P0171: System too Lean (Bank 1) need help
01-28-2011, 12:50 PM
#48
I'm an ASE master tech, also L1 advanced engine performance certified. Ohio E-check certified. Owned my own shop 23+ years, own 5 scan tools, subscribe to Alldata & the International Automotive Technicians Network. I know I'm bragging but also showing I'm old. $100 says I can solve it in 1 hour. Oh, and I spray carb. cleaner too.
07-12-2012, 06:17 AM
#54
10 Second Club
10-26-2012, 05:52 PM
#55
Well I passed emissions the other week. Any way I took the intake off today could not see any vacuum leaks or cracked hoses. I replaced all intake gaskets and fuel injector o rings.
Go figure I took a hot lap down the road ran it hard came back in the driveway and code came back!
Go figure I took a hot lap down the road ran it hard came back in the driveway and code came back!
10-26-2012, 05:55 PM
#56
You need to look at O2 data for bank 1. At idle it should at times go over 800 mv and under 200 mv. If it doesn't go over 800mv try to force it by driving WOT. Because there is no bank 2 code (P0174) I would assume you will see bank 2 go over 800 mv. If it does not go over 800 mv at WOT and bank 2 does it is most likely an O2 sensor. If it does go over 800 mv when loaded but not at idle it probably has a vacuum leak.
Guess I will have to buy a tool to look at the 02 data. This will be my next step. Of course it would be cheaper to buy new 02 sensors. I wonder if I could have a crack in the intake or head? I am not going to give up yet.
11-14-2012, 11:02 AM
#57
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Well Ive done all I can think of. I have a 2001 Silverado. 5.3. 215000miles. It started a few months ago. O2 sensors. Replace one then another one Replaced all 4. Then catalyst code. Replace y pipe with two new cat converters. Still bank 1 lean condition 02 sensor low volts. Mulit cylinder misfire. Replaced fuel filter fuel pump. Wires Plugs. Cleaned MAF sensor MAP sensor. Got a crank sensor code. Replaced that. I figured with that many miles these things should be replaced. I bought the truck new and plan on keeping it for awhile. Now the truck runs strong really nice. But still get the Bank 1 lean condition, 02 Bank 1 sensor 1 low volts multi cylinder misfire Bank 1
. The truck runs ok but if you hold it about 2000 it will miss like crazy but straighten out past that and idles ok. Did the seafoam and other injector treatments. Looked for vacum leaks found none. Traced the wire from o2 sensors didnt see any problems and checked all fuses. So do I have to wave a black rooster over my head in a grave yard at midnight to get this thing to run right. Ive done everything else.
. The truck runs ok but if you hold it about 2000 it will miss like crazy but straighten out past that and idles ok. Did the seafoam and other injector treatments. Looked for vacum leaks found none. Traced the wire from o2 sensors didnt see any problems and checked all fuses. So do I have to wave a black rooster over my head in a grave yard at midnight to get this thing to run right. Ive done everything else.
Last edited by 69duke; 11-14-2012 at 11:08 AM.
11-14-2012, 12:36 PM
#58
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Pretty simple really, hook up a scanner and look at the fuel trims. If they are high you know something needs attention on that bank. Next look at the 02 sensor readings and start looking at the obvious 1st. If both banks are lean check the fuel pressure and fuel system, if its only one bank could be anything from a vacuum leak to a clogged injector to a exhaust leak. Sometimes high mileage vechicles have odd problems, look for frayed wires or bad connections etc.
11-15-2012, 11:14 AM
#59
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Ok thanks. Ive been all over the engine for vacuum leaks. Have changed all 4 o2 sensors because when this started it was giving me o2 sensor low volts, no contact so I replaced them also both cat converters. New Exhaust all welded no leaks. Only bank 1 lean condition. and random cylinder misfire. with o2 sensor 1 on bank 1 low volts. I checked the volts and have .04 I think that was what I saw on here as normal. Traced all the wires from the o2 sensors to the top of the transmission to the firewall and then into the fuse box on the driver side fender well. All fuses are ok. Put new wires and new iridium plugs. Only think I havent checked is fuel injectors. It runs strong and sometimes the check engine light will flash but not come on then it goes off. Also replaced the MAF sensor. I know it seems like Im just throwin money at this thing and I am. The OBD instrument is giving me these codes so I go with it. I am hard headed and and old from Missouri so Im stubborn at a mule. guess Ill have to give up and go to Chevy and let them check it out. I also replaced the crankshaft position sensor. that may be my problem I intend to keep the truck Ive had it since new. .Oh and "get the hell off my lawn" practicing for when the neighbor hood kids start comin around LOL
Last edited by 69duke; 11-15-2012 at 11:18 AM. Reason: Repeat info