Lean left and right bank
Thread Starter
Intermediate
Joined: Mar 2008
Posts: 30
Likes: 0
Lean left and right bank
I have a 01 Z06 and it has set a lean left and right bank code. I have been told that it was either the ecu needed to be flashed or it needed intake gaskets. Anyone have any ideas?
Racer
Joined: Jul 2006
Posts: 285
Likes: 1
From: Placentia CA
I’ll assume it’s throwing both a PO171 and a PO174. Just means that the PCM has had to add more fuel than it thinks is right to make the O2 sensors happy. Since its both bank 1 and 2 I would start looking for a vacuum leak that is common to both banks. Don’t jump to the repair until you have diagnosed the problem. Might just be a PCV line etc. Good luck.
Last edited by RonSS; Apr 3, 2008 at 10:28 PM. Reason: Kant speel wort ahh damb
Thread Starter
Intermediate
Joined: Mar 2008
Posts: 30
Likes: 0
I took it to the dealership Friday and the guy gave it a good looking at. The fuel trim value is at 25% when it should be at 15%. We did everything from checking the fuel for to much alcohol to look everywhere for vaccum leaks. We never did find the problem. There is a perfomance tuner here in town that I will take it to next. It does have a few after market parts on it but the mass air is stock. He even took a new mass air from stock and put it on there and no change. So back to the drawing board!!
Former Vendor
Joined: Apr 2007
Posts: 1,331
Likes: 4
From: Jacksonville Florida
I took it to the dealership Friday and the guy gave it a good looking at. The fuel trim value is at 25% when it should be at 15%. We did everything from checking the fuel for to much alcohol to look everywhere for vaccum leaks. We never did find the problem. There is a perfomance tuner here in town that I will take it to next. It does have a few after market parts on it but the mass air is stock. He even took a new mass air from stock and put it on there and no change. So back to the drawing board!!
Tech Contributor
Joined: Dec 1999
Posts: 32,910
Likes: 2,402
From: Anthony TX
CI 6,7,8,9,11 Vet
St. Jude Donor '08
Instead of trying to have a tuner change the tune to correct an obvious problem using tuning, I recommend that investigate to see if you have a air leak and fix the real mechanical problem and thats causing the lean problem and then get it tuned.
If you spend 300-500 for a tune and the problem is later found later down the road and repaired, then your tune wont be wort 50 cents. Your fuel trims will 25% in the negative direction
Fuel trims don't change that way unless theres an issue. Sometimes a cold air intake install can the trims to change.
What modification do you have??? Please list them. I added Headers, VARARAM, and a ported TB and my trims went out to lunch. Same issue you have. The VARARAM can cause trims to change.
BC
If you spend 300-500 for a tune and the problem is later found later down the road and repaired, then your tune wont be wort 50 cents. Your fuel trims will 25% in the negative direction
Fuel trims don't change that way unless theres an issue. Sometimes a cold air intake install can the trims to change.
What modification do you have??? Please list them. I added Headers, VARARAM, and a ported TB and my trims went out to lunch. Same issue you have. The VARARAM can cause trims to change.
BC
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Thread Starter
Intermediate
Joined: Mar 2008
Posts: 30
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It has the cold air intake. Not sure which brand but it has dual K&N filters on it. It also has a BBK 80mm throttle body. The only other thing I can tell is changed is the plug wires. Also it seems they have removed the mufflers. It has cats and resinators?. At least I think that is what they are. The car at one time had a supercharger on it and the guy I got it from had removed it. Everything else checked out including fuel pressure.
Race Director
Joined: Jan 2006
Posts: 10,554
Likes: 33
From: Not on either liberal coast.
More than likely, you've got an air intake leak somewhere where there's a clamped connection. Check the bellows beneath the throttle body, that's where the (rigid silicone?) couplers typically will pucker on the very bottom causing an air leak.
Pro
Joined: Mar 2002
Posts: 670
Likes: 46
From: New Orleans LA
I've been having the same 2 codes thrown at me over the past year. ONLY thing I have is a K&N filter in the stock box and codes started coming not too long after the mod. Checked everywhere for leak and tightened everything. Tech seems to think its an 02 sensor.
Last edited by badass7; Apr 7, 2008 at 10:52 PM.
Le Mans Master
Joined: Aug 2005
Posts: 5,375
Likes: 328
From: CA.
St. Jude Donor '13-'14-'15
I agree with the others---If it has been running fine up until now with the same mods and suddenly started throwing lean codes---i would look at maintenance items or broken or torn hoses---
1.Check the fuel filter--and the fuel pressure--should be around 50 PSI
2.Air intake hose on the AIR system connected to the front of the air cleaner---they come off sometime--
3.Vacuum leaks---
4.Secondary AIR check valves--they get stuck open with carbon
5.Exhaust leaks----
6. Make sure your 02 sensors are oscillating while in losed loop--could be bad 02 sensors--got fouled with some bad gas or fuel additives
7. Dirty MAF --oil fouled from too much air filter oil
Good luck-----
1.Check the fuel filter--and the fuel pressure--should be around 50 PSI
2.Air intake hose on the AIR system connected to the front of the air cleaner---they come off sometime--
3.Vacuum leaks---
4.Secondary AIR check valves--they get stuck open with carbon
5.Exhaust leaks----
6. Make sure your 02 sensors are oscillating while in losed loop--could be bad 02 sensors--got fouled with some bad gas or fuel additives
7. Dirty MAF --oil fouled from too much air filter oil
Good luck-----
Thread Starter
Intermediate
Joined: Mar 2008
Posts: 30
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I sprayed chem tool around all of the intake and blocked off all of the vaccum and AIR pump hoses and it didnt change anything. I also checked the fuel pressure and it was 59 psi with key on and 65 psi at idle. We also checked the alcohol content and it was at 10%. The tech didnt seem to think the fuel was a problem. We also put a new MAF on it and no change. I will check all of my connection points on the air intake.
Race Director
Joined: Jan 2006
Posts: 10,554
Likes: 33
From: Not on either liberal coast.
I sprayed chem tool around all of the intake and blocked off all of the vaccum and AIR pump hoses and it didnt change anything. I also checked the fuel pressure and it was 59 psi with key on and 65 psi at idle. We also checked the alcohol content and it was at 10%. The tech didnt seem to think the fuel was a problem. We also put a new MAF on it and no change. I will check all of my connection points on the air intake.
I finally gave up and returned to a modified oem intake. So, I'm pretty sure it was related to the increase in air along with the altitude probably already putting my car at close to the outside parameters that the computer could compensate for. But, no more codes!
