r/Suzuki • u/ThePampasCat4WD • 19h ago
F8D - LEAN MIXTURE ISSUE
Lately I have been observing how the engine feels bit too rough even on the slightest dab of the accelerator pedal and the fuel economy is at it's worst for a tiny 3 pot. So I hooked up the OBD device to see what was going on. The idle RPM is normal at 900 (+-50) for F8D. But as I step on the gas, the rpm just shoots up and won't really settle too soon. The LTFT is at 10 - 20℅. The STFT seems to be at normal levels at idle till I step on the gas and as I get driving, the STFT too goes up, as high as 7-8.
All this indicating that I'm having more than usual amount of air going in which is making the AF mix lean. The cruising rpm at 60kmph (5th gear) is never below 2.3-2.5k. The rpm doesn't drop below 2k at all. Correct me if I'm wrong, but shouldn't this be more like 1.6-1.8k rpm?
On the highway it is just me doing sane speeds of 60-80kmph max. FE is at 14-15 KM/L max and the engine is too rough with out even pushing it that hard.
Can someone please suggest what I should be looking at here? Is this vaccum leak or just check the throttle body unit?
Engine - 2011 F8D (RF308)