Uploaded October 2025 | Updated September 2026, 3 weeks ago

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2001 Ford F-150 4.2L with Bank 1 running rich at -15% and Bank 2 running slightly lean at 10%. Many parts have been replaced before we got to this truck, including the cats. No real symptoms that we could feel initially except a little bit of a rough idle. Power loss on a test drive was questionable.

00:00 - at my brother shop
01:07 - initial view of O2 and Fuel Trim
03:50 - O2 heater current and signal looks poor on bank 1
05:44 - how to baseline test any O2 or AF sensor (full rich/full lean range)
10:00 - suspecting an O2 problem
12:16 - why I want to swap the upstream O2 sensors
17:17 - the dangers of O2 removal in the rust belt!
18:15 - why oxygen sensor "response time" is important
22:24 - data after swapping O2 sensors
25:33 - causes of negative trim on one bank and positive on the other
26:25 - relative compression sound test
27:01 - cylinder contribution test
27:56 - link to injector balance test video
How to identify injector flow problems (Toyota 1.8L) part 1
youtu.be/ZnFSUNjwDPQ?si=YfqlZeYKNxtaaSTK
28:15 - Rosedale Technical College mention
28:37 - picoscope and pressure transducer tests on the fuel rail mentioned
30:36 - the downside of filming live
31:18 - exhaust backpressure test
33:35 - how a restricted cat on one side can create a fuel trim imbalance
35:24 - SDP videos on backpressure testing with a scope
How to test for a plugged exhaust (picoscope & psi transducer)
youtu.be/kO91s0CoM_4?si=ybikhdmsE4uT8NOm
How to test for a plugged exhaust (picoscope and psi transducer) Part 2
youtu.be/YookV4zyQdU?si=R7gisfr5TxeWvsTG
37:17 - HC test in the cooling system for headgasket failure

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