Well the car is feeling good and tonight i did a couple of pulls to 120 mph. When i would get to around 117 mph there would be some kind of flapping sound coming from the engine bay. The noise is only when i get to that speed. I didnt go faster then that so i dont know if it would continue doing it. At all other speeds below that there is no noise. Anyone have this problem or know what might be the problem. Thanx

 

1) did you put back all of the screws/bolts for the undercarriage coverings? (One of the times I forgot to put back 2 of the bolts and when I got up to ~80 MPH, it started to drag and make weird noises...I zip tied it back and fixed the problem)

2) are the belts tight?

3) have you check if the crank pulley bolt is secure?


*I wouldn't think that a problem with the crank pulley would cause a 'flapping' sound...I would guess that if there's a problem with the pulley, it'd be more of a vibrational symptom.

hope that helps,
Peter

 

1) the undercarriage is secure.
2) the belts feel tight.
3) have not checked this yet.
I know its weird that theres a flapping sound but when i first heard it i thought it sounded as if a belt had come off the pulleys. Im sure its related to the pulley install because it never did this before. Everything runs fine till i get around that speed. I guess ill have to take it off and put it back on.

 

Did you use the right belt for the underdrive setup?

 

i bought the ones from performance nissan.

 

bump

 

I thought i would have more posts then this. With all the people with the ur pulley no one has had this problem?

 

I think it may be the undercarriage cover. Did you notice a difference with the pulley?

 

i hope its the undercarriage, im going to mess with it tomorrow night. What do you mean by notice a diffrence with the pulley.

 

Its probably some plastic underneath the car. A part of mine came off, I have crappy roads.

 

I mean did you feel any difference over the stock pulley

 

O yeah, the throttle response is alot better and the engine runs so much smoother, also i probably dont even have 75 miles on it and unorthodox claims 7 days for the full potential. I know everything doesnt always work out the first time so i still believe this mod is worth getting.

 

most likely some lower engine cover or something is loose and at that speed is rattling...

last i checked... at 120 MPH in 6th gear the engine speed is lower then when at 7000 RPM in 1st or 2nd gear when accelerating... if you dont hear it then, its not pulley related........

 

tonight i jacked it up and got the car to speed and it didnt do it but i dont know if not having it under load made a diffrence. im missing some bolts for the undercarriage so that is a possible explanation. i tightend the belts and im gonna put new bolts in tomorrow and give it a test drive. i hope all goes well. thanx for your help everybody.

 

Like Jason said I doubt it's a pulley problem since you only hear it at a certain speed not RPM!!!! Although you go through the RPM's slower as you get higher in the gears. Try going through them at the speed but I doubt it. Got to be something loose even under the hood. Just go through everything you took off, moved etc...... Good luck.

 

weird, never had problems with mine.

 

as other folks have said -- your problem is bolded above. It's speed related not RPM related therefore the air going under the car (or through the engine bay) at high speed needs to go somewhere and it's moving your inadequately secured undercarriage cover.

a couple screws or zip ties should solve the problem

i've put 20k miles and almost three years on my pulley set with no issues!

 

Ok i dropped my car off today to have the test pipes put on. i tightend all the bolts and secured the undercarriage and everything was fine, no flapping noise. im getting my car detailed (clay bar and wax) and picking it up tomorrow. Ill post the review on my other post. I really appreciate everyones help.