Bad O2 or not?

[Redline Motorsports]

2008 ZO6
2 miles on the car
We just installed LT headers and camshaft (routine install)

The car fires up fine and after 8-10 seconds of running it runs rough like a plug wire has been pulled. The left side bank plugs are black and the right side and clean.

I logged the O2's and it looks like one is going flatline. Seems like the PCM has some kind of delay that happens after crank before the O2's can report. Machically the car is fine as we have checked everything. I have a hard time believing its an injector issue.

Tomorrow we are going to swap in some new o2's and see what happens. Any thoughts would be appreciated.

HT

[BlackGMC]

I may be wrong but I don't think the O2 start oscilating until the car goes into closed loop, correct? I think you go into closed loop when the car warms up....

Do you have any exhaust leaks? BTW when I put my Long tubes on, one of my O2s died... But I only figured it out when the truck went into open loop and one O2 would oscilate and the other was really lazy then it would flat line....

[joecar]

Howard,

I don't know how easy this is to do (on a Y-body the transmission is not in the way),
but is there any chance that the O2S sub-harnesses are crossed front-back or left-right..?

Cheers,
Joe

[Redline Motorsports]

Howard,

I don't know how easy this is to do (on a Y-body the transmission is not in the way),
but is there any chance that the O2S sub-harnesses are crossed front-back or left-right..?

Cheers,
Joe

When we install the Kooks headers, we don't even unhook the o2's from the car. We are able to remove them from the stock manifolds and re-screw them back into the headers. The rears use harness extensions and don't think they would be the issue since the rears function anyway is more for comparison vs. fueling.

[Redline Motorsports]

I may be wrong but I don't think the O2 start oscilating until the car goes into closed loop, correct? I think you go into closed loop when the car warms up....

Do you have any exhaust leaks? BTW when I put my Long tubes on, one of my O2s died... But I only figured it out when the truck went into open loop and one O2 would oscilate and the other was really lazy then it would flat line....

I agree to some extent. The o2's "shouldn't" be contributing until closed loop conditions are met but I think the E38 might still be looking at them for something even this early on.

If you look at the log, they are at .450 mv until a certain point in which one just heads right to 1.00 mv while the other starts a weak oscilation.

[Redline Motorsports]

Update but no resolution.

We switched 02's from bank to bank and the problem still exists. This means the o2's are good. I also noticed that the problem only starts when closed loop is enabled. So what I did was disabled all parameters that enabled closed loop. The car runs perfect! Startup and cruise are like stock. As soon as enabled the CL.......it starts running like crap. Since the right bank 02 is reporting a rich condition (.980 mv+). The PCM is commanding a lean command which explains the real clean plugs on that bank and why the car runs poor.

It's not a mechanical issue, nor a problematic 02. I think there is an issue with that side wiring from the 02 connection to the PCM. Hard to believe in a 08' with less then 10 miles on it. Still checking to see if there are any TSB's on this.

Still open for ideas.

Thanks

Howard

[Aloicious]

Update but no resolution.

We switched 02's from bank to bank and the problem still exists. This means the o2's are good. I also noticed that the problem only starts when closed loop is enabled. So what I did was disabled all parameters that enabled closed loop. The car runs perfect! Startup and cruise are like stock. As soon as enabled the CL.......it starts running like crap. Since the right bank 02 is reporting a rich condition (.980 mv+). The PCM is commanding a lean command which explains the real clean plugs on that bank and why the car runs poor.

It's not a mechanical issue, nor a problematic 02. I think there is an issue with that side wiring from the 02 connection to the PCM. Hard to believe in a 08' with less then 10 miles on it. Still checking to see if there are any TSB's on this.

Still open for ideas.

Thanks

Howard

Hey Howard, I've got a really simmilar problem, so I'm interested in how this turns out. I've got my bank 1 O2 set with LTFT running 0 to -2, and my bank 2 sensor runs at like -9 to -10.5 when in CL. switched sensors and same outcome on the same side, so the O2's are good. checked for exhaust leaks and tightened everything down and no change. I'm starting to suspect an injector issue. but my injectors were cleaned, and setup, and flowtested less than 1000 miles ago, maybe one is leaking????....however I'm not getting a rough running problem OL or CL. and I'm running a different PCM, and OS...

keep us posted on this and I'll let you know if I find anything out.

[Ritch]

solutions? or are they trade secrets?

[CoryF]

I think I'm having the same problem... :(

I switched my car from OL to CL for emissions and now when I first start up it is fine, then once it fades out of the cranking conditions, my AFR will climb to 17~18 after about 10 seconds of running my wideband reads like 18AFR.

I checked all the connections under the hood and everything looks fine, I used the scan tool to cut the fuel to each cylinder but its so hard to hear the difference for some cylinders.

Did you guys ever figure out what the problem was with your cars?

-CoryF

[swingtan]

Corey,

if you are running an E38, check here......

http://forum.efilive.com/showthread....ean+cold+start

You'll need to work on B0141 and B0143, along with B0146 to fix the lean spike after cranking.

Simon.