High mileage with high LTFT's
03-09-22, 08:29 PM
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High mileage with high LTFT's
I have a 98 GS300 with 305,000 miles that runs great but my long term fuel trims are running high at idle. Bank 1 will be +25 and bank 2 +27. Short terms are running normal. I do NOT have a check engine light. The numbers have been consistent over the last few years. The long terms come way down if bringing the RPM up past idle it looks better at both banks at around +14 LTFT. I have smoke tested for leaks and found a few very minor ones that I also fixed those with no change. I have replaced the MASS airflow with a OEM with no change as well. I do not have any major blow by. I have decided to just leave well enough alone since I don't have a check engine lights for a lean condition (YET). Will a extreme high mileage engine have high LTFT's? Thanks for any insight!
03-18-22, 05:31 PM
#2
Not normal for a high mileage car to have high LTFT With positive LTFT and fixing any air leaks I would clean your maf.
Basically since it's probably not leaking air we should be looking at the critical engine sensors. A slight miss even imperceivable without tools can show lean on the oxygen sensor.
The maf will just show the ecu skewed data both of which would mess with your LTFT.
If the LTFT were considerably different between the two banks I would suspect spark plugs. It's something affecting both banks
Basically since it's probably not leaking air we should be looking at the critical engine sensors. A slight miss even imperceivable without tools can show lean on the oxygen sensor.
The maf will just show the ecu skewed data both of which would mess with your LTFT.
If the LTFT were considerably different between the two banks I would suspect spark plugs. It's something affecting both banks
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