QR25DE Tuning

[jaf]

6E11 is the main CAM map. Hard to say whether the calculation for units should be the same as a 40 degree VVT model or not. A log would show the correct way. The uneven spacing is taken care of in the spreadsheet if you look carefully. The first image I posted is skewed since I did not have the axis info then.
6AD1 is probably cold ign timing believe it or not.
Why am I thinking specVs have 10:1 compression and 200HP? Maybe it was year dependent? I have pics of SpecV pistons which were flat tops initially.
If you are going to tune, certainly get the hang of WinOLS for its presentation of data and ease of editing - obviously it is a copy and paste out of there when done since it cannot cope with Nissan ROMs.
The code is more diabolical than the X-Trail for sure - that is why I asked you for the axis info. If it didn't have NATS, I would be swapping ROMs and starting from there.

[Tom]

It's interesting what you say about the CAM maps jaf. I finally got hold of stock 350gt ROM and can now compare it to my Japanese tuned one. The CAM map looks a lot different on the 350GT though. The peak seems to be at high load and lowish RPM. I wonder if I should try changing it a bit.

[attachment=1]350GT stock CAM.png[/attachment]

[attachment=0]350GT flashed CAM.png[/attachment]

BTW. I flashed my ECU with different 350Z and G35 ROMs and never had a problem with NATS. I was getting trouble codes (not NATS) but the car always started and was drivable.

[jaf]

Hi Tom,

Not sure what conversion formula you are using on your maps? Does your logging agree more or less with the expected advance? I assume you have around 32 degrees absolute max advance so 35 degrees really means max?
For a quick fix on the original ROM, I would shift everything left one column and flatten the max advance out a few degrees. Also add a few more degrees at max rpm. See attached example. That should give you a real good feeling as to what the motor wants.
I'll do up a more comprehensive map over the weekend that will give you a few ideas to try.
The X-Trail is tuned as good as it is ever going to be (which is incredibly impressive) after pinching a couple of ideas from the Sentra ROM regarding ign timing.
I'll publish the final figures shortly and a logging run to go with it.

John

[jaf]

A bit of a diversion from the QR25 but all useful stuff....

Here is an example of cam timing for the 350GT utilizing the later scheme adopted by Nissan and most others:

1. The "hump" lowers compression and therefore pumping losses. It also introduces a degree of EGR action. If it coincides precisely with cruising loads and rpms, it will enhance fuel economy and engine smoothness without hurting performance. It must fall back quickly to optimum cam timing for power when load is increased otherwise performance will feel uninspiring.

2. Bringing more cam in at lighter loads will increase part throttle aggressiveness. Too much, and the engine will become "raspy" and economy will suffer. Adjust to suit taste.

3. Advance Vs RPM curve is based on typical Nissan Cam timing with next to zero overlap at idle. Too much cam advance acts similar to too little in that volumetric efficiency is reduced. Factory tuning does this on purpose so a lot of timing is pulled back for more performance contrary to expectations of many.

4. If you take out the hump, the map should be close to an optimum performance only orientated map.

5. The factory map is awful.

[jaf]

As promised, this is pretty much the final state of tune for my X-Trail.
After flashing over 150 times trying out every permutation possible, it has boiled down to a relatively simple tuning of cam advance, AFR and ign timing.
The constraints have always been:
1. It must run on 91 octane.
2. It is my daily driver so it must be smooth running and reliable.
3. Fuel economy must be better than stock.
I have minor modifications to the intake duct (remove a stupid plastic deflector and fit K&N panel filter) and exhaust is stock except for a 4into1 shorty header.
Tuning started with a wideband O2 sensor and MAF interceptor fitted plus Blazt II adapter and NDSII but that got annoying seeing, but not being able to adjust cams etc.
I now know why these Consult II cars are so difficult to hack - the Nissan engineers were so embarrassed by the crap job they had done, they tried to hide the evidence.
Keep a close eye on rpm and load axis if comparing my X-Trail tune to the Sentra.

[AK_Eyes]

Jaf and/or Tom,

How are you guys reflashing your ECU!? I have a 2006 350Z ECU with a Renesas SH7058 MCU. I was working on reflashing via SH Bootmode and Renesas Flash Development Toolkit but never successfully got the ECU into "boot mode". I do however think that I must have established communication and Renesas software erased the ROM because I can no longer talk to the ECU via K Line or CAN and no traffic on CAN TX/RX or SCI TX/RX. Next step will be to try and connect via the AUD port. Any help would be greatly appreciated.

Thanks!

[Tom]

I personally used the Renesas Flash Development Toolkit. The key is to supply 250Hz clock signal (green wire on the attached pic) while flashing otherwise the external WDT will reset the MCU. This method is specially useful if you have a bricked ECU.

[attachment=0]flash connection s.jpg[/attachment]

There is an easier way to flash it (but longer) if you have an activated NDSII software and the ECU is working ok. PM me if interested.

[moldbruja]

hey great work you guys doing!!!! there,s have been some dyno testing mostly found on b15u so if guys found vias activation address setting it to 4700 rather than the usual 5200 well get you 3whp acrros the line starting from activation point!!! top end afr i suposed to big pig reach to detune qr25de , stock qr25 never wot !00% in fact closes 20% at top end and finally rev limiter ill pay for who ever reflash my02 spec v for higher rev limit im running c1 cams springs, etc its really frustrating hitting that rev limiter so early and the only option we have for 02 -03 specv is jwt 300$ for just the revlimiter .... just one question has anyone identify 02 spec v mcu its suppose to be impossible to reflash

[Tom]

If it's impossible to flash it how are they upping the rev limiter...
Have you tried dumping the ROM?

[moldbruja]

ok so i manage to dump 21k today just as a test i use free diag but im planning on buying ndsII this week and guess what uses a sh7055 too which bring me to question why uprev doesnt support to 02-03 specv´s