P0172 runing rich on bank one issue. 2005 matrix, 1.8l 4cyl (FIXED)
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I would start testing the fuel delivery. Check fuel pressure and fuel regulator. I believe psi should be 44-50 at idle.
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If you pulled off PCV, you are forcing air bypass Maf, so readings should go down, since air passing through Maf sensor is reduced.
My little experience tells me at idle minimum reading should be above 1.8gr/sec (Don´t you think scannerJhon?. could be you know that engine better than me (i don´t know it at all). I Suggest you unplug Maf sensor at idle and see where fuel trims go (so that you can rule Maf out (only for idle condition)
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If Maf sensor is bad (or dirty but i don´t think is the case), you should see fuel trims changing (STFT going to +28% (or the opposite LTFT value). If fuel trims don´t change after some minutes, i would say Maf is not the root cause.
Rich mixture could be caused by:
*Leaking injectors (you can unplug one at a time and watch fuel trims PID´s)
*Fuel pressure too high
*PCM is not "seing" the real operating conditions (load (Maf or Map), ECT, IAT)
*Contaminated oil (you should not smell too much fuel on it)
*Fuel vapors coming to intake manifold from fuel tank through evap valve (purge valve canister). You can unplug evap hose at idle and watch fuel trims PID´s
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You can test O2 sensor by making a vacuum leak (voltage going down to 0.2 or below) and by enriching mixture (adding some gas) and seing O2 sensor voltage going up. There is another test to check O2 sensor agging (which depends on respond timing), but i think we need to check first sensor activity.
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So then if logic and design dictates that maf readings should go down......why then, did they infact go up?Hi guys, There is a detail which doesn´t make too much sense to me.
If you pulled off PCV, you are forcing air bypass Maf, so readings should go down, since air passing through Maf sensor is reduced.
My little experience tells me at idle minimum reading should be above 1.8gr/sec (Don´t you think scannerJhon?. could be you know that engine better than me (i don´t know it at all). I Suggest you unplug Maf sensor at idle and see where fuel trims go (so that you can rule Maf out (only for idle condition)
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G/S should be equal to engine L. 1.4g/s instead of 1.8g/s I did not think was that big of a problem for 20 or higher rich condition.
I am leaning to the fuel problem.
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Anyway, let´s wait for tests from John side, hopping they give us a direction. Thanks
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- juergen.scholl
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So then if logic and design dictates that maf readings should go down......why then, did they infact go up?Hi guys, There is a detail which doesn´t make too much sense to me.
If you pulled off PCV, you are forcing air bypass Maf, so readings should go down, since air passing through Maf sensor is reduced.
My little experience tells me at idle minimum reading should be above 1.8gr/sec (Don´t you think scannerJhon?. could be you know that engine better than me (i don´t know it at all). I Suggest you unplug Maf sensor at idle and see where fuel trims go (so that you can rule Maf out (only for idle condition)
This may shed some light on why the MAF reading can go up when creating a vacuum leak:
www.scannerdanner.com/forum/scannerdanne...ith-vacuum-leak.html
How are the fuel trims behaving at different rpm and load conditions??
The scan data shows 0% STFT, probably the ecm entered open loop mode due to the disconnected MAF?
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MAF is connected and codes were cleared.
I must also mention that yesterday when i was testing with the maf off I took another look at my vacuum lines and noticed quite a few cracks right at the ends, some of them weren't holding air when i blew through them, so as a temp fix until i could get some tubing I wrapped up the ends with some electrical tape nice and tight and I have to say that my G/S rose from that 1.2 - 1.4 that i reported earlier, to between 1.8 - 2.0. I'm going to attach some recorded data as well as some live data. Based on what I'm seeing here I'm starting to lean more to what scannerjohn said.....for me to look in the area of fuel.....furthermore, I'm starting to think that MAF isn't my problem but the O2 is still seeing a rich condition so that tells me that combustion isn't being completed.....I'm thinking I need to put my focus in the area AFTER maf and BEFORE O2S1 which would mean plugs, coil packs, and fuel injectors. Let me know what your brilliant minds come up with as my solution.
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Juergen.scholl. That make sense to me. you should see rpm going down for few seconds once you make the vacuum leak and then IAC opening to compensate rpm. Thanks.This may shed some light on why the MAF reading can go up when creating a vacuum leak:
www.scannerdanner.com/forum/scannerdanne...ith-vacuum-leak.html
John1920. I guess you have found root cause for Maf readings (nice). I would say now we don´t need to keep an eye on Maf as a problem now.
As i understand, LTFT is affected no matter PCM is on closed loop or open loop, so by unplugging Maf, LTFT on -35% is still telling us there is too much fuel
What the other tests are telling me is the amount of fuel that is leftover at idle, is becoming diluted at higher rpm (fuel trims going to less negative and O2S2 going to little leaner).
BTW. it would be great to have O2S1 readings instead of O2S2, since upstream sensor is not affected directly by CAT. Also fuel tank pressure and Map.
I´ll be pending on the other tests we suggested because we have not found root cause for excess of fuel.
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O2S2: When CAT is cold, you can see a voltage similary to O2S1 because CAT is not able to use oxygen passing through it. Once CAT is hot, you can see a steady voltage (depending on CAT efficiency between 0.4v to 0.6v). That steady voltage means CAT is using oxygen to convert CO into CO2 and HC into H2O. That voltage also means absence of oxygen (or at least there is less oxygen than present in atmospheric air).
If you have more oxygen than CAT can storage, It passes through CAT and O2S2 voltage drops.
About O2S1 screenshot, I´m not seing it bouncing and based on time you recorded, it should jumped into closed loop. Have you tested it?
Test O2 circuit integrity by unpluging the sensor and watching PID (should be 0.45v). Also you can check O2 sensor (plugged) making a vacuum leak and watching voltage droping.
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So no more scans to review because I believe I solved the P0172. I took the advice of looking into the area of fuel and cleaned up my old injectors....thank goodness I make the habit of keeping old parts......I cleaned them, tested their spray pattern and nothing told me that they were bad, so my youngest daughter and I popped them back in and fuel trims started to fluctuate closer to stoichiometric. They are more on the leaner side than I would want but that's because I'm still waiting on a throttle body gasket to come in and I still need to change those vacuum lines that I had mentioned.....EVAP line to the intake and PCV hose. I'm sure after taking care of those my trims will be spot on.
Thanks, Scanner John for sticking your ground and pointing what you know. I was getting ready to replace a MAF that cost $300 where I am when all I need was to give my OEM injectors some lovin. Not sure if I had mentioned but I did put in some new injectors that I got off of amazon, it goes to show you....new isn't always good.
Finally! I went for a 30 min drive this morning and NO CODES. Thanks guys! really mean it
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