RomRaider

Hi,
I'm trying to figure out why my 2010 JDM STi is adding so much fuel in correction, then suddenly stops as below


The fuel pressure seems ok - far right column is the Fuel Pressure error - (Actual (from sensor) vs what it should be) which is calculated from actual fuel pressure (from Left TGV) less target pressure (based on 43.5 + manifold relative ).
Stock maf/intake, ID1050xds, aem 340 pump, 3 in down pipe, no cat, Turbosmart By-pass valve plumbed in like stock
Injectors have low pulse width compensation and latencies set correct (from the ID spreadsheet ) etc

Just trying to under stand why this is happening.

Also note - brand new O2 sensor (tried with old one too - same), is it possible the in this aftermarket down pipe (Possum bourne NZ company made it) the O2 sensor is not in the exhaust stream properly so taking too long to see in the exhaust the ECU's a/f Adjustments (so ecu keeps adjusting)?, although when looking at it, its more to the side away from the waste-gate so suspect its in the right place, just trying to guess why its doing this.

I Have tried another Maf sensor and it has the same results.

More mod details;
No TGV's (gutted, and none cruise tables copied over cruise tables in ecu), PCV delete with AEM AOS (no crank case air going into the intake - Race edition), all blocked off correctly on the Perrin turbo inlet. (Process west top mount).

Attached in the current version of my Rom (AZ1G800S - JDM EJ207)

I could possibly add this to the load compensation tables (currently all 0), but I want to make sure thats what I have to do and that I've not missed something in the tune etc that actually causing it.

Yup that can be fixed by Engine Load Compensation, seems like it have lean condition when you hit small amount of boost in that range (highway crusing/accel?).

What I've recently did on 2010 STI, I added a few more columns in Engine Load Compensation for conditions like >0-8 psi and added about 15-20% more fuel in desired RPM range. That helped a lot. Additionally, added slightly more to MAF scaling in same region. Now AFR are going high 12, mid 13 in this range when boost is like 3-8 psi in 3200RPM range in highway crusing/accel.

Thanks, I've update the load compensation table, and as expected - it seems a lot better but not 100% (just dumping in extra fuel at those revs/pressures), but going to replace the fuel rails, as I suspect there is a resonance there, I'll look to post a big write up on my findings around the resonance (once I've changed the rails, and done a full set of pressure testing etc), its quite interesting (including issues with current solutions for it).