2001 LQ4 not entering closed loop

[5.3LS10]

Hi everyone,

I have a 2001 LQ4 that has been swapped into an older car. It runs fine except that it never enters closed loop. I have checked over the MAT vs CLT table and have made sure that both CLT and MAT sensors are reading fine and are in the correct range where it should be entering closed loop.

Engine is completely stock with no modifications done besides disabling rear 02 sensors, CAGS, EGR, etc...

From what I can tell the fueling is almost dead on as is and the O2 sensors are reading very consistent. The rear 02 sensors have been deleted and COT has been disabled.

If someone could kick me in the right direction I would really appreciate it. I did not know about the option to force closed loop in VCM scanner so next time I am working on it I will try it and see what it does but did not try it during the datalogs.

I am still very much a novice with HPTuners so feel free to point me in the direction of any documentation or reading that may help explain what I need to change to fix this problem.

Thanks!

[5FDP]

The o2 sensors might read consistant but they are reading that way because they have a major problem with them.

450mv is a dead give away that you have no power to the o2 sensors, it will never enter closed loop when they are not switching around. They would be bouncing lean and rich of 450mv (stoich) all the time. You have a wiring problem on your hands or something. It will run in open loop forever until that is fixed.

[5.3LS10]

The o2 sensors might read consistant but they are reading that way because they have a major problem with them.

450mv is a dead give away that you have no power to the o2 sensors, it will never enter closed loop when they are not switching around. They would be bouncing lean and rich of 450mv (stoich) all the time. You have a wiring problem on your hands or something. It will run in open loop forever until that is fixed.

Wow I guess I overlooked that big time....

Thank you very much for your time. I will trace down the wires now and see where the issue is.

[5.3LS10]

Hey everyone,

I finally had some time to go back around to this project and after looking around I found that I DID indeed wire the O2 sensors wrong.

I did not realize that the isolated grounded 01-02 6.0L had a different wiring diagram.

I had the o2 sensors wired to a case grounded 4.8/5.3 setup.

I have since fixed the wiring (also purchased new o2 sensors incase I ruined the old ones) but am still having the same issue.

I still seem the same ~500mv for both O2 sensors. If I force the scanner into closed loop it runs okay for a little bit but then keeps getting worse and worse as do the STFT and LTFT which would be expected if it is correcting off of incorrect O2 readings.

Any ideas what is next?

My O2 sensors are wired like this.

S1B1
Pins:
A: Blue 29
B: Blue 69
D: Red 74
E: Red 80


S1B2
Pins:
A: Blue 26
B: Blue 66
D: Red 74
E: Red 80

All input appreciated.

Thanks!
Shane

[5.3LS10]

Bump anyone have any ideas where to look next?

[Earwax]

Here are the schematics for the o2s. 02 6.0 used 2 different wiring diaghams

https://gsi.ext.gm.com/gsi/showDoc.d...770062&from=sm

https://gsi.ext.gm.com/gsi/showDoc.d...770053&from=sm

[85K5Jake]

Here's a diagram I followed I had the same problem. The tan wires all need to be together and going to the correct pin on the pcm connector. When you read the dtcs with the scanner, the o2 sensors will say incomplete or complete. Complete means you wired it correctly. I believe the tan is a ground from the pcm that you need. http://lt1swap.com/01_6.0_case&isolated.gif

[5.3LS10]

Here's a diagram I followed I had the same problem. The tan wires all need to be together and going to the correct pin on the pcm connector. When you read the dtcs with the scanner, the o2 sensors will say incomplete or complete. Complete means you wired it correctly. I believe the tan is a ground from the pcm that you need. http://lt1swap.com/01_6.0_case&isolated.gif

Hmm I think I might have missed pin 63 that goes to pin A on both connectors. Let me double check that all 5 connections are all tied together

[5.3LS10]

Here are the schematics for the o2s. 02 6.0 used 2 different wiring diaghams

https://gsi.ext.gm.com/gsi/showDoc.d...770062&from=sm

https://gsi.ext.gm.com/gsi/showDoc.d...770053&from=sm

Hmm the links are not working for me. Also it is a 2001 not 2002

[5.3LS10]

Here's a diagram I followed I had the same problem. The tan wires all need to be together and going to the correct pin on the pcm connector. When you read the dtcs with the scanner, the o2 sensors will say incomplete or complete. Complete means you wired it correctly. I believe the tan is a ground from the pcm that you need. http://lt1swap.com/01_6.0_case&isolated.gif

It's fixed!! Pin 63 was not connected. Hooked it up and as soon as it was up to temp it went straight into closed loop.

Thank you for the help!!

[85K5Jake]

Glad I could help