Strange issue I came across yesterday:

Just had some tires put on the truck 2 days ago. I had some unusual road noises and other noises with the old tires so I've been listening for other sounds with the new (different brand) tires for the last day and a half. I noticed on the freeway and on regular roads yesterday some kind of sound, similar to air escaping from somewhere, but it's only happening when I'm pressing the accellerator. Doesn't matter the speed of the truck.

When I was at a red light, I decided to put it in neutral and rev the engine so I could try to hear the sound better without the road and wind noise of the truck moving. I was trying to rev the engine to a relatively high RPM, but not to redline or anything. Anyways, something strange happened. Once the RPM's got to 3,000 it wouldn't rev any higher and even though I was holding the pedal down, the tach kept bouncing off of the 3,000 mark, almost as if it was hitting a rev limiter. I tried this multiple times over the course of a few hours to see if it was just a fluke thing but it kept happening.

Now maybe I just never tried reving the engine that high before (I don't recall if I have or not) and am just now experiencing this for the first time, but does this sound normal? Also, does anyone know what the sound of air escaping from somewhere could be coming from? For what it's worth, I didn't notice the air sound up the 3,000 RPM that the truck would rev to, so it seemed like it was only while moving, but only while moving AND pressing the accellerator.

 

our engines have a 3k rev limit that is normal, and it sounds like ur just hearing air get sucked in through the intake? which is also normal.

 

If it's an automatic, all 01+ trucks have a Neutral and Park rev limiter set at 3000rpm.



Air escaping could be simply a winter noise of the heater system you've forgotten about from last winter. Or, it could be a fluke vacuum issue that suddendly started or you noticed after those new tires were put on. I'd check all your air intake tube connections/joints for a bad clamp or bad seal. Those are my thoughts, good luck on finding the issue.

 

That's good to know regarding the rev limiter. I had no idea. I had the A/C on when I heard the noise. Didn't think to try turning it off to see if that changed anything. I was thinking some kind of vacuum leak too, but i suppose it could be air being sucked into the intake and I just never heard/noticed it before.

 

i have a couple times put my truck in drive, but it must have sat just right where the truck didn't "know" it was in driev, so it still had the rev limiter. I just fumbled with the shifter a bit until it seated properly. it's happened like 2-3 times ever in all my times of putting it into drive.