By on April 27, 2011

Frank in Boston writes:


I am the original owner and caretaker of a beloved 1995 Acura Integra LS. The car has only 68K pampered miles with all maintenance done based on “time-out” rather than mileage. It lives on a steady diet of E-10 Mobil regular dispensed in and around greater Boston. It is my ‘Orient Panther’ and ran like the proverbial Swiss watch until…

My problem began when an old glass-pack ANSA muffler imploded from years of internal rusting. The glass collapsed while driving and the subsequent back-pressure forced oil into two spark plug tubes through the gaskets, and shorted them out. The unburnt fuel from the 2 dead cylinders passed through to the exhaust where it cooked the cat in short order.

We towed the car to a local muffler place where everything from the stock header flange back was replaced. When we got the car back, it got new plugs, plug wires, fuel and air filter, PCV valve, valve adjustment, oil and filter. There were no unexpected findings with the “tune-up”, except the engine oil that was inside the #1 and #2 spark plug hole. Back to running like a watch after the work, except the odor from the exhaust was that of partially burnt acetone.

We drove it for about 10 days after the exhaust repair when I noticed a rattle from underneath. Close inspection revealed that the new cat’s core had broken loose inside the can-it was fried. At this point we had a “test pipe” installed in place of the cat, and I set about replacing the single O2 sensor.

Of course, the god-awful smell is worse (even after complete warm up), without the cat eating some of those unburnt hydrocarbons. I should say that the oil and coolant were and are clear, with no evidence of mixing. It starts with one turn, smoothly idles and revs all the way to the redline without missing or skipping. I think I can rule out a head gasket issue, or burnt valves. No unusual sounds, white or blue smoke under any conditions. No oil or coolant disappearing. Gas mileage is slightly down, but still in the mid to upper 20’s. I have not gone so far as to test Lambda, but I’ve never had a CEL and yes the light works. When stopped, if the right breeze pushes the exhaust towards the front of the car, it gets sucked in through the vents, and my eyes water from the smell.

So, am I missing something? Do I live with the burnt oxygenated E-10 winter-blend smell? Do I replace the cat morally, practically? If it is running rich, how do you adjust the fuel delivery on an OBD car? Thank you for any advice you have.

Sajeev answers:

That’s an excellent analysis. Honestly (and completely off topic) if we had more vocal politicians with your grasp of the situation and your ability to analyze a problem from multiple perspectives, we be a happier, healthier nation.

Odds are winter fuel isn’t a problem; it’s a necessary evil and nothing more. I looked into why catalytic converters fail and perhaps you drove over a snow bank, causing thermal shock to the honeycomb inside? Which is kinda fun: one of my college roommates used snow banks as parking “stops” around Metro Detroit one winter. Gave us all the giggles except the one time Audi 4000 Quattro in question couldn’t dig itself out. Then we stopped that stupid little game. But I digress…

I’d Seafoam this “Orient Panther.” Why? The rusty muffler forced oil into places it’s not supposed to go, so perhaps you have even more misplaced oil. Seafoam (fed via PCV) line will clean out any carbon/oil/crud in the PCV and intake system. Your neighbors will not appreciate the smoke signals so be careful where you do the dirty deed. On the plus side, if you see no smoke, you have no carbon!

Let’s say there’s no smoke, and the problem remains. Since the motor is running like a top and you changed the Lambda (Oxygen Sensor to most folks) I’d suggest a close look at your EGR/PCV systems and every vacuum line under the hood. Sometimes a bad PCV valve and associated rubber lines can cause a lean condition, but maybe the opposite is also true. And at this age, replacing (cracked, brittle or gooey) vacuum lines is never a bad idea.

I must admit, I’m drawing at straws with this diagnosis, it’s a tough one. But fear not, no matter how badly I screwed this up, we have the B&B to fix it!

Send your queries to [email protected] Spare no details and ask for a speedy resolution if you’re in a hurry.

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26 Comments on “Piston Slap: The Quandary of The “Orient Panther”...”

  • avatar
    Educator(of teachers)Dan

    Get a dog.  Have him ride with you at all times.  Blame him for the smell.  Problem solved.

  • avatar

    Good guess with the vacuum lines may have been brittle but still “solid” when the initial problem occurred but with multiple hands and tools significantly moving around under the hood a brittle line could have been cracked.  But what do I know, I’m just piling on Sajeev’s guesses.

  • avatar
    Uncle Mellow

    Lovely car .” 68K pampered miles”. I’m jealous.

  • avatar
    bumpy ii

    So, what exactly is the problem? The stinky exhaust from the test pipe?

  • avatar

    I don’t have anything to add . Those are great cars. We had one for 7 years and about 130,000 miles, very reliable and fun to drive.
    One clutch plus basic maintenance.
    Sold in 24 hours to the first punter.

  • avatar

    No cat and your exhaust smells.. ok, next question?

    • 0 avatar

      That’s what I was thinking, but I figure that I’m missing something.

      • 0 avatar

        You’re missing the fact that the cat shouldn’t make a difference. It’s legal where I live to run without a cat. Even a muffler shop can legally remove them and throw a straight pipe in there. I’ve never heard of this causing an odor problem on the many cat-less vehicles I’ve rode in or driven.

  • avatar

    I had a similar problem when a cat failed. A hose running from the EGR to the sensor that controls the EGR had popped off. Whenever I started or parked the car exhaust fumes would smell very strong. When your cat/exhuast backed up it sent high pressure exhaust gas through the EGR likely forcing it open possibly breaking it. I wouldn’t be surprised if the EGR line leading to the sensor has a hole burned in it or simply popped off and is filling your engine compartment with exhaust gas. Replace the EGR, EGR tube and EGR sensor.

  • avatar

    I’d do the Seafoam thing, then replace the catalytic converter.

    In some states, that converter is needed by law (along with the other emissions equipment), regardless of whether your car passes an emissions test without it (which I’m sure it won’t at this point).  A direct fit catalytic converter at Rock Auto is $92 – cheap.

    You can’t adjust the fuel delivery on that car without chipping it, and it still may not pass emissions and/or may run poorly.  Just repair it properly, and you’ll be happy.

    • 0 avatar

      “In some sates, that converter is needed by law [..]” — no kidding.  We call these the “United States.”

      AFAIK, removing the cat is a federal offense, and it ain’t cheap if you get caught.  More to the point, it’s not cool to remove the cat.  That’s against the car guy code.  To do a test, sure, but the car’s gotta run right or no fair.

      As far as “The light’s not on and I know it works” I call BS… if the system were working properly, the light would have come on after removing the cat.  So something isn’t working right.

      I understood ” We towed the car to a local muffler place where everything from the stock header flange back was replaced.  [..]

      We drove it for about 10 days after the exhaust repair when I noticed a rattle from underneath. Close inspection revealed that the new cat’s core had broken loose inside the can-it was fried.”

      So the question is — was that the original, re-installed cat?  It’s so old it’s got every right to go bad; stick in a new one and go from there.

      Or was it a replacement part — “header flange back” ???  If a new cat failed inside 10 days, something’s seriously wrong, and it might get pretty esoteric.  

      Nice car, and it should last a long time yet.  I wish you good luck with it.

  • avatar

    So what type of smell is it?

    When you talk about oil in the spark plugs do you mean into the HT lead?

  • avatar

    One, removing the cat on  OBD I car should not set a MIL as there is no post cat sensor.  I would have the car emission checked to see just what is in that exhaust.  Oil that entered the plug hole should have burned off by now.  Now, why did you remove the replacement cat?  If it failed in 10 days, the shop owes you a new one, not a test pipe.  I am not sure if you need the seafoam thing, but I do know those who swear by it.  If your usage of this car is like mine (95 Probe GT, flawless condition, 71K, garaged and used on occasion) you are not looking at a gunked up engine.  If you said daily driven for a couple of miles, well, you would be looking at a dirty engine.  Once you find what is excessive in your exhaust you can start looking for the source.  Without the cat your numbers are going to be skewed but if you are running really rich you are going to strain the new cat.  Pull the plugs and see if one cylinder is fuel fouled.  You said your mileage decreased.  Again, that points to rich running.  With a scan tool, check for long and short term fuel trim.  Your car ECU might be fooled into thinking it is running lean – anything that is allowing extra oxygen into the exhaust will fool the sensor into thinking you are lean and will boost the fuel trim accordingly.  Rich plus no cat equals old time car smell.  So what may be allowing the extra oxygen into the exhaust?  By chance is there damage to the air inlet between the MAF sensor and the intake?  “False” unmetered air is a major reason for fuel delivery problems on old(er) fuel injected cars…now get this car running right…they are awesome. I fondly remember doing back to back comparisons with your very car…

  • avatar

    I’m going to make a slightly different guess…from previous experience with failed exhausts/cats.  The original cat failed…plugging the exhaust and causing a huge backpressure which lifted the head.  You aren’t getting the typical radiator fluid into the cylinders but you may be drawing in oil.  You may need a new head gasket…or worse case, have a warped head.  I’ve read about the latter with that generation of Honda engines.

  • avatar

    Are you SURE you didn’t miss anything? Cars nowadays are designed only to run properly with all the stuff properly attached and in working order. So…replace the catalytic converter – the system isn’t designed to work without it, plus it’s illegal. You can either get a one-size-fits-all after market converter for about $100.00 or so, or go the OEM route which is much more. Your call. Either way, get one. So, replace the cat, replace the PCV, O2 sensor and all vacuum hoses that just don’t look or feel right and double-check all connections. Many times vacuum lines crack at the connection points and even the plastic junctions break where more than one line meet. For grins, buy a vacuum gauge and hook it up and see if the needle bounces around or if the readings are out of whack. Good hunting!

    • 0 avatar

      “Cars nowadays are designed only to run properly with all the stuff properly attached and in working order.”

      And, when you remove a flow restriction like a cat, they run even better!

  • avatar

    Peace and love to all the replies!

    Some clarifications:
    Odor was present when the new cat was installed after the first meltdown-test pipe expectedly worse but only slightly..
    There is no EGR valve on this generation engine. Confirmed with service manual.
    CEL works because when I changed the O2 sensor, I cut the leads and it came on. With the new O2 properly wired up-no light. Golden2Husky wins this one. Since there is no post-cat sensor, the ECU doesn’t care what happens after the cat.
    In the Peoples Republic of Massachusetts, cars manufactured before 1996 are NOT emission tested. I don’t want to risk another melt-down until this is cleared up. Plus my ‘test pipe’ is a resonator-looks like a cat. Catch me if you can.
    1200 cc straight-pipe Fat Boy’s smell like Fabreeze compared to my stink pipe.
    Oil usage= 1/2 qt in 2000 miles.
    Disconnected every vac line I could see, engine stumbles, idle lopes, smell still there before and after.

    • 0 avatar

      Interesting: Seafoam, buy vacuum line by the foot and replace everything.

    • 0 avatar

      No EGR, strange, how about did you check the reed valve at the end of the line for the smog pump? Actually is the line in good shape and connected itself even? You might have missed it, it might be in a strange place like running under the battery and then along the transmission. Also if the cat failed so soon, the shop probably did not sell you a new cat. They likely opened it up and welded some of the bigger chunks back in.

  • avatar
    bumpy ii

    It’s pretty common for a new exhaust to smell nasty for a few days until the solvents and oils from the manufacturing process burn off. In your case, the new cat broke about that time and was replaced with the test pipe, introducing a new source of stinkiness.

    If the car is running rich, the exhaust tip and maybe the rear bumper should be coated with black soot by now. If it’s not, just put another cat on and call it a day. If it is, see if you can find a OBD1 adapter and a Scanguage to check for open- and closed-loop operation.

  • avatar

    Thats really too bad, because this is one of the best cars ever made, you are lucky to have one, especially in such nice shape.  And such a strange issue, it is going to be difficult to diagnose, since you already covered all the obvious things.

    But, the good news is, there is literally TONS of aftermarket support for this car, I doubt there is anything you need that cannot be found, brand new and not even expensive.  I understand everyone’s obsession with the CAT, but lets face it, you are not the only Integra driver rolling around with a test pipe, almost every fart-can equipped Honda/Acura I see in the Tampa Bay area goes cat-less.  And, they dont even stink too bad.  A bone stock Honda engine with no cat shouldnt really smell THAT bad.  Even cat-less Mustangs arent too stinky.

    So, my point:  Is it bone stock?  The glass pack muffler failure begs the question, why did you have that on there in the first place?  Anything else non-OEM on there?  And how reputable is the muffler shop who did your work?  I havent even seen a “muffler shop” in years, there isnt that much muffler work to be had anymore, besides putting straight pipes on jacked up pickups.  Anyone with a nice import like yours is going to go to one of the dozens of import racing garages for exhaust install.

    I would find a really good shops that knows Hondas well and have them take a look, my bet is your original failed muffler caused more damage than you thought.  That happens a lot with the MR2 Spyder and Celica, the cats are prone to failure and the backpressure causes cylinder scoring, once that happens the engine is toast.  Worst case scenario is a new engine, luckily those are plentiful and fairly cheap for that car.

  • avatar

    There is no federal standard or law preventing owners from modifying their cars in any way. Repair shops, however, are prohibited from doing it for you.

    Individual states differ.

    Michigan is completely free of these kinds fo restrictions.


  • avatar

    I am a little foggy on the replacement cat that got fried the second time. Was it a Genuine Honda cat? Was it aftermarket? Was it used from a junk yard?

  • avatar

    > Thats really too bad, because this is one of the best cars ever made

    Say what? 

  • avatar

    Thee hath violated the first rule of Acuraism. Thou shalt not install non-OE parts and expect long life.

    Sermon aside, how about ye olde Italian tune up? At or near redline in 2nd gear for 10 miles or so should help with malodorous condition.

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