Replaced Upstream O2s - Now A Question...
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From: Eastern TN
Replaced Upstream O2s - Now A Question...(Updated)
2004, 6 lb. lower, Magnaflow cat back, JLP intake, Accufab, FTVB, etc.
405/520 on a Mustang Dyno tune from Sam @ Coastal Dyno.
Truck has 92,000 on her and I have been watching the mileage slowly decline over the past 9 months or so.
I always fill up at the same station, always around 22 gallons to fill up. I have noticed that my mileage has slowly decreased between fill-ups.
I normally get around 320 miles per tank, mixed use driving. I am now getting around 290. This trend has been going on since around May of '08.
I've also had a kind of miss when I get on it hard to merge on a Interstate. Not from a dead stop, more along when you are going 50 or so and need to step it up to 75, without downshifting. The truck just didn't pull like it used to.
Anyway, I decided to replace the upstream O2s today. 20 minutes getting the truck on stands and gathering tools, 20 minutes doing the driver side, 65 minutes doing the passenger side. I could shoot the guys who decided to put that baby where it is !!!
Anyway, the 50-75 MPH miss is gone and the truck seems more responsive and it idles smoother.
This leads to my question - should I go ahead and replace the downstream O2s ? It's only $100 or so for the parts, but if it won't gain me anything I would rather not do it.
Advice or suggestions ?
TIA...
Merry Christmas to you all !!! :santa:
(Update)
I took her on a long drive yesterday - stop and go, country road 50MPH cruising and a couple of 75+MPH blasts on the Interstate.
All I can say is Wow !! I should have done this 20,000 miles ago. She pulls and runs like she did back when she was younger and the mods were new...
Just thought I would share.
BTW - The rear O2s were turned off in my tune so I don't need to think about those anymore.
405/520 on a Mustang Dyno tune from Sam @ Coastal Dyno.
Truck has 92,000 on her and I have been watching the mileage slowly decline over the past 9 months or so.
I always fill up at the same station, always around 22 gallons to fill up. I have noticed that my mileage has slowly decreased between fill-ups.
I normally get around 320 miles per tank, mixed use driving. I am now getting around 290. This trend has been going on since around May of '08.
I've also had a kind of miss when I get on it hard to merge on a Interstate. Not from a dead stop, more along when you are going 50 or so and need to step it up to 75, without downshifting. The truck just didn't pull like it used to.
Anyway, I decided to replace the upstream O2s today. 20 minutes getting the truck on stands and gathering tools, 20 minutes doing the driver side, 65 minutes doing the passenger side. I could shoot the guys who decided to put that baby where it is !!!
Anyway, the 50-75 MPH miss is gone and the truck seems more responsive and it idles smoother.
This leads to my question - should I go ahead and replace the downstream O2s ? It's only $100 or so for the parts, but if it won't gain me anything I would rather not do it.
Advice or suggestions ?
TIA...
Merry Christmas to you all !!! :santa:
(Update)
I took her on a long drive yesterday - stop and go, country road 50MPH cruising and a couple of 75+MPH blasts on the Interstate.
All I can say is Wow !! I should have done this 20,000 miles ago. She pulls and runs like she did back when she was younger and the mods were new...
Just thought I would share.
BTW - The rear O2s were turned off in my tune so I don't need to think about those anymore.
Last edited by B-Man; Dec 25, 2008 at 08:46 AM. Reason: Additional Info
Member
Joined: Jan 2005
Posts: 78
Likes: 0
From: South Florida
O2 sensors are not used at wot. They can definetaly cause mpg issues. I would check your plugs and cop's. Just a thought but My milage has gone down as well with the addition of the 10% ethanol deal. I would throw a set of tr6's on her,change the fuel filter and see how she acts. I would not replace the downstream o2's. Good luck
Ryan
Ryan