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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need to pass DEQ!

Postby only_oneA » Wed Oct 22, 2014 8:40 pm

so as the title says i need to pass deq, im on my last trip permit. so to start of i have gone in to deq twice. the first time it failed, hc were at 569 at idle limit is 220. after revving it up to 2500 rpm it dropped to 732. so i took it home and checked ignition timing. it was at 30 btdc, so i properly adjusted it to 15 btdc.
which please correct me if im wrong is the third mark from the left. i also replaced the thermostat with a nissan oe one. the one that was in there before
was a autozone one. but the lower radiator hose never got even warm, and my coolant gauge would only stay at 1/4 which is why i replaced it. gauge still only stays at about 1/4.
so i went in again today to deq. once again it failed, this time at idle it was at 642, and after 2500rpm 531 once again limit is 220. it does have a code 34 (knock sensor fault). so im just wondering if there are any tricks that i can do to make it pass. or do i have to fix that code 34? the next step i was thinking about was check the knock sensor and replace as needed. also maybe seafoam? oh and i guess clean the maf. the truck runs awesome does not stubble, no missfires from what i can tell. it idles nicely at about 750 800ish.
let me know what are your thoughts. not sure what else there is that i can do, any help would be greatly appreciated. thanks in advance really anything helps. so let me know whats up. oh yeah its a 95 v6.

things i have done to it:
timing belt
water pump
thermostat
cam seals
crank seal
valve guide seals
head gaskets
valve cover gaskets
spark plugs
spark plug wires
dist cap
dist rotor
fuel filter
recharged the k&n filter
oil change
pcv valve


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smj999smj
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Postby smj999smj » Wed Oct 22, 2014 8:57 pm

When was the last time the oxygen sensor has been replaced?

only_oneA
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Postby only_oneA » Wed Oct 22, 2014 9:14 pm

not sure i bought the pathfinder about three months ago with no record of anything. but seeing as how everything else looked i would say its mosty likely
the original one. wouldnt it through a fault for the o2 sensor if it was bad though?

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smj999smj
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Postby smj999smj » Thu Oct 23, 2014 2:26 pm

Not necessarily. If the sensor had an open circuit, or was shorted, it would likely set a trouble code. If it was reacting slowly or reacting with a lean or rich shift, probably not. You have to remember we're dealing with OBD I; it was state of the art when it came out, but a bit crude by OBD II standards. If you think the oxygen sensor is original, then it's time for a new one being almost 20 years old. I would also check the fuel pressure and make sure it's within spec. If the regulator is bad, it will cause the excessive fuel pressure and a richer mixture. The knock sensor will not cause excessive emissions. When it detects a knock, the ECM will read the signal and retard the timing slightly to try and prevent engine damage. Since your emissions are so out of whack, it could be setting a knock sensor code in reaction to the problem that is causing the high emissions. So, I would fix that problem first, erase the code, then see if it returns. The knock sensor is under the intake manifold, so it's no easy job to replace. Many purchase a 95 Maxima knock sensor and subharness and relocate the sensor to the top side of the intake, rather than teardown the top of the engine.

only_oneA
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Postby only_oneA » Thu Oct 23, 2014 6:09 pm

k cool, is there any way to test the o2 sensor? i have a dvm but its some cheap one not a true rms meter. yeah i have heard of that whole
relocating of the knock sensor. although i have not looked to much into it, maybe i should start thinking about it. thanks alot for the feed back by the way
i really appreciate it. especially since my trip permit expires on the first of November.

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smj999smj
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Postby smj999smj » Fri Oct 24, 2014 1:04 pm

There are a number of checks you can do. There is a component check, requiring to use an ohmmeter to test the resistance of the sensor at a given temperature. There was also a way to test it using the LED lights on the ECM in mode II. I would suggest you refer a factory service manual. Me, personally, would just get an NTK oxygen sensor (the OE manufacturer of the original part) from Rockauto.com for $35+shipping.

only_oneA
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Postby only_oneA » Fri Oct 24, 2014 8:48 pm

hmm well i have done mode 1 which is checking the o2 sensor i believe. it blinks fine with the five times with in ten seconds. but i think it does take just a little longer from the first blink to the second. however it still blinks the right amount of times in the specific time limit. i also tryed mode 2 which is checking the fuel and air mixture. which both lights blink simultaneously, i believe that is good right? also i checked the o2 connector last night and did find some corrosion on the power side of both the harness side and the sensor
side. but i did a voltage drop from the power on the harness side to a good ground. it was good at 12v. i just dont want to through a sensor at it if it turns
out to be a cat or something else. im thnking maybe the cat as well. it is after all the original cat for sure. i been looking into it and how to test it. people have been saying you can test it with a infrared thermometer before the cat and after. do you by any chance know anything about this?

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Postby smj999smj » Sat Oct 25, 2014 9:01 am


only_oneA
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Postby only_oneA » Sat Oct 25, 2014 4:03 pm

well i checked the cat temp and its at about 350-360 at the front weld, and 360-370 at the rear cat weld. so im guessing its ok. although i believe they were saying on the video that it should be about 100-150 degrees hotter then the front. would the test i performed with the ecm be valid ones for checking the o2 sensor? also today i did hear a little bit of a chatter from the right bank.
it was definitely an top engine chatter like the rocker arms or something. you think this might have an effect? and should my temp gauge go to half way? mine only gets to about 1/3. im kinda thinking about cleaning the corroded o2 sensor connector at the ecm harness and just replacing the o2 sensor. but im just afraid that it wouldn't fix it, and ill just be dumping money into unneeded parts.

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Postby smj999smj » Sat Oct 25, 2014 6:35 pm

Hydraulic lifter tap can occur on these engines over time, as well as a "clicking" noise from the exhaust manifold gasket when the exhaust manifold studs breaks, which is very common, especially on the right side bank.

The temperature gauge should read in the middle of the gauge. Aftermarket thermostats can tend to make the engine run a little colder that genuine Nissan thermostats, by my experience. Could also be a slightly stuck open thermostat or an inaccurate gauge reading. Best way to check would be to use a thermometer in the coolant. You'll want to see something close to 175-185 degrees F.

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Postby only_oneA » Sun Oct 26, 2014 1:23 pm

So high hc is from running to rich/ incomplete combustion right? So then a leaking fuel line that connects the two fuel rails would not cause high hc right? I also noticed that one of my coolant hoses is some what pinched. Its one of the two L shaped hoses. The ones that connect to the heater core pipes. I had to replace it when i did the head gaskets. So i figured regular hose would do it. I dont know if there is a lot of pressure back there or not. But i figured it couldnt be to much. Oh and i kinda hear a hissing like sound, like a vacuum leak. way in the back near the fire wall. I tryed move my hand back and forth to see if i could feel anything or make it louder by disterbing something. But no luck, any ideas on what it could be? I also removed the hose from the fpr and plugged the intake manifold end and the fpr. But i was still able to hear it.

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Postby smj999smj » Sun Oct 26, 2014 2:40 pm


only_oneA
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Postby only_oneA » Tue Oct 28, 2014 6:43 am

so little bit of an update. I found a thread that talked about people cleaning out there egr valves. So i figured what the hell its the only thing i have not looked into. So i riped the egr off along with that valve that sits on top of it. Found that the egr valve was pretty clean not much of any build up. Then i remembered some one saying something about the bracket that holds up the othere valve up. If you remove that bracket you will see its not just a bracket. Its also a passage for the egr gasses to flow through. So i removed that and sure enough it was completly clogged, completly couldnt see light from one end to the other. So i cleaned that out along with the egr port to the manifold. I also tested both valves and both are in working order. Also checked my plugs and found they were red, i guess from the fuel addative i had in there. I plan on cleaning them up, and throwing them back in. By the way they are some iridum ngk plugs, not sure if these are ok on the pathfinders or not. Then ill take it to deq again, iguess if this doesnt work, then ill throw a o2 sensor.

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smj999smj
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Postby smj999smj » Tue Oct 28, 2014 10:42 am

The fact that you're using Iridium plugs is not an issue as long as it's the correct plug, which in NGK would be the BKR6EIX.

only_oneA
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Postby only_oneA » Tue Oct 28, 2014 3:35 pm

So i went again today and it failed again. Cleaning out that port made no difference. 695 at idle then after reving it up it went down to 522. I also checked my plugs and they are the platnium ngk bkr6egp.


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