Twice. Didn't do a darned thing.) And despite your bleatings (okay, that's harsh; let's go with "earnest postings"), you've provided exactly zero hard evidence to the contrary.

Nothing personal, Russ. Your brother will agree I've always been a skeptical hard-butt.

 

Yeah, about your last comment. LOL he talked to me about you when he was here this past week. Nothing bad, but just to watch out for you. lol

Anyways, I am done here. I have driven VQ cars for 10 years. And on the G35 it seems to be the most noticeable car with a ECU reset. I use to believe it in the MAxima days on the 2000-2001 Maxima when people said to do it. I thought I noticed it but it never did a thing on that car. This car seems to really show a much bigger difference after a reset. But like you said, it could be for just a few days, then the ECU goes back to the original parameters and since we get use to it, we don't notice it as much loosing as gaining.

I personally will admit I am not really sure how the ECU works. I have been told by a few respected members on this site that are really into the car and are engineers as well. They showed me and explained the SM and how it works which makes sense. I can't explain it as good of course.

 

Are there any serious G35 owners who knows WTF they're talking about and can point to ECU program (that one can find in the factory service manual) that adapts the car to the way you drive? What if you have two regular drivers, one pansy, one a dick. What's the 'learn' time of the ECU? Two hours. 10 starts, 50 starts?

 

Let me throw this idea into the mix:

The typical ECU takes current and historical information from its various sensors to determine the optimal fuel/air mix, most probably in the interest of fuel economy, engine longevity, and emissions compliance. If there isn't any historical information (i.e. after a reset?), the ECU will resort to essentially what is a flat-program of pre-determined values until this individual engine's values are learned. Isn't it possible that this default or flat-programming is perhaps richer fuel-wise than what the computer orders up over time, as it learns how lean it can run this engine, in the interest of fuel economy? If its richer, it will certainly “feel” stronger.

No, no engineering degree here, just a concept I wanted to mention.