It sounds like a possible exhaust leak up near the cats. Isn't heard as much up top with the hood open, just when crouched down near the front wheels. The sound is a modest metallic clatter at idle, especially off the line, but modulates with engine speed and goes away at 2500rpm. I'm actually hoping it's something involved with the exhaust, as it seems, to give me a solid excuse to 'repair' (re: modify!) this soon. It's just noticeable enough in the cabin that I'd have to explain it to a passenger (as I did my wife last night), so I'll need to address this sooner than later as it just sounds bad.

Of note, I did briefly see a 'restricted performance' message on the dash for all of 3 seconds last week on a cold startup, but it went away and hasn't come back since. I haven't experienced any loss of power from normal, and all is well otherwise (still driving it nearly daily). Any thoughts?

 

Chris, I wonder if the knock sensor picked up something when you got the RP?
I seem to remember you did the top tensioners , did you check the lowers and chain slack while in there?
Very worrier some I'm sure.


Wayne

 

I had a Cat break up on an X308 and it sounded like pebbles rattling around inside a tin can .........

Graham

 

I'm with Graham. Go past a drive-thru window at a bank with your windows down and listen for the echo coming back at you from the building's wall. Pebbles-rattling-around-inside-a-tin-can is a classic description of a failed catalytic converter....

 

I have something similar for the first few minutes after start up, I was thinking manifold or egr gasket.

 

Mine made a noise like that when I got it and it was the parking brake cable was loose and rattling. The adjuster nut was rusty and broke when I tried to adjust it so I bought a new nut and threaded rod for about $20 from Terrys Jags.


Dave

 

Hrmmm. May be time to put it up on a lift and check things out next. My handbrake is all but broken already (flacid as... well, a wet noodle since this is a family website), so I wonder if that's the last bit about to go, though it still works. The cats I've been wondering about, as there's no mention of them being replaced yet. I wasn't getting 'pebbles', but perhaps. I'll take another listen tomorrow. Perhaps more credence for the exhaust upgrades...

 

Quick update- haven't driven it since! Cranked it up yesterday and it doesn't modulate with the RPMs as much as I thought before. Definitely not. More of an afterthought sound with engine speed, which seems to point to the exhaust. I lightly revved the engine in my garage and it sounds very smooth- the clatter is just strictly under the car. Nothing up top or 'in the middle' that I can tell. I can't imagine this being a brake cable...

I'll try and put it up on jacks and ramps tomorrow and break out the stethoscope, but can anyone recommended a high-flow cat replacement, or regular replacement? If the cats are indeed what this is, I'll plan to put my exhaust plan (err, TBD) into action as well.

 

Cranked it up again today, and not even a sound! I drove it a couple miles and it just purrs. Going to drive it this week and see if it comes back up... stay tuned.

 

I had a similar metallic sound that we thought was the brake shield lightly nicking the wheel, therefore more and faster with more speed or rpms. However, it turned out to be rear wheel bearing, which won't show up on a lift or just revving engine. You might want to check wheel bearings, front and back.

 

Have you checked the emer brake cables?


Dave

 

Heat shield, maybe?

 

I am not sure where that noise is resonating from but if it is on the left front I would guess one of your A/C lines. Turn the A/C on to low and look down at the A/C compressor.

 

Thanks, guys- I'll check all of the above probably this weekend. But I may have gotten confirmation about the cats last night, when the CEL popped on the dash a mile from the house. Here's what I found when I ran the codes a few hours after (cooled down a bit):

P0430 - Catalyst System Efficiency Below Threshold (Bank 2)
P0302 - Cylinder 2 Misfire Detected
P1316 - Misfire Rate Exceeds Emissions
P1111 - System Pass

Odd on the last one, especially considering the glowing CEL on the dash and unlikelyhood of me passing a state inspection now (luckily it did in July!). But what do you guys think? Bad cats and/or O2 sensor? Bad spark plugs?

Strange that the rattle is intermittent- it was indeed back again most of yesterday.

 

I'm still betting on a failed catalytic converter....

 

I say #2 coil pack or plug or oil in plug valley.

 

I'll check it out. Is this the correct pattern, standing in front of the car, where 4 and 8 are closest to the front bumper?

1 5
2 6
3 7
4 8

Bank 1 left, bank 2 right? Or...?

Rattle may be something else coincidental.

 

This link to my page should help with cylinder numbering

Link http://www.jagrepair.com/images/Auto..._numbering.pdf

 

Thanks, Gus. No oil in the valley, coil packs and wiring 'look' OK, and not sure if the plugs are the originals at this mileage or not (131k), but are NGK Iridiums which are OE, IIRC. Just ordered a new set of NGK Iridium IFR5N10s that will be here Wednesday.

The maintenance records stack that came with this car was... nonexistent actually. Just some notes jotted down completed 'recently' without any mileage or datestamps (tensioners were noted!), so I'm still developing a baseline in some areas. More Wednesday night if I can sneak it in before Turkey Day...

Anyway, tackling this first to hopefully to kill the related codes and will then get back to 'the rattle'.

 

1.Fill up with 93 octane and add a bottle of sea foam in the tank.

2.Remove all coils,remove the coil boots, spray the springs clean with electrical contact cleaner, let dry,replace any damaged boots, replace any coils showing damage at the tips of the coil,that the spring goes to.

3.Replace all your spark plugs.

4.Clean the MAF sensor by removing and spraying the electrical contact cleaner above on the metal reader wire that's inside the air box.

5.Replace your air filter,change your oil and filter, hit the highway