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Thread: running too lean

  1. #1
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    running too lean

    Need some help as to why Im getting the po171 'running too lean' code after my install of a Spectre cold air intake kit. The setup was originally designed for 99-06 trucks, but they ammended their fitment schedule to allow for the nnbs trucks, with modifications. I know WHY Im getting a lean code, but Im surprised to see this issue pop up on such a minor mod. Is this intake tube really allowing THAT much more air into the engine, and if so, what do I need to do to fix this quickly, before my motor burns up? Is it possible that I need a tune to get my a/f back to normal, or am I looking at injector or fuel sender upgrades? Ive rarely heard of this problem on a CAI install, but I understand why it could happen. Just seems like such a generic upgrade to pull a code like this, already.
    Also, my truck ran kinda hot today in stop and go traffic. This truck has NEVER had a temp fluctuation before. Coolant temp jumped up to 220*, but when I cranked the heater it went right back down. Im afraid my motor is gonna fry if I dont get on top of this. Any suggestions?
    Last edited by Mang213; 08-16-2009 at 06:23 PM.

  2. #2
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    No way a CAI alone passes enough air to cause lean codes or hurt the engine. You have a leak or something not tight....the computer has at least +/-25% fuel delivery capability when operating as designed. Missing oil cap, dipstick, loose breather tube can all cause P0171.

  3. #3
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    thanks Nathan, you just cleared it up for me then. The Spectre kit isnt an exact fit for the nnbs trucks. Had to cut the intake tube down 2.5" and there is no bung for the breather tube. I havent drilled a hole for it yet, so that must be my issue. Any advice as to why my truck was running so hot today tho? It was over 95 degrees here, and I was in dead stopped traffic, but Ive never had a Silverado get hot on me before, and this thing just started going up quite quickly. Another breather tube issue, you think?

  4. #4
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    Not sure. It was 102 here and I had two AC units running and 5 people breathing hot air in mine and the coolant didn't top 190 and the trans stayed under 180 yesterday and today.

  5. #5
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    Well Im still waiting on my trans cooler, so we'll see how that goes. I suspect that the trans is helping to overheat my motor. I bought the 40k cooler, so Im assuming it'll be able to solve most of those issues.

  6. #6
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    the trans went up to 217 degrees again today, too, which was about where the motor was getting to when it started running hot

  7. #7
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    Quote Originally Posted by Mang213 View Post
    thanks Nathan, you just cleared it up for me then. The Spectre kit isnt an exact fit for the nnbs trucks. Had to cut the intake tube down 2.5" and there is no bung for the breather tube. I havent drilled a hole for it yet, so that must be my issue. Any advice as to why my truck was running so hot today tho? It was over 95 degrees here, and I was in dead stopped traffic, but Ive never had a Silverado get hot on me before, and this thing just started going up quite quickly. Another breather tube issue, you think?
    I just put a filter on my crank vent. I also had to cut it down 2.5".

    1969 Chevy RCLB C10 350/TH400 SOLD
    2007 Chevy RCSB 4.8 4x4 LS SOLD
    2008 Chevy RCSB 5.3 4x4 LT SOLD
    2010 Chevy CCSB 6.2 4x4 LT SOLD
    2005 GMC CCLB DRW 6.6 Duramax 4x4 191,000 and counting
    2013 FORD CCSB F350 6.7 Powerstroke 4x4


  8. #8
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    yeah I heard about these mods AFTER I did my truck yesterday. Anyhow, my check engine light went out, even tho I didnt clear my 'lean' code, and I still havent hooked up my breather tube

  9. #9
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    It's probably still in history and will return when the conditions are met to run and fail.

  10. #10
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    You most likely have a loose clamp. If you need pictures of my install, let me know.

    1969 Chevy RCLB C10 350/TH400 SOLD
    2007 Chevy RCSB 4.8 4x4 LS SOLD
    2008 Chevy RCSB 5.3 4x4 LT SOLD
    2010 Chevy CCSB 6.2 4x4 LT SOLD
    2005 GMC CCLB DRW 6.6 Duramax 4x4 191,000 and counting
    2013 FORD CCSB F350 6.7 Powerstroke 4x4


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