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2JZ-GTE VVTI, M150, AFR gets lean after shifting for 0.2 to 0.3 of a second

MoTeC M1 Software Tutorial

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Dear All ,

I hope someone can help me with this issue. Thanks.

I have a 2jz-gte vvti engine with Motec M150, If I'm shifting hard and pushing the throttle 100% for the first 0.2 seconds the car is a bit rich but as the engine builds boost again from 100 kpa to around 180 kpa in around 0.2 to 0.3 of a second the engine gets extremely lean ( it can reach 18 when the aim is 12 ) and then it goes back on the AFR target from around 1 bar until 1.5 bar and end of rpm at 7100 rpm (it happens also if I reduce the boost to 1.2 bar, same problem). I tried almost everything in the fuel film primary. I tried increasing the amount in the main table after 100 kpa , I tried reducing fuel film primary fast increase time constant to 0.05 and also increased it to 0.2. I tried increasing the time of fuel film primary slow increase time constant to 1 second and also tried at 0.6 , the fuel film primary offset, I tried from 30 to 500 .Nothing seems to be fixing the problem after a shift with a hard push on the throttle.

Injectors installed are ID 1050X, Turbo Precision 6766 , calibration for injectors downloaded from Motec, Package installed is John Reed Racing package for 2jz-gte vvti. I'd appreciate it if anyone could suggest a fix for this problem as 18 AFR when the car is building boost is extremely dangerous on the engine , it takes 0.2 seconds after the shift but it is very dangerous.

Do you have some sort of shift cut active?

Also, a lean measurement of your O2 sensor can also mean a misfire or incomplete combustion where still unburnt O2 passes the sensor.

Dear Christoph,

Thank you for your reply. I don't have a shift cut. I have tried numerous settings with fuel film . Even when I slam the throttle at 2000 rpm with no boost , sometimes it just goes richer but other times it goes lean and then richer , I tried to increase the table and reduce the fast part time constant to 0.01 but I still get the same problem, as if the injectors can't react on time which I really can't understand . I had previously Denso 800 cc injectors which was side feed and I had the same problem and then I switched to ID1050X and I still have same problem. The strange thing is when calibrating fuel film as I told you at 20 KPA 2000 rpm and I slam it sometimes it is ok and then I try the same 20kpa 2000 rpm and I slam it and it leans before getting rich, the car doesn't hesitate or bog but when I'm pushing it hard at 7000 RPM and then I shift and it is getting in to boost and I see it lean to 18, it is very dangerous. I have a log file with the new injectors that I didn't push to end of rpm , just shift as I get boost and I slam the throttle in the next gear. I have the warning source of Lambda immediately activated after the slam on the throttle. I'd really appreciate it if you can have a look on the Motec I2 log file and advise . Easiest way to see where the lambda gets lean is put in the channels you are viewing the warning source and you will see three warnings through out the log.Right before the warning source you will see how the exhaust lambda gets lean than the aim.

Attached Files

I was finally able to fix the lean problem after shifting . The fuel film main table had to be totally changed to encounter for the sudden boost after the shift. I had to increase the numbers substantially after 100 kpa and the problem was fixed.Thank you all.

Glad you got it fixed!

How far did you have to tune fuel film past 100KPa? Is this common for turbo setup to adjust for some positive boost during part throttle as well?

After I thought all was fine, I started trying different rpm and found same problem . So I disabled the system and found that the car doesn't get lean that much when the system is disabled so I found out that I have put too much fuel which causes the sensor to read lean although there is a lot of unburnt fuel and this is what caused it to read very lean. My advice is to follow exactly the motec advice on how to tune for the fuel film and you will get excellent results but to be honest I never reached zero lean reading after a shift, I can get to 12.5 instead of 11.5 for 0.1 of a second but the car is performing well and I have no knock so I just have let it go.