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1995 Nissan Quest Question: I replaced the knock sensor on my van.. after that is has been running like crap

 

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damnvillager, 3.0L V6, Vallejo, CA, September 27, 2012, 14:52
 Rookie

It's throwing a lot of smoke... sometimes when i first start it it doesn't blow any smoke, after a while of revving the engine it starts running rough and smoking heavily.. I'm really at a loss.. only 100,000 miles I think it may have to do with the fuel injectors as i don't see a cause from anything else.. No blow by gasses from the oil filler the engine sounds good... no knocking.. would clogged injectors cause excess smoke and poor idle? Undrivable in it's current state.. i know it has got to be something simple. PLEASE HELP!

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  • Answer #1

    pushrod September 27, 2012, 17:31
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     Master

    HAVE A COMBUSTION LEAK TEST DONE. IS IT SMOKE OR STEAM THAT YOU SEE?
    LOOSING ANY FLUIDS? DON'T SEE HOW IT IS RELATED TO KNOCK SENSOR.

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    damnvillager, September 27, 2012, 18:28
     Rookie

    Thank you for your response,

    I may do a combustion check.. the car seems to run well though aside form a slight miss. It's not steam that's coming from the exhaust.. it stays in the air a long time. It's a gray smoke.. it had smelled like burned oil but then I changed the pcv valve and hose (hose was cracked) Now it doesn't smoke as much and doesn't really smell like burning oil anymore ( last time i took off the intake it had oil in the first two ports on the phlenum). I don't see what the knock sensor has to do with it either. It ran well before I changed the knock sensor.. I was thinking maybe theres a broken wire or something in the harness.. I don't know what I could have done to make it run so poorly.. I even took everything off and re installed it to make sure I didn't miss anything. I really don't think that changing the knock sensor could have cause it to blow a piston ring.. but I could be wrong.. it wasn't passing California emission tests prior to me replacing the knock sensor due to high NOX..

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    pushrod, September 27, 2012, 18:35
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     Master

    Make sure breather is open on engine and oil not ponding in valve covers.
    Bought all i know.

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    damnvillager, September 27, 2012, 18:50
     Rookie

    I'm going to see where the breather is on the car and then I'll check that.

    I also wanted to note I took off the front valve cover earlier this week and there was oil puddled underneath the valve cover on top of the head.. is it not supposed to have oil puddled?

    I also wanted to note when i started it just now. the fuel pump made an odd noise (I replaced the in take fuel pump back in 2010)

    Also when I started it, while holding the accelerator steady in park the engine was surging intermittenly sometimes the rpm would be unstable and a few minutes later the rpm would stable..

    I am so very confused at what the problem is.

    thank you for your tips

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    pushrod, September 27, 2012, 19:09
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     Master

    Not so much oil that it ran over the cyl. head when you removed the cover. But there will be some oil there.
    Might have to get someone that can actually LOOK at this for you, GOOD LUCK.
    One more thing check pcv hose very close does it feel spongey? If so replace it.

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    ziptie12, September 27, 2012, 19:17
     Master

    Just a random thought with the smoke isuue..... the oil level isn't to high is it?

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    damnvillager, September 27, 2012, 19:44
     Rookie

    I replaced the PCV hose, it was cracked. It had more oil on one side ( under the valve cover) than on the other.. it might be something worth checking. Thanks so much for all your tips. I may have it towed to a mechanic. It kills me that I can't figure it out...I've never been this stumped over a vehicle before.

    @ziptie.

    I should check that, It didn't have too much oil before I changed the knock sensor. It couldn't hurt to check
    though.

    A side note.. I did hear a suspicious sound from the fuel pump..when i turn the ignition on but before I start the car. that wouldn't cause it to smoke would it? I replaced it in 2010... though I do note that most parts aren't made very well anymore.

    I'd also like to add that one time upon running the vehicle, some of the water/condensation that appeared at the tail pipe had a smell like burned electronics/burning transmission.. but I don't know where it would suck trans fluid into the intake from.

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    pushrod, September 27, 2012, 20:12
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     Master

    DON'T FEEL BAD, I DO THIS S---T FOR A LIVING AND GET STUMPED ALL THE TIME!! LET US KNOW WHAT THE OUTCOME IS.

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    ziptie12, September 28, 2012, 05:53
     Master

    Is S---T the best you could come up with? What happened to $@#@^$(&^(&^$%%(!!!!!!!!!!!!!!........? I primarily work on only one make and that is enough for me! AFTERMAKET is much tougher than most people give credit for.

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    pushrod, September 28, 2012, 06:22
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     Master

    THEY TOOK US OFF ONE PAGE REMEMBER THE GUY WHO WANTED ADVICE ON HIS WIPER MOTOR?
    NOT THAT IT BOTHERED ME AT ALL!! HEY I CAN THINK OF A 'BUNCH' JUST CANT PUT IT DOWN HERE.
    YOU KNOW YOU CANT EVEN TRY TO HELP SOME PEOPLE. I GUESS I JUST REMEMBER BETTER DAYS.
    AND I KNOW YOU DO TOO. AND YOU ARE RIGHT,ABOUT AFTERMARKET, AND IT IS GETTING
    WORSE BY THE DAY. WHEN I STARTED IT WAS POINTS,PLUGS AND CARBS.

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    damnvillager, September 28, 2012, 09:00
     Rookie

    Hey everyone,

    I finally did a compression test got paid and bought a cheap tester at harbor freight.. It has compression on all cylinders except for 1... one cylinder shows zero on the gauge.. when I press the pressure relief valve a little air escapes.. UGH any suggestions of the cause?

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