Plum Nuts' Datamaster Log

[meissen]

Hey guys,

We have a few gurus on here now so I thought I'd post it. Dad's car is throwing Left O2 lean and I'm having a hard time trying to figure out if the o2 sensor is bad or it's a fueling issue that's leaning out the left bank.

If anyone wants to watch the datamaster log, it's pretty straight forward - a lot of idling and then me revving it a few times. No driving - still up on wooden stands.

You can clearly see where it throws the Lean o2 code - the RPM will blip just slightly and that's when it jumps from Closed Loop back to Open Loop.

When it went back to Open Loop, I let it idle for a bit and then started revving it and it went back into Closed Loop. A few minutes later it threw another Lean O2 code and went back to Open Loop again. Tried revving it up but couldn't get it to go back into Closed.

http://www.meissenation.com/datamaster/PlumNuts1.uni

Thanks in advance to anyone who is willing to look at it and give some feedback.

[Phantom409]

Man I need to get this stuff

[prorac1]

Looks like either your left side o2 is bad, or has a bad connection or broken wire. Thats where id check. The right seems ok. Eric L

[meissen]

Thanks Eric. The main concern is that my dad lengthened the O2 wires himself yesterday rather than buying the o2 extensions. We did that with my car, but my o2s are tuned out so it's not as big of a deal. We'll have to recheck those connections and/or replace that O2. I wouldn't be surprised if it was bad too.

[JoeliusZ28]

check your wiring first, thats a known source of issues with oxygen sensors.

[sman]

You shouldnt/cant extend your o2's on your own. I tried, and had all sorts of problems. Also not accurate if you do. I picked up a pair of the vette o2s that come with the long wires.

[meissen]

I did it on the v6-LT1 swap and the guys at Murrays actually recommended it. As long as you're using comparable gauge wire.

[1BADAIR]

sman I think the lt1 connector is flat instead of square like ls1's

[meissen]

yeah it is

[sman]

Thats a bummer on the wrong connector.

Im glad it worked for you, but with all the problems I had, and from what ive read, im betting thats your problem. I didnt half ass mine either, soldered and heatshrunk then wrapped in a factory like mesh. I kept getting o2 codes and it would spit and sputter, and the exhaust smelt like gas bad.

Just my experience.

[meissen]

Yeah, I can't say how it went for dad - he did it a little differently than we did on my car. I believe he was planning on spending today sorting out the issues.

[sman]

Best of luck, I absolutely HATE electrical stuff in cars...

[meissen]

Ah, I don't mind them. The thing with electricals is that it's so straight forward - a wire goes from one location to another and it either has voltage or it doesn't (I know there's more to it than that, but still).

[steve40]

look at rec 1127, your short trims are way off for both sensors.

its like there is one of the following

bad wiring
bad sensors
exhaust leaks.....does the car have a full exhaust on? if not, how far are the o2's from the open end of the exhaust? the sensors could be reading the outside air as well...

[meissen]

Full exhaust, ypipe was only slipped into the intermediate but the o2s are at the end of the headers.

I think dad and I are leaning towards bad wiring and bad sensors. I kinda regret agreeing with him on extending the stock wiring like he did - when we lengthened mine we lengthened the wires on the o2 sensor so they'd reach the stock engine harness's o2 plug... which meant if we effed the wiring, a new o2 would fix the wiring issue. Now that he's tampered with the stock wiring he has to fix it, can't go back to how it was.