I had a wierd idea maybe one of you would want to try.

Since the injector correction factor is limited MAF voltage to the stock ECU at around 4.3 volts, depending on where you set it for you own personal tune... we all know how that effects ignition timing. If you log your E-Manage you know the MAF is reporting a pretty much solid 5.0 volts and thats the line that your tuning matters the most.

I had an idea.

What if you went into the airflow correction map, and did this...

starting at 3500 RPM and about 70% throttle... start ADDING back in airflow.. but do it linear so that 100% throttle is at maybe adding 15 percent, and 70% throttle is at maybe 4 percent and have it a nice percentage increase per throttle...

The effect I am considering is if you get the MAF voltage back up closer to 5.0 volts than perhaps the stock ECU will pull a little bit of timing out itself seeing that the engine is actually under more load than it was thinking before.

Worth a shot.. but needs to be done by someone who can datalog their timing.

This is all a big waste of time of course unless a stock 350z actually hits over 4.3 volts on the MAF during full throttle runs anyway... cause if it doesnt than this is the regular airflow/load that the ECU is used to seeing at full throttle and its already got its timing maps taken care of.


What made me think of this was Honda experience. In a Honda ECU there is an internal barometric pressure sensor. When you first key on the car it compares the baro to the MAP sensor, and of course it should be EQUAL... but with a airflow correction (MAP correction on a Hondas case) you are not letting the stock ECU see the true MAP voltage... it thinks that the barometric pressure sensor is bad, and trips a CEL.... so what you do is you go into the airflow correction map and you add fuel at the very top left cell so that with key on, 0 RPM, no throttle... you have negated the injector correction and the MAP sensor voltage to the stock ECU is close enough that the readings are close enough in line with the barometric pressure sensor that you get no more CEL on key on!!!

Same thing right? Not really, but its comparable.

-Charles

 

My MAF sensor is well over 4 volts....as soon as the boost kicks in, and then is clamped at 5V via emanage. So once you are WOT, you are essentially at peak load, and the timing should be near its max retarding. Hope that makes sense...but I'm not sure how increases airflow voltage more would help us in the case, given that we are near the limits of the MAF very very quickly....

 

I was thinking about a similar idea, but with regards to the big injector idling issue.

My theory is since the eManage is scaling the injectors through MAF conditioning, ie reducing MAF voltage to the ECU to reduce pulse width, and pulse widthxRPM determines timing, then I figure once you pull enough pulse width to compensate for 440cc or larger injectors, the timing at idle gets too low.

So, possibly try adding in timing at idle RPM to compensate for the loss due to scaling.

 

gq: your not thinking about it deep enough. Like I said, the MAF is maxed out to 5 volts under boost (which you said also)... but dont forget you have an injector correction factor in the E-Manage. Your stock ECU will never see that 5 volts no matter what.

The MAF's max output is 5 volts... and after its filters thru the E-Manage its around 4.3 volts getting to the ECU. I am talking about letting the ECU see that true 5 volts once your boosting and the injector correction is no longer needed. This would mean putting the MAF signal back up to spec (thru the airflow map) and then not adding so much fuel thru the additional injection map until the top end where it will need it anyway.

If you were to add fuel in the airflow map in the E-Manage, you could get that entire 5 volts to the ECU so that it sees how much load the car is truely under. I am thinking that if this was the case, the stock ECU might not run as aggressive of timing thru full throttle pulls.

 

Phunk, do you have a profec? If so, log and it and check for yourself. The "output MAF Voltage" is 4.98V at peak boost and RPM....believe me...the ECU is seeing very very close to 5V very quickly in the boost and RPM area.

 

interesting... with the injector correction factor it should not be seeing that. My car never sees more than 4.3 volts of the 5.0!!!

-Charles

 

The voltage that the ECU is clamped at 5.0V via the profec, so I guess that's why it maxes out at 4.97V...just to keep a tiny sliver of a cushion away from 5.0V. If it's clamped at 5.0V, then why is yours showing max voltage at only 4.3V? That is the part that is sorta confusing.

 

because the injector correction factor is always dropping the MAF voltage... as you know thats how it controls the larger injectors. It adds a static percentage of MAF voltage drop to keep the injectors. Are you sure that your MAF output to the ECU is actually going that high?

 

i will check when I get my car back...if I ever get my car back!