2005 3.5 colorado goes into OL fail

[bk2life]

I think i have narrowed it down to an intermitant bad 02 sensor.

is there a way to test and actually see if the 02 is bad/going bad, or if there is another issue that is turning the 02 sensor off?

This happens at almost any time cold start, warmed up, 30 mile drive etc. When ideling itll be fine, then go into a 'raspy' idle like it has a big cam, and goes into OL failed mode for 10 seconds or so, then CL smooths out.

I can see on the chart/graph when it switche to OL and back to CL.

Everything looks fine, so id like to pinpoint the issue, before spendng money on a new 02 sensor.

thank you for any help

[blindsquirrel]

With the experience you've gained from making 290 posts here, do you think that maybe it would be a good idea to post a log file showing the thing you describe happening?

[blindsquirrel]

Current prices:
NTK 21054: $38.79
DENSO 2344119: $41.79
GM GENUINE 2131570(almost certainly a reboxed NTK or Denso): $46.79

For that amount of money, I'm not sure how much time I would waste on chasing after intermittent ghosts.

[bk2life]

With the experience you've gained from making 290 posts here, do you think that maybe it would be a good idea to post a log file showing the thing you describe happening?

lol, come on man, got to keep you going on with stuff.
I posted that, and later i thought, sh*t, i didnt upload the files, I'm going to get flamed for that.

You didn't let me down, thank you.

[bk2life]

here

2nd.hpl

[blindsquirrel]

Doesn't look like a dead/dying O2, those typically will go open circuit and sit at the default ~450mV. It looks like it's reading an actual lean condition. Internally shorted to ground will typically be much lower voltage than yours goes to, like 5-10mV.

Have you looked into the P0449? May seem unrelated, but then there's that rule of 'fix the obvious problems first'.

That said, if the upstream O2 is old or of unknown age, it's almost never a waste to replace it as a matter of routine maintenance. They do wear out over time.

[blindsquirrel]

It looks like the FTC changing between 17 & 37 could be related... 17 is Idle EVAP (purge) Open and 37 is Idle EVAP Closed.

[blindsquirrel]

Um... why is the coolant temp stuck at -40* for the entire log? Is that some scanner/PID weirdness?

[bk2life]

Have you looked into the P0449?
That said, if the upstream O2 is old or of unknown age

not sure why that code is back on, there is no evap canister or valve. This is all swapped into a pre emissions vehicle.
O2 sensor just turned 110k last weekend.

[bk2life]

Um... why is the coolant temp stuck at -40* for the entire log? Is that some scanner/PID weirdness?

yes weirdness, ill upload another scan

[bk2life]

17 is Idle EVAP (purge) Open and 37 is Idle EVAP Closed.

how did you know this? is there a chart or something i havent seen?

[bk2life]

longer scan

balzer 1st.hpl

[blindsquirrel]

Fuel Trims LS1 V8
0 - 15 defined by the LTFT RPM and MAP boundaries
16 - Idle PN (AC on)
17 - Idle PN (AC off)
18 - Idle InGear (AC on)
19 - Idle InGear (AC off)
20 - Idle (EVAP closed)
21 - Coastdown (EVAP closed)
22 - Non-Idle (EVAP Closed)

Usually EVAP closes at WOT hence cell #22 is mostly used at WOT, but you will see it used during warmup (before evap purge begins). At WOT you will also see cell #15 if the EVAP purge opens (ie. vacuum drops enough for the purge to begin).


Fuel Trims LS2/LS7/L76, Cobalt SS 2.0L s/c and other later model vehicles that use RPM/MAP boundaries
The LS2/7 and others have more cells but follow a similar pattern to the LS1:

EVAP Open
0 - 15 defined by the LTFT RPM and MAP boundaries
16 - Idle PN (AC on)
17 - Idle PN (AC off)
18 - Idle InGear (AC on)
19 - Idle InGear (AC off)
20 - Decel

EVAP Closed
21 - 36 defined by the LTFT RPM and MAP boundaries
37 - Idle
38 - Decel


Fuel Trims later LS3 and other later model vehicles that use Airflow Mode boundaries

EVAP Open
0 - 5 defined by the LTFT Airflow Mode Purge On boundaries
6 - Idle
7 - Decel

EVAP Closed
8 - 13 defined by the LTFT Airflow Mode Purge Off boundaries
14 - Idle
15 - Decel


Fuel Trims V6 vehicles
0 = Idle
1 = Decel
2 = Light Load / Engine Not Running
3 = High Load

[blindsquirrel]

If there is no more EVAP stuff, and P0449 hasn't been set to No Error, what else hasn't been set to No Error? Is there a purge valve?

[bk2life]

Is there a purge valve?

no, blocked off.

This is/was a mailorder 'tune' that was done several years ago.

If you remeber when i first came back on here, i was very green as i forgot lots, and needed to learn tuning again.

Since then, i have re claibrated 2 of my vehicles, and the third, this one, i am starting on. Obviously i cant go forward until the cause of this idle is found.

And as i have stated before, I do appreciate all the help and suggestions you provide.

-james

[blindsquirrel]

Unfortunately, that log isn't exactly useful - no O2 PID being logged.

[bk2life]

Unfortunately, that log isn't exactly useful - no O2 PID being logged.

weird how things show incorrectly, or not logged (ie temp)

[blindsquirrel]

Have all those blank spaces in the log been added at random, or are you trying to record that many channels and some of them just don't show up?

[bk2life]

Have all those blank spaces in the log been added at random,

channels from a different 'log', the blank spaces aren?t compatible with this ecm.

scanner.jpg

[bk2life]

here is another scan, roughly 10 mile trip.
i went through the diagnostics and turned off (no error) several things that should have already been turned off


sherwin home.hpl