bad Friday ending
#121
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I may be asking stupid questions as a Newbie, but wouldn’t the mech replace the coil on the one cylinder that is suspect (since it is 99.9999% won’t be the plug, and then crank the car up? If it runs right stop there? Same amount of time as walking around the car?
#122
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OK ... so, hcamp replaces plugs when it was unnecessary, then there is an issue, apparently with one coil that occurred in a suspect time following the plug change. A shop determines #5 is misfiring on Friday, but then next week determines #3 and #5 misfiring. Shop then replaces coils and plugs on both cylinders. Given the plugs were new and only #5 was determined to be misfiring, why would a mech replace two plugs, and two coils? Does anyone think it likely that two coils failed at the same time? That the plugs were suspect?
Remember, only the coils on 3 and 5 were replaced, right - along with the plugs that just been replaced? Why not all of the coils? Why not replace the plugs, again? I don't get it.
If coils were $50-100 apiece, I would replace them when they failed. If this wasn't logical, why would the testing device read out plug by plug - ie identifying the specific failure, why not just read out "This is a Porsche and is special so replace all coils just in case and/or because the parts and labor are so expensive?."
Remember, only the coils on 3 and 5 were replaced, right - along with the plugs that just been replaced? Why not all of the coils? Why not replace the plugs, again? I don't get it.
If coils were $50-100 apiece, I would replace them when they failed. If this wasn't logical, why would the testing device read out plug by plug - ie identifying the specific failure, why not just read out "This is a Porsche and is special so replace all coils just in case and/or because the parts and labor are so expensive?."
Last edited by RennListUser01; 02-24-2022 at 05:19 PM.
#123
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OK ... so, hcamp replaces plugs when it was unnecessary, then there is an issue, apparently with one coil that occurred in a suspect time following the plug change. A shop determines #5 is misfiring on Friday, but then next week determines #3 and #5 misfiring. Shop then replaces coils and plugs on both cylinders. Given the plugs were new and only #5 was determined to be misfiring, why would a mech replace two plugs, and two coils? Does anyone think it likely that two coils failed at the same time? That the plugs were suspect?
Remember, only the coils on 3 and 5 were replaced, right - along with the plugs that just been replaced? Why not all of the coils? Why not replace the plugs, again? I don't get it.
If coils were $50-100 apiece, I would replace them when they failed. If this wasn't logical, why would the testing device read out plug by plug - ie identifying the specific failure, why not just read out "This is a Porsche and is special so replace all coils just in case and/or because the parts and labor are so expensive?."
Remember, only the coils on 3 and 5 were replaced, right - along with the plugs that just been replaced? Why not all of the coils? Why not replace the plugs, again? I don't get it.
If coils were $50-100 apiece, I would replace them when they failed. If this wasn't logical, why would the testing device read out plug by plug - ie identifying the specific failure, why not just read out "This is a Porsche and is special so replace all coils just in case and/or because the parts and labor are so expensive?."
I despise coil packs. With my E90 BMW, I fought and argued with the dealer as coil packs went bad one at a time under warranty.
Over a 5 month period, I had three coil packs fail. One at a time. They replaced them. One at a time.
After the third one went I replaced the other three at my cost at home to overcome the madness.
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So, scratching this a different direction ... which manufacturer coil on plug devices are better? Denso and NGK make them ... are these better worse than whatever the OEM crap appears to be? Where are the OEM coils made, and by what company? Where are the various aftermarket coils made, by company?
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#125
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Seems to be a reasonable thought train.
I despise coil packs. With my E90 BMW, I fought and argued with the dealer as coil packs went bad one at a time under warranty.
Over a 5 month period, I had three coil packs fail. One at a time. They replaced them. One at a time.
After the third one went I replaced the other three at my cost at home to overcome the madness.
I despise coil packs. With my E90 BMW, I fought and argued with the dealer as coil packs went bad one at a time under warranty.
Over a 5 month period, I had three coil packs fail. One at a time. They replaced them. One at a time.
After the third one went I replaced the other three at my cost at home to overcome the madness.
I assume you kept two of the ones you preventively removed in the trunk? JIC?
#126
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OK ... so, hcamp replaces plugs when it was unnecessary, then there is an issue, apparently with one coil that occurred in a suspect time following the plug change. A shop determines #5 is misfiring on Friday, but then next week determines #3 and #5 misfiring. Shop then replaces coils and plugs on both cylinders. Given the plugs were new and only #5 was determined to be misfiring, why would a mech replace two plugs, and two coils? Does anyone think it likely that two coils failed at the same time? That the plugs were suspect?
Remember, only the coils on 3 and 5 were replaced, right - along with the plugs that just been replaced? Why not all of the coils? Why not replace the plugs, again? I don't get it.
If coils were $50-100 apiece, I would replace them when they failed. If this wasn't logical, why would the testing device read out plug by plug - ie identifying the specific failure, why not just read out "This is a Porsche and is special so replace all coils just in case and/or because the parts and labor are so expensive?."
Remember, only the coils on 3 and 5 were replaced, right - along with the plugs that just been replaced? Why not all of the coils? Why not replace the plugs, again? I don't get it.
If coils were $50-100 apiece, I would replace them when they failed. If this wasn't logical, why would the testing device read out plug by plug - ie identifying the specific failure, why not just read out "This is a Porsche and is special so replace all coils just in case and/or because the parts and labor are so expensive?."
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GT3FZS (10-31-2022)
#127
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I may be asking stupid questions as a Newbie, but wouldn’t the mech replace the coil on the one cylinder that is suspect (since it is 99.9999% won’t be the plug, and then crank the car up? If it runs right stop there? Same amount of time as walking around the car?
The coils are not that expensive in the grand scheme of things, so it makes sense to just treat them as wear items like the plugs themselves. Swapping the coils out every other plug change interval makes sense to me. The part #s are constantly being revised, again because somebody doesn't know what they're doing, so this will also provide some assurance that you have the latest/greatest parts.
#128
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I gave up keeping parts and tools in modern cars. I have basics, a compressor, and tire plug kit. But thats it. I do keep some additional items in classic cars.
Back on topic...my 991.2 T has under 1000 miles. Its approaching 4 years old. (yes I need to drive it more, no I am not insane, just have very little personal time in the past few years).
There is no way I am pulling plugs yet. Porsche's age based service guidelines are largely a gift to dealers. Plain and simple.
#129
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Porsche recommends that the plugs be replaced at 30k miles or 4 years. Although I now think that is overkill, I was doing what was recommended and concurred to by some on this forum. The shop DID put new plugs in both #3 and #5. I think you need to carefully read my post from yesterday again. Some other items to consider:: 1) These plugs are not easy to get to and impossible to work on when the engine is hot. 2) You have to remove the rear wheels and heat shields to get to the plugs. 3) To properly evaluate a repair, the car should be running at operating temperature and driven. It was reasonable for the shop to repair it the way they did. If it hadn't been for the absolute weirdness of the problem not following the plug and coil from #3 to #2, I would have done it myself and saved the money. I had already changed all the plugs once (which means having the coils out). BTW, these coils from Pelican or FCP are $75.00 each, $85.00 from this shop. I don't want them to replace anything that is not showing a problem, that's just additional and unnecessary labor and parts expense.
Also, people's definition of expensive differs: IMO, replacing 6 x $75 = $450 every eight years is rather cheap.
#130
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The onboard diagnostics are garbage. Speaking as an EE, it should be the most trivial thing in the world to detect which of 6 coils is associated with a misfire condition and report a specific error that tells the tech exactly what coil to replace. Instead, Porsche has elected to display all kinds of completely random error messages that have nothing to do with anything that's actually happening, leaving the tech to sort it out at the customer's expense.
The coils are not that expensive in the grand scheme of things, so it makes sense to just treat them as wear items like the plugs themselves. Swapping the coils out every other plug change interval makes sense to me. The part #s are constantly being revised, again because somebody doesn't know what they're doing, so this will also provide some assurance that you have the latest/greatest parts.
The coils are not that expensive in the grand scheme of things, so it makes sense to just treat them as wear items like the plugs themselves. Swapping the coils out every other plug change interval makes sense to me. The part #s are constantly being revised, again because somebody doesn't know what they're doing, so this will also provide some assurance that you have the latest/greatest parts.
The car should be able to know if it fired the plug, opened the injector, etc.
#131
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EE here as well. Do these cars use 4 wire coil packs? I recently used a toyota 4 wire pack for a project. It has a feedback pin that works quite well. It basically tells the ECU if it fired or not. Very simple and straightforward. Porsche could make reporting misfires simple. Unfortunately there seems to be all sorts of schemes for this like looking at crank position sensors etc.
The car should be able to know if it fired the plug, opened the injector, etc.
The car should be able to know if it fired the plug, opened the injector, etc.
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#132
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#133
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Hmmm ... so, it sounds like there is no data available on which coils are prone to failure, allowing folks to choose which to use to replace failing coils?
I've changed a lot of plugs - on cars, outboard motors, motorcycles, etc over the years - on a couple of worn out engines with point type ignition I've seen oil deposits, but I never have on a high energy ignition system, including engines with 100,000 plus miles of pretty hard use. In every photo of a normally maintained and otherwise normally operating Porsche engine, I have only seen perfectly fine plugs ... I guess I just don't understand the desire to replace operating components, unless the car is in warranty and it is required,
Working the logic in reverse ... if you don't maintain your car yourself, it is going to cost a fortune regardless - so, why not wait till the coil or plug stops working? If you are not going to drive it when this happens, it doesn't really matter, does it?
If one is really worried about plugs becoming stuck in the heads, aren't there penetrating lubricants that will help? And, is this just rumor or is their data - not the anecdotal stuff - that plays to this tune?
I'm trying hard to adapt to the Porsche mindset, but this sort of things makes me spend a lot of brain cells over too many martinis.
I've changed a lot of plugs - on cars, outboard motors, motorcycles, etc over the years - on a couple of worn out engines with point type ignition I've seen oil deposits, but I never have on a high energy ignition system, including engines with 100,000 plus miles of pretty hard use. In every photo of a normally maintained and otherwise normally operating Porsche engine, I have only seen perfectly fine plugs ... I guess I just don't understand the desire to replace operating components, unless the car is in warranty and it is required,
Working the logic in reverse ... if you don't maintain your car yourself, it is going to cost a fortune regardless - so, why not wait till the coil or plug stops working? If you are not going to drive it when this happens, it doesn't really matter, does it?
If one is really worried about plugs becoming stuck in the heads, aren't there penetrating lubricants that will help? And, is this just rumor or is their data - not the anecdotal stuff - that plays to this tune?
I'm trying hard to adapt to the Porsche mindset, but this sort of things makes me spend a lot of brain cells over too many martinis.
Last edited by RennListUser01; 02-26-2022 at 07:47 PM.
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GT3FZS (10-31-2022)
#134
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I recently did my plugs on my 2014 at 20K miles and that #5 plug felt like it did not want to come out. Had me sweating a bit andI even stopped and to think about it for a day. It did come out but with much more torque than I'm accustomed to on a sparkplug job. I didn't see any thread damage or corrosion, so I don't know if it's just the nature of the beast. But yeah, I will keep to the 4 year interval. And be very sure not to over-torque.
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This, then, begs another question. What does the curve look like on a plug getting stuck in a head ... ie, does a plug increasingly get more stuck over the first x number of heat cycles then flatten out? And, is it related to time or heat cycles? If not changed at 3 years or 4 years does the "stuckness" not increase, or increase more slowly?
Should one use PB Blaster prior to pulling the plugs?
Someone noted new plugs have a thread coating to help? Would it be better to pull the plugs immediately after delivery and put antiseize on the threads? What would a drop of oil do - given this is done all the time on other engines?
It sounds as if Porsche has different timelines for different markets? This doesn't seem to follow any engineering logic?
Think of all the other questions begged. What percentage of dealership income is related to unnecessary maintenance? Has this increased over time as Porsche slowly convinces owners of the specialness of their cars relative to other cars?
Sigh ...
Should one use PB Blaster prior to pulling the plugs?
Someone noted new plugs have a thread coating to help? Would it be better to pull the plugs immediately after delivery and put antiseize on the threads? What would a drop of oil do - given this is done all the time on other engines?
It sounds as if Porsche has different timelines for different markets? This doesn't seem to follow any engineering logic?
Think of all the other questions begged. What percentage of dealership income is related to unnecessary maintenance? Has this increased over time as Porsche slowly convinces owners of the specialness of their cars relative to other cars?
Sigh ...
Last edited by RennListUser01; 02-26-2022 at 10:01 PM.