eMacPaul
11-02-2011, 03:34 AM
I'm having some trouble with my car. It started with an erratic idle at startup. Then it progressed to running rough, the engine sounds terrible, hardly any power, very low boost, and the exhaust manifold glowing after just an easy two-mile drive.
I took it to the dealership, who thought it was a plugged cat. I took it to the exhaust shop to confirm and replace if necessary, but they said the cat was fine. So back to the dealership, where they checked for boost leaks, then determined the turbo was bad by bypassing the wastegate actuator and observing that it still didn't boost properly.
They replaced the turbo, but the next day it started running a little rough again, and even worse the next day. Since I was pretty sure I hadn't destroyed the turbo overnight, the only thing I could think of was that the battery had been disconnected while the turbo was replaced and that had reset something.
So I disconnected the battery over night, and the next morning it ran perfectly. A couple days later, it started running rough again, I disconnected the battery for a few minutes, and it's good again.
From the symptoms, I'm guessing it's running very lean. However, in all this process there have been no CELs, and the temperature gauge has been rock steady in the middle. I'm guessing the ECU must be pulling boost due to the high temperatures.
I'm planning to move to Seattle on Saturday, so I'm leery of bringing it back to the dealership without a firm diagnosis at this point since their diagnostic capability seems to be slightly sub-par, and I don't have time for them to take their time figuring this out.
So my questions are, what can I do to confirm whether the ECU is causing it to run lean, and how can I figure out why the ECU is doing this? I have VCDS for doing any logging.
Would an O2 sensor failure cause this, but have its failure masked by the stage 2 software? Or does that only block CELs due to inefficient catalytic converter action (can they be distinguished)?
I'm in way over my head, so I appreciate any help!
I took it to the dealership, who thought it was a plugged cat. I took it to the exhaust shop to confirm and replace if necessary, but they said the cat was fine. So back to the dealership, where they checked for boost leaks, then determined the turbo was bad by bypassing the wastegate actuator and observing that it still didn't boost properly.
They replaced the turbo, but the next day it started running a little rough again, and even worse the next day. Since I was pretty sure I hadn't destroyed the turbo overnight, the only thing I could think of was that the battery had been disconnected while the turbo was replaced and that had reset something.
So I disconnected the battery over night, and the next morning it ran perfectly. A couple days later, it started running rough again, I disconnected the battery for a few minutes, and it's good again.
From the symptoms, I'm guessing it's running very lean. However, in all this process there have been no CELs, and the temperature gauge has been rock steady in the middle. I'm guessing the ECU must be pulling boost due to the high temperatures.
I'm planning to move to Seattle on Saturday, so I'm leery of bringing it back to the dealership without a firm diagnosis at this point since their diagnostic capability seems to be slightly sub-par, and I don't have time for them to take their time figuring this out.
So my questions are, what can I do to confirm whether the ECU is causing it to run lean, and how can I figure out why the ECU is doing this? I have VCDS for doing any logging.
Would an O2 sensor failure cause this, but have its failure masked by the stage 2 software? Or does that only block CELs due to inefficient catalytic converter action (can they be distinguished)?
I'm in way over my head, so I appreciate any help!