2004 Toyota Sienna P0171 and P0174. High LTFT under load

Hi Everyone,

My Toyota Sienna has < 10% Long Term Fuel Trims under idle conditions.
As soon as the engine RPMs start climbing, however, the LTFT starts climbing, before maxing out around 35.

The short term values go from -20 to +20.

After cleaning the MAF and noticing no difference, I ordered a new one.
There was also an exhaust leak that was fixed, but seemed to only lower the LTFT by about 5.

Now beginning to suspect a fuel issue. Waiting on the new MAF before doing anything else.

Thoughts on how to proceed from here?

Thanks,
Amit

One test you could do would be to measure the MAF g/s and Calculated Engine Load while going WOT all the way through first gear and into second. In your captures, it looks like you may have done a throttle snap or briefly accelerated. That's good, but not quite enough to nail down a potential air measurement issue.

If your results show good air measurement, then move towards a fuel delivery problem. If your results show low airflow, hurry up and wait for your MAF to arrive.