Resolved 2G Lean issue

[StanleyDSM]

So I finally got my new 99 GST finished today. I went to go start it with a new battery, and it ran really nice for about five minutes. Then it started to run really bad and produced a tint of blue in the exhaust fumes.

So I went plugged in my ECMLink. I had a code of P0141 rear o2 malfunction. Could that cause my really bad idle and lean issue?

 

[Chaoticdopey]

yes it could, i think there is a way to disable the rear o2 in ecmlink and see if it runs better after.

 

[StanleyDSM]

Yeah it was my rear o2 sensor. It runs perfectly now. Haha

 

[ThunderChild]

Interesting...I was under the impression the rear o2 was only for cat efficiency, not able to affect fuel trims?

 

[Boost-Junkie]

Interesting...I was under the impression the rear o2 was only for cat efficiency, not able to affect fuel trims?

I agree is this an ecmlink function I'm not aware of?

 

[StanleyDSM]

Yeah I had a extra o2 sensor from my spyder so I plugged it up and ran smooth as it ever could.

 

[turbolover10]

yes it could, i think there is a way to disable the rear o2 in ecmlink and see if it runs better after.

Yep I disabled mine!

 

[Boost-Junkie]

I'm still unresolved as to why the secondary would matter just trying to clear my thought process. Unless it acts as a secondary check confirming primary readings

 

[gofer]

The ECU monitors the front o2 (upstream) sensor to vary injector pulse width (IPW) to control the AFR. Other sensors can affect IPW also the TPS, RPM, ECT, IAT (located in the MAS), VSS, and battery voltage but the front o2 is the main contributor during closed loop operation

Typing this directly from my 2g Eclipse Technical Info FSM...

"Downstream
The downstream heated oxygen sensor threads into the exhaust pipe at the rear of the catalytic convertor. The downstream heated oxygen sensor input is used to detect catalytic convertor deterioration. As the convertor deteriorates, the input from the downstream sensor begins to match the upstream sensor input except for the slight time delay. By comparing the downstream heated o2 sensor input to the input from the upstream sensor, the PCM calculates the catalytic convertor efficiency."

Basically, what that's saying is the rear o2 sensor failing wasn't the cause for the blue "puff" of smoke you saw, it was the result of it. You replaced the sensor with a working one but odds are whatever caused your blue "puff" of smoke will rear its ugly head again and could potentially take out the rear o2 sensor again. Blue smoke like that is oil making it's way into the exhaust and if it was bad enough to take out your rear o2 sensor odds are it got the front o2 sensor too, maybe not causing it to fail but it saw the worst of it. I'd pull the exhaust manifold and check for oil in the exhaust manifold and/or the exhaust ports on the head to see if there's any oil or oil residue visible, especially if it happens again.

 

[Boost-Junkie]

Without proper o2 readings both upper and lower its hard to confirm. Maybe just maybe the exhaust was removed to replace secondary o2 sensor and a exhaust leak forward of the primary o2 was resolved with tightening bolts? It's a toss up

 

[StanleyDSM]

Idk, like I said when I put the new o2 sensor in the afr was better and it would actually pull. I've already replaced the headgasket. The exhaust manifold is good for no oil. There's only at most 26k on this rebuild. But like I said everything is good now with her. Haha

Oh and my transistor pack was bad.