Tricky-Ricky

Knock detection doesn't restrict rpm, it just retards the ignition timing a few degrees, I would go for the mixed up coil pack theory, providing the DE doesn't run wasted spark? but it is an odd one, I did wonder if it had something to do with the restricted throttle opening in lower gears, but that shouldn't restrict overall rpm.

Unfortunately knock detection only extends to 5K rpm, after that its disabled, so its not going to be that.

Didn't fake Ben Taylor post some info on some testing done on the DE during a dyno run that reveled a big restriction through the plenum and throttle body? That graph carries the info "DE 350Z_PLENUM,VELOCITY STACK,DE-CATS_UPREV" so there is definitely a restriction somewhere ahead of the plenum/throttle body, or even in the plenum?

That's odd, so 0.11" /2.794mm = an extra 4 ribs? and how can a difference of 0.11" in width equal 66.7% wider?

TBH I don't think going from 2.75" to 2.86" is going to make that much difference, how do you arrive at 60% more contact area? I would be looking more at friction materials myself.

Its always worth fitting a larger battery if you can, more cold cranking amps/more amp/hours, as the std battery Is rather underpowered, also because these cars are CANbus, low voltage can cause a whole host of problems.

This was my last project, got to start with the knife making again though.

Just been digging around on my old NAS looking for my old log files, and re downloaded Innovate logworks, but I have found that for some reason some of the logs have been corrupted, so its not looking too hopeful to use as example's.

Thanks Mark, be very interested to get you views on the std ECU, but if I remember rightly the target maps are in AFR but the fuel compensation maps are in % which makes it difficult to directly relate. I just found this AFR data point map that I took from my DE engine with the Innovate software, and it stay pretty lean until high RPM/load, trouble is I cant remember if this was before or after adding mods, but I do think it was after adding a true dual exhaust system.

I've logged the output of the lambda on my 370 when on the dyno and although its a wideband its VERY slow to respond to afr changes Interesting, and a little worrying for what should be a slightly more advanced ECU in the 370Z, I know my Innovate setup was very fast to respond. Yep I was able to see the live data from Jez's innovate wideband (Bosch sensor) and compare it to the data coming off my oem wideband and it was consistently lagging behind, this was without cats btw . I've innovate stuff myself and always found it good , had wideband sensors and displays in both my r33 and Evo 6 and i used to map the latter myself. So the std wide-band sensors are slow then, as I said that a bit worrying for the newer tech, yeah I like Innovate stuff, AEM just doesn't seem to have the display resolution.

While I agree that adding a free flow filter, and even a plenum spacer will not increase airflow to any great degree, however add a decent free flowing exhaust and decats will allow the engine to pump more air, after all that all it is a pump. Now the whole point of this thread is to try and debunk the myth that the std ECU will dial out any bolt on power/airflow improvements and NOT make any more bhp, yet you guys have just said you think the std ECU is able to adjust the fuelling to compensate, which I agree with, but you really cannot expect the engine to not make more power as a result...no matter how small, it would be very interesting to see the result of fitting some lumpier cams and see how far the ECU s compensation maps can be pushed.

Dam! that's worrying.

You see that's my point, what happens when the std ECUs airflow takes things beyond the target value? what does the ECU do to prevent damage from running too weak, if the airflow is outside the parameters that its capable of compensating for? I have seen people running cosworth plenum's along with exhaust filter etc without a remap yet they don't sustain any damage, and how is it able to run the correct AFRs for the increased airflow...without making more power, even a worn engine would still make more power from increased airflow and fuel.

I've logged the output of the lambda on my 370 when on the dyno and although its a wideband its VERY slow to respond to afr changes Interesting, and a little worrying for what should be a slightly more advanced ECU in the 370Z, I know my Innovate setup was very fast to respond.

I am pretty sure that on the DE ECU closed loop is pretty much full term, N/A is not like turbo there is no need to adjust fuelling in line with boost pressure, Airflow voltage is used to scale the maps so there is always a target figure, so as far as I know lambda feedback is used pretty much full time, in any case once a fixed map is used its usually deliberately rich as a safety measure, and this would be also make sense if there is no knock control on the DE ECU at high load/RPM. Since only the J spec is supposed to have narrow band, and the UK wide-band this would be able to cope no problem, its how most modern ECU are configured especially the lean burn type.

I am inclined to agree with that, I added breathing mods, the AFRs remained the same, which to me says that the ECU has adjusted fuelling to accommodate the extra airflow.....BUT the dyno showed a std BHP figure, however the engine could well have been making less power from wear and tear before the dyno. But it was a low mileage engine that had very good even compression figures, and I also leak down tested when I got it, if only I had dynoed it before hand, but the fact that I was intending to self tune it made me not bother. My naturally suspicious side does make me think that it could be a well maintained myth, after all if you where able to increase power by simple bolt ons, it wouldn't make tuners so much money, Although I am not saying that it helps to optimise ECU settings, but the number of people that run breathing mods for a long time with no ECU tweaking without any detrimental effects says that the ECU is able to adapt fuelling to suite.

An unfortunate effect of the ageing process..... the older you get the more you see those people you grew up listening to or watching pass away, there seems far too many just lately, sat with the misses the other night just looking up all the movie stars we liked to see who was still alive...it was quite a shock the most worrying part is that I am not that far behind the average age that they all seem to reach their demise at

First off SuperStu I have read that in the manual, and its just a general explanation of how the system works, and really doesn't offer any incite on how it responds to breathing mods. Floydbax although I see your point I really don't think the ECU is able to modulate the throttle on a full time basis to modulate the airflow, especially since it also has to respond to normal driving input as well. And regarding ignition timing, I think you will find that if the std map is limited in some way, and its unlikely to be just timing based anyway, it would be far easier to get more that the usual 300BHP from the DE motor, if that was the case. Also the so called "gentleman's agreement" was for earlier cars, and was abandoned before the Z arrived. davey_83 I agree to a point, especially the debated for years but nothing concrete has ever been published that I have seen, which I s why I broached the subject. I am hoping for a reply from someone who is either willing to disclose the full facts, or who works in ECU/map side the industry. Everything else is conjecture, but well thought out theory is always interesting.

Thought there would be more interest given the amount of comment on this over the years, yet there is still nothing concrete as far as explanation's go, just a lot of conjecture.

WARNING! this may get a little long winded and boring to some, however it may ultimately prove useful to some. I thought this might have a few replies, given the amount of arguments about dyno figures and breathing mods on the other thread. Anyway this is not intended to be an argument/discussion about dyno figures, more if an how the std ECU works , and in relation to adding breathing mods etc. Now I am no expert, but I have mapped a few piggybacks and stand alones, but a while ago and older tech, but I like to think I have a fair grasp on just what goes on with your average ECU and how it controls the engine parameters. Now when I first bought my Skyline 350GT (Z in sheep's clothing) I fully intended to self tune using Up-rev software, so as a prelude to this I first bought an Innovate LM2 twin wide-band set up and fitted it to the cats (and yes I am fully aware that this will gave a slightly scewd AFR signal) anyway I monitored and logged as I fitted some breathing mods, long tube intake, dual exhaust and the obligatory plenum spacer, and can honestly say that I didn't see any major changes in the AFRs, and further to this the car was dynoed at Abby by Mark and made pretty much std power and toque figures. Unfortunately I never did get around to buying up-rev and self tuning. On to the std ECU, we all know that the ECU meters the fuel and ignition timing to make the motor run efficiently, but in order to discuss things further I am going to have to outline pretty much the whole process, so sorry! I am sure that you can find all the relevant info on-line however I think it wont relate so well if you have to keep going elsewhere for reference. ECU over view.(kept relatively simple) And as I said I am no expert and if anything is blatantly wrong then those that really know like Mark or Jezz etc please feel free to correct me. Basically we start at the AFM which meters/measures the amount of air that's being drawn into the engine, a simple voltage signal, the ECU uses this voltage in the form of a table made up from this voltage and RPM and load, which it uses to calculate the amount of fuel to be injected at any one time. There is also a similar scale/map that it uses for ignition timing, the problem is thats where things get a lot more complicated, as there are separate maps for each part of the process and condition, there are maps for cold starting, fine adjustment for coolant temp, intake temp, engine knock, dynamic ignition timing, short and long term learned fuelling and timing maps, and last but not least lambda feedback. Lambda sensors as we know report the amount of un burned oxygen in the combustion process, which is known as AFR (air fuel ratio) which in turn gives the ECU the information to know if its supplying the correct amount of fuel. Now with regard to adding breathing mods etc we only really need to concern with the main and adaptive fuel and timing maps, and in particular lambda feedback, now being N/A the ECU uses lambda feedback the majority of the time, the ECU has its own pre programed comparator maps which are what it expects to see in terms of AFRs, if the AFRs go outside of these figures it will adjust fuelling to get things back to within the parameters in the map. This is where I start to fall down a little in my understanding, as say for arguments sake you add a free flowing exhaust system, and intake, and as a result the engine is able to draw more air, so the ECU sees more air/voltage from the AFM and so in the lookup table it finds the correct fuelling for this amount of airflow/load and adjusts accordingly, and this will be verified by the AFRs that the lambda sensor reports, so you would then expect to see a little more power because the engine is getting a little more air and fuel. But this is what I have trouble with, if this amount of airflow is outside the lookup table, limits how does the ECU behave? it cannot change the amount of airflow, but it can change fuel, so does it run things weak because it hasn't got a matching fuel table? or does it simply richen things up excessively, or simply retard ignition timing to reduce overall power? but this if too much could cause knock, I am just not sure how it can limit power from airflow increase, So if any real expert's can actually explain the finer points of this? To me if any of the breathing mods can increase the overall airflow enough to make the ECU change fueling to match, it should result in more power, but its obvious that the ECU was adapting the fuelling as my wide-band logs showed no significant change in AFRs before or after I fitted breathing mods.

Its late and I'm heading for bed but I thought it might be an idea to start this thread, especially since the way the thread by zippypooz dyno run went, and I have just searched and could find nothing relating to the actual capabilities and limitations of the std ECU, especially when it comes to adding breathing mods etc, and explain just how and why its thought to negate breathing mods...or not.

While that maybe true to a degree, in that a newbie comes along and does a search and finds this thread, he will also find an awful lot of others that say that breathing mods without a remap will achieve nothing, and if he only chooses to believe this one then that's his problem for not being thorough, and the likelihood of screwing your engine through adding breathing mods are pretty slim.

Let the poor guy have his pleasure at the dyno figure, and if it feels quicker to him who's to say there isn't an improvement, if it was on Abbeys or Horshams dynos I bet there wouldn't be so much negativity.

Aren't the VVT sprockets keyed to the cams? if so you should have no problem, the VVTs don't actuate during start up and low RPM so that wont effect things, low compression will hinder starting, so re check that. If the ECU has got water into it its entirely possible that this is causing no start as well, but check out the compression first.

You shouldn't have low compression just from rebuild, have you tried a little oil in the cylinders to see if it makes a big difference to compression reading? As for the cam and crank sensors its a little difficult as they are hall effect and need close proximity to a metal tooth, but I would have thought introducing something metal close to it with ignition on and coil pack attached to an earthed plug would make it trigger a spark, however I am not sure without going through the manual which sensor is responsible for ignition.