P0171 & P0174

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Rich_007

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2001 5.4 P0171 & P0174
These codes are keeping me from passing my inspection for reg renew. I can reset them and they show up as pending in about 30 miles and light the CEL after about 100 miles. Prob is if they show up as pending within 30-40 miles after a reset: computer says "not avail" to the inspection guy, even though the CEL isn't lit yet. Looked around for obvious vacuum leak and cant find any. Mechanic said he needs to smoke check it and go from there. Was just wondering if based on the pics from my OBD scanner if it points to anything particular. Had a fuel pump put in last year. Its an old wagon with over a quarter million miles on it. Was thinking since I got a good mechanic I trust and with that age, all the hoses etc... could be suspect, I would let him handle it instead of me shotgunning it and replacing all the hoses before I got done and still not find the problem. I am in an apartment, so I would have to do all the maint outside in the parking lot (which the mgmt would complain about). If I knew what it was, (anything short of ripping the intake off) I would do myself in the parking lot.121518 obd.jpg
 

1955moose

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Rich, we've got another member going through same deal. Smoking the intake is the best and fastest way to find your intake leak. In some cases it's just the rubber elbow coming off the pcv valve, but most of the time it's more involved. Your kinda limited living in the apartment. Your mechanic will more than likely find multiple hoses that are rotted and leaking, causing your intake leak. 17 years, and a bunch of heat, moisture, they get brittle.

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Tonyray

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I see you replaced the pump last year. I would check for vacuum leaks. The PVC hose going to the Throttle body goes bad and is hard to see.
 
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Petesexpy

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Same problem. turned out intake manifold gasket and $500... if both banks show lean, it's most likely a manifold gasket.
 
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Rich_007

Rich_007

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Update: dropped it off at mechanic today. He will smoke the intake and see.
Hopefully I get an answer tomorrow. If its the intake (which it probably is), I will have to decide if I want to fix it or just keep the money and get another vehicle. The age and mileage have lowered my pain threshold how much I will spend on it.
 
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Rich_007

Rich_007

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update: mechanic called and said he wanted to replace EGR and PCV. Said something about that's the only place smoke came out. Not exactly sure, I was sleeping when he called. I said do it. That was about 1:00 this afternoon and I haven't heard back yet. Hope he isn't shotgunning. Hopefully find out tomorrow.
If it was a cracked intake: the smoke test would have shown that, right??? keeping fingers crossed here.
 

Petesexpy

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update: mechanic called and said he wanted to replace EGR and PCV. Said something about that's the only place smoke came out. Not exactly sure, I was sleeping when he called. I said do it. That was about 1:00 this afternoon and I haven't heard back yet. Hope he isn't shotgunning. Hopefully find out tomorrow.
If it was a cracked intake: the smoke test would have shown that, right??? keeping fingers crossed here.
Yes, smoke test would show intake manifold gasket. PCV likely means a leaky hoce. EGR is possible, but My bet is still on intake manifold gasket. Keep us posted.
 

1955moose

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Egr valve can be tested with a vacuum pump. He's covering his butt by changing egr valve and gasket. But who knows. Ask for old parts back, it's your right. Pcv valves rarely fail, occasionally they get stuck, but it's cheap enough. Make sure he changes all the hoses and elbows going up to the valve. You'll find out if that's all it was.

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Petesexpy

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Egr valve can be tested with a vacuum pump. He's covering his butt by changing egr valve and gasket. But who knows. Ask for old parts back, it's your right. Pcv valves rarely fail, occasionally they get stuck, but it's cheap enough. Make sure he changes all the hoses and elbows going up to the valve. You'll find out if that's all it was.

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I agree. It's more likely vacuum hoses are leaking.
 
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