Monday, May 27, 2013

Catalytic converter making ringing noises... that's not good!

What happened to shops doing quality work, selling quality parts? A lot of the early posts reflected my
frustration with the shops I've been using. A lesson learned is to no longer trust Yelp reviews since they're up for sale:

And just so you don't think I'm a "Negative Nelly" about others touching my cars, here are some shops which have done exceptional work for me and my friends. I HIGHLY recommend every one of them.

San Diego/Ramona, CA (exhaust work. My motorhome runs fantastic now, and sounds GREAT) They're getting my 4Runner this time. (general auto repair) (motorcycle)

Portland, OR (alignment. They ROCK.) (fantastic experience and prices for my BMW car services)

Green Valley/Tucson, AZ (general services) I learned the art of working on cars here and providing customers value for dollar paid. Rocky is the best. If he can't do it well, he won't. He's also an ex Alfa/Porsche/Mercedes/etc. mechanic. (Radiator and AC)
The engine rebuilder I used there has changed hands, so I can't vouch for their current products, but holy cow did that place build me some great motors at some awesome prices.

When the engine was installed, I had a 2.5" exhaust setup installed. This replaced everything from the turbo downpipe (came as 2.5") back to the exhaust tip, including catalytic converter and muffler.

In retrospect, a lot of the problems I've had now make total sense. Let's start at the beginning.

Several months after having the exhaust/engine done, the truck started having boost problems. It would intermittently boost a max of 2psi. The dyno shop I'd gone to had told me the wastegate actuator on the turbo was messed up and very finicky, so I assumed that was it. Over time, the level of boost dropped even further.

What was weird is that it would do that from time to time, other times it worked great - but never over 5psi. I completely unhooked it, which should have had it boosting high pressures.... 5psi.  Except when it boosted 2psi or less. Meh.

A friend who's good at this stuff (he's designed and built controllers for Banks and others) told me it had to be a constriction in the exhaust.

I took the truck into the shop and asked them to check. They used one of their little cameras and gave me a picture of the internals of a cat that was fine! (it's around here somewhere, you'll see why soon). Around that time, I'd noticed the back seat had MELTED from the heat of the muffler. The shop had, for reasons unknown, removed the muffler heat shield (the bolt areas were shiny and clean). Even so, that shouldn't have melted the seat. They put the heat shield back on and had an upholsterer patch the seat. Geez, Louise - it's so critical to have a GOOD shop work on your stuff.

Unfortunately, I didn't apply any logic to it at the time...

The truck's intermittently run well and poorly, turning in 13.5mpg average pretty regularly, which is miserable for one of these. Guys I wheel with are getting 19mpg on 35s. For a very short bit, it turned in 19mpg, but that didn't last. For some reason, as soon as I lifted the truck and installed bigger tires, gears, power went out the window and mpg settled into 13.5 mpg. I was confused, but my personal life and work was my top priority and I shelved this.

Fast forward months where work was running me 100 hours a week for months on end, and the 4Runner sat and sat and sat....

I finally got a weekend and headed out with one of my clubs to go on a light 4x4 trip. Had a great time, but all of a sudden, the boost dropped to 2psi on the way home. When I stopped in front of my house, admittedly a little firmly as I was kinda chapped, I heard a single "tong!" from under the truck. When I tapped the cat, it made rattling noises. The flex joint in front of the cat was ballooned out. And the cat only had a flange on the front.

Suddenly everything came together for me.

A) The muffler should not have gotten hot enough melt the seat. From the factory, the cat for 2000 Cherokees didn't have a heat shield. They worked great until you towed, then the could set fire to the carpet.  More than a few Cherokees have burned to the ground because of this. My 2000 Cherokee started the carpet smoking climbing Grapevine with a 4000 pound load on a trailer, which is how I learned of this.

B) The catalytic converter had fallen apart, sending catalytic chunks into the muffler, where they did their job, getting hot enough to cook the seat.

C) There was a big chunk in the cat which was blocking the outlet, causing the 2psi boost issue and ballooning the flex joint.

D) The pic the shop had given me was only of the front of the cat. They were probably thinking of running lean, melting the cat, but since the truck is running overly rich, there's no way it would have melty damage.

E) The first thing I did after lifting and locking the truck was go climb things. Vertical things where all I could see was sky out of the windshield. The big chunk would have rolled to the back and ended up getting wedged in the pipe, creating the performance problem.

Check out these pics when the cat got cut off

Here's the front, the side with the only flange. Looks good.

Here's the back of the cat - the side without a flange, and which was not inspected when I brought it in the last time. 2 of the 3 bulkheads are broken.


Moral of the story - have them check BOTH sides of the cat if you think the cat's at fault. AND make sure the muffler gets replaced. After I posted this on FB, a friend pointed out that the Nissan Titans had a similar issue. Even worse, they would suck up some of the grit from the cat and cause engine damage. With a turbo, I'm a little less concerned about that, but inside, I'm expecting to start using oil at a prodigious rate any minute...

I'm waiting for the warranty cat (5 more days), and none too thrilled to  have the same brand cat. I may get a Magnaflow installed and take the replacement for this one and eBay or Craigslist it. 

In the meantime, there's a test pipe in place and I can say that the truck runs awesome. Boost now climbs and falls easily, and it hits 7psi every time. It runs MUCH better too. I was able to do 75 with at least a 30mph headwind on Saturday, with pedal left. That felt soooo good.

It feels awesome to be making progress.

Even so, that "boost controller" the dyno shop sold me? Doesn't work. I spent 20 minutes toying with it and have now just ordered a real one online.

I'm getting really excited again!

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