Twentyhurtz

Vehicle: 2000 Sierra w/ 4.8, stock exhaust, gutted stock cats, black bear tune.

So when I got my BB tune back in Feb, I asked for the EGR to be turned off.
Also, The previous owner gutted cats, so I had a CEL for the downstream o2 sensors, the BB tuned turned both of those codes off.

This past week I finally got around to deleting the EGR. I made a plate to cap off the factory exhaust manifold and used an expanding rubber plug for the intake.

First crank, the truck cranked perfect, 10 minutes later I tried to crank it again and it would turn over 1-2 times and stop. After about 20 minutes I tried again and the truck fired right up.
The only sensors that I unplugged during the entire process was the MAF, TPS, and another sensor on the TB as i removed both the intake and TB during this process.

Two days later in the morning time, the truck would not start again, later that day it cranked.

The next day on the way to work the CEL came on, code P1153 - verified this using my ELM 327. (H02S Insufficient Switches, Bank 2 Sensor 1)

This evening I switched both upstream o2 sensors around to see if the problem would travel to Bank 1.

Nothing happened, even disconnected the battery hoping for a code reset. After reading the code multiple times, I still received P1153.

Lastly, I used the ELM 327 to read the o2 sensor voltages, keep in mind the downstream sensors have been disabled or the CEL for them has been turned off in tuning.

Voltages are Fluctuating between these values:

Left side upstream 0.4-.63V
Left side dwnstream 0.1V consistent

Right side upstream .08-.81V -cycles high to low
Right side dwnstream 0.8V consistent
(These values were read without the engine warmed up and at engine idle)

Maybe I should wait until the engine is warm to read these again, but even cold I am seeing the downstreams reading completely opposite ends of the spectrum from each other.
I am seeing the upstreams both fluctuate, but the Bank 2 definitely has more range in this condition than the Bank 1.

If this was a sensor issue, I would have expected it to move to the opposite side.

Maybe this is an exhaust leak through the EGR mounting hole? I did use a little gasket maker on the gasket when applying it (which i now regret as some may have made it into the manifold I fear). So maybe this is to a lack of air flow on the Bank 2 side.

Twentyhurtz

Update: This morning I drove the truck about 10 minutes and monitored the voltage on the o2 sensors again and they all 4 were reading about 0.85-0.89V consistently.

nonnieselman

iTrader: (10)

I cant rem but i think the oxygen sensors arent used until it hits closed loop which is 164* i think.
Havent fooled with this stuff in awhile since my truck is speed density haha.



What do you mean when you say it wont start?
Would just spin and not fire?

kelsey_canard

iTrader: (5)

This. I would see if you can log fuel system status. Then you can tell if you are in open loop or closed loop. During open loop, the o2 sensors won't adjust fueling if the fuel trims are cleared. Can you log TPS position? If the tps reads above 90% it activates flood clear iirc. That will cut all fuel during cranking. I'd also check fuel pressure and check for a vacuum leak. Going to need more data to diagnose properly.

Twentyhurtz

I believe i can log TPS with the ELM software and email it to myself - I will experiment with this.

What I mean by the truck won't start is that the truck appears to crank for about 2 seconds and then dies. It is not as if it is out of fuel and continually turns over, but simply cranks then dies - maybe that is a better description of what is happening.

Also, during my lunch break today I noticed that the CEL light turned off. Last night i took a risk of trying to clean the o2 sensor by spraying it with MAF sensor cleaner since I figured it was damaged anyways, and possibly the code just needed time to turn off as opposed to turning off immediately.

Even with the code now off the truck still feels like it is lagging pretty badly, I will gather more data.

Twentyhurtz

By the way Keysey_canard, I have been to Mountain View and I have to say that is the "whitest" place I have ever been!

Twentyhurtz

Sorry, I am thinking about Mountain Home, Arkansas.

kelsey_canard

iTrader: (5)

Yea mountain home is just down the road from here. Mountain view is even "whiter" than mountain home Bunch of retired folks here. If your ever around this way, give me a shout.