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Normally I try to give a mech the benefit of the doubt, but in this case, your mechanic is either the genuinely worst mechanic ever born, or is just lying to you (or both, I suppose). There is NO WAY that the coils failed like that. They're essentially inert electronic devices with a lifespan that's normally a lot longer than the vehicle. It's extremely rare for one to fail - so do the math on the possibility of all SIX failing. Now, try to imagine a scenario where "back pressure causes the ignition coils to HIT the spark plugs". That might just be the dumbest thing I've ever heard uttered by a mechanic. The lower inch or so of the plug is firmly screwed into a thick piece of aluminum (the head) while the rest of it lives happily outside of all the mayhem going on inside the engine. If something "HIT" the spark plugs hard enough to damage a coil, it would be because a chunk of the head was blown out by a piston coming apart. Maybe. Six of 'em? You have a better chance of being hit by lighting and a meteor simultaneously.

I didn't read anywhere in your description that a valve adjustment had ever been done. That can cause multiple misfire codes like you have, and enough misfires CAN clog up a catalytic converter and cause the kind of problems you're seeing. That much is plausible. I've seen it happen (on a buddy's Nissan, FWIW). FYI, the valves should be adjusted every 100,000 miles or so, or you'll end up with the multiple misfires. This is a good example of why maintenance IS important.

I think the best - at least most entertaining - thing to do would be to go to your "professional" mechanic and ask him (I assume it's a guy) to explain just how spark plugs can physically damage coils. If you see that he actually believes whatever convoluted explanation he spouts, he's too dumb to work on your car. If you can tell he's just lying to you to sell six more coils and a hefty labor charge, he's too dishonest to work on your car. So yeah, look for another mechanic and file a case with the BBB to see if you can recoup any of the money the first guy charged you. And find a reputable mechanic - one that knows his/her way around a Honda this time.
 

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I think the best - at least most entertaining - thing to do would be to go to your "professional" mechanic and ask him (I assume it's a guy) to explain just how spark plugs can physically damage coils. If you see that he actually believes whatever convoluted explanation he spouts, he's too dumb to work on your car. If you can tell he's just lying to you to sell six more coils and a hefty labor charge, he's too dishonest to work on your car. So yeah, look for another mechanic and file a case with the BBB to see if you can recoup any of the money the first guy charged you. And find a reputable mechanic - one that knows his/her way around a Honda this time.
He also wants to sell a brand new catalytic converter since it's apparently causing all this back pressure trouble, can't forget that. I asked them for a tune-up and to check the exhaust system in Aug and they said all I needed was a timing belt and water pump. Muffler almost fell off a couple weeks later and the CEL came on right after leaving shop. They didn't bother with the tune up apparently now that all six coils are failing somehow?

I get the sense they just swindle people into expensive repairs. Sucks that I fell for it, but I guess you just move on?

How do I get my car outta there and to a reputable mechanic while minimizing monetary cost and damage to the car? Feels pretty undriveable as is.
 

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From what the mechanic said, the catalytic converter is so clogged that the back pressure is causing the ignition coils to hit the spark plugs and hence misfire.
Ignition coils what? Run and never come back to this shop!

The coils go on top of the spark plugs (as a sort of a condom, if you will :)). The spark plugs are screwed securely into the engine block sealing the cylinders to create sparks for combustion and compression in them. They are designed to withstand multiple combustion within cylinders and keep them pressurized. That pressure is much bigger than any theoretical exhaust gas blow back.

My advice - go to Acura and pay them for diagnostics. They'll give you a full report of what's actually wrong with your vehicle and you can then decide what to do and where.
 

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Thanks for your advice, AA. Trying to get the car out by tomorrow and going for a second opinion to a reputable acura/Honda specialist shop. Hoping I can avoid paying the shop that currently holds it another dime. Hoping the coils that are in now aren't totally effed; guy was saying they were (both the three new they replaced last week-covered under warranty-and the originals) but I now know better than to take that at face value.

So to recap: we're thinking valve adjustment? From what I've read, a bad EGR valve could be the culprit as well. Is this info I should feed the new shop or should I state symptoms and let them diagnose?
 

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There's no way that the coils are going to be damaged - in fact, the three they replaced were most likely fine as well.

I think the best way to proceed would be to let the shop know that you've conferred with some "experts" (don't use the term "on an online forum" though...) and you know they're over their head diagnosing your car. If necessary, use their inability to describe the physical situation that would result in vibrations magically damaging ALL SIX coils as a basis.

If they get twitchy about you taking the car, let them know that you can always let the BBB, yelp and other social media understand what they tried to do. There's no way they really want news of their "diagnosis" getting out in the public domain since it makes them look as bad as they really are.

And just for clarity, I do believe it's quite likely that you will need a new catalytic converter (which can fail because of the "clogging" that happens when raw gas is dumped in from misfiring cylinders for too long). I've read online accounts of people "clearing" their cats with various methods, but I suspect it's unlikely to work once the obstruction is bad enough to cause serious engine performance issues.
 

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There's no way that the coils are going to be damaged - in fact, the three they replaced were most likely fine as well.

I think the best way to proceed would be to let the shop know that you've conferred with some "experts" (don't use the term "on an online forum" though...) and you know they're over their head diagnosing your car. If necessary, use their inability to describe the physical situation that would result in vibrations magically damaging ALL SIX coils as a basis.

If they get twitchy about you taking the car, let them know that you can always let the BBB, yelp and other social media understand what they tried to do. There's no way they really want news of their "diagnosis" getting out in the public domain since it makes them look as bad as they really are.

And just for clarity, I do believe it's quite likely that you will need a new catalytic converter (which can fail because of the "clogging" that happens when raw gas is dumped in from misfiring cylinders for too long). I've read online accounts of people "clearing" their cats with various methods, but I suspect it's unlikely to work once the obstruction is bad enough to cause serious engine performance issues.
Thank you, habbyguy. Yours and others' advice has given me a good idea of what to do as well as peace of mind.

Unfortunately, I don't think we're gonna see the resolution to this one. I am really leaning toward getting a new car. I feel it's not worth dumping more into the cat and whatever else needs to be done (which puts me at or above the bluebook) and risk having some other stuff pop up down the road.

That being said--and I'm just throwing this out there--if anyone wants to come grab a project car for cheap in Maryland, PM me! You have full disclosure.
 

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Just a thought - think of this car as the "devil you know". I really think it's likely that with a valve adjustment and (maybe) a new catalytic converter, your MDX might be back to running like a top. The MDX is really one of the most reliable vehicles you're going to find anywhere, particularly for the money (hard to imagine finding a 7-passenger luxury SUV for less money than a 1G MDX). If you end up with a sorted MDX for "bluebook money", you're driving a bargain (pardon the kinda pun). When you roll the dice by buying a "new" used car, you could end up in worse shape than you are now, even if there's nothing obviously wrong with it.

Just as an example, the 133,000 mile 2006 Audi A3 I just bought would have impressed almost anyone test-driving it, but I ended up dropping $1000 or so into it for parts (I do the wrench-twisting, of course). It was overdue for a timing belt / water pump, had a bad thermostat (a 3-4 hour job, believe it or not), control arm bushings (simple on one side, a nightmare on the other), shocks and struts, and a host of "little stuff" that any used car really needs, like wiper blades, serpentine belts, fluids and filters, tires, etc. Very "worth it" but if I had taken the car to an Audi dealership, I'd probably be $4-5,000 deeper into it than I am.
 

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Just a thought - think of this car as the "devil you know". I really think it's likely that with a valve adjustment and (maybe) a new catalytic converter, your MDX might be back to running like a top. The MDX is really one of the most reliable vehicles you're going to find anywhere, particularly for the money (hard to imagine finding a 7-passenger luxury SUV for less money than a 1G MDX). If you end up with a sorted MDX for "bluebook money", you're driving a bargain (pardon the kinda pun). When you roll the dice by buying a "new" used car, you could end up in worse shape than you are now, even if there's nothing obviously wrong with it.

Just as an example, the 133,000 mile 2006 Audi A3 I just bought would have impressed almost anyone test-driving it, but I ended up dropping $1000 or so into it for parts (I do the wrench-twisting, of course). It was overdue for a timing belt / water pump, had a bad thermostat (a 3-4 hour job, believe it or not), control arm bushings (simple on one side, a nightmare on the other), shocks and struts, and a host of "little stuff" that any used car really needs, like wiper blades, serpentine belts, fluids and filters, tires, etc. Very "worth it" but if I had taken the car to an Audi dealership, I'd probably be $4-5,000 deeper into it than I am.
True enough. I thought about it long and hard. If I were more mechanically inclined, I'd probably go that route. Thing is, it definitely needs other work, like sway bar and front struts. I would be paying shop prices for any other repairs it might need (besides really simple stuff like rotors and pads). I really don't want to roll the dice on that possibility.

I plan on buying a brand new hybrid sedan (first brand new purchase ever), so no worries on inheriting a problem. Don't really need the SUV size these days and my commute isn't short so I'll save a good deal of money on gas.

If the cat is shot, which sounds quite likely (I can check that myself I suppose), that alone puts it out of value range for me. With the sway bars, valve adjustment and whatever else pops up, I'm way out. Even if I end up paying more, I can write that off as affording peace of mind.
 

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One way to look at this is that the monthly payment for that hybrid will be the equivalent of a fairly major repair on your MDX. Every month. And you will want to check on the lifespan / replacement cost of the batteries on a hybrid (often, the cost of the batteries is high enough that the car is essentially "totaled" when the battery wears out). For some folks with the right number of commute miles, it can make sense by offsetting these costs with money they save on gas. For others, they'll end up spending a LOT more than another more conventional vehicle might cost them over the lifespan of the vehicle.
 

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Discussion Starter #30
Thanks for this interesting back and forth habbyguy and ssg223. I'm still having the same intermittent engine issues with my '01. I thought that possibly it might have something to do with a bad coil as we have an '03 BMW 525i wagon that had similar issues a few years ago that were solved by replacing some faulty coils. Now I'm not so sure this is something worth pursuing based on habbyguy's response. I haven't been driving it much the past few weeks and have been too busy to really explore his advice. Planning to look into some of these recommendations in the next week or two. Will keep you posted.
 

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I have an '03.5 BMW 330i (ZHP) and recall (no pun intended) that there was a recall on those coils, which did tend to go bad. Not so with the boringly reliable MDX's' though. I always counsel to NOT replace the coils as you'll probably be making the vehicle less reliable in the end. Sure, replacing a bad coil makes perfect sense, but the other five aren't any more likely to fail than any other electrical component in the vehicle (and that's not very likely). You will want to get that car scanned for OBD trouble codes - that's likely to point you in the right direction (or at least dramatically improve the quality of advice you get here). ;-)
 

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Discussion Starter #32
Thanks habbyguy. New weird stuff starting happening today. Door locks started clicking like they were locking and unlocking on their own. Intermittent issue - was occurring both when the car was running and when it was turned off. And the car alarm went off 3 different times for no apparent reason. Happened when the car was locked and unlocked. Think that possibly the locking/unlocking is setting off the security system. Just disconnected the battery so that it doesn't go off again in the middle of the night. Anyone ever heard of this?
 

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One of two things happening here.

1) There could be a problem with the module that controls the locking and alarm functions (going to be hard to troubleshoot unless you can get it to stay in "failure mode" long enough to trace the issue down), or...
2) You might have a problem with your keyfob remote - if a stray drop of water got into it, it could be intermittently sending lock / unlock / alarm requests to the car. Probably the easiest way to check this is to remove the battery from the keyfob(s) and see if the problem stops.
 

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Discussion Starter #34
Figured out a solution to the alarm going off w/out having to disconnect the battery. Since NAV screen has been on fritz and comes on only intermittently anymore I didn't enter the code to reactivate it when I started car after reconnecting battery a few days ago. Not sure if the security system is related to the function of the touch/NAV screen, but the alarm hasn't gone off in 3 days.

On the intermittent engine issues: Started the car this morning with a code reader attached to OBD2 port and the CEL & VTM-4 lights came on, so I drove it around for a while to see what codes and live data I could pull. attached some pics I took of the code reader's screen showing the code detail and live data while the car was idling as it was producing these codes. Same cylinder misfire codes I got over 5 years ago. These codes were not from an event where the engine quit on me which is the main thing I am trying to figure the cause of. Will keep the reader attached as I drive to try and catch it if it stops.
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I think your plan is a good one - a couple cylinders misfiring occasionally won't shut the engine down (not by a long shot) so hopefully it'll throw a meaningful code if/when it does flame out again. Good luck!
 

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Got mine outta the shop a couple weeks ago. Drove it about 10 miles from the shop to the house with no blinking CEL. Mech did the warranty work on the three coils he said were bad, that's it. Not going back because he clearly doesn't know what he's doing it seems.

Still haven't bought a car or anything. Thinking if the cat were still good I'd throw a few hundred into it but have not checked it yet. There's a reputable Honda shop in town, but they charge $90/hr to diagnose. My cousin knows Acura (has an Integra from same era that he brought back to life) but lives 80 miles away. Thinking about getting it looked at again.
 
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