exhaust rattle?

StuntDriver06 · 07-21-2006, 02:43 PM

i noticed from day one that if i rev my truck in neutral, not hard just slightly to like 3500-4000 rpms, i get a rattle as rpms come down, sounds like something inside of cat or something of the sort, i was just wondering if anybody else has had this problem and how to fix it if so...

sudden urge · 07-21-2006, 02:53 PM

I have noticed that too, and it is probably just a harmonic vibration from the heat shield. I'm not concerned about it.

StuntDriver06 · 07-21-2006, 03:17 PM

well i dont like it, guess the wife needs to rev it while i lookn under it...

sudden urge · 07-21-2006, 06:06 PM

Please report back on what you find.

Steamguy · 07-22-2006, 07:50 AM

It could be the nature of the truck. Does it sort of go 'popity-pop'?

Here's what the likely cause is, and it's not really fixable. Nissan doesn't shut down the fuel injection when decelerating, so what you actually hear is the result of the over-rich mixture exploding in the exhaust header.

I suggest looking at it in a different way: This is actually the mark of a free-flowing exhaust system. Us old hot-rodders used to try tuning the exhaust for that sound. The more racous the rattle, the better...

If there are any gas (not diesel of course) school buses in your area, listen to them as they decelerate. The combination of the long, long exhaust pipe and the muffler 'way up front gives a terrific 'deceleration crackle'.

Hope this helps.

sudden urge · 07-22-2006, 08:27 AM

No it's not a popity pop, it sounds more like an empty potato chip bag being crumpled for a few seconds. I only notice it when you rev it up in a garage or next to a wall, otherwise you can't hear it.

StuntDriver06 · 07-23-2006, 04:00 PM

Quote:

Originally Posted by Steamguy

It could be the nature of the truck. Does it sort of go 'popity-pop'?

Here's what the likely cause is, and it's not really fixable. Nissan doesn't shut down the fuel injection when decelerating, so what you actually hear is the result of the over-rich mixture exploding in the exhaust header.

I suggest looking at it in a different way: This is actually the mark of a free-flowing exhaust system. Us old hot-rodders used to try tuning the exhaust for that sound. The more racous the rattle, the better...

If there are any gas (not diesel of course) school buses in your area, listen to them as they decelerate. The combination of the long, long exhaust pipe and the muffler 'way up front gives a terrific 'deceleration crackle'.

Hope this helps.

you are partially right... titan does not shut down fuel immediately.. it takes a sec or 2.. so you do get that sound but this is a metallic rattle only heard in P or N when just free-revving...

yobreaux · 07-28-2006, 04:07 PM

Same Issue Since Day 1...sounds Like Someone Shaking A Tin Can Full Of Pebbles As Rpm's Drop...doesn't Seem To Be A Problem...17,500 Miles On Truck (04) And All Is Ok! Probably A Rattle In The Heat Shield.

titanmoon · 07-28-2006, 04:29 PM

Quote:

Originally Posted by StuntDriver06

i noticed from day one that if i rev my truck in neutral, not hard just slightly to like 3500-4000 rpms, i get a rattle as rpms come down, sounds like something inside of cat or something of the sort, i was just wondering if anybody else has had this problem and how to fix it if so...

On mine it is at about 900 RPM- as you gently rev past 900 and as the engine slows down below 900. Same rattle- like pebbles in a can- seems to be left front like maybe left front cat.

Last summer and now again this week as the Titan was hot from a long drive in 90+ heat, the rattle became really bad but almost disappears when cool.

Have not taken it in yet- when I did when new they said noise was normal.

Steamguy · 07-29-2006, 11:44 AM

Quote:

Originally Posted by StuntDriver06

you are partially right... titan does not shut down fuel immediately.. it takes a sec or 2.. so you do get that sound but this is a metallic rattle only heard in P or N when just free-revving...

Yours may be different, but on mine, the fuel is never off. They cut it back, but it never goes off. In one of my refresher schools, they pointed out that this was done for emissions reasons, so the mixture wouldn't go too lean.

Check me out, here: On a long hill, when you're decelerating, reach over and switch off the key. {DISCLAIMER: BE SAFE when you're doing this, since switching the engine off kills your power steering and brakes!} On my truck, you feel all that extra drag when the engine quits. See how it does with yours. Maybe they've changed it since the early '04 models, since I have one of the very early ones.

Oh, and don't leave the key off for more than a second or so. Besides the control issues above, the transmission relies upon the engine turning it for its internal lubrication pump to be operating. You'll probably have to kick the trans to neutral to restart the engine with the key.

Check it out - let me know! This would be an interesting thing to know if they did actually change it. Thanks!

StuntDriver06 · 07-29-2006, 07:24 PM

they may have.. that sounds feasible that they would keep some fuel there... i know around 00-02 most vehicles would shut down fuel as soon as decel was detected (almost immeadiately) as shown on a snap-on MT-2500.... wish i still had access to one i could tell you... maybe someone with cipher could check this out?

titanmoon · 08-05-2006, 07:57 PM

Quote:

Originally Posted by titanmoon

On mine it is at about 900 RPM- as you gently rev past 900 and as the engine slows down below 900. Same rattle- like pebbles in a can- seems to be left front like maybe left front cat.

Last summer and now again this week as the Titan was hot from a long drive in 90+ heat, the rattle became really bad but almost disappears when cool.

Have not taken it in yet- when I did when new they said noise was normal.

I finally was able to have someone rev the engine while I listen. It's underneath the drivers area.

I crawled under and banged on the exhaust. The heat shield on the cross pipe near the cat on the driver side rattles. No visible defects- straps holding heat shield are tight.

God I hate taking it in to the dealer again. Dealer has:
-dented hood after oil change
-left off 2 of the 4 front bolts on the skid plate (just found this today)
-scratched a fender after another service call
- left paint overspray on a door, hood, grill, bumper after they repaired
that dent.

For most of the time since bought Oct. 2004 dealer has been excellent. But I wonder if there is something simple I could do to stop rattle- has anyone else fixed this themselves?

sudden urge · 08-05-2006, 08:12 PM

As I said in an earlier post, it's just sound resonating off that heat shield. I will be surprised if they can do anything about it.

jolarsen · 08-06-2006, 08:59 PM

I took my Titan in for a ticking noise in the engine and soo anyway too make a long story short. I got it back and they said there were rocks in my cat shield. HHmmmm, I told them I have not had it on any dirt roads(17000 miles) and besides that I heard that noise since it had 59 miles on it.I just figured it was the nature of the truck. So check you rock shields on your exhaust. The bad news is the noise that I really took it on for is still there. I really noticed the ticking noise this weekend when I was leveling up my camper at the lake it was idling in drive and I heard the tick. Aby suggestion son my actual problem? I hope I have helped some of you. Take Care

titanmoon · 08-07-2006, 06:48 PM

Took it in to the dealer today and it is the heat shields rattle. They said they replaced and tightened some clamps. I can't see anything new but whatever they did cured it! That great Titan engine and exhaust sound is back without the rattle!

Also I no longer have as much of that clicking from the heat shields. It used to be almost deafening at a drive through window.

The service writer said they usually just remove problem heat shieds but they didn't think I would like that on a new vehicle.