I noticed a rattling sound coming from my exhaust a couple days ago, I jacked the car up thinking maybe one of the hangers fell off or a flange was loose, but could not find anything visually wrong. I kept driving the car for a couple days and noticed an extreme loss in power. Not thinking it was related to the exhaust rattling sound, I just assumed it jumped timing cause it was instantaneous when the car lost all its power and the belt was loose anyway, so I retimed it and took it for a ride, still felt the same. It then occured to me it might be the cat, so I get out of the car and have my friend rev it a little, sure enough the rattling is clearly coming from the cat. The next day I drop the exhaust and take it for a spin just to be sure and it felt alot better. I bought this cat brand new and its only been on my car for 6 months, it sounds like the honeycomb just fell out and clogged it. Has anybody else had a similar problem with magnaflow highflow cats? I have another highflow cat I found in my basement, must have been from one of my old cars, but im debating whether I should put that on or to avoid this happening again just go with a test pipe. Any help is appreciated.

 

I've have a Magnaflow cat on mycar for about a year now, and haven't had a problem with it. I've heard of internal baffles breaking loose inside mufflers before since they are usually just tack welded in place, but have never seen it happen to a cat. I wouldn't doubt that its possible though. Can you return/warranty it? If stuff is rattling inside then a shop should definitely take it back.

 

I talked to an exhaust shop and they said Magnaflow will find any reason not to honor there warranty so im not even going to bother.

 

Are the chunks coming out melted looking? If it overheated(raw fuel, rich mixtures, high heat) and melted it breaks up, or if its hit hard enough it will just start to get loose and then hammer it self apart coming out in non melted chunks. If its just busted up and no external damage is seen its a faulty cat from poor manufacturing. Go get the warranty you paid for it.

 

Unfortunately the exhaust is all welded as one piece including the cat, so in order to return it I would have to cut it or unweld it and I just lost my job, so im looking for the simplest most cost efficient solution which I have come to the conclusion is to just gut the cat the best I can so I can drive my car again and deal with another cat some other time. I would take it up with Magnaflow since this problem came from their faulty manufacturing, but I doubt they will honor their warranty anyway and I just need my car back so I can get another job.

 

bump for having the exact same problem. bought my direct fit magnaflow cat for my '96 prelude vtec 6 months ago exactly (to cure a P0420 code), and now I have a rattling in my exhaust with loss of power with the P0420 cat code again. thinking of going 2.25" universal this time to mate with my greddy evo2 catback, but wondering if I should give magnaflow another chance or go with catco or something?

any thoughts?

 

I had issues with my magnaflow. The honeycomb didn't fall apart, but it did start throwing codes. If you decide to return it, you need to have a mechanic fill out their form stating the P0420 code is on and there's not a problem with the engine that did damage to the cat. Magnaflow will try everything not to accept it. The vendor that I bought it from didn't have me get this paper signed and then made it sound like it was my problem. In the end I was refunded half.... Still a lot cheaper than other alternatives. The replacement magnaflow cat has been fine for 6 months now knock on wood.

 

I wont buy from Magnaflow again, if I do end up getting another cat, ill probably go with Vibrant like I should have in the first place.

 

Aftermarkets Cats are like band aids. They don't stand up as well as the OEM's.

 

But are worth the power gains. I put an aftermarket cat on a stock exhaust and it made a huge difference compared to OEM.

 

Even if I wanted one I don't think I could get a brand new OEM cat for my '96 prelude anymore...pretty sure they're discontinued. Seriously debating whether or not to get another magnaflow...