I have a 2005 Toyota Sienna with 197,000 miles. It's running fine but the check engine light recently came on with code P0174. I cleaned the MAF sensor but that didn't change anything. When I look at the live data with my scan tool both banks 1 and 2 are showing a long term fuel trim of over 20%. All the other data looks normal as far as I can tell. Any idea what I should do next?
Take a picture/screenshot of the spreadsheet & upload it to a host such as imgur/postimages. Then paste the direct link here.
After further investigation I found when I spray the Intake Air Control Valve actuator shaft with carb cleaner the short term fuel trim drops significantly beyond what one would expect from random variation. I also found a TSB documenting a problem in this area. The solution is to replace the Intake Air Control Valve but that's a $177 part and it looks like a pain in the rear to replace. My plan is to seal up around the shaft with RTV and disconnect and plug the vacuum line thus disabling the Intake Air Control Valve. I'll probably end up losing a little torque at the low end or hp at the high end, not sure which. But this is an old car that we mainly use for hauling and work. I bet I don't even notice a difference but if I do and it bothers me I can always replace the part later.
Here's a link to the TSB: https://discountconverter.com/tech-tips/news_page.cfm?Key=catalytic_converter-&News=240
I just road tested the van and the short term fuel trim looks great. The long term fuel trim dropped from over 20 to around 10. This may be just residual since I didn't disconnect the battery to reset everything because I didn't want to lose my radio presets. As far as drivability, I didn't notice any difference. Same power, torque and everything although it's probably hard to detect the absence of a few hp especially when one is not racing or pushing it hard. I consider this fix an unqualified success. Yah!
Even though you're only throwing a lean code on one cylinder bank you're running really lean on both banks.
I'd suspect it's time for a new fuel pump.
You can check your fuel pressure to confirm. I don't think you have a Schrader valve on your fuel rail so it takes a little longer. There's youtubes on how to hook up a fuel pressure gauge to a Toyota that doesn't have a Schrader valve. It's easy.
Thanks, I'll check the fuel pump. The only other thing I can think of is an intake leak. I'll check that as well. Do you have any idea which one is more likely?
Look at the fuel trims at idle and then hold the engine at around 3,000 rpms
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Give it a little time to see if the Short Term Fuel trims start to go Negative
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If the positive fuel trims go down at higher rpms it points to a vacuum leak. If they don't or get worse, it point's to a fuel starvation problem
Thanks, that makes a lot of sense. The fuel trim does go down when rpm's increase, therefore, I'll check for a vacuum leak first. Also, it has no problem starting quickly. It never requires a lot of cranking. I believe starting difficulty is a symptom of a fuel pump problem and it's not present on my van.
Well I took some parts off and checked for a vacuum leak but nothing obvious stuck out. I looked at the rubber parts because I thought those would be the most likely to crack and leak but they looked good. Then I sprayed some carburetor cleaner around different areas of the intake system and had my wife check the fuel trims. Long term fuel trim showed no change, short term did show some changes but it was really hard to tell what it corresponded to. Anyway, I think I'll drive it again, record the data and post it here to see if that gives people any clues.
I drove around today and recorded some data with my scan tool. Here it is:
Parameter/Frame,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,21,22,23,24,25,26,27,28,29,30,31,32,33,34,35,36,37,38,39,40,41,42,43,44,45
DTC_CNT,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0
FUELSYS1,CL,OL-Drive,CL,CL,CL,CL,CL,CL,CL,CL,CL,CL,CL,CL,CL,CL,CL,CL,CL,CL,CL,CL,CL,CL,CL,CL,CL,CL,CL,CL,CL,CL,CL,CL,CL,CL,CL,CL,CL,CL,OL-Drive,OL-Drive,OL-Drive,CL,CL
FUELSYS2,CL,OL-Drive,CL,CL,CL,CL,CL,CL,CL,CL,CL,CL,CL,CL,CL,CL,CL,CL,CL,CL,CL,CL,CL,CL,CL,CL,CL,CL,CL,CL,CL,CL,CL,CL,CL,CL,CL,CL,CL,CL,OL-Drive,OL-Drive,OL-Drive,CL,CL
LOAD_PCT(%),59.6,9.8,18.4,14.9,69.8,73.7,63.5,62,41.6,38.8,35.3,45.9,53.7,42,68.6,55.7,25.1,48.2,45.9,39.2,45.1,50.2,47.5,44.3,42.4,44.7,45.5,47.1,38.8,42.4,56.5,60.8,47.8,51.8,50.6,53.7,54.9,52.5,45.9,51,11,10.6,11.4,12.5,15.7
ECT(°C),79,79,78,78,78,78,78,79,79,80,80,80,80,80,80,80,80,80,79,79,79,79,80,80,79,79,79,79,79,79,79,79,79,79,79,79,79,79,80,80,80,80,80,80,80
SHRTFT1(%),0.8,0,-10.2,-6.3,-3.9,-3.9,-6.3,-3.9,3.9,2.3,3.1,1.6,-0.8,0,-3.9,3.1,5.5,1.6,0.8,2.3,0.8,-1.6,-0.8,0.8,-0.8,0.8,1.6,-0.8,-0.8,2.3,-1.6,-3.1,0.8,0.8,2.3,0.8,0,0,0.8,0.8,0,0,0,-8.6,-10.2
LONGFT1(%),7,20.3,20.3,20.3,7.8,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,20.3,20.3,20.3,20.3,20.3
SHRTFT2(%),-0.8,0,-7,-3.1,-0.8,-3.1,-4.7,-3.9,0.8,2.3,1.6,-0.8,-3.1,2.3,-2.3,-9.4,2.3,-2.3,2.3,2.3,-1.6,-2.3,-0.8,0,1.6,-1.6,-1.6,-1.6,0.8,1.6,-2.3,-0.8,2.3,0.8,0.8,-0.8,-0.8,-0.8,2.3,0,0,0,0,-4.7,-10.2
LONGFT2(%),7.8,20.3,20.3,20.3,8.6,8.6,8.6,8.6,7,6.3,7,7.8,8.6,8.6,8.6,7.8,6.3,8.6,8.6,7,8.6,8.6,8.6,8.6,7.8,8.6,8.6,8.6,7,8.6,8.6,8.6,8.6,8.6,8.6,8.6,8.6,8.6,8.6,8.6,20.3,20.3,20.3,20.3,20.3
RPM(rpm),3810,1513,876,944,4180,4023,3353,2482,1758,1764,1755,1755,1759,1784,2840,2920,1991,2006,2013,2007,2000,2007,2006,2010,2007,2007,2004,2012,2015,1998,2269,2250,2012,2007,2013,2011,2009,2010,2012,1997,1386,1718,1655,1558,1164
VSS(km/h),28,45,31,11,29,61,81,93,93,94,93,93,93,95,101,109,107,106,107,108,108,107,108,107,107,107,108,108,107,107,106,108,107,107,107,107,107,108,107,107,101,92,88,84,65
SPARKADV(°),22.5,34.5,19,16,17.5,18.5,23.5,45,25.5,30.5,34.5,20,17.5,17.5,17.5,44.5,27.5,22.5,29.5,31,23.5,22.5,26,28,28,25.5,26,25.5,33.5,23.5,17.5,19.5,23,21.5,21.5,20,18.5,21,25.5,30,28,34.5,34,32,23.5
IAT(°C),21,21,20,20,20,18,17,16,16,17,17,17,17,17,17,16,16,16,17,17,17,16,16,16,16,16,16,16,16,16,16,16,16,16,16,16,16,16,16,16,16,16,16,17,17
MAF(g/s),91.73,6.73,5.48,24.54,104.76,95.25,70.4,14.01,25.26,21.39,22.43,29.96,30.92,41.51,64.85,15.18,30.21,32.5,28.53,27.34,31.68,32.07,30.59,27.65,29.34,30.03,30.85,30.71,25.89,33.54,46.9,39.71,32.9,35.32,35.04,36.92,36.71,33.46,30.2,10.48,5.71,6.32,6.76,6.95,6.95
TP(%),36.5,16.9,16.1,25.9,42.7,44.3,36.9,20.4,24.3,22.7,23.1,28.2,27.8,37.6,43.5,19.6,26.7,27.8,25.5,25.1,28.2,27.8,26.7,25.5,26.3,26.7,27.1,26.7,24.3,29.4,36.5,29.4,27.8,29.4,29.8,31.4,31.4,28.2,26.7,18,16.5,16.5,16.9,16.9,16.9
O2SLOC,B1S12--B2S12--,B1S12--B2S12--,B1S12--B2S12--,B1S12--B2S12--,B1S12--B2S12--,B1S12--B2S12--,B1S12--B2S12--,B1S12--B2S12--,B1S12--B2S12--,B1S12--B2S12--,B1S12--B2S12--,B1S12--B2S12--,B1S12--B2S12--,B1S12--B2S12--,B1S12--B2S12--,B1S12--B2S12--,B1S12--B2S12--,B1S12--B2S12--,B1S12--B2S12--,B1S12--B2S12--,B1S12--B2S12--,B1S12--B2S12--,B1S12--B2S12--,B1S12--B2S12--,B1S12--B2S12--,B1S12--B2S12--,B1S12--B2S12--,B1S12--B2S12--,B1S12--B2S12--,B1S12--B2S12--,B1S12--B2S12--,B1S12--B2S12--,B1S12--B2S12--,B1S12--B2S12--,B1S12--B2S12--,B1S12--B2S12--,B1S12--B2S12--,B1S12--B2S12--,B1S12--B2S12--,B1S12--B2S12--,B1S12--B2S12--,B1S12--B2S12--,B1S12--B2S12--,B1S12--B2S12--,B1S12--B2S12--
O2B1S2(V),0.445,0.075,0.585,0.115,0.21,0.465,0.35,0.7,0.485,0.425,0.425,0.565,0.605,0.625,0.565,0.425,0.23,0.605,0.605,0.605,0.625,0.625,0.605,0.545,0.585,0.545,0.585,0.605,0.525,0.625,0.64,0.465,0.525,0.565,0.625,0.585,0.64,0.565,0.565,0.545,0,0.935,0.875,0.8,0.78
SHRTFTB1S2(%),N/A,N/A,N/A,N/A,N/A,N/A,N/A,N/A,N/A,N/A,N/A,N/A,N/A,N/A,N/A,N/A,N/A,N/A,N/A,N/A,N/A,N/A,N/A,N/A,N/A,N/A,N/A,N/A,N/A,N/A,N/A,N/A,N/A,N/A,N/A,N/A,N/A,N/A,N/A,N/A,N/A,N/A,N/A,N/A,N/A
O2B2S2(V),0.78,0.075,0.155,0.66,0.78,0.565,0.505,0.76,0.625,0.485,0.445,0.605,0.625,0.64,0.605,0.585,0.525,0.565,0.505,0.525,0.625,0.605,0.625,0.605,0.605,0.585,0.625,0.625,0.485,0.625,0.68,0.605,0.525,0.625,0.625,0.605,0.625,0.565,0.585,0.525,0,0.935,0.855,0.82,0.8
SHRTFTB2S2(%),99.2,99.2,99.2,99.2,99.2,99.2,99.2,99.2,99.2,99.2,99.2,99.2,99.2,99.2,99.2,99.2,99.2,99.2,99.2,99.2,99.2,99.2,99.2,99.2,99.2,99.2,99.2,99.2,99.2,99.2,99.2,99.2,99.2,99.2,99.2,99.2,99.2,99.2,99.2,99.2,99.2,99.2,99.2,99.2,99.2
OBDSUP,OBDII,OBDII,OBDII,OBDII,OBDII,OBDII,OBDII,OBDII,OBDII,OBDII,OBDII,OBDII,OBDII,OBDII,OBDII,OBDII,OBDII,OBDII,OBDII,OBDII,OBDII,OBDII,OBDII,OBDII,OBDII,OBDII,OBDII,OBDII,OBDII,OBDII,OBDII,OBDII,OBDII,OBDII,OBDII,OBDII,OBDII,OBDII,OBDII,OBDII,OBDII,OBDII,OBDII,OBDII,OBDII
EQ_RATB1S1,0.865,0.998,0.996,0.986,1.064,1.011,1.012,1.021,1.009,0.996,1.004,0.991,0.996,1.019,1.009,1.016,0.998,1.006,1.005,1.015,1.009,1.003,1.005,1.011,1.008,0.995,1.005,1.007,1.002,0.995,0.992,1.013,0.98,0.999,1.003,1.001,1.007,1.012,1.014,0.996,1.234,0.823,1.018,0.998,1.011
O2B1S1(V),2.329,3.169,3.274,3.252,3.487,3.309,3.359,3.402,3.3,3.268,3.28,3.25,3.272,3.368,3.33,3.375,3.266,3.321,3.324,3.338,3.329,3.279,3.302,3.349,3.307,3.264,3.31,3.314,3.298,3.264,3.255,3.316,3.211,3.291,3.283,3.289,3.308,3.303,3.333,3.135,4.997,1.941,3.357,3.3,3.354
EQ_RATB2S1,0.823,0.97,0.947,1.009,1.001,0.983,0.977,0.998,0.997,1.004,0.997,1.006,1.012,0.98,0.99,1.035,0.987,1.001,1.004,0.989,0.996,0.995,0.994,1.012,0.98,1.013,0.994,1.001,0.995,0.991,1,0.982,1.004,1.004,0.993,1.004,1.015,1,0.987,0.892,1.234,0.862,1.002,1.003,1.016
O2B2S1(V),1.697,2.983,2.995,3.311,3.228,3.089,3.087,3.199,3.239,3.298,3.242,3.308,3.348,3.066,3.218,3.415,3.214,3.277,3.3287,3.226,3.26,3.276,3.248,3.297,3.175,3.358,3.231,3.283,3.232,3.249,3.26,3.157,3.288,3.292,3.231,3.298,3.316,3.263,3.2,2.464,4.997,2.233,3.277,3.288,3.358
It might be hard to read but I couldn't see a way to attached a spreadsheet. Anyway, you can see the fuel trim going high when the rpm's are lower. It's most pronounced at idle.
Unsure about that certain car but is ur upstream O2 sensors also control the afr? What's ur afr at idle? Just had to replace my bank 2 upstream on my gt500 as it was running up to 20% lean while doing a datalog for my new tune. Even at 20% it threw no code.
