[Tyler_Canada]

I did some research, and I found out that it's true, the Nissan ECU's DO attempt to correct for power mods, such as intakes. Check out this quote from someone who helped Technosquare develop the first ECU for the 2003 350Z:

More info about the infamous 'dialing back' of power...

the deal is that the stock ecu bases some of its fuel/air input through the oxygen sensors in the car. The computer will try to follow the pre-set map from the factory and uses feedback from the o2 sensors to do minor adjustments to the ignition/fuel mapping. So when you put on the new intake system the computer senses much more air flow than the stock mapping so, with this happening, the computer goes to the feedback value that's stored in the fuel/ignition timing maps to try to put it back stock levels. Which means the car is adding RETARDATION in the timing map. This takes away the ability for the engine to make more power with the additional air from the higher flowing intake.. so we're reducing that feedback value.

 

[Tyler_Canada]

And the official quote from TechnoSquareInc (aka TSI):

One of the major problems on this car was a feedback system that compensates for modifications. The oxygen sensors detects fuel mixture and will tell the ECU to richen up or lean out the mixture. This correction factor was way too wide, so some performance components upgrades (intake, exhaust) would actually result in a loss of HP below stock!
We adjusted the correction factor to reduce that compensation reaction. Our tests showed consistent power and torque improvement following installation of an intake system.
We will be conducting additional testing on various intake and exhaust systems for the compatibility of our ECU. Although we anticipate a dramatic improvement per component upgrades, some may require custom tuning to take full advantage of their performance.

 

[Eric L.]

I doubt an aftermarket intake like the JWT cone would overwhelm the MAF sensor so much that it cannot compensate for the airflow, causing incomplete combustion that the O2 sensors would detect. I guess anything is possible, but previous VQ30DE and VQ35DE Nissans have all showed dyno gains with intakes.

 

[jaak]

Oh great, now we're going to have people packaging a 3 cent resistor into a box to connect between the O2 sensor and the ECU to go along with the one on the air flow sensor... The latest eBay craze!

Good work Tyler, it looks like the best mod would be the one's recommended with the ECU update.

Sure would be interesting to slap on a data acquisition system to monitor what the ECU does on various days and loads.

 

[jaak]

Oh, the A/F sensor too. So four of them have to be fooled.

 

[jaak]

Also of interest:

NTD control system decides the target traction based on the accelerator operation status and the current driving condition. It then selects the engine torque target by correcting running resistance and atmospheric pressure, and controlling the power-train. Using electric throttle control actuator, it achieves the engine torque development target which corresponds linearly to the driver's accelerator operation.

Running resistance correction control compares the engine torque estimate value, measured vehicle acceleration, and running resistance on a flat road, and estimates vehicle weight gain and running resistance variation caused by slopes to correct the engine torque estimate value.

Atmospheric pressure correction control compares the engine torque estimate value from the airflow rate and the target engine torque for the target traction, and estimates variation of atmospheric pressure to correct the target engine torque. This system achieves powerful driving without reducing engine performance in the practical speed range in mountains and high-altitude areas.

 

[jaak]

Air Conditioning Cut Control

SYSTEM DESCRIPTION
This system improves engine operation when the air conditioner is used.
Under the following conditions, the air conditioner is turned off.

When the accelerator pedal is fully depressed.

When cranking the engine.

At high engine speeds.

When the engine coolant temperature becomes excessively high.

When operating power steering during low engine speed or low vehicle speed.

When engine speed is excessively low.

When refrigerant pressure is excessively low or high.

 

[dmako]

Then why do dyno results from Nissan performance magazine, and Injen show an increase in HP and torque with CAI's?

 

[jaak]

Maybe they have the hood open and the fan running on one, and not on the other?

Or they reset the ECU on one and not the other?

Or they did it immediately after so the ECU didn't have enough data to make adjustments?

Or it was different atmospheric pressures and temperature?

Or the tires were warmer on one run than the other?

Advertisers allow magazines to make money. They don't want to publish articles saying their advertisers products suck, don't buy them.... So if they can find two curves that show an improvement, then everyone's happy, including those of us that don't have dynos at home.

Just speculation, of course.

I remember watching a show (Horsepower TV? is that it?) where they stuck a CAI and exhaust system on a Honda at the same time. There was no dyno measurement with just one mod, they did both, then measured. I thought that sucked, as how can you tell which one actually made the majority of the difference?

 

[jaak]

So if you make a change to the intake, what should you do next? Would this make a difference?

Idle Air Volume Learning

DESCRIPTION
Idle Air Volume Learning is an operation to learn the idle air volume that keeps each engine within the specific range. It must be performed under any of the following conditions:

Each time electric throttle control actuator or ECM is replaced.

Idle speed or ignition timing is out of specification.

PREPARATION
Before performing Idle Air Volume Learning, make sure that all of the following conditions are satisfied. Learning will be cancelled if any of the following conditions are missed for even a moment.

Battery voltage: More than 12.9V (At idle)

Engine coolant temperature: 70 - 100°C (158 - 212°F)

PNP switch: ON

Electric load switch: OFF

On vehicles equipped with daytime light systems, if the parking brake is applied before the engine is start the headlamp will not be illuminated.

Steering wheel: Neutral (Straight-ahead position)

Vehicle speed: Stopped

Transmission: Warmed-up

For models without CONSULT-II, drive vehicle for 10 minutes.

OPERATION PROCEDURE
Without CONSULT-II
NOTE:

It is better to count the time accurately with a clock.

It is impossible to switch the diagnostic mode when an accelerator pedal position sensor circuit has a malfunction.
1. Perform EC-43, "Accelerator Pedal Released Position Learning"
2. Perform EC-43, "Throttle Valve Closed Position Learning" .
3. Start engine and warm it up to normal operating temperature.
4. Check that all items listed under the topic PREPARATION (previously mentioned) are in good order.
5. Turn ignition switch OFF and wait at least 10 seconds.
6. Confirm that accelerator pedal is fully released, turn ignition switch ON and wait 3 seconds.
7. Repeat the following procedure quickly five times within 5 seconds.
a. Fully depress the accelerator pedal.
b. Fully release the accelerator pedal.
8. Wait 7 seconds, fully depress the accelerator pedal and keep it for approx. 20 seconds until the MIL stops blinking and turned ON.
9. Fully release the accelerator pedal within 3 seconds after the MIL turned ON.
10. Start engine and let it idle.
11. Wait 20 seconds.
12. Rev up the engine two or three times and make sure that idle speed and ignition timing are within the specifications.
13. If idle speed and ignition timing are not within the specification, Idle Air Volume Learning will not be carried out successfully. In this case, find the cause of the incident by referring to the DIAGNOSTIC PROCEDURE below.

DIAGNOSTIC PROCEDURE
If idle air volume learning cannot be performed successfully, proceed as follows:
1. Check that throttle valve is fully closed.
2. Check PCV valve operation.
3. Check that downstream of throttle valve is free from air leakage.
4. When the above three items check out OK, engine component parts and their installation condition are questionable. Check and eliminate the cause of the incident.
It is useful to perform EC-127, "TROUBLE DIAGNOSIS - SPECIFICATION VALUE" .
5. If any of the following conditions occur after the engine has started, eliminate the cause of the incident and perform “Idle air volume learning” all over again:

Engine stalls.

Erroneous idle.

 

[jaak]

Part of the reason you have to send in your ECU:

NVIS (Nissan Vehicle Immobilizer System — NATS)


If the security indicator lights up with the ignition switch in the ON position or “NATS MALFUNCTION” is displayed on “SELF-DIAG RESULTS” screen, perform self-diagnostic results mode with CONSULT-II using NATS program card. Refer to BL-119, "NVIS (NISSAN VEHICLE IMMOBILIZER SYSTEM-NATS)" .

Confirm no self-diagnostic results of NVIS (NATS) is displayed before touching “ERASE” in “SELF-DIAG RESULTS” mode with CONSULT-II.

When replacing ECM, initialization of NVIS (NATS) system and registration of all NVIS (NATS) ignition key IDs must be carried out with CONSULT-II using NATS program card.
Therefore, be sure to receive all keys from vehicle owner. Regarding the procedures of NVIS (NATS) initialization and NVIS (NATS) ignition key ID registration, refer to CONSULT-II operation manual, IVIS/NVIS.

 

[Dalite]

Also of interest:

Very similar to the torque based turbo management that DCX used on the PT Cruiser GT.

Provides consistent torque in relationship to throttle (accelerator) position, regardless of humidity, altitude, ambient temp, etc.

Man, did I forever have a hard time trying to get some of the gearheads over in the PT forums to understand this concept; even with quotes from the designers and some of the Sport Compact Magazines coverage of the same system in the SRT-4.

Computer control and compensation for owner's "mods" seems to be the wave of the future; primarily to assure that the engine and drivetrain will last through the manufacturers liability period - sometimes referred to as a warranty.

 

[Dalite]

Then why do dyno results from Nissan performance magazine, and Injen show an increase in HP and torque with CAI's?

It would be interesting to see if the same increases were experienced after a complete cycle of the Task Manager in the ECU; guestimating around 140 miles of driving after a mod has been applied to a monitored engine component.

On other vehicles with modern OBDII computers, the initial gains are often brought back under control by the computer so that the measured data returns within the realm of the computer's anticipated data ranges...

 

[grfg8r]

DaLite,
Were you the one talking about your experiences with trying to dump ECU memory before?

 

[Dalite]

DaLite,
Were you the one talking about your experiences with trying to dump ECU memory before?

Not on this forum...

There are encryption and checksum issues to overcome.

The Nissan, like most of the current cars sold in the US market can use either SAE ior ISO standards (or a combination of both) for it's communications. This makes it harder to research, and more difficult to determine the actual communications protocol used. My guess would be VPW (Variable Pulse Width) modulation, but that is a very uneducated guess on my part. Call it a WASG.

Like any computer with EEPROM firmware, you have to either apply voltage, or pull down the CE (Chip Enable (or equivalent label) pin to write to the eeprom.

I haven't looked into the Nissan ECU, but with the number of 350Z, 240Z, 280Z user groups around, someone has the info to allow you to read the ECU from the diagnostic port.

Since we share the same basic engine as the 350Z, there should be a number of places developing "go-fast" options.

One of the salesmen at the dealership where I bought my Murano said that I could put in 350Z cams and ECU into the Murano.

However, until more historical data on the CVT with an engine as large as the 3.5L in the Murano is available, I will sit back and watch someone else play Captain Kirk on this one (Go where no man has gone before).

It may be possible to bypass some of the more mundane ECU monitored systems and use the extra memory to write more complex programming, but it is way beyond my ability to do more than speculate.

 

[grfg8r]

Do you think the hold up is due to the CVT overheating? If one can, why not add a tranx cooler? Or, are there other issues w/ the CVT as well?

 

[Dalite]

I feel that the CVT is still being cautiously treated since the fiasco with the Subaru Justy in the late '80s.

From what I have seen, the 3.5L engine is the largest to be mated with a CVT in the market today, and pparently Nissan is keeping the performance of the Murano subdued until they can gather more historical data about how much torque and HP the CVT can hold up to.

This is just theory, I have no absolute date to base this on...

 

[grfg8r]

I wonder if they'll ask for "Test Rats!" :roadtrip:

 

[jaak]

If I had the time.... And that's a huge if, I could acquire the data with a logic analyser.

What would be more interesting would be to buy a Consult II and flash the Murano with it, having the L/A attached. The L/A would basically capture the entire process.

But I don't have the time... Well, unless I found a Nissan mechanic that was curious.

Then we'd need someone to help pull apart the code. Considering how hard it's been to get someone to write code for a PIC or Atmel just to enable the audio inputs on the radio, I give up now.

 

[Tyler_Canada]

My belief as to why the dyno charts show gains when an intake or intake + exhaust are added is because the dyno test is done immediately. What I've read is that people are doing a dyno immediately, and then doing another down the road (4 months was stated in one case) and finding the gains are "mysteriously" gone.

What I intend to do to verify all of this is get my OBDII interface finished (just have to populate the circuit board) and log the timing. According to what I've posted, the timing is retarded in order to keep the power the same. So then I'll log the timing with the pop charger, then take it off, reset the computer, run for a while to let it relearn the stock intake, and log the timing again (at similar humidity and temperature).