PLX Wideband/O2 sensor EIO issue

[RX-Ben]

Hello. I've installed a PLX-250 with the gauge on my LS1. The gauge hops around to different readings as it should, but HP Tuners logs a constant 12.65 AFR. (I hooked up the wideband out put from the PLX box to the white wire on the EIO interface, then configured input one as a PLX).

I then hooked up the narrowband output to the purple wire (signal) for O2 sensor that the wideband replaced. However, the dash display shows that this O2 sensor is disconnected (it always reads around 450mv)

Here is another problem- when I check out the ST and LT fuel trims, all the trims are at zero. How amazing! Especially considering that the car is untuned! I do have a C5 rear O2 sensor installed on the passenger's side (I'm using long tube headers).

I have the PLX box grounded with the EIO box, which grounds to the chassis (at a seperate place than the PCM).

How can the wideband gauge work fine, but HPTuners logs that same wire as a constant voltage? And what is up with the fuel trims??

I'm slated to get tuned this week for a big race next week (One Lap of America) so any help is greatly appreciated.

Thanks!!!!!!!!!!!!!!
Ben

[horist]

if you're getting an SES for a bad O2, then it'll stay running open loop and won't even try doing an LTRIM learn (since O2 sensors aren't used in open loop and are required for closed loop operation)

Have you measured the voltage w/a volt meter coming out of the wideband? (the wire you plug into HPT) ? If it's sitting at a steady voltage then the problem is w/the wideband hookup ... Never used that one so not sure what all is adjustable on it

[RX-Ben]

I'll check the voltage for the O2 sensor going into HPTuners. I would've done it already but I had to drop the car off at a bodyshop.

I wasn't getting a code for any O2 sensor, from what I remember, but I could be wrong. I think one of the tables in the base tune I got is keeping the system out of closed loop mode which might explain this.

I'll re-check all the wiring. see if HPTuners will log just the voltage input, and give PLX a call and see what they say.

Thanks- getting help around here is as easy as I'd hoped when I bought the software
Ben

[RX-Ben]

Also- nothing is adjustable on the PLX (or at least the M250 that I have)- it just has a wideband output and a narrowband output.

Ben

[sspeedracer]

I then hooked up the narrowband output to the purple wire (signal) for O2 sensor that the wideband replaced. However, the dash display shows that this O2 sensor is disconnected (it always reads around 450mv)

You need a load resistor in place or the VCM will flag an O2 fault. I suggest not screwing with substituting the WB O2 for the stock NB O2. Weld an additional bung and use both.

[RX-Ben]

Sage advice, thanks. I just happen to have to drop the exhaust system and I'll weld on an additional bung.

Ben

[BQuicksilver]

Are you sure you're logging the WBO2 in the correct slot on the table? Look at the help file, you have to log the WBO2 in the corect box. this sounds like the problem i had with my PLX M250, it worked perfectly once I set it up right.

BTW, I also added a separate bung for it.

[RX-Ben]

That was the problem- I found that the O2 voltage was correct and it was going into the correct wire, but turns out that I was one "slot" off on telling HPTuners which input to log. I corrected the problem only to have a lifter roller lose its needle bearings and destroy the engine.
Oh well.....

Ben