PCM Diagnostics & Tuning HP Tuners | Holley | Diablo

o2's acting strange

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Old Mar 8, 2008 | 08:07 PM
  #1  
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From: Athens, AL
Default o2's acting strange

Car has bolt-ons and a cam.

For some reason at idle both o2's randomly nosedive to around 30mv and
stay there until you stab the throttle. When this happens the car idles like its
missing. After you blip the throttle the idle settles back down and will idle
fine, then randomly the same thing happens again.

Bank 1 o2 has been replaced and the same thing still happens. Bank 2 will be
replaced but they had to order one.

I've posted a scan of this happening with the new bank 1 sensor. It happens
around the 3 minute mark.

Anyone know what would cause this?

I'm open to all suggestions and if there's anything else you would like to see
in a scan let me know, and I'll do it.

Thanks
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Old Mar 10, 2008 | 07:24 PM
  #2  
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From: HUNTSVILLE,AL
Default

Noone has ever seen this happen before???????
This is my car that is having the problem,and I would be VERY greatful,for any help...

Both o2s are new,and the problem is still the same.
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Old Mar 27, 2008 | 04:56 PM
  #3  
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Bump for some guys that need some advice lol.... Wish I could help..
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Old Mar 27, 2008 | 05:50 PM
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Didn't look at your scan, but Main cause for o2's to go limp at idle is your afr is off from stoich. I got the same issue, but only temporary as I'm trying to get inspected, then back to olsd.

Try to figure out how to get your o2's to control your afr at idle and should keep in line I would think, but I've not worked in CL in very long time so don't go by what I say.
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Old Mar 27, 2008 | 07:57 PM
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check the O2 sensor fuse. if the heater doesnt work you will have simmaler problems.
I had what sounds like the same problem on an 2002 vette and it was the fuse
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Old Mar 28, 2008 | 12:37 AM
  #6  
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Sorry I forgot to update this thread....

Once the maf is unplugged the problem goes away. It's
a ported maf so thats probably the cause of it.

Runs fine in SD though.
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Old Mar 28, 2008 | 12:38 AM
  #7  
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i changed all 4 of my o2s and it stil says they are bad...and it only comes on when i beat up my car and then go away 20 miles later...can anyone help

sorry to hijack
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Old Mar 29, 2008 | 01:46 AM
  #8  
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Originally Posted by Caspernicus
Sorry I forgot to update this thread....

Once the maf is unplugged the problem goes away. It's
a ported maf so thats probably the cause of it.

Runs fine in SD though.
That would explain some of it, but I would think you could tune the maf table...

o2s don't like to operate beyond stoich, they just go limp.
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