2jzge itb intake popping

[tdgarage]

here's the low down and what was done to the engine set up,

Set up:

2jzge none vvti, stock internals

efi hardware intake/itb set up with r35 gtr fuel injectors. 

The car was running fine before with a modified throttle cable minus issues starting most times.

Intake was removed to adapt the new EFI hardware dbw actuator which i posted before and got figured out.

Nothing was touched on ignition set up, or wires or distributor. During the time the intake was off i found out that the 

bore of the itb was larger than the intake manifold, causing a lip to disturb air flow, so i match ported that to the intake.

Installed everything as it was, installed new spark plugs, changed oil,finally got the dbw set up to work properly. 

The issue:

When the engine first fired up i let it idle as i was messing with the dbw angle, and noticed my afr being in the 10's. I started hearing popping sound from under the hood, and noticed i could see flashes behind the number 5/6 itb butterflies. 

I checked the wires to make sure everything was connected right, i removed cylinder 5/6 spark plugs to double check them, and installed them back on the car. 

the next day i tried to start the car again and i wasn't getting any popping from cylinders 5/6, however i starting getting intake popping from cylinders 1/2. 

again nothing with timing was touched mechanically or through ecu. 

trying to pinpoint what may have changed, i thought maybe it's getting more air now, so the original fuel map was too lean, but not sure why the afr still read in the 10's. 

 

there's another problem with start up but this is from before any of the new added parts, but it's still around. 

sometimes i have to start the car multiple times because the first start up the car will run rough like there was too much fuel and plugs fouled out, so i will have to shut off the engine, and try again until i get a clean start. 

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[Adamw]

I would guess its very likely your throttles are out of sync, the intake backfires are a common symptom of that.  Im not so sure the rich AFR would be due to that but occasionally a lambda probe will read rich when there is a misfire.  My intuition would have me leaning more towards it being an issue with the sensor or controller, but fix the sync issue first then investigate the AFR if it is still not right after that. 

A seasoned ITB veteran can sync them with a stethoscope or piece of vacuum hose stuck in his ear, but for most less experienced I would suggest a Synchrometer.  The STE ones are good and less than $100 here in NZ so probably cheaper everywhere else in the world.  Do the syncing with the engine fully warmed up.  

 

[tdgarage]

I have both of these tools, the only problem is that when the throttle keeps backfiring it makes it difficult to make accurate adjustments. 

but i will give it a go and see what i can do and keep you posted. Thank you Adam for the info. 

[Adamw]

Forget what the wideband is telling you and try making it richer, that will probably fix the lean backfire.