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Discussion Starter · #1 ·
I have a 2000 Isuzu Rodeo LS and for the past year or so I have been getting oxygen sensor codes such as fuel system too lean, fuel system too rich, PO157 and PO137 (these codes are low input in the post-cat sensors) just to name them off the top of my head. A while back I got a MAF sensor code so I changed that out but the problem came back. The problem is that I am basically playing musical oxygen sensors with my Zu. I first got codes for the MAF and oxygen sensors a year ago so I swapped out all 4 sensors. It worked ok for a while (emphasis on ok not 100%) but I got another code so I took it to a local mechanic and they swapped out bank 2 sensor 1. Everything was just ok again and it came up again when it was time to smog it this May and the mechanic changed out bank 2 sensor 2. I was only really embarrassed by this because I went on a run with the local 4x4 club on a pretty hard trail and could have made it given I had full power but because of this problem I only have about 80% power. This slight lack of power causes the auto transmission to 'hunt' for gears and force me to manually change it so it downshifts but it is especially bad going up hills. It idles just fine on startup and stays that way. I have researched this site and others to try to find a solution to this ongoing problem but I just cant pinpoint it but something tells me its not the oxygen sensors. If anyone could offer any help that would be much appreciated.

~ Kris
 

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If you've replaced all 4 and it did "ok" and a mechanic replaced 2 more that also did "ok" for a time and came back then you don't have a problem with O2 sensors. In fact sounds to me like they are doing their job and telling you there is an issue somewhere else.

I'd start with making sure your fuel delivery is normal and consistent. Also make sure there are no air leaks in the intake system anywhere. Do you know exactly what the MAF code was? As in the description not the number?
 

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Discussion Starter · #3 ·
I honestly cannot recall as that was May of 2010 and it only came up once.

I am suspicious of the a leak in the intake somewhere but it idles ok but sometimes when I give it some throttle it will rise 500 RPM, stop for maybe a quarter of a second and kind of sputter real quick then keep rising.
 

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Sounds like plugged cats or an intake leak...
 

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Discussion Starter · #5 ·
So I sprayed carb cleaner all around the intake manifold and got nothing. I didn't think that was the problem anyway. So I then turned my attention to the EGR valve. I removed it and sprayed it with some carb cleaner just because i'm basically trying anything now. I just got back from driving it 30 miles on road and about 5 off road and no CEL and it seems like a I have that tremendous power i used to have in 4 low. overall I am satisfied for now but only time will tell. My money is on the fact that something will come up again but oh well lets wait and see. I'll post updates every 100 miles or so to let anyone coming here know what is going on.
 

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Try the cats. Make sure they aren't clogged. If you can pull the exhaust off (I don't know about your truck) run something long through there to try to knock "it" loose. Then dump whatever it may be out before it has a chance to smack the O2 sensor! If that doesn't do it... I'm not sure where to go next.
 

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If it's cheap enough for you try to replace it, if not you can run a pipe through it and knock it around until all the insides fall out. That will have a small effect on noise, make it a little louder, but is the cheapest way. and not likely legal where you live.
 

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For it to send all those codes, there's something else going on... Post this in the drivetrain problems section and you'll get more help there...
 
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