BRZ GT86 - High LTFT & Knock Issues - Possible DI issues?

Looking for some advice please! I've been tasked with a tune on a 13 FRS. The vehicle has a stock ECU (B01C) and is complete with a full bolt on Turbo kit. All sensors & Fuel system components are currently stock.

Not being particularly familiar with this application I potentially missed a diagnostic step before I started tuning. The vehicle come in with a Lean O2 code and LTFT were stuck on 40+, STFT we're also high. I assumed that this may have been due to the Turbo installation and I made the applicable changes in the MAF scaling to bring the fuel trims into check.

I've then continued to tune the car making small steps in ignition timing, spending quite some time trying to flatten the torque curve. All was heading in the right direction until the car suddenly started to Knock heavily. I can hear it via my Audio headphones and also very clearly under the engine bay itself. I tried going backwards on timing, more fuel etc but any sort of boost around 3000RPM and this noise would come rattling.

I pulled the spark plugs (what a PITA!) and #1 has a very white, cracked Insulator. All other plugs have a tanned appearance.

I've done a bit of homework on the Direct Injection system on these but I don't have much hands on experience. I'm leaning towards a Direct Injection issue, maybe just on that 1 cylinder or maybe even globally. I have pulled the DI injectors, 2 & 4 looked clean, 1 & 3 had a good amount of "sludge" around the Injector shaft and Seal.

I'm planning on dropping the Injectors with Toyota next week to see if we are able to have them flow tested somehow and then serviced. The engine sounded healthy at idle and could be driven at low load at all RPM's without any odd noises. I really think its spark knock but I'm open to other suggestions.

Any input is greatly appreciated.

The fact you had a lean O2 DTC and +40% LTFT prior to tuning is very worrying and potentially suggests something was wrong prior to you getting started. You shouldn't need to be making changes to the MAF scaling of 40% for a basic bolt on turbo kit (assuming the MAF sensor is still in the factory housing). Have you followed through the BRZ/86 worked example in our Practical Reflashing course? This car was fitted with a supercharger which for all intents and purposes responds quite similar to a turbo kit (although the SC will take a lot more timing).

One of the common faults with the FA20 is the DI injector seals failing. This seems to be the result of the engine suffering from knock as the seals can't handle the pressure spikes. This becomes obvious with a rough idle and a loud cracking noise at low to moderate rpm. We've also had one instance of a DI injector failing altogether so this is a possible scenario. Unfortunately testing a DI injector for flow is a very specialised task due to the pressures they run at so most workshops won't be able to do this for you.

Thanks for the reply Andre - The MAF has been relocated to an aluminum charge pipe within a couple of inches from the Throttle Body - its in a blow through configuration. It seems to be a common location for these Turbo Kits.

I don`t currently have access to that course but it sounds like I should look into it.

The actual tuning process was going OK and heading in a logical direction until this noise occurred. Certainly not the easiest vehicle to diagnose - on our software (ECUFlash/Openport) we don't have a huge amount of PIDS available and are lacking information on Inj PW/DC.

In the failures that you have seen, has the error been reported via the OEM ECU? Codes etc? I'd have thought that the DI ECU and PI ECU would be in constant communication but it seems from the research that I've done that the DI system is a bit of a "dumb" system without much of a feedback loop.

It was a holiday here today but I'm planning to speak with Toyota directly tomorrow and see if they will offer any kind of "Inspection & Service" on the DI Injectors.

Ah yes, if the MAF is blow through then ignore the above as it's not relevant.

I haven't tuned an 86 on opensource software but I can say that EcuTek is pretty comprehensive in terms of parameters available. Generally when there's a DI seal issue the first thing you'll notice is the audible sound at low rpm. From memory one of the cars I had that issue with brought up a misfire DTC but I'm struggling to recall the specifics.

The car that had the failed injector didn't report any errors.