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LTFT on 100% stock standard car

Practical Reflash Tuning

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Hey guys,

I plugged in my obd2 scan tool on my 2019 Suzuki Swift Hybrid just out of curiosity to have a look at what parameters were available and noticed something a bit odd.

The car is 100% stock standard just the way it left Suzuki Japan, yet the LTFT is sitting at -11.7% at idle and cruise meaning the engine is running quite rich. The car is extremely low mileage only 9000kms, any insight on why the ecu is having to trim this much constantly on a stock standard car?


Why would the car be running rich if there are fuel trims? Do you mean the OEM tune seems to be richer than you expect?

Perhaps there is a manifold pressure leak, dirty MAF sensor, or clogged air filter. Was the car at full warmed up conditions when you monitored the fuel trims. How does it change after a highspeed blast down the road (ie, Road Dyno Ramp Run)

Yes the trims are obviously bringing it back to stoich so its nat actually running rich (that is the job of the trims after all) but without them it means the engine is rich hence the ecu having to pull that much fuel out while in closed loop.

The trim held from cold start even straight through to operating temp.

I will look into the possibilities you mentioned.

At wot it does exactly as expected, it carries forward the same LTFT in open loop

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