need to pass DEQ!

You gotta Love these old VG30E/i powered beasts, raw truck DNA to the core.

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only_oneA
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Joined: Wed Jun 04, 2014 12:56 am

Postby only_oneA » Thu Oct 30, 2014 8:31 pm

ok, well i checked my o2 sensor with a true rms meter. what i found was that my
o2 sensor was slow. so i decided to remove it and clean it. i simply sprayed brake
cleaner on it and lit it on fire a couple of times. i threw it back on and the tested it again. now my o2 sensor is jumping voltage up and down like it should. before it was going to about .8v and maybe after about 5-8 seconds it would come down to about .2-.3v. then it would stick there for about another 5-8 seconds before jumping back to about 8v. after "cleaning it" its now fluctuating between
-.2v i think it was to about +.4-5v and rapidly. i also replaced the fpr hose. i then took it in to deq again and it failed of course. but on a good not the hc dropped to about 398. then after the rev up it dropped down to 353. the numbers before this change was about 700, and 522. so i then went ahead and smoke tested the motor and immediately saw the egrc-bpt valve leak like crazy.
so im thinking about just blocking the both lines that go to that vlave. seeing as how the egr is still there i figured this might help me pass. i just need to pass then ill through a good one back in eventually. is this a good way to by pass the valve? or should i connect the lines together? they dont look under the hood so im really not worried about them looking at it.


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smj999smj
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Postby smj999smj » Thu Oct 30, 2014 10:29 pm

I don't think a smoke test is the proper way to test a BPT valve. It does act like a vent, so seeing smoke come out of it during a smoke test would make sense. There's a vacuum test in the service manual to component test the valve. My bigger concern would be the O2 sensor; the readings you are seeing are too low. Normal range for an oxygen sensor usually range between 0 volts and up to 1.1 volt. If you are seeing -.2 volt, that's a problem as oxygen sensors produce voltage, so they should never give a reading less than 0 volts. Personally, I would replace the sensor. Also, when doing emissions testing, it's best to do the testing after a good ride so that the exhaust is good and hot. One of the problems with the old Pathfinders---and not just Pathfinders, but many older vehicles in the '80's---is that the oxygen sensor is pretty far down the exhaust (late model vehicles have the front oxygen sensor in the manifold or close to it in the front pipe). The sensors also do not have built-in heaters like modern sensors. Oxygen sensors work best when they are hot, so having the testing done immediately after you drive it there is a good time to test the emissions.

only_oneA
Posts: 18
Joined: Wed Jun 04, 2014 12:56 am

Postby only_oneA » Thu Oct 30, 2014 11:32 pm

ok yeah i just saw the procedure to test the valve. i guess you apply pressure to the bottom and then suck from one of the top nipples while the other is plugged. it does test out good as i suck there is no air flowing through the one i am sucking through. yeah, i thought it was weird that it was going into the
negative. i ordered the o2 sensor and plan on changing it tomorrow. but unfortunately i dont think ill be able to take it in to get tested until Saturday. i am how ever making sure to take it in while its nice and hot. i make sure that the cat temp is at about 450. i figure at that point its probably not going to get a whole lot hotter. it tends to fluctuate from 450 up to about 490. guess ill let you know when i get it tested again.


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