Gtr r35 fuel trims problem.

Hi. We have a problem with our gtr. Bank 2 short fuel trim goes to 120% while bank 1 is 105%. And the car goes to limp mode. Same problem on dyno and on road. Car is tuned on ecutec. But i think its something mechanical. But I run out of ideas what to check. Maybie somebody had same issue, and can help a little?

I attached dyno log. Thanks in advance

Car mods:

Billet engine

Mad sweeden intake

Dual brushles pumps

12 injector asnu drivers.

And so on...

I would look for a clogged injector, or failed injector wiring. Alternately a failed coil or coil wiring can have the same effect. One cylinder not firing on a bank is going to cause a large lean condition (not unusual to see 25-33%)

David has great suggestions.

Since you mentioned 12 injector, is the disparity present during 6 injector operation or only 12?

Significantly modified R35 GTR engines seem to have a bit more bank to bank disparity than I'm used on on other platforms, but hopefully you'll be able to nail down a specific cause and resolve it.

It could also be an intake or exhaust leak on that bank.

I would check variable cam positions to confirm they're essentially the same on both banks as that can cause this as well.

little update. injectors are good, all of them checked on test stand. swaped between banks, no changes. all the injector wirings there changed to new one. same situation. tested on tune using only 6 injectors. same fuel trim problem.

After checking and inspecting everything, we swaped lambdas to new ones. at first it was same problem. and after testing some different tunes, with 6 injectors and lastly testing with first tune, everything became good. fuel trims there: bank1 98%, bank2 100%. all the time. after lots of testing the problem was gone without finding actual problem for 100%.

so if anybody have some thoughts, it would be intresting to hear.

thank you

Vytenis,

Any time a car "fixes itself" usually one of two things has happened.

A) Someone fixed the car

or

B) The car isn't fixed, but the issue isn't presenting itself at the moment.

Ideally the car really did get fixed, but it sounds like based on the work you're aware of, installing new sensors didn't solve it.

Unless you loaded a tune which has per bank compensation and that got your fuel trims closer to even, here are a few mechanical ideas to start:

Are you running an intercooler that joins air from both turbos or keeps it separate?

Do the wastegates for both banks have identical springs pressures, no leaks?

If you have turbo shaft speed data, are they similar?

Are pre throttle pressures similar?