P0171-Bank1 Lean

[gdbford]

Called the auto parts stores and they led me down the most expensive path, replaced BOTH oxygen sensors - $120.00 wasted, code came back.
They then suggested the MASS AIRFLOW SENSOR - $100.00 to $180.00, I didn't buy it. I cleaned the one I have with electrical contact cleaner, cleared code, it came back. Went to AUTOZONE, had them suggest a vacuum leak, made sense. Sprayed QUICKSTART (ether) around the intake system. Got a rise in idle near the throttle body. Replaced the Throttle Body gasket ($15.00)& Intake Manifold gaskets ($30.00), cleared code, it came back. AUTOZONE put their code reader on it and scanned the readings and said the idle was reading under load, he again said vacuum leak. Sprayed QUICKSTART again and the idle increased again near the throttle boy??? Pulled the car up on my car ramps and crawled under it. FOUND THE PROBLEM! On the bottom of the INTAKE MANIFOLD fou have a 90 degree "SOFT" rubber elbow on the PCV system. The hose is about 2' long with a solid insert and two 90degree soft rubber elbows on each end ($25.00). One connects to the intake manifold, it then passes over the bell housing to the front of the car where it goes onto the PCV valve. The elbow going to the intake manifold had deteriorated and had a HOLE through it, pulling in outside air and leaning out the mixture. Cleared code and its running great!

[jcantu1982]

Man, that sure was a tough one. Appreciate you posting it. I'll definitely remember it.

Good fix dude.

[jeffcoslacker]

Thanks for posting that. Sounds like it could be a trouble spot. Had an Escort in the shop once with a steady misfire on one hole at idle, ran the usual battery of tests to try to find out why, and determined it to be a vacuum leak. Used a spray bottle of water to hunt for it, and got it to run smooth everytime I hit one certain area around the intake manifold, just like you did. Checked all around and under with a mirror, looking for a missing line or a gasket leak. Finally was able to see the water bubble as it was drawn into a hairline crack about 1/2" long in the underside of the #2 runner. Was glad I didn't just start putting gaskets on, woulda drove me nuts!

[jcantu1982]

Hey Jeff, I'm a newbie and don't know your AF history, other than you've helped out a ton of people scratching their heads. What's the story with that red engine pic in your replies? Did you build that, have it, or what? Just curious.
Later,
Jose'

[jeffcoslacker]

Originally Posted by jcantu1982

Hey Jeff, I'm a newbie and don't know your AF history, other than you've helped out a ton of people scratching their heads. What's the story with that red engine pic in your replies? Did you build that, have it, or what? Just curious.
Later,
Jose'

No, not mine, just got a kick out of the pic. As far as I can tell, It's a 60 degree GM 231 cid V6, highly modified (duh!)

It reminded me of one my friend and I did way back, a '72 Impala with a 400 small block, he was a machinist and welder, and fabbed an 8 runner intake for it, onto which we put 8 one barrel Mikuni motorcycle carbs with velocity stacks. Looked great! Wounldn't stay in synch more than a week or so, very impractical but went over well at car shows!

[Xtort]

HOLY CRAP! You saved me alot of headaches and money with that post!!! The one on my Zx2 had turned into like stereo surround it was so bad.

THANK YOU!!!!!

[darkradar]

Just found the same problem in my 2000 ZX2 @ 71000 miles. Engine light on, rough idle, and oil emulsion mess on my air filter from the breather separator line.

[darkradar]

My ZX is in for inspection and my mechanic said the exact same code came down PO171-Bank1Lean. He said since I repaired it I have to drive the car about 100 miles before the micro woll take a reset. Too bad the Commonwealth? of Pennsylvania does let him pass a car on emissions when the check engine light is on! Good thing it isn't due until the end of November. Any confirmation out there on the driving 100 miles thing?

I found that the after-market HELP product line has PCV valve elbows. I bought 2 and replaced the cheap thin-wall molded elbows at each end of that vac line (I couldn't find an auto parts that stocked it including NAPA). Two cost me $5 plus a couple of hose clamps and I'm done. I also tried on-line parts suppliers. I'm glad I didn't have to go to a dealer!

[zx2srdotnet]

taking the neg term off the bettery and letting it sit 15-20 min will reset the computer and clear and codes.

[darkradar]

Thanks zx2sr, I passed it on to the garage, he said certain years will do that, others might not (has to re-learn under alot of driving conditions etc etc). Mysteriously enough, when I picked it up after-hours the light was out!