Pump or O2?

jeepfiend

Well-known member
Apr 20, 2004
110
0
Southeast Idaho
Some of you may recall from the old board, I was having som fuel pressure issues on my '97. I have gotten repeated O2 and knock sensor errors. Now the problem mainly surfaces once the tank is below 1/2 tank. I have had lean conditions and rich conditions within one day of each other. My question, it appears that only one sensor is faulting out, the bank 1 sensor 1, could this problem be more the O2 than the pump? I have already purchased a pump so it is somewhat a moot point for the pump. I have 110k on it, so I am sure the pump needs to be replaced anyway. Do you think this O2 could also be bad? I really don't want to do the pump and have the light come right back on (this would not please the wife!). I have seen some universal O2's for $45, has anyone used one of these or are they just a pipe dream? They claim you just wire the disco pigtail on and go. After dropping the $250 for the pump, I am not so sure the wife will be too pleased with another $150 for the sensor.
Don't be offended by the user name, it is just the name I have on every other board I am registerd with. Formerly, my user name was Kris Carlquist.
Thanks,
Kris
 

Joey

Well-known member
Apr 19, 2004
976
0
Liberty Township, Ohio
Kris, first off I tried the Pipe dream, the $45 O2 sensors do not fit a Disco at least not a '97. Unless you have found one someplace other than where I looked. The Disco takes a 12mm vice a standard 18mm O2 sensor.

Have you tried using a good OBDII reader that can monitor what the O2's are acually reading, or are you just using a code reader? If just a code reader, it would be worth either going to someone who has something a little better or dare I say it, go visit the dealer and have them check your Disco with the Testbook.
 

jeepfiend

Well-known member
Apr 20, 2004
110
0
Southeast Idaho
My software will graph the O2 readings, it will do each sensor individually, and I can even graph two at a time to compare. It seems that sensor 1 bank 1 is the only one that is responding slowly, at least consistently (I always get the slow transition time error on 1 first). When I have it plugged into the computer, they will all respond slow at first, but 1 is the worst. The fuel pressure has been all over the place. At startup it is 30, barely. After it is warm it drops to 28 or so and then if it is below half tank, it will drop to 26 or 27. I have ordered a gauge that I am installing on the plenum so I can get a better reading. What is odd, once I pulled plugs, and they were all chalky white (lean), this time I also had both knock sensors out of range. The next day I pulled plugs again, all rich, but the fuel pressure was still low. I need to look at the O2's again and see what they are doing. I have to suppose that the pump is bad, just because of the fuel pressure. I have replaced the filter, could it be the pressure regulator? I actually found a place that had the advanced evap pump for $243, so with shipping it was just over $250. All in all, not a bad deal. I was really surprised, but AB had the next best price. I will have to look again and find the $45 O2's I am sure it is too good to be true, but it is nice to dream. I did find another place that had them for $95 and you again had to reuse the stock pigtail. I just hope I can avoid the $160 on the O2. If I drove the rover more, it would not be a problem, but it really aggravates my wife to have the CE light on all the time. I am going to replace the pump no matter what, it has almost 110k on it, and I hear that is pretty close to the lifespan of a Disco pump. I am pretty much considering the pump as preventive maintenance, but I don't want to turn around and have to do an O2 as well.
Thanks
Kris
 

jeepfiend

Well-known member
Apr 20, 2004
110
0
Southeast Idaho
Okay, a little update, mostly for information. I replaced the pump, sadly, no pressure change. What next, the regulator. Now before you all say, of course you dummy the regulator costs less, why not replace it first? When I bought the Discovery, I was told by the salesman, at the dealer, they had just replaced my regulator and fuel rail, so I did not look at the regulator. Come to find out, the saleman lied, surprise, surprise. The salesman no longer works for the dealer, but I did find out that something was replaced before I bought it, the valves. At least I have the new carbon breaker valves. Knowledge I wish I would have had prior. In hindsight, I should have dead headed the return line to really see what kind of pump pressure I had, it would have saved me the cost of the new pump. I don't feel too bad about it though, I understand most of the Disco pumps die around 100k anyway, and I already had 112k.
 
A

anthony

Guest
thats about right on the
pump. mine went out @ 107k, neighbors went out @ 111k. just think of it as prevenitive maintenance...that is preventing yourself from a potentially long walk out a trail somewhere!

good luck