I have very slow primary (pre-cat) oxygen sensor readings on my 02' Corolla (2ZZ-GE, 141kW N/A).
While trying to investigate the issue, I repeated diagnostics frequently. Before every diagnostic attempt, I fully warmed the engine and raced it @ 2500 RPM for about two minutes.
Output of oxygen sensor readings:
- typical 0.1Hz, max. 0.2Hz @ idle (very slow and not constant)
- typical 0.5Hz, max. 0.8Hz @ 2500 RPM (extremely slow and not constant)
Additional and possibly related troubles:
- Erratic idle
- Engine speed follows oxygen sensor signal
- LTFT -15% at @ idle and about 0% on next minimal TPS reading
I have tried the following:
- changed to a new OEM oxygen sensor (primary, pre-cat).
- changed to a new OEM MAF sensor.
- changed to a new OEM PCV valve.
- changed to a new set of spark plugs.
- changed to a set of used, low millage and cleaned OEM fuel injectors.
- cleaned throttle body and idle air control valve.
- checked VVTL-i (lift) valve and filter. Working and perfectly clean.
- checked for intake air leaks. No were found.
- checked for exhaust air leaks. No audible/evident leaks were found.
- reset ECU.
No success at all. What else can I try? Thanks :)