Knocking - Low RPM Knock

fxlr8

fxlr8

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When in park and slightly pressing the gas my engine makes a knocking sound, has been happening for the last couple weeks. Also this happens in all gears, including neutral. I know it is not the gas because I went through a couple tanks already.

Any ideas?
 
Did you try a different brand? Despite popular opinion, Cali Arco has been my best performer. I knock w/ 76.
Are you flashed?
 
When I drove to Colorado, every fill up was with 91, and I went through at least 3-4 tanks. I never had any issues going up or down mountains or in high altitude, at least that I noticed. Maybe I just got lucky with the brands of gas though.
 
Jeff, is it a very faint sound happing around 2000 rpms? More audible while the engine is at load (hill climb, left foot brake)? If so, it might be the valve selonoid...
 
Does the Knocking sound come from the passingers side under the dash...?? I had a knocking sound and it was the a fuel damper or how it's called.... is so lett me know i can figure it out for you......
 
it happens all the time in low rpm's or lightly pressing the gas pedal. I can't really hear it under heavy load since the exhaust drowns it out. It is a low faint knock and increases with the rpms. I am sure it isn't the gas since I tried different brands..chevron etc. I am going to try a stethoscope and see if I can find the exact location of the noise.
 
Just took my wifes stethoscope and listened for the sound while my son pressed the gas slightly. The sound only appears in the very low rpms and disappears before 2000 rpm. Using the stethoscope I could here the noise pretty well around the passenger side ignition coils, so it must be coming from that area somewhere.
 
ive got a pretty nasty lifter tap in mine, but more like taptaptap instead of knock knock knock, & don't go away with higher revs either...

checked the service manual, theres no adjustment, but they do make like 19 different thickness of lifters, so measure the gap, the cam has to come out & replace with a thicker lifter...not going to bother, just waiting for it to blow up completely at this point:tongue:
 
Finally! Somebody else with the same problem (or at least it sounds like it)! The tech at the dealer told me it was normal. I'm gonna ask that they look at it again next time I bring it in.

I don't know if it goes away, or if the engine/exhaust noise just masks it. Hopefully you'll have better luck figuring it out than me.
 
fxlr8 said:
Just took my wifes stethoscope and listened for the sound while my son pressed the gas slightly. The sound only appears in the very low rpms and disappears before 2000 rpm. Using the stethoscope I could here the noise pretty well around the passenger side ignition coils, so it must be coming from that area somewhere.
Click to expand...

It might be your injectors, I've read that Nissan injectors can be a little noisy.
 
I believe I have the same problem. Mine happens around 2200 rpm or so. Any sometimes, when I start my car I will hear some vibration like tapping noises from under the car. :sad:
 
This is what i mean.....watch the attachment :tup:

They are talking about the fuel feed hose.....It's a common problem with the FX and i changed it and the sound was gone.
 
raymond said:
This is what i mean.....watch the attachment :tup:

They are talking about the fuel feed hose.....It's a common problem with the FX and i changed it and the sound was gone.
Click to expand...

Thanks, will test this later today.

Was yours a constant knock or only while slightly pressing the gas pedal? also did the noise disappear around 2000 rpm?
 
fxlr8 said:
Thanks, will test this later today.

Was yours a constant knock or only while slightly pressing the gas pedal? also did the noise disappear around 2000 rpm?
Click to expand...

Jup i noticed it when the engine idle'd when giving a bit gas i was still there except when driving.
Think you should really look into this.

Good luck...!!
 
Just checked the fuel damper by feeling and listening with a stethoscope, and it is not coming from there. Tried listening again by ignition coil 1 and 3 and definitely can hear it in that location. Just did a sea foam treatment and am going to check the plugs next.
 
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