My truck is a California model. I can only assume that it has a catalytic converter on it. The exhaust is bone stock and is making a vibration noise. All connections are tight and I cannot find any loose hangars or any rubbing (I have plenty of room as it passes by the tranny). The only thing I can think of is that either the rubber hangars are old and allowing too much movement (6 years old and 177K) or something is coming loose in the muffler (I can apply a little pressure with my foot on the tip and the vibration stops). I'm going to call around to see what it would cost to do a muffler delete since I want to get rid of it anyway with the stock exhaust. Before you ask, no a new exhaust is not in the cards right now (ball joints are the next big thing coming). I was thinking of deleting the cat too, but I can't find one. It's all just one big pipe from the turbo to the muffler and then from the muffler, over the axle and to the tip. You can usually spot the cat as it has different dimensions or some kind of shielding/insulation around it. I also looked for any obvious welded sections of piping and I can't find any.

Can a cat just look like a piece of piping? Or did my CA truck just not come with one? If my rig was a 49 state model I wouldn't give it a second thought and consider myself lucky, but it being a CA model makes me leery that I wouldn't have one.

 

Brian, find a muffler delete like you said and get it installed. I don't think its the muffler if you can put pressure on the tail pipe and the noise stops. Either you have a loose hanger or it is rubbing on something in the back. Either way you should find the problem while installing the straight pipe.

You should see the cat if it is on the exhaust. If you bought the truck new, I don't know, if you bought it used, the PO may have taken it off.

 

are You sure You have stock Exhaust on the truck. If You bought it 2nd hand it might have a aftermarket exhaust. Measure the tail pipe and see what size it is. Stock is 3 1/2"

 

I don't see any sections that were 'replaced' on the piping. There aren't any obvious weld spots where something may have been changed either.

It's definitely stock from the turbo to the tip. I don't think it's the muffler either but with no rubbing the only other options are one of the welds is starting to go and I just can't see it yet or the rubber hangars are getting old and allowing too much play. I've never heard of that happening before. I bought the truck and it was bone stock. The little notch on the top of the tip (which is really just the end of the exhaust piping) is a dead giveaway for stock too.

 

The manual tranny came with the Cat (in CA at least), but not the automatic.

Phil

 

My CA model with an auto had a cat...

 

Oops. From everything I've learned, the only reason for the cat on manuals was because the ECM couldn't control fuel delivery during the shift, like it can on autos. A few emissions could leak out the tailpipe, oh no!

So I guess it's like everything else..... sometimes yes, sometimes no. And a few times maybe.

Do you think it was only certain years where the auto had a cat? Like they were in a learning curve?

Sounds like the OP doesn't have one from what he's posted.

Phil

 

Thats what i was thinking, the state of Cali don't care if its auto or stick, maybe the truck was from another state i would assume.

 

Mine has a CA emissions sticker but no cat. Totally stock and untouched exhaust (for a few more weeks anyway).

Phil

 

Do you guys with CA truck have a GP module or standard a standard relay?

 

Alot of early birds even non CA trucks had cats.

 

I've got the module.

From posts here at FTE, it seems that most trucks have a "reminder" light on the dash for the glowplugs that has no relationship to the amount of time they are energized.

I've watched mine and it stays on longer if it is colder out. Seems to be a definate relationship to air temp and how long the light stays on. I assumed this may be a difference with the module.

Phil

 

i know my early bird had a cat for about three weeks after i bought it

 

I'm assuming my '03 is a CA truck. My build sheet says CA emmissions, I have the GP module, and the hood sticker says CA compliant( w/ big letters- NON-CATALYST). And no, theres no cat. I just can't figure out why a CA truck was originally sold in CT.

 

some one wanted a brand new truck with a 7.3L engine and the cali truck is what was found by the dealer