Bad o2 or bad cat?

Disclaimer: Links on this page pointing to Amazon, eBay and other sites may include affiliate code. If you click them and make a purchase, we may earn a small commission.

OP
OP
C

crownvic31

Full Access Member
Joined
Jun 13, 2022
Posts
212
Reaction score
176
Can the tune safely be turned off / turned on, to shake down things from an unaltered stand point?

If you had a battery lead off the first thing I’d do is reboot or discover how to reload the tune from a blank slate. If your BCM was pissed off about the momentary voltage loss it may have sent it over the edge or corrupted a file.
What exactly are you saying?
I should upload the stock tune back on the escalade? Ans then re install the blackbear tune?
 

Fless

Staff member
Moderator
Joined
Apr 2, 2017
Posts
16,278
Reaction score
33,631
Location
People's Republic of Colorado
Another video parked and rpms at 1k and increasing to 1500.


Your other videos didn't show it adding that much fuel at idle (was 5% or so IIRC). But the high positive trims (+12 now) at idle go down with RPM (from what I can tell) and that indicates a vacuum leak. Not a big one, but one that affects the trims.
 

j91z28d1

Full Access Member
Joined
Feb 28, 2022
Posts
4,602
Reaction score
5,863
I say wait to hear back from black bear. their data log should have much more info in it and they can see if it's what they are used to seeing.



I kown you've had it looked at, but my curiosity would be, go find where that battery cable runs, I don't have a truck like yours, so I don't know if that's like all the way from battery to starter or something else. but I'd click the key on, turn on a bunch of stuff to get a good battery. get a meter, set to DC voltage, put on lead on end of the cable, and the other on the other end. you should have next to no voltage drop across it. like 0.2 or so at most. if it's a half volt or more, I'd suspect it's a bad connection somewhere.
 

petethepug

Michael
Joined
May 4, 2016
Posts
3,788
Reaction score
4,355
Location
SoCal
Yes, a reboot from baseline to BB tune, emphasis on if BB advises that after all else checks out.

Keep it simple and work backwards from the changes made prior to when all was good. Fingers crossed you find a voltage issue on the new cable with a/c, lights, seat heaters & wipers on.

Did you change both +\~ cables?

What prompted you to change the battery cable?
 
OP
OP
C

crownvic31

Full Access Member
Joined
Jun 13, 2022
Posts
212
Reaction score
176
Yes, a reboot from baseline to BB tune, emphasis on if BB advises that after all else checks out.

Keep it simple and work backwards from the changes made prior to when all was good. Fingers crossed you find a voltage issue on the new cable with a/c, lights, seat heaters & wipers on.

Did you change both +\~ cables?

What prompted you to change the battery cable?
Reason why i changed the cable was just because i changed all ground cables when i 1st bought the truck. They looked all pretty corroded. Never got around to chsnging the positive one. Thats the reason why I canged it.

I will wait for black Bear to get back to me with the data they requested.
 
OP
OP
C

crownvic31

Full Access Member
Joined
Jun 13, 2022
Posts
212
Reaction score
176
Your other videos didn't show it adding that much fuel at idle (was 5% or so IIRC). But the high positive trims (+12 now) at idle go down with RPM (from what I can tell) and that indicates a vacuum leak. Not a big one, but one that affects the trims.
I also want to say that there was alot of popping when i was doing this.
 

petethepug

Michael
Joined
May 4, 2016
Posts
3,788
Reaction score
4,355
Location
SoCal
You’re on the right path. Change the other battery cable while your waiting.
 

j91z28d1

Full Access Member
Joined
Feb 28, 2022
Posts
4,602
Reaction score
5,863
this will be an interesting one when you figure it out.

my random guess is glazed plugs since it's modded and tuned. look fine but miss firing. the unburnt air from the miss fire telling the o2 is lean. ecm adding more fuel making it all worse
 
OP
OP
C

crownvic31

Full Access Member
Joined
Jun 13, 2022
Posts
212
Reaction score
176
this will be an interesting one when you figure it out.

my random guess is glazed plugs since it's modded and tuned. look fine but miss firing. the unburnt air from the miss fire telling the o2 is lean. ecm adding more fuel making it all worse
Its just interesting how we go from running fine to this by changing the ******** positive battery cable.

Cant wait for blackbear to get back. They must be behind due to the holidays.
 

Dustin Jackson

Full Access Member
Joined
Aug 9, 2018
Posts
1,788
Reaction score
2,064
@crownvic31 I think he is saying put the old cable back in. You said the problem started after you put the new battery cable in, so logically you would undo changes until you reached your baseline.

If you do have a vacuum leak it's possible the factory tune did a good job of compensating for it but now that you are on an aftermarket tune the leak is presenting itself more.
 
OP
OP
C

crownvic31

Full Access Member
Joined
Jun 13, 2022
Posts
212
Reaction score
176
I will run another smoke test later today. My ladt smoke test i used the hose off the brake booster and sealed the end of the intake pipe with maf removed.

Any other suggestions on where to hook up my smoke machine?
 
OP
OP
C

crownvic31

Full Access Member
Joined
Jun 13, 2022
Posts
212
Reaction score
176
Hello guys

So Just received an email from blackbearperformance in reference to the data log they received and my issue. His reply in regards to the data log was


"Fuel delivery (quantity) looks very very close to ideal. Fuel quality may be an issue though, as there is quite a bit of knock activity."

I gave him the brand and octane I'm using which is Exxon and sometimes BP and its always 93. Been running this one for years with no issue. I also replaced with explaining when this all started happening. Lets see what he recommends. I am at lost with this.
 
OP
OP
C

crownvic31

Full Access Member
Joined
Jun 13, 2022
Posts
212
Reaction score
176
Im this folloing video i am trying to figure out the rear o2 sensors. To my understanding, they are there to tell is the cats are good or bad. With this reading of my 02 sensors, there is something going on.

Am i correct here or am i still at lost?
 

j91z28d1

Full Access Member
Joined
Feb 28, 2022
Posts
4,602
Reaction score
5,863
I only see 2 o2 sensors and rpm on the graph?

are you wanting to look at the rear o2 sensor data?


edit. I missed is says sensor 2 yeah from what I've seen when working correctly sensor 2 is basically a flat line around 450mv
 
OP
OP
C

crownvic31

Full Access Member
Joined
Jun 13, 2022
Posts
212
Reaction score
176
I only see 2 o2 sensors and rpm on the graph?

are you wanting to look at the rear o2 sensor data?


edit. I missed is says sensor 2 yeah from what I've seen when working correctly sensor 2 is basically a flat line around 450mv
Does this mean i should be looking into my rear o2 sensors and/or cats?
 

j91z28d1

Full Access Member
Joined
Feb 28, 2022
Posts
4,602
Reaction score
5,863
well that's the thing.. cats are very expensive to replace. but yes, it looks there like your cats are catting lol. but the rear o2 sensors shouldn't have any effect on how the engine is running and it's running badly right? like bad gas mileage and rough running? seems like rather than throw a lot of money at new cats, and maybe melt down the new ones too. first I'd fix why it's running badly. and then if that doesn't change anything, you can have a look at the cats. if melted, then yes they need to be replaced or depending on your situation, you could just have the rear o2s turned off in the code.

cats get hotter depending on how rich the air fuel mixture is. if it's running rich enough they can get hot enough to melt the Platinum grid inside. restricting air flow and not doing the catalystic effect anymore.
 
OP
OP
C

crownvic31

Full Access Member
Joined
Jun 13, 2022
Posts
212
Reaction score
176
Not sure if i mentioned this but i have long tube headers and high flow spun magnaflow cats which werent that expensive at 150 each. Tune was done by blackbear performance. Been running this set up for about 3-4 months now. I ran the escalade for a few weeks before getting the tune done. After the tune was done, everything was running well since 2 weeks ago after I replaced the power steering pump and the positive battery cable. Then escalade started running funky.

Reading about the symptoms of bad rear o2 sensors and what im experienceing, i can match a few with mine symptoms.

Noticeable Loss of Fuel Efficiency
Sulfur smell from Exhaust.
Engine bucking/jerking
And the readings from my rear o2 sensors are not the same.

As per the catalytic converter, i read this:

"A clogged converter can make your vehicle misfire and accelerate slower. When the material breaks up inside of the converter, it blocks the exhaust and creates backpressure on the engine, causing it to misfire. "

I yet have no codes.
 
OP
OP
C

crownvic31

Full Access Member
Joined
Jun 13, 2022
Posts
212
Reaction score
176
Here are some pics of how my exhaust is set up.
 

Attachments

  • 20231006_145353.jpg
    20231006_145353.jpg
    193.3 KB · Views: 20
  • 20231006_145402.jpg
    20231006_145402.jpg
    253.6 KB · Views: 23
  • 20231006_145418.jpg
    20231006_145418.jpg
    275.1 KB · Views: 27
  • 20231006_145424.jpg
    20231006_145424.jpg
    189.8 KB · Views: 23
  • 20231006_145436.jpg
    20231006_145436.jpg
    226.2 KB · Views: 27
OP
OP
C

crownvic31

Full Access Member
Joined
Jun 13, 2022
Posts
212
Reaction score
176
Sorry for all the post guys. Im just trying to educate myself here and just ask for advice and opinions.

So in the email sent by blackbear performance, he mentioned that there was knock activity and questioning my gas.

So reading more i came across this:

"a bad catalytic converter can potentially cause a knock sensor code. A failing catalytic converter can lead to an increase in exhaust back pressure, which can in turn cause abnormal engine combustion and trigger a knock sensor code"

Now i do not have a code. But this can be the cause to why he was able to see knock in my data log. Also, the vacuum leak i here coming from the orfice(pcv valve) which is not a vacuum leak because ive done several smoke test and the engine is sealed, this might be that extra exhaust back pressure?

Hmmmmmm
 

Forum statistics

Threads
137,687
Posts
1,989,629
Members
102,689
Latest member
Woned2004
Back
Top