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Eric, I have a 2007 suburban with a 5.3L when I hook the scan tool up to read live data, I’m getting no readings on the fuel trims, they are staying at 0 even if I accelerate. I’ve got a code of p0304, which it is skipping on no.4 cylinder, and it had code p0171 and p0174 lean on bank 1 and bank 2, we found the 2 vacuum leaks and repaired those but still no readings for fuel trim, what could be the issue?
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Check to see if is it going out of closed loop when you scan it and/or if it is stuck in open loop when you see 0 fuel trim…
What are the B1S1 and B2S1 reporting?
-Karl
Some cheapie scan tools are not capable of reading all the data supplied. My cheapie only shows o2 and fuel trims for 1 o2 sensor. My van has 3 sensors.
When I use the good scanner at work it shows 3 sensors and fuel trims.
My b1s1 and b2s1 readings are staying lean around.25 but when you accelerate they will read around .800-.900
What you should see when it closed loop is a switching from rich to lean on the primary sensors. It may be that your scan tool is too slow to pick up on the switching or there is some other issue. You might see if you can get your hands on a different scan tool just to see if there’s a difference in readings.
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