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Hi all --

Not my first post by a long shot -- I was PuMoDi until the board got hacked and people had to change their passwords. For some reason, mine was unchangeable (it was not sending the change to my registered email address) and when I notified administrators way back when I never heard back so I gave up, but I used to post regularly.

Anyhow I'm back and here's why.

My 2015 sGT (2.5L, manual) is 3.5 years old now and has about 70K miles on it. It has generally been very reliable and has been a blast to drive and own. But as with all good things sometimes there's a hiccup.

Over the weekend I was pulling out of my development and suddenly the car went into a "limp home" mode. Very little power, wouldn't accelerate past a certain speed (25 mph at most?) and the engine was shaking fairly violently. I also had the check engine light flashing quickly (and for some odd reason as it drove the TPMS and DSC system lights lit up too, but were steady and not flashing).

I knew right away I had to get it back to my driveway so I did. I popped the hood, saw the violent shaking and figured a cylinder wasn't firing to cause that. No cylinder means no fuel, air or spark.

Quick web searched led me to believe it was spark and a similar result on another board indicated it might be a coil. So I called the dealer. They said get it towed so as not to damage the catalytic converters. I did just that.

Took them two days to get to it but today they tell me it was the #3 cylinder coil that failed (so I was 75% of the way there, I just didn't know which cylinder).

The shame of it is I'm mechanically adept enough to know how to swap a coil (and change the plugs since it's almost time anyway as it approaches 75K) and all that, but because I lacked the diagnostics and didn't know if it was something worse I decided to let the "experts" do it.

So they're changing the coil, changing the plugs (makes sense), but then they recommended a "fuel induction service." I asked them to clarify if this was akin to a carbon cleaning since these are DI engines and they said no, it was just a fuel injector cleaning, mumbled that it did some stuff in the "top end" too (I presumed the service adviser meant combustion chamber) and kinda started avoiding telling me more about it other than the fact that the mechanic strongly recommended it and -- oh by the way -- it costs $140!

So I didn't authorize it. It doesn't sound much more like someone dumping a can of BG44 or Techron into the tank to let it run. At most maybe they pull a vacuum line and run it through closer to the motor -- not sure exactly. But the price seemed outrageous.

But it also got me to thinking. Have any of you experienced this yet? Having a coil fry at only 70K miles? If so (or even if not) what do you think would cause that? Typically bad plugs I would think would cause resistance issues so when I go pick the car up I'll ask about the condition of the plugs. But working downstream from there does anyone think it could have been cruddy fuel to foul a plug or plugs? I almost always use Sunoco (90% of the time) or another top brand -- on rare occasion I've been known to use one particular Sheetz I've always used. Could a tank of bad fuel also have messed up the injectors? And if so would that even cause the plug to foul? Or have some other adverse impact on the coil?

If anything I've overmaintained this car -- despite mostly highway driving at 20K miles a year I have all the oil changes done (and other services) at 5K intervals. I use quality fuel (though I guess it's possible to get a bad tank now and again). It doesn't seem carbon related. But despite overmaintaining it, I won't pay for garbage ideas -- I have always had the dealer stick to the factory maintenance only so I'm not keen on the idea of made up services.

All that said, it did get me to thinking about maybe something should be done there but not at $140.

Thoughts on causes? Thoughts on whether I should get the injectors cleaned? Sound made up? Always appreciate the minds here weighing in. Sorry for the length and thanks! :)
 

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Don't bother with injector cleaning, unless you are experiencing problems with the injectors being partially blocked. Throw in a bottle of injector cleaner into the tank if you feel the need. That's all the $140 does.

If I were you, I would ask Mazda head office and see if they would assist you with the coil pack. I've not heard of the packs going bad after such a short time. Maybe you pay for labour and they supply the pack?
 

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For future reference, figuring out which coil is bad is often easy. I haven't popped off the engine cover, but I'm assuming we have coil-on-plugs, and each coil has a connector on top, with wires going to the ecm.

With the engine running, and one coil obviously failing, disconnect one coil at a time from its connector going to the ecm. If it immediately runs more rough, that coil was working, so reconnect. If there is no change, that coil was not working.

I drove an Audi for ten years that would pop a coil pack annually. I kept a spare and a flat head screwdriver in the glove box, and could diagnose and swap it in about two minutes on the side of the road. That being said, I've never heard of this issue on Mazdas before.
 

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Check the DTC and reset restart and see if the same DTC returns.
Not the best idea for several reason however a DIY can swap out a known working plug/coil for the suspected one and see if the DTC returns to that Cylinder.
Fuel injection professionally serviced is nothing like using a fuel tank chemical. It takes me almost an hour to do one for a customer and with a F/I System Cleaner KIT that comes with gauges, connectors ,adapters, etc. and you must use a special threaded top F/I cleaner to attach to one or more of the F/I hoses.
Pulling a F/I connector off a running engine will simply cause from single to multiple DTCs and not the best way to diagnosis a cylinder misfire problem. It is much like creating a condition of a F/I becoming plugged or a connector failing etc.

If you really do not know how to use a Diagnostic scanner as a valuable Diagnostic Tool to solve or help starting to track down a problem it is doubtful IMHO you have the experience to easily solve the issue and should take it to a ASE Service Shop or Dealership.

Like most EFIU/ECU issues there is a PROBLEM SOLVING procedure (tree) that always includes testing other parts which requires some knowledge of Diagnostic procedures or experience.

Off topic a bit .....
When you get a full estimate for a dealership or shop (depending on the start ) the BAR REQUIRES that everything be documented. An estimate BEFORE any service work is performed and everything written in easy to understand language for the finish service documentation. This is why often times if you do not carefully listen and ask questions from your service adviser many people come on forums and talk negatively about what a shop told them and the estimated cost of a possible needed service of something and relate that to "RIPPING YOU OFF". I spend at least a an hour or more every day documenting everything I or my service Techs do labor related , the parts they replaced and any and all contact with the customer on the final invoice that they read and MUST sign when they pick up their repaired vehicle.

Members or visitors of forum should read and understand this most of all when seeking advise in this manor of internet interaction with people everywhere whop are trying to sincerely help you but may unintentionally be HELPING you as they should?
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Danger also exists for puling F/I connector, with possible damage to PZT type injector. Special electronics controls the driving signal for rate of rise and fall, preventing fracture of the PZT element. Pulling connector while running, may result in abrupt signal, or injector stuck on, dumping fuel.

As suggested, reading diagnostics best approach.
 

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Hi all --
So they're changing the coil, changing the plugs (makes sense), but then they recommended a "fuel induction service." I asked them to clarify if this was akin to a carbon cleaning since these are DI engines and they said no, it was just a fuel injector cleaning, mumbled that it did some stuff in the "top end" too (I presumed the service adviser meant combustion chamber) and kinda started avoiding telling me more about it other than the fact that the mechanic strongly recommended it and -- oh by the way -- it costs $140!

So I didn't authorize it. It doesn't sound much more like someone dumping a can of BG44 or Techron into the tank to let it run. At most maybe they pull a vacuum line and run it through closer to the motor -- not sure exactly. But the price seemed outrageous.

But it also got me to thinking. Have any of you experienced this yet? Having a coil fry at only 70K miles? If so (or even if not) what do you think would cause that? Typically bad plugs I would think would cause resistance issues so when I go pick the car up I'll ask about the condition of the plugs. But working downstream from there does anyone think it could have been cruddy fuel to foul a plug or plugs? I almost always use Sunoco (90% of the time) or another top brand -- on rare occasion I've been known to use one particular Sheetz I've always used. Could a tank of bad fuel also have messed up the injectors? And if so would that even cause the plug to foul? Or have some other adverse impact on the coil?

If anything I've overmaintained this car -- despite mostly highway driving at 20K miles a year I have all the oil changes done (and other services) at 5K intervals. I use quality fuel (though I guess it's possible to get a bad tank now and again). It doesn't seem carbon related. But despite overmaintaining it, I won't pay for garbage ideas -- I have always had the dealer stick to the factory maintenance only so I'm not keen on the idea of made up services.

All that said, it did get me to thinking about maybe something should be done there but not at $140.

Thoughts on causes? Thoughts on whether I should get the injectors cleaned? Sound made up? Always appreciate the minds here weighing in. Sorry for the length and thanks! :)
Some things to consider here-
Mazda Service Bulletin 00-002/16 says this about "injector cleaning"
• Cleaning injectors without an actual power related complaint from the
customer, does not improve engine performance.
• Fuel injector malfunctions should only be repaired by replacement

There is nothing in any Mazda service procedures about "induction service", whatever that may be. This comes up fairly frequently and its mostly a dealer thing designed to separate you from your money. A bottle of injection cleaner in the tank, run some Seafoam through the intake and your wallet is $140 lighter. All you need to do is Google "induction cleaning service" and you'll see all you need to know for yourself. It is right up there with paying the dealer a bunch of money to put nitrogen in your tires....:smile2:

Its quite possible that a bad plug or wire could have caused the coil to burn out. If the coil is operated without a load (a bad plug that is barely firing or stops firing entirely for any reason) it will burn out. This is a fairly common thing on older Mazdas such as the 1.8l engine as found in the first generation of MX-5s. Coil failure can also happen if you try to do a compression check without disconnecting the power to the coil, another frequent occurence with inexperienced DIYers.
 
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