RTH supercharger bypass hose

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"Go on a living spree"
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Dec 4, 2012
greenville mi
I keep getting a code po171 on my 80. I have replaced the fuel filter, fuel pump, unhooked the charcoal canister, new O2 sensors, tested and cleaned injectors. I do have a cx racing header with deleted cats and a rear O2 sensor mod to fix po420. I have checked everything for leaks and have found one thing that concerns me.
The very short supercharger bypass hose looks to be possibly split. I cannot tell for sure if it is all the way through but it is definitely going. So to all of you SC gurus, do you think this would throw a po171 code for a lean condition? I know @landtank that you know this stuff very well so i would very much appreciate an opinion.
One other thing is if i clear the code cruising down the highway, it wont trip a code. If i do stop and go driving, it trips quickly.

Im leaving for Colorado (1200 miles) tomorrow and would love some input to posdibly get it fixed in the morning.

That kind of makes sense. The air has gone past the MAF and been metered. In stop and go conditions that portion of the intake is under vacuum so it would pull in unmetered air and run lean. I know that because I tried to replace my metal elbow there with a silicone one and it collapsed when idling.

When cruising you're probably boosting or at atmospheric so it will tend to lose air and run rich.
Any leak on the intake side post MAF can cause this code. If you have the ability to scan the OBDII system look at the LTFT value. First at idle and them while driving. In one of those states you should see the value exceed +20%. That is the trigger for that code. I think that if the idling value is over +20% then that hose is probably suspect.

If everything is near or over that threshold then look at FPR, FP relay, dirty MAF or even loose connectors at the MAF. I've seen the loose connectors at the MAF a couple of times.

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