AaRoN said:
Elevated HC and CO tailpipe emissions are often symptoms of a fouled converter or a faulty air supply. Converters don't just plug up or die for no good reason. Prolonged overheating or short term severe overheating are the leading causes of catalytic converter plugging. The problem is often fouled or misfiring spark plugs, or a burned exhaust valve that leaks compression and allows unburned fuel to pass through the combustion chamber into the exhaust. To diagnose a plugged catalytic converter, you can check intake vacuum or exhaust backpressure. To check intake vacuum, connect a vacuum gauge to a vacuum port on the intake manifold. Start the engine and watch the vacuum reading at idle. Then increase RPM's to about 2500 and hold it there. Normal vacuum at idle for most engines should be 18 to 22 inches Hg.
When was your last tune up (plugs, wires, coil packs, etc.)? Normal maintenance issues must be addressed. Also, do you have any CEL's?
Thanks for the info. Since I took off the stock mid pipe 2+ years ago, I've had 2 different aftermarket mid pipes on my car - both were purchased
used, so I really don't know what condition the cats were in (age, mileage, etc) before installation. When I swapped over to this Basanni pipe a few weeks ago, the UPR pipe I had on previously
wasn't plugged. One side was totally blown out and hollow, and the other side appeared ok but I figured it was probably crap too so I tossed the pipe. This Basanni pipe appeared to be in great condition so I was hoping the cats were still good, but learned after this efficiency test that they're no good as well. So yes, I totally agree that cats don't foul for no reason, but I can't honestly say that my car has fouled any cats since I never knew their true condition when they were installed on the car.
As for the last tune up - I'm always doing that stuff on time or ahead of time. It got all new plugs (Autolite's - 2 ranges colder than stock as suggested to me by Johnny Langton over at Modular Depot years ago) and wires about 2 years ago when the PI cams and intake were done. Coil packs are still originals but seem to be doing the job just fine. It had a fresh oil change before the last Etest too; I do those at every 5,000 kilometers or less.
uncltrvlnmatt said:
What Aaron said. Plus don't get cats for a carb certified cats, get the cats for OBD2.
I know you said you don't want to get a tune, but with the PI intake, PI cams, You may be overfueling. Over time that could cause cat problems.
Why not CARB certified cats? Wouldn't they be the best ones? Or is it a waste of money when an OBD II certified cat should work just as well at a fraction of the price? And what about ceramic vs metallic core? I'm thinkin' metallic core might be my best option since it can withstand a bit more heat and general abuse...?
Also, if she was overfueling I would think that would have shown up in my A/F ratio reading (among other readings) above, no? My A/F readings of 15:1 and 17:1 are actually showing that I'm running a little LEAN rather than rich. I'm not arguing that a tune wouldn't do me well, but .... read below, I don't want to be too redundant...
Lightning Struck said:
simple fix, YOU NEED A TUNE. End of story, the intake and cams has thrown a monkey wrench into the a/f mapping so you need a tune to correct it. I did the same on my old 98 and the tune took care of everything.
I appreciate your advice, but seriously, it's too easy to just say "get a tune and everything will be solved". I know a tune would probably solve all this emissions crap for me (and also yeild me better gains from the mods I've done) - I knew it before the first person ever suggested it to me, and I still know it after the hundredth person has suggested it to me.
BUT a tune isn't the
ONLY answer here - it's just the easiest one to suggest (and also the most expensive one). Before I did the PI cams and intake I did a TON of reasearch among all the top Mustang forums (including this one of course!). I knew all the write-ups like the back of my hand and I also got in touch with a number of people who had personally done the swap and could tell me first hand what they experienced. From that I can assure you that the majority of people I talked to who installed PI cams and a PI intake did NOT need to get a tune in order to have their car run up-to-snuff, including from an emissions standpoint.
I'm certainly not arguing that a tune would solve my problems, but I'm just saying that I'm sure I can get my car running correctly via other means which wont cost near as much. A tune is going to cost me, say $400 for the actual tuner. Fair enough. But I've called/asked around and nobody does "canned tunes" for PI cam/intake swapped NPI's, so that means dyno time on top of that. The best local price I got (from Steeda in Milton, Ontario) was going to be like $700 for the tuner and 3 custom tunes. Sorry, but that's too much for me man.
All I want to do is know that my engine's running the way it should be. If it is (according to the numbers I've provided) than I'll just slap a couple well-made, dependable, NEW cats on there and hopefully pass the sniffer test and be off to the races. If it's not running right and other things need to be fixed, I want to do that stuff before I go and throw $300 worth of new cats on it just to foul/ruin them because the engine's not running right - ya know?
