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Clicking/snapping under acceleration


Tungsten
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Many of you with MPFI engine trucks probably experienced that somewhat high pitch quick clicking/snapping sound under acceleration. It always bugged me but I always thought it was either the fuel injectors or broken manifold studs.

Currently, I have all new studs and they are the 300zx turbo studs too and the sound is still there. Then somehow I don't believe it is the fuel injectors that are making that sound either.

For example, the VG30E Nissan Quest does not make this noise.

 

A member of the forum here (adamzan) told me that the sound may come from the EGR system or the BPT valve, probably due to it being old and broken.

Due to the high pitch of this clicking sound, a camera microphone is unable to capture it. I think the sound is probably filtered out as noise.

That rules out rod knock and detonation as a camera microphone is able to pick those up just fine. Also, this is NOT lifter tick because that goes away after a few seconds.

Edited by Tungsten
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no. my egr valve clicks. ive got it to do it. only at certain rpms. like highway speeds. been under the hood messing with it and stuck my finger in the holes on the under side of it and push in while reving. and it did click and reved much better... :scratchhead:

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I have had this problem on my truck for almost 3 years. Apparently if the BPT valve is leaking the egr will not function properly, no wonder my truck will barely squeeze past emissions even with a brand new cat on it. I had a brand new exhaust put on a couple years ago including manifolds planed, new gaskets and studs, and I still heard the noise. Figured out what it was but was too ignorant at the time of the emissions test trouble to make a connection. The EGR valve still stumbles the motor when you press on it so I guess that is still good. The only place online I've found new BPT valves are at Nissan. I am going to try and source one locally and if not I will check the one on my parts truck.

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