Both Banks Lean?

[nwilson44]

Hey guys I need a little advice. I have some P0174 and P0171, which are bank 1 & 2 lean. Well I have been having P0174 very consistently before this weekend. I just finished installing the pacesetters this weekend along with a magnaflow catalytic converter. The lean condition burned out my last converter so I had to change it. Well I ran the car open y-pipe for 1 night because I didnt finish it in time before the muffler shop closed (I dont have a welder). They welded my cat and y pipe crossover. Well, not even 5 miles down the road "service engine soon" comes on and its bank 1 & 2 Lean codes. so The new cat and exhaust now has both banks running lean?!?!?! I left the 3rd O2 sensor in the factory location instead of putting it in the pacesetter y-pipe in front of the cat. So its behind the cat in the factory location and the y-pipe has the plug in it. my car is a 2001 and I have no clue why its running like that. Its at the dealer now, but any Ideas?!?!


Only other important things I can think of that may be important, is that I have a K&N CAI, Accel Coils, I just changed the plugs while doing the install to E3 Diamond fires, MSD Super conductors, and for now I am running the stock tune until I get it straightened out. Also running stock cat-back for now, until I get it running right.

[FIREBIRDV6RAGE]

Are they the oem one that came with the car? They might just be going out if so then just change all 3. Maybe that's it.

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[fbodyrs96]

Re: Both Banks Lean?

Fyi the pre cat bung is for the 95-98 3.8 , they had both pre and post sensors.

[nwilson44]

Re: Both Banks Lean?

They were replaced 8 months ago and the passenger one is new

[nwilson44]

Re: Both Banks Lean?

Fyi the pre cat bung is for the 95-98 3.8 , they had both pre and post sensors.

ohh thanks

[Docta]

Re: Both Banks Lean?

If you have a way to monitor fuel trims that'll help. If its lean at idle, look for a vacuum leak. If its cruising, clean the maf and recheck.

[nwilson44]

Re: Both Banks Lean?

If you have a way to monitor fuel trims that'll help. If its lean at idle, look for a vacuum leak. If its cruising, clean the maf and recheck.

I wish I did have a way to check. The dealer said I need a custom tune... So I think I am just going to do that. any comments about that?

[FIREBIRDV6RAGE]

Maybe , sounds wierd. but the cars were made to stay factory. Maybe those headers and other mods threw the car off?


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[FIREBIRDV6RAGE]

I wish I did have a way to check. The dealer said I need a custom tune... So I think I am just going to do that. any comments about that?

Know any one that has an obd2 code scaner. That's how I figured out why mine were throwing the codes . Just turnes out the o2 sensors were going out. And one was disconected

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[nwilson44]

Re: Both Banks Lean?

I have a hypertech yes, but that just modifies the factory tune for a mostly stock vehicle. So I talked to 510 Race engineering here in Houston, and they think their tune will correct my lean issue. Anyone else with intake and headers that had the same issue?

[nwilson44]

Re: Both Banks Lean?

Anyone had the same issues?

[Hib Halverson]

Re: Both Banks Lean?

In reading the first post, I'm a little confused..

Was the engine setting lean codes before you put the headers on or only after?

[nwilson44]

Re: Both Banks Lean?

In reading the first post, I'm a little confused..

Was the engine setting lean codes before you put the headers on or only after?

It had a P0174 prior to having them. The manifolds were leaking a bit. When I was running open headers, I had no lean codes. And now that the Magnaflow cat is on I have both banks lean. But I am getting low to mid 20's gas mileage wise in the CITY!

[Hib Halverson]

Re: Both Banks Lean?

If it was setting both lean codes before you put on the headers, the exhaust change by itself, has likely no affected whatever is causing those codes to set.

That those codes are setting indicates the engine is lean in closed loop. It may or may not be lean at WOT. You need a wideband to test that.

First thing to do is make sure there are no exhaust leaks near the O2Ses.

Then I'd look for vacuum leaks.

Also, the third O2S goes behind the cat not in front of it.

None of the other mods would run the engine lean enough to set those codes.

[nwilson44]

Re: Both Banks Lean?

If it was setting both lean codes before you put on the headers, the exhaust change by itself, has likely no affected whatever is causing those codes to set.

That those codes are setting indicates the engine is lean in closed loop. It may or may not be lean at WOT. You need a wideband to test that.

First thing to do is make sure there are no exhaust leaks near the O2Ses.

Then I'd look for vacuum leaks.

Also, the third O2S goes behind the cat not in front of it.

None of the other mods would run the engine lean enough to set those codes.

So all of the mods should work just fine without a tune?