No 02 sensor response on 2 LS swapped Vehicles

[Mobile Chassis Dyno]

Cliffs - Both vehicle wiring harnesses have been checked pin by pin and mulitple 02 sensors have been used in trying to diag this.


One vehicle is a 72 nova with a truck wiring harness from tech rods and a F body PCM. The other vehicle is a 98 vortec truck with a 6.0 L and wiring harness out of a 2003 LS truck.

Nova - I have tried a 02 F Body - 01 F body - 02 Silverado OS's as a starting point.

Truck - 02 F Body and 02 Silverado

All tunes have had VATS turned off. As far as Beta I am using 2.23.571

Both vehicles running show aproximately 450 mv with the key on. Just like when you have the 02's unplugged.


The nova swap does do a little something different then the truck swap. On the nova if you take the 12 volts going to the 02 sensors away they will read in the scanner. Less then 100 mv when the car has sat for sometime and over 600 mv's if the car was running. Introduce power to them again and they go back to 450 mv.

The truck reads 450 mv regardless.



My question is could turning Vats off in the tune cause the 02 sensors to be stuck at 450 mv's? I have never seen this before with a swapped vehicle.

Both customers are a drive and my next idea is to try a using 2.22 instead of a beta to see if anything changes...

Please advise.


In the 6 years that I have been tuning with HPT I have never seen this before.....

[Bill@HPTuners]

Turning off vats wouldn't cause the o2's to be stuck at 450

[Mobile Chassis Dyno]

Turning off vats wouldn't cause the o2's to be stuck at 450

I agree.

However I can not figure out why both of these cars have 02's that do not work. The truck 02's were pulled and put into a hummer and they work fine. The guy working on the truck has been swapping LS transplants for several years. The only common denominator between the truck and nova is I am the one who has flashed them. Could it be a beta issue changing something to the binary that it writes? I remember something about beta changing VATS with the 3800 at one point.

Any ideas on where to look is appreciated. I think I may try flashing a pcm with the EASE hardware with a stock tune based on vin and turn the key on and see if the 02's read.

[Bill@HPTuners]

Highly unlikely to be a software issue.

If I remember correctly I think if you set the o2 DTC's to no error reported it might make the reading stay at 450, I think I had ran some tests on this years ago...

[Mobile Chassis Dyno]

At this point Bill I want to be able to be sure for these guys that it is not a HPT issue. I have never seen anything like this in the 6 years that I have been using it.


Please Advise.

[Mobile Chassis Dyno]

Highly unlikely to be a software issue.

If I remember correctly I think if you set the o2 DTC's to no error reported it might make the reading stay at 450, I think I had ran some tests on this years ago...

Only o2 dtc's disabled are the rear o2's. On both vehicles I tried flashing in stock OS's with just the Vats disabled and the IFR scaled so it would start. To the best of my knowledge the OS's being used are totally stock.


What makes me think it is not an HPT issue at least for nova is I used another 3 bar tune from another car I did just last month with the same Beta and had no 02 issues with it. All I did was scale the injectors for 160's instead of 80's and turned off vats to start the car. This is when I found the 02's with no response.

[Mobile Chassis Dyno]

One last thing for now.

Nova is saying he found some posts on another LS forum talking about 02's not reading after being flashed with HPT. He is at work now and does not have internet access. Waiting on him to forward the links to me in the morning.

[acehaag]

I had this same problem when I first wired my truck. I needed to add a ground to pin 63 in the blue connector and tie it to the tan wires at 26 and 29 in the blue connector.

[acehaag]

and an 03 truck pinout will not be correct for an 02 and earlier silverado tune and pcm