I just installed my Motordyne copper iso thermal 5/16" plenum spacer. I noticed that when the ignition is on (engine off) there is a faint high pitched humming sound coming from the plenum area. Is this normal?

Also, there is a loud hissing noise when I rev the engine around 2500 RPMs. What could be the problem?

Thanks in advance for your help guys.

 

Sounds like you might have a leak, you should check your seal, turn on the car and have someone rev up the engine for you while you look for the leak.

 

Leak as in my bolts are not torqued enough? I don't think it could be a loose tube because I double checked all the connections.

 

I know with older crawfordz plenums, they had leaking problems due to the aluminum warping, this is fixed with adding an additional gasket. I don't know if you'd get the same results with your spacer.

Another mistake that sometimes happen, is people accidentally torque down the spacer and the rubber collar for the oil lid get's stuck in between the spacer and the plenum. you should check it out.

Is it a new spacer or used?

 

The spacer is brand new.

Any idea on the faint humming sound coming from the plenum area with the ignition on and engine off?

 

Unfortunatly im stumped on that... I'm thinking it has something to do with a seal though... You can try to reset your ecu, try this:
https://g35driver.com/forums/showthr...light=easy+ecu

 

I highly doubt it's b/c your bolts aren't torqued enough. I just installed the 1/2" spacer a few weeks ago myself. It is very easy to over-torque the bolts. 100 in/lbs is not a lot of force. There are several hoses you would have had to disconnect so I would double double check those first. This would explain the noise above 2.5K. I have no idea what would make that noise with the engine off. Something electrical is likely.

 

I installed the copper iso version so it may be that air flowing through the old tubes in the throttle body according to another G35 member:

I began hearing this noise when as soon as i installed my MD 1/2 Copper iso-thermal spacer. Here's what I think, and what i did:

1). If you have the copper kit, you replace the gasket in the throttle body with the new copper gasket and connect the rubber tubes to this, but, there's still the old tubes coming of the throttle body that don't connect to anything. I *think* that there is where the whistle is coming from. I put electrical tape over the tubes that didn't connect to anything that did seem to quiet the whistle. Its not totally gone, but its significantly less.

2). The whistle will also come from the extra volume of air now being sucked in by the intake.

 

Anyone one else who has installed the copper throttle body heater experience a whistling sound at around 2,500 to 3,000 RPMs?

 

Normal on all VQ's. Its the TB electric motor assembly holding the TB valve just slightly open to the idle position.


Air rushing past the TB butterfly valve while its in the partially open position.
Its normal.

 

Make sure you didn't crimp the rubber oil fill!!! I did it on mine, its really easy to do...

 

That buzzing sound you hear when its turned on is the low duty cycle electrical pulse width signal sent to the electric motor in the TB assembly.

Have you ever used a cordless drill that has variable speed? If you just slightly depress the trigger you will hear a similar buzzing sound. That is the electronics sending a fast on/off signal to the electric motor. This is how it varies the power level up or down... by varying the duty cycle of the electrical power sent to the motor.

The same thing is done in the TB of your car. A low duty cycle makes for a low throttle position (and you hear the buzzing). A high duty cycle makes for a wide open throttle position... and you will hear little, if anything, because the signal is at or near 100% DC.

Tony

 

need help getting more performance gains. would pulleys help? cant afford pipes yet.

2003 G35 coupe auto, afe stage2 air intake, AAM spec angled plenum spacer, performance speed chip. using a a bel fx1 performance timer, cant get anything better than 0-60 5.85 secs. 1/4 mile @ 96.9mph.

 

Test pipes are really cheap and they make good/easy gains.
And they are safe for your engine.

Pullies OTOH... I won't ever put them on my car.

Just look up all the pully debates for more info.