OK, it's been almost 4 years that the 350Z is on the streets and I have a feeling we still don't know much about how the ECU works in this car.

There is one really essential question that no one has been able to provide an thorough answer for.

What we know:

The 350Z ECU (and that is not only true for the REVUP engines with the wideband O2 sensors) has the ability to determine A/F ratios under WOT and adjust according to factory presets. It does this by the so called long-term fuel trim, originally intended to compensate for deterioration of the catalitic converters or consistent use of low quality fuel - for one rearson? in order to preserve the required emission standards.

What we do not know:

Given the aforementioned the ECU will fight any modification that leads to an alteration in A/F ratios, be it a "hardware" modification (intake, exhaust, cams, fuel systemetc) or any kind of piggy-back input intercept "software" modification. The ECU will try to compensate the changes by the long-term fuel trim if the A/F ratio is out of factory target.

So the questions are:

How far can the long-term fuel trim go? What adjustment range does it have before it gives up and what happens then (CEL?)?

How consistent can tuning by piggy-back ECUs like the E-Manage, the UTEC and others be assuming the are working by intercepting and changing the MAF signal?

Finaly, which tuning solution will provide the most consistent results (which one works differently from the MAF-intercept approch).

Let the discussion beginn. I am all eager to learn and understand.

 

Maybe we should ask the Japanese tuners since they seem to have 'cracked the code.'

They're getting over 300hp easily w/o going FI by going ***** out on the engine and ECU tuning.

 

I guess Technosquare has hacked the code for the original ECU too but that leads to the next question (or maybe a conclusion) that you would have to start with a ECU reflash and remove or change the ECUs long-term fuel trim habit in order to make consistent tunes/gains with any aftermarket part (hard or soft).

 

Are you sure about TS? I've been reading about how their reflash isn't holding up to standards. The reflash can only do so much. I personally don't think they've hacked anything.

 

Not 100% sure regarding TS... I just had the impression they did by reading the info on their website.

 

Publication No. SM4E-1V35U9 Edition: October 2003 Revision: February 2004:
We can only speculate until someone (TS, UpRev, CT and possible others) who have 'cracked the code' posts the info or releases the code.
But, according to Q45tech post on this or other Nissan sites, if I remember correctly, long-term fuel trim is not that long at all – something like minutes.

 

You personally are wrong, no offense, but TS was one of the pioneers in hacking the ECU on the 03's and their research did not have any bullsh1t flying around.

You say "reflash can only do so much" but unless you know those limits (such as fuel/timing map resolution) you shouldn't knock the stock ECU's potential.

 

i personally don't think you know anything about the subject.

TechnoSquare first cracked the ECU code in 2003 after having my car as R&D for six months+. Techtom, Technosquare's parent company in japan supplies the hardware to ALL of the JDM tuners and pretty much all the ECU flashers here in the US. TS, AA, JWT, Vishnu, etc. etc. use all of Techtom's hardware. TechnoSquare then proceeded to generate the software mappings for the Z.. Then after about 100+ dyno runs they had their first set of tuning maps.

Since then they've tuned countless Zs, Gs, FX, Muranos, Maximas, Altima, and pretty much all of nissan's VQ35DE line cars & others with flash memory ECUs and have made significant gains.. Some cars more than others due to 'de-tuning' from the factory to make it safer for the wide range of gasoline grades and for the vehicle use (i.e. Towing for the Titan, and "econo-box" commuting in the Sentra)

you will never see the 'code' since it's proprietary information, (example: Windows XP: source code. etc) however you WILL get the stock ECU code after you purchase the ECU Reflash hardware. from there, you can generate your own maps granted you have a dyno at your leisure and know what you're doing.

technosquare constantly updates their libraries with the latest ECU versions that are coming out, and will be working on the new 07 Zs as soon as they get their hands on it.

if you really have questions, all it takes is a phone call to Tadashi and he can explain what they do and what is and isn't possible..

 

TS was definately one of the earlier pioneers in VQ35 ECU tuning.

In regards to the original question, the stock ECU reverts to its set map under open loop operation, and does not have feedback control, per se. This is the reason that excessive NA modding tends to result in consistently leaner AF ratios. AF ratios at WOT will vary based on a myriad of factors, so its not realistic for someone to expect PERFECT consistency between runs, or days on the dyno. The goal of the tuner is to dial in the AF ratio (among other things) in order to maximize power and trq across the broadest area of the powerband, while maintaining a margin of safety for a street driven car. Although each pull, or each day, will result in slightly different AF ratios, this is perfectly normal and acceptable. Higher end engine management systems provide for AF feedback compensation under load (such as the FCON), but it is is a common practice for tuners to disable the feedback under load, particularlly with forced induction cars, in fear that a bad 02 sensor could cause the engine to run outside of the safety zone at WOT.

Hope that helps.