What are normal MAF, Fuel Trim, O2 Readings for 3.0i
What are normal reading from these sensors using a tool the Torque Pro? I'm trying to diagnose a P1092 code. A local Indy shop said I needed a new MAF and new primary oxygen sensors. They also said my MAF went bad because I'm running a K&N and they got BMW code for fuel trim errors. They also performed a smoke test and found no leaks.
From the report: TECHNICIAN NOTES:Faults stored for bank 1 oxygen sensor trimming. Multiplicative values are extremely high. Performed intake system smoke test and found no leaks. Found K&N air filter to be installed on vehicle. Recommend replacement of air mass meter and both primary o2 sensors with a new OE air filter at this time. When I talked to Bavarian Auto they said MAF was unlikely and said I should replace the CCV / oil separator. I have a 2005 with 109K miles - the rub is that the car runs perfectly just a stupid light. Yesterday I replaced the primary O2, new plugs, cleaned the MAF with MAF cleaner. As most know, the CCV rebuild is rather involved - not the most fun job for winter time - for now, I'm holding off or may need to get a shop to do it - I would like to replace it once spring hits since it is way overdue according to what I've read. A day or so before I got a light, I did hear a strange whistling sound on a cold day - another possible CCV clue. After the tune-up, the car seems even more smooth - but it's hard to tell - a bit like how the car seems faster after washing and waxing all day ;) The easy next step, would be to replace the MAF and hope for the best - but that approach rarely works. If I look at my MAF values reported in Torque, the graph makes sense to me - gradual smooth rise off idle, drops with gear change, then ramps, then drops if I let off the gas. The display lags by a second or two, but I assume that is due to the ODBII, Bluetooth, app, display. I wish I had some baseline measures - I would appreciate if folks could post their readings for cars with no codes etc Sent from my iPad using Tapatalk |
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Here is plot of my MAF vs RPM - all looks normal to me:
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Here is a plot comparing the short term fuel trims on each bank vs rpm:
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This compares my Short Term, Long Term Fuel Trims and O2 on bank 2
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This compares the post-cat O2 sensors
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Here is a plot of the pre-cat O2 sensors on bank 1 & 2 - brand new Bosch
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Either your cats needs to be replaced or you need to replace both post cat 02 sensors. The graph for a post car 02 sensor should be almost a horizontal lines once the engine is in close loop. The graph that you show have the post cat 02 sensors bouncing up and down.
https://xoutpost.com/attachments/x5-...-3-0i-o2-2.jpg Here's a link to Scannerdanner video on determining a bad cat with the use of the 02 sensors pre and post cat. https://www.youtube.com/watch?v=vyVnhCIMDnw |
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I was also surprised by the irregularity of the secondary O2's - I need to replace them since they are original, but I think they are working properly. Since I never took a baseline measurement of my X5 / didn't really know what working O2 signals look like, I also grabbed the same data (using the same tool - TorquePro) from my wife's CX-9. The CX-9 run is much longer - so the cat's likely got much warmer. I was expecting a smooth line, what I got instead was something that looked a lot like my X5 – but it seems to then smooth out a bit – still with some good spikes.
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The big difference I see between my X5 and the CX-9 is the LT fuel trim. The X-5 is sitting at 7-8 %. The CX-9 is sitting around 0 - with a lot of adjustment going on. Would love to see data on a X-5 with no codes / running great - hence the reason for the thread.
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The engine needs to be in Close Loop before the 02 sensors come into play. When the engine is running in Open loop it is following a predetermine default engine management values.
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