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2002 Frontier 3.3L Supercharged 4X4 Crew cab long bed with 85K miles. I have an odd vibration that is buzzing the gas pedal only at exactly 2,000 rpm while driving, or if it is not moving and I do a “power brake” test. It does not do it when it is in park and you rev the motor to 2k rpm.

When I say vibrating, I mean it goes all the way up your leg and is extremely annoying. This issue of a vibrating gas pedal in a Nissan Frontier seems to be a fairly common complaint on the internet, yet there are posts that identify the cause and a solution. I find that strange for a vehicle that’s 15 years old, someone has to know the cause of it and how to fix it.

It is not the tires, the driveshaft, u-joints, cv-joints, axles, or calipers because I can make it happen while stopped, doing a power brake test. It has to be an issue with the motor or transmission.

Trying to diagnose it: Yesterday I went to my mechanic (again) to see if he could identify the vibration. This time he used a stethoscope to see if he could hear a component that is vibrating and causing the issue.

While he was using the stethoscope I did the power brake test for about 10 seconds at a time, several times. He put the metal probe on the intake, the tensioner pulley bracket, all pulleys, water pump, AC compressor, power steering pump, anything that spins.

At idle, in park or drive, the metal bracket that the tensioner pulley is mounted to made the metal probe buzz on the metal, at 2,000 rpm in drive it would vibrate a lot. However, he could not identify exactly what was causing the bracket to vibrate excessively. The only item connected to the serpentine belt that slightly buzzed was the water pump, however it wasn’t enough that would transmit all the way up to make the bracket buzz like it was.

My tech is a smart guy, highly train and he’s done a lot of research online about this issue with no resolve. Here are his ideas that may be causing the vibration. Any input or experience with this issue on this motor would be appreciated.

1) Replace PCV valve
2) Replace “blow off valve” and hoses on the backside of the super charger. Logic is that it may not function correctly causing mass air sensor to mess up the fuel to air mixture to be off at that rpm making an odd vibration. (see bad fuel economy issue below)
3) Check the engine for TDC, it may be off causing the engine to vibrate at exactly 2,000 rpm
4) Harmonic balancer is worn out?
5) Transmission? – Cracked pressure plate? Some other unknown defective part that could be causing a severe vibration
As a side note, since purchasing it in March with 77k miles on it, I have put all new hoses, belts, new rear-main seal, spark plugs, spark plug wires, distributor cap, replaced fluids including transmission, differential, transfer case, re-packed all bearings. So maintenance wise, it’s up to date.

It has never gotten above 13 mpg, which is horrible. I keep the new tires at 36 psi and it’s had an alignment. It gets the same gas miles whether I run premium or mid-grade fuel in it. I realize it’s not a dragster, but it feels like it’s working way to hard and lacking power.

I purchased a Frontier exactly like this one new in 2002. It never got below 15 mpg, usually was in the 16 to 18mpg range and had decent power so something is up with this one that’s causing the vibration and poor fuel economy.

Again, any thoughts or ideas of what could be causing this would be appreciated!
 

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2017 Pro-4X w/Luxury Package
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Power brake test?!? If that's reving the engine while keeping your foot on the brake, in Drive, why the heck would you do that to your transmission?

Back to your vibration issue, at 2000 RPM if you touch the throttle cable under the hood do you feel the vibration there?

Last, have you replaced the knock sensor? That could cause low power, and it doesn't trip a CEL so you wouldn't know it that way.
 

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If you think the vibration might be coming from that tensioner pulley bracket then you should try your test with the belt off, if the vibration goes away then there's your answer
 
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