Both O2s unplugged but no engine light?

[ddoublee]

Today I replaced my valve cover and forgot to reconnect my primary O2 sensors. The car started up and drove seemingly perfectly normal. I eased into a couple pulls and someting felt off, so I pulled up MHD and thats when I noticed that neither bank was reading AF, both were stuck at 15.3. I pulled over and found that the O2 sensors were not connected, and after plugged them back in, everything was reading correctly, but it was too late.

On that short drive with no O2 sensors I managed to crack ringlands on cylinder 5 and 6.

When I checked trouble codes, I did have a stored code for the O2 sensors, but the check engine light never came on when I was driving. I would have expected something that to trigger limp mode. Does Reflex+ somehow prevent the DME from going to limp mode?

 

[carabuser]

You should get a CEL from an open-circuit fault. It's possible the codes are disabled in the tune. I would suspect tuners disable a lot of common DTCs just to minimise customer call-backs.

 

[ddoublee]

You should get a CEL from an open-circuit fault. It's possible the codes are disabled in the tune. I would suspect tuners disable a lot of common DTCs just to minimise customer call-backs.

I am the tuner and I am fairly certain none of the codes are disabled.

2C9C and 2C9D are the codes that were triggered, but no CEL was triggered.

Here is a link to the log from the pull where things went bad.

Reflex+ - E85 FF - PI - Primary O2s unplugged by mistake - No CEL - Cracked Ringlands on 5 and 6

After replacing my valve cover, I went for a test drive, not realizing I had mistakenly left both primary O2s unplugged. Car felt normal and did not show a Service Engine Light. I made a couple light pulls in 2nd gear, had no issues, so I tried...

www.spoolstreet.com

I've started to think back, and I think there is something going on with the Reflex that is interfering with the DME triggering the CEL and limp mode. Since installing the Reflex, it seems that anytime I have had a code that would normally trigger limp mode, I do not get a CEL, however for smaller codes that would not trigger limp mode, I DO get a CEL.

For instance, I had some secondary O2s that were going bad, and occasionally they would throw a signal or aging code, I would always get a CEL. But, I have had misfire codes stored before that did not trigger a CEL or limp mode, and prior to the Reflex, a misfire code would always trigger limp mode. The only time I've seen the car go into limp mode since installing the Reflex was if I get a CANBUS error.

@Jake@MHD Am I going crazy here, or is there something to this?

 

[wheela]

Despite running without O2 control, your timing corrections don't seem too bad in that log? What are theories for that run blowing 2 pistons, just really high cylinder temps from running lean? I'd have thought if you were lean enough for that to happen you'd be getting alot worse timing corrections from detonation, and the detonation would be what cracked you ring lands, but maybe not with high e-content?

 

[wheela]

Sorry this happened by the way, what a nightmare...

 

[ddoublee]

Despite running without O2 control, your timing corrections don't seem too bad in that log? What are theories for that run blowing 2 pistons, just really high cylinder temps from running lean? I'd have thought if you were lean enough for that to happen you'd be getting alot worse timing corrections from detonation, and the detonation would be what cracked you ring lands, but maybe not with high e-content?

Yes, this is my best guess that it went lean and detonated. I too am surprised that the corrections were not worse though. The car has been the same basic setup for 4.5 years now, but previously was DI only running FF up to E40 and in March I added the Reflex and PI and have mostly been running straight E85 ever since. I've been running this same flash for about 4 months with no issues, and map 1 on this tune is just a direct copy of the previous tune I'd been running since about March. This tune targets 26psi and about 12 degrees peak timing, and normally I get basically no corrections at all.

My first thought was since the AF was pegged at 15.3, then it would have been dumping fuel to compensate, but looking at the trims they stayed at 0 the whole time. Since I do not know what it was actually doing AF wise, I can only speculate, but on this tune, as the PI kicks in at 3000 RPM I usually have a short spike in trims where I see around +15, and then it usually pulls fuel from 3500 plus. I'm guessing it ran pretty lean in that area yesterday as the weather much cooler than it has been.

Sorry this happened by the way, what a nightmare...

Thanks, yeah I am pretty sad about it. Car has 198k miles and the motor was still in incredible shape. Cylinder walls all look great and compression test was 175 across the board. But now #5 is 120 and #6 is 90.

All I can do now is figure out a plan to move forward, but I really want to understand what happened with the CEL so that this doesn't happen again, to me or anyone else.