Recently i got a CEL. Read it an it's a 171. possible vaccuum leak. or my exhaust leak has gotten bad enough? ever since i bought this thing i've had an exhaust leak. 12k miles and no problems with that though. now i've got a code 171 and my long term fuel trim is only at 1.5%.. that doesn't sound right. primary (first) 02 sensor is reading from .050 to .8 and bouncing back and forth. is this correct? i know it's supposed to bounce, but that much? i have checked for intake leaks with carb cleaner to no luck. PCV is new. possibly my exhaust leak is finally bad enough or is the sensor finally gone? 183k. i'm trying to sell this thing, too! i have a buyer lined up and all, but now is when it finally gives me trouble.. <img src="/forums/images/graemlins/frown.gif" alt="" />

I think that's the same code I was getting when the intake hose between the filter box and throttle body intake had some splits down in the corrugations. Couldn't see them until I pulled the hose and bent it a little. That leak caused a deviation in the air flow measured by the MAF sensor and the fuel/air ratio based on the O2 sensors. Any air leak in the intake between the MAF and the block will kick that code, though there can be other causes. That's an easy part to check...

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Here's the split hose. It was caused by the body lift stretching the old rubber...




And here's the fix: 2 silicone elbows, one metal coupling and a reducer plenty of length and the silicone will stay pliable for many years to come...

Hmmm. I will check mine. I sprayed carb cleaner everywhere and no idle fluctuations. The weird thing is thag from what I've read the cel isn't supposed to come on until it sees 23% difference in fuel trim. I'm only getting max 2%.. I monitored it on my way home last night for 55 miles. Heck, short term was at 0.0% when going up and down steep hills!! I just don't understand.

Strange... How are you monitoring your fuel values on the fly? I've tried it on my Sporty using an OBDII code reader. But it will only link up with ECU when the engine is running and the tranny is in park.

my friends' OBD2 scanner. pretty sure it's the exhaust manifold. looks like the back stud is broken. Also, i actually sold it anyways. <img src="/forums/images/graemlins/frown.gif" alt="" />

It's been fun guys. I'mma miss y'all. These are really neat trucks, but i needed the cash for my new "addition". Baby girl is going to be born in about two weeks!