Shot o2 sensor causing pulled timing?

[DsmKid98GST]

I've been some having timing issues for the last week. I figured out, the colder the air the less timing being pulled during boost. I havn't really been pushing it hard after I noticed this was a continuous deal and I had time to log the problem.

There were 2 CEL concerning the o2 sensor, one for both parts of the sensor (can't remember what they were called) There was no reading on the logger of any o2 count either. Once I hit any kind of boost the timing will be pulled and the car will hesitate. I'm sure that since there were 2 CELs concerning the o2 sensor that it's the o2 sensor that went bad. But doesn't the o2 sensor show some type of degration while it's failing not just go out all at once? Would the o2 sensor being shot be the cause of my pulled timing during boost?

Right now my wideband is showing me running super rich while driving the car, but normal while idling (14-15ish)

My mods are all up to date in the list.

Thanks

 

[timloomis]

Yes the 02 can just die and not work,or it can go slowly and just work half the time.I've had both happen to me.If your super rich while driving,you might be getting rich knock,which would pull timing.If your wideband is showing your rich while at wot,then the o2 is your problem.

 

[GVR4592]

O2 readings don't affect WOT and it is extremely difficult to get rich knock. The engine will usually just cut out and bog before it gets anywhere near detonation with an overly rich condition.

Can you post a datalog?

 

[DsmKid98GST]

Yes the 02 can just die and not work,or it can go slowly and just work half the time.I've had both happen to me.If your super rich while driving,you might be getting rich knock,which would pull timing.If your wideband is showing your rich while at wot,then the o2 is your problem.

I do go completely rich during WOT, has been like this for about a while. I'll work on posting a log shortly

 

[CanadianTSi]

I do go completely rich during WOT, has been like this for about a while. I'll work on posting a log shortly

Boost Leak.

 

[DsmKid98GST]

I'm pretty sure it's not a boost leak.

I just installed a new turbo, manifold and wastegate today and did a leak test and there were no leaks except at the MBC with only gave me a 1psi loss. Unless that little hole near the MBC is causing my entire car to knock and pull timing i don't know what's up. I was holding 19psi strong while we were running the test.

EDIT: This problem was occuring while i had the t-25, stock mani and wastegate on.

 

[BISHILVR]

I still have issues with mine also, even with the knock sensor unplugged, good luck with it.

 

[DsmKid98GST]

Alright, the o2 was shot and the mbc has a valve that releases pressure. The shot o2 sensor caused me to run real rich. The mbc valve caused me to run even richer. The two combined caused me to knock real bad during boost.

I took the MBC off and there was no more knock during boost, but i was still running super rich at WOT and crusie from the shot o2 sensor.

I replaced the o2 sensor with a new OEM sensor. No more richness at WOT or cruising and no more knock during boost. Ran 11psi strong no knock.

Put the mbc back on at 11 psi, no knock. Put MBC to 16psi WOOWEE does she fly. I love my 50trim. I can't wait until I get my FMIC and bump the boost up a little more.

Hope this helps anybody else who runs into the same problem as me.

Thanks for all those who helped me diagnosis the problem.

Thanks to CanadianTSI for mentioning boost leak and opening my eyes, making me realize the MBC little valve was contributing and basically causing all of the knock.

 

[GVR4592]

The O2 sensor will not affect WOT fueling at all. I bet your knock was due to tuning and/or excessive boost.

 

[BISHILVR]

The ecu is in "open loop" at wide open throttle, o2 sensor values are ignored/extropolated. Try disconnecting your battery to reset your octane values.

 

[DsmKid98GST]

It could have possibly been the tune as I did install an AFPR and ran it with a tune that was created without an AFPR on.

As soon as I replaced the o2 sensor though, the knock went away without changing the tune and she is running like a champ. So, I just stated what fixed my problem and how I did it.

 

[Kevin Jewer]

The MBC vent will not cause knock. Everyone running an MBC without knock can attest to this. Compared to the amount of air you are flowing at WOT, that leak is insignificant. And I also find it impossible for the bad O2 sensor to affect WOT AFRs. All trims should drop to zero at WOT and have no effect. Must have been some combination of bizarre coincidences leading to the cause and the cure of that knock problem.

 

[DsmKid98GST]

I hear ya there 95gsxracer. Let's add this combination of bizarre coincidences to the list of bizarre coincidences haha.

Thanks for all the replys fellas.