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LS guys, help?

Beerj

Sonzabitches!
Joined
Dec 7, 2014
Messages
3,721
Location
Amish Country
Bone stock lq4 here. Last trip out I developed a rough idle after taking a hard hit to the belly. Checked the codes and it's showing a dead o2 sensor, which makes sense. Haven't touched it in over a month but went to move it today and it's idling the same at cold start. I figured if it was on o2, it wouldn't act up until it went to closed loop. Codes are still just showing that bad o2, not even picking up a misfire and fuel pressure is about 62 lbs at the rails. Any ideas?
Screenshot_20210701-160200_Torque.jpg

 

Bebop

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Jan 27, 2013
Messages
1,732
It has a O2 code. Start by pulling the O2 readings and check if they're normal. If they're not, find where the problem is.

Also, look at what your long term trims. If they're pegged because of you running with a ****ed O2 reading for a while, they'll totally influence your fuel map, even in open loop.
 

Beerj

Sonzabitches!
Joined
Dec 7, 2014
Messages
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Location
Amish Country
It has a O2 code. Start by pulling the O2 readings and check if they're normal. If they're not, find where the problem is.

Also, look at what your long term trims. If they're pegged because of you running with a ****ed O2 reading for a while, they'll totally influence your fuel map, even in open loop.
I'm not sure I'm able to look at long term trims with my scanner/app. But you might be on to something with them being off. I'm wondering if with my limited resources, I replace the o2 and pull the constant 12v from the ecu for a while to reset things and see if it adjusts back to normal.
 

TMac

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GA
I'm not sure I'm able to look at long term trims with my scanner/app. But you might be on to something with them being off. I'm wondering if with my limited resources, I replace the o2 and pull the constant 12v from the ecu for a while to reset things and see if it adjusts back to normal.
I have a pretty basic amazon scanner and it’s LONGFT1 and LONGFT2 on mine under the data stream menu
 

Beerj

Sonzabitches!
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Messages
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Location
Amish Country
I have a pretty basic amazon scanner and it’s LONGFT1 and LONGFT2 on mine under the data stream menu
Gotcha. I'll have to do some digging tomorrow. I think I'll actually have the wife's yj ready for a shakedown run on monday so need to get the buggy addressed before then as well.
 

Bebop

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Jan 27, 2013
Messages
1,732
I'm not sure I'm able to look at long term trims with my scanner/app. But you might be on to something with them being off. I'm wondering if with my limited resources, I replace the o2 and pull the constant 12v from the ecu for a while to reset things and see if it adjusts back to normal.
I'll be available to talk tomorrow after 5pm EST. Call me.
And no, you need more than that.
 

Lil ugly

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Oct 6, 2011
Messages
676
Location
Jacksonville, Fl
A hard hit could easily damage the ceramics in an o2 sensor. Assuming you are only running 2 out of 4 sensors. Swap 02 sensors from left to right. If the code switches banks then you know that the sensor is bad.
 

Beerj

Sonzabitches!
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Dec 7, 2014
Messages
3,721
Location
Amish Country
A hard hit could easily damage the ceramics in an o2 sensor. Assuming you are only running 2 out of 4 sensors. Swap 02 sensors from left to right. If the code switches banks then you know that the sensor is bad.
I was just talking to Enzo a little bit ago. He said the same thing. I had already picked up another o2, figured it'd be a spare if nothing else. Swapped it in and scanned, no more codes. Haven't started it yet though, trying not to piss off the neighbors too much. Still haven't found fuel trims in my Torque Pro app but probably just need to keep looking
 

Beerj

Sonzabitches!
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Dec 7, 2014
Messages
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Location
Amish Country
Update!

So after swapping the o2 I let it run for a while. Didn't seem to make a difference. For the hell of it, decided to try again today. Just happened to notice something else though.
20210704_145110.jpg

Apparently, a large amount of air entering the intake AFTER the MAF can make it run like crap... I'm an idiot. Lol
 

Beerj

Sonzabitches!
Joined
Dec 7, 2014
Messages
3,721
Location
Amish Country
is your intake pipe broke or does it just not have anything to clamp to?
Not broke, just not a lot of straight part to catch the clamp on the top side. I had always planned on remaking it but until now, it's always worked fine. But definitely explains why it ran rough after the hard hit.
 

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