How to Troubleshoot Negative Fuel Trim?

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How to Troubleshoot Negative Fuel Trim?

I have a 1zzfe engine in my car and Ive noticed that LTFT at idle is at -20%.

Im not sure if this is normal o r if theres an issue. If it needs to be diagnosed, where should I start? I would really appreciate any advice o r insights. Thanks!

Sajid Khan asked on 14 Feb 2023 11:37:49 am

1 Answer

6 views |

Sumaiya Akbar - on 16 Feb 2023 11:36:23 am

Its not surprising that your fuel economy is suffering, as the ECU is adding 20% more fuel than normal. Additionally, since your engine is burning oil.

its possible that this could slightly affect the AFR sensor. Its important to have a qualified mechanic diagnose this issue. Some things to look out for include changes in the trim value to negative at higher RPM, the health of the MAF sensor, and whether o r not it has been cleaned properly using carb cleaner.