Random performance question

Dudeirock5 · January 28, 2007

I recently installed a K&N air intake into my 5.3L V8 Sierra. I've noticed a nice increase in power, sounds awesome, but I when i hit the gas (not flooring it) i here a high pitch sound just before the tranny switches gears and the RPM's drop. Now I honestly don't know a d**n thing about cars, so after asking around, I've come to find out that this isn't completely normal.

I've only received one suggestion and that is to replace the stock muffler, but not necessarily an entire exhaust system. Once again I don't know a thing about cars, so hopefully someone here can give me a helpful answer.

Feel free to message me if you need a more detailed description.

Thanks in advance,

Matt

C & A s Dad · January 28, 2007

It did not make this sound with the stock air filter?

I really cannot help you with the sound but I can offer some info on the exhaust. From everything that I have read while considering replacing my exhaust, unless you are looking for HP gains at the very upper RPM range, or you just want to hear that really nice rumble, don't do it. You will see some gains at the upper RPM range but it will hurt your TQ and HP in the low to mid range.

Good luck with finding out what the sound is.

Cranky1 · January 28, 2007

My truck makes a high pitch noise at the same time your does. Mine will only make it when the engine is not at operating temperature and it has sat for a while (over night) This was noticed 3 years ago when I installed the K&N filter. It has never got worse and it is sporadic. I never thought about the air filter until you mentioned it.

I have always contributed it to an alternator bearing or accessory belt tension pulley on it's way out. I have checked the alternator and tension pulley when cold for play and siezing and they seem fine.

Like C&As dad said, it is hard to diagnos without hearing the sound, it is just as hard to diagnos sometimes even if you can hear the sound.

If you find what is causing your problem, please post the cause.

uh6077 · January 28, 2007

Does you air intake have the box that goes around the filter. The cheaper ones do not. The filter is cone shaped and when lots of air is being taken in the air will whistle. It would make since because you said it would do it right before it shifted which is when it is taking in the most air. If the filter does not have the box around it then you are doing more harm than good. Cold air intakes are sealed off from the engine and only bring in COLD air from outside. Without the box the filter is sucking in the hot air from the engine compartment.

dewfpo · January 29, 2007

Changing your muffler is not going to solve your air intake noise. Make sure all the seals on the filter, tube, etc... are tight.

DEWFP

Dudeirock5 · January 29, 2007

Does you air intake have the box that goes around the filter. The cheaper ones do not. The filter is cone shaped and when lots of air is being taken in the air will whistle. It would make since because you said it would do it right before it shifted which is when it is taking in the most air. If the filter does not have the box around it then you are doing more harm than good. Cold air intakes are sealed off from the engine and only bring in COLD air from outside. Without the box the filter is sucking in the hot air from the engine compartment.

To clear up any confusion, this happens to be the exact system I have installed:

http://www.knfilters.com/search/product.aspx?Prod=57-3021-1

The general consensus I'm getting from here is that this is somewhat normal, or nothing to really worry about. I'll keep looking around and drive the thing into the ground as I always to to see if anything changes, for better or for worse.

Thanks for the feedback guys.

If anyone else reads this, let me know what you think