Random/multiple cylinder misfire

[krjohnson]

I've seen this topic in the forum but need a bit more information because of the alarming information from my dealer (flywheel replacement). My early 2005 US MY certified (but out of warranty) Carrera with 48,000 miles showed a check engine light shortly after a fill up at Costco (not my usual spot but necessary due to low fuel). Shortly thereafter the ck engine light came on intermittently, then off until it stayed on. My mechanic did a thorough check (checked the faults, P0300 and P0302 and looked at plugs) and suspected bad gasoline from Costco. After using up the tank I went back to Shell 91 octane gas and the light went off, but came on again after a couple of weeks. Took it to the dealer and they 'reprogrammed' because I was a version behind, and said that if this did not solve the warning light, it was probably an out of round flywheel (they have seen this on other 2005's) which would have to be replaced ($$$$). I have had no similar problems in my 43,000 miles of ownership and despite the light, the car runs strong although recently it idles intermittently with the tach moving +/- 30 rpm. Any thoughts on other things to look at? I have only heard an actual consistent misfire on one occasion (it was on the 4 5 6 side) and it vanished with more rpms.

One other item. The fault output I got from the dealer included a section on 'Number of ignitions, range 1', 2, 3 through 6. Does anyone have a precise definition for the different ranges? All I know is that 4, 5 and 6 are very bad, possibly terminal for the engine.

BTW, I just got back from a museum and factory tour in Stuttgart-Zuffenhausen and highly recommend it to all.

[Mijostyn]

I'm itching to do a European delivery. The out of round flywheel makes no sence. How does a fly wheel suddenly go out of round. Warped maybe but, how would the ignition computer know this? I have seen bad gas do a lot of funny things like f up your fuel filter.

I have always stuck with 93 octane fuels in these cars and prefer Mobil or Sunoco. I only use other fuels under duress.

I would check your fuel filter, tank up with good gas and see how it goes. I would also find an independent mechanic who knows what he is doing. Up here the real Porsche guys use Blair Talbot. ( New Hampshire) I do all the routine stuff, oil, brakes and such. Warranty stuff goes to the dealer and everything else goes to Blair.

Edited June 8, 2013 by Mijostyn

[Ahsai]

Did they inspect or replace the #2 coil?

[binger]

Did the last shop get the freeze frame data? if you had that it would point you in better direction than just throwing parts at it. You need to verify if the coil is intermittently bad. If the CEL light is on you will need to get the freeze frame data and make note of it then clear the codes. if you have P0302 its cylinder #2 misfire. Next take a sharpie and number all the coils on there cylinders. now take the #2 coil and swap it out with coil # 4 or #5 whatever is not giving you a issue. Drive and see if you have a misfire on the new cylinder with the #2 coil. If you do that coil is bad. Hope this helps please keep us posted. Also if the flywheel is out of round you would see more then one cylinder misfiring.

[Skootnasty]

. The out of round flywheel makes no sence. How does a fly wheel suddenly go out of round. Warped maybe but, how would the ignition computer know this? I have seen bad gas do a lot of funny things like f up your fuel filter.

I have always stuck with 93 octane fuels in these cars and prefer Mobil or Sunoco. I only use other fuels under duress.

The flywheel "out of round" causes P0300 because it causes the crankshaft to vibrate. The crankshaft position sensor sends the pulse data to the DME which sees abnormal input from the sensor. It's only recourse is to flag misfire DTC for the slow then fast pulse information from the crankshaft sensor. If there wa not a P0302 attached, I would be more inclined to buy into the plausability of the diagnosis. I would alo ask what test they did to eliminate ignition, fuel, and internal mechanical systems before recommending the flywheel.

But to be clear, Yes the flywheel can and will cause P0300. It, however, may not be your actual issue.

Skoot

[spiffyjiff]

One other item. The fault output I got from the dealer included a section on 'Number of ignitions, range 1', 2, 3 through 6. Does anyone have a precise definition for the different ranges? All I know is that 4, 5 and 6 are very bad, possibly terminal for the engine.

Range 1: 7300-7500 RPMRange 2: 7500-7700 RPMRange 3: 7700-7900 RPMRange 4: 7900-8400 RPMRange 5: 8400-9500 RPMRange 6: 9500-11000 RPM

the readout should tell you: how many ignitions in each range (there are 3 ignitions per revolution), and the operating hour of the last recorded overrev.

track guys usu have (lots of!) R1 and often R2. a "money shift" can easily spin up thru R5 (ask me how i know). it's an accepted notion that R1-3 are usually fine, no damage despite what porsche says/warranty's. and if the last overrev in R4-6 happened long ago and engine is still running fine, then you should be ok also.

but then again, these things could grenade at any time so who the heck knows. :p

[krjohnson]

I'm itching to do a European delivery. The out of round flywheel makes no sence. How does a fly wheel suddenly go out of round. Warped maybe but, how would the ignition computer know this? I have seen bad gas do a lot of funny things like f up your fuel filter.

I have always stuck with 93 octane fuels in these cars and prefer Mobil or Sunoco. I only use other fuels under duress.

I would check your fuel filter, tank up with good gas and see how it goes. I would also find an independent mechanic who knows what he is doing. Up here the real Porsche guys use Blair Talbot. ( New Hampshire) I do all the routine stuff, oil, brakes and such. Warranty stuff goes to the dealer and everything else goes to Blair.

My independent mechanic verified that this can happen to the 2-piece flywheel, although it is infrequent. Another responder confirmed this possibility. My independent mechanic does not believe this to be the case on my car and suspects that the DME programming will make the idel mixture more rich and solve the problem. I do have other contingency plans in place if that does not work. It has worked for the last 3 days. Also, here in CA we only get 91 octane gas unless you go to a specialty outlet which has some 100 but it costs like $9/gal and it probably isn't suitable for everyday driving. I have never had prior trouble with the high quality 91 grade fuels until I got the Costco junk. Thanks for the input.

[krjohnson]

Did they inspect or replace the #2 coil?

Did they inspect or replace the #2 coil?

If I don't get this resolved through the better gas and the DME programming, there are some next steps to take and this would be one of them, not sure right now if it would be the next step or a step after some other diagnostics. I also got a count of misfires on cylinder 1 in a different section of the readout but there was no corresponding P0301 code to go with it. Thanks for the input.

[krjohnson]

Did the last shop get the freeze frame data? if you had that it would point you in better direction than just throwing parts at it. You need to verify if the coil is intermittently bad. If the CEL light is on you will need to get the freeze frame data and make note of it then clear the codes. if you have P0302 its cylinder #2 misfire. Next take a sharpie and number all the coils on there cylinders. now take the #2 coil and swap it out with coil # 4 or #5 whatever is not giving you a issue. Drive and see if you have a misfire on the new cylinder with the #2 coil. If you do that coil is bad. Hope this helps please keep us posted. Also if the flywheel is out of round you would see more then one cylinder misfiring.

I did not get the freeze frame data (and am not sure what it is). I'll talk to my independent mechanic about this and take this into consideration if the better gas and DME programming don't clear the issue. The report shows a misfire count on cyl 1 as well and I think there were prior reports (since cleared) that showed other cylinders, which led to the idea that it was initially bad gas. I intend to do as much diagnosis as possible before getting into the expensive parts and labor, because the car runs strong and the worst thing is an intermittent slightly rough idle. Thanks for the input.

[krjohnson]

One other item. The fault output I got from the dealer included a section on 'Number of ignitions, range 1', 2, 3 through 6. Does anyone have a precise definition for the different ranges? All I know is that 4, 5 and 6 are very bad, possibly terminal for the engine.

Range 1: 7300-7500 RPMRange 2: 7500-7700 RPMRange 3: 7700-7900 RPMRange 4: 7900-8400 RPMRange 5: 8400-9500 RPMRange 6: 9500-11000 RPM

the readout should tell you: how many ignitions in each range (there are 3 ignitions per revolution), and the operating hour of the last recorded overrev.

track guys usu have (lots of!) R1 and often R2. a "money shift" can easily spin up thru R5 (ask me how i know). it's an accepted notion that R1-3 are usually fine, no damage despite what porsche says/warranty's. and if the last overrev in R4-6 happened long ago and engine is still running fine, then you should be ok also.

but then again, these things could grenade at any time so who the heck knows. :P

Thanks for the definition. The dealer tech (who seems to follow the company line you referenced) could not define the range limits but suggested that they were all bad, with the single 4 range value really serious. What is most interesting to me is that the car experienced all of its range values (#1-3 and a single #4) before I bought the car from a dealer as a certified car with warranty. So apparently the dealer Sales Department does not consult with the Porsche technical people when delivering a certified car to a customer. I have 43,000 problem-free miles on the car since the #4 value so I'm not too worried except for some mild concern getting the misfires solved and corrected.

[krjohnson]

. The out of round flywheel makes no sence. How does a fly wheel suddenly go out of round. Warped maybe but, how would the ignition computer know this? I have seen bad gas do a lot of funny things like f up your fuel filter.

I have always stuck with 93 octane fuels in these cars and prefer Mobil or Sunoco. I only use other fuels under duress.

The flywheel "out of round" causes P0300 because it causes the crankshaft to vibrate. The crankshaft position sensor sends the pulse data to the DME which sees abnormal input from the sensor. It's only recourse is to flag misfire DTC for the slow then fast pulse information from the crankshaft sensor. If there wa not a P0302 attached, I would be more inclined to buy into the plausability of the diagnosis. I would alo ask what test they did to eliminate ignition, fuel, and internal mechanical systems before recommending the flywheel.

But to be clear, Yes the flywheel can and will cause P0300. It, however, may not be your actual issue.

Skoot

You confirm exactly what my independent mechanic reported, and he added that an out of balance flywheel can make the car shake/vibrate noticeably at idle. The car does not have that symptom. Thanks for your suggestions for additional diagnoses to consider if the problem is not resolved and certainly before I take a wad of cash to the dealer for a flywheel replacement and a recommended new clutch because the car is at 48,000 miles. Thanks for the input.

[spiffyjiff]

Thanks for the definition. The dealer tech (who seems to follow the company line you referenced) could not define the range limits but suggested that they were all bad, with the single 4 range value really serious. What is most interesting to me is that the car experienced all of its range values (#1-3 and a single #4) before I bought the car from a dealer as a certified car with warranty. So apparently the dealer Sales Department does not consult with the Porsche technical people when delivering a certified car to a customer. I have 43,000 problem-free miles on the car since the #4 value so I'm not too worried except for some mild concern getting the misfires solved and corrected.

FYI, it's also accepted notion (and maybe even confirmed somewhere by knowledgable techs?) that a "1" in a range is usually a ghost. it didnt happen. e.g. there is a poster on RL recently who had a "1" in R2-4 or something. obviously this is an impossibility given the fact that the engine needs to spin up then BACK down thru the ranges. plus i've seen mention of a "1" in R1. again, it's probably a ghost.

besides, if you do the math, a single ignition is an infintessimally small amount of time to be in a range. i actually have "3" in my R5 (oops!) and even that amount of time - .02 of a sec - seems too small to be able to record.

[krjohnson]

Thanks for the definition. The dealer tech (who seems to follow the company line you referenced) could not define the range limits but suggested that they were all bad, with the single 4 range value really serious. What is most interesting to me is that the car experienced all of its range values (#1-3 and a single #4) before I bought the car from a dealer as a certified car with warranty. So apparently the dealer Sales Department does not consult with the Porsche technical people when delivering a certified car to a customer. I have 43,000 problem-free miles on the car since the #4 value so I'm not too worried except for some mild concern getting the misfires solved and corrected.

FYI, it's also accepted notion (and maybe even confirmed somewhere by knowledgable techs?) that a "1" in a range is usually a ghost. it didnt happen. e.g. there is a poster on RL recently who had a "1" in R2-4 or something. obviously this is an impossibility given the fact that the engine needs to spin up then BACK down thru the ranges. plus i've seen mention of a "1" in R1. again, it's probably a ghost.

besides, if you do the math, a single ignition is an infintessimally small amount of time to be in a range. i actually have "3" in my R5 (oops!) and even that amount of time - .02 of a sec - seems too small to be able to record.

When I took the factory tour 2 weeks ago, whilst in the engine assembly line section the guide said that the assembled basic engine unit (heads, cylinders, crank, block before all the add-ons) is mechanically rotated at 10,000 rpm to test for vibrations or other detectable problems. This happened right at a station on the line that our group viewed. So each engine has an unrecorded range 6 even before it leaves the factory. I'm not suggesting that this is equivalent to a mechanical over-rev, but the stress level of this test suggests to me that there is maximum quality engineered/built into the engine and that while it is not wise to abuse the limits, the car is built to tolerate some exuberant driving.

[binger]

Before you just start reprogramming the DME you need to get to the root cause of the issue. IE: Mechanical, Fuel, or Ignition / Electrical related. Once you drill down on or more of the list it will point you in proper direction of diagnosis.

Do not just shotgun this you will waste a lot of time and money. As for fuel you used up the tank of Costco so I would move on as you do not have a sample to test for ethanol or water.

As for using racing fuel to solve your issue its not practical and a waste of money unless you planing on running at the track.

Also sounds like this car has been on the track? You might want to find out when is was over revved. The DME records when the vehicle has used the rev-limiter and at what RPM and Hrs of operation it occurred. As for the flywheel diagnosis I would use a lab scope to see the sensor waveform before starting to condemn the flywheel.

Don't you just love technology! :D

Edited June 11, 2013 by binger

[krjohnson]

Before you just start reprogramming the DME you need to get to the root cause of the issue. IE: Mechanical, Fuel, or Ignition / Electrical related. Once you drill down on or more of the list it will point you in proper direction of diagnosis.

Do not just shotgun this you will waste a lot of time and money. As for fuel you used up the tank of Costco so I would move on as you do not have a sample to test for ethanol or water.

As for using racing fuel to solve your issue its not practical and a waste of money unless you planing on running at the track.

Also sounds like this car has been on the track? You might want to find out when is was over revved. The DME records when the vehicle has used the rev-limiter and at what RPM and Hrs of operation it occurred. As for the flywheel diagnosis I would use a lab scope to see the sensor waveform before starting to condemn the flywheel.

Don't you just love technology! :D

You have outlined a logical approach for resolving this problem, which may still turn out to be a false positive of some kind. The dealer programmed the DME as a "first step to eliminating the DME codes", saying that my car was behind one update. Previously my independent had looked at the ignition system and plugs without finding anything significant. As for the fuel, I was horrified to see that it was 10% ethanol as I was finishing up at Costco, so my bad. But the research I did indicated that the car would adjust the timing and run on it but was not recommended. My independent's opinion is that the Costco fuel is second rate and not on par with Shell, 76 and Chevron, the best quality brands available in So Cal. The car was not tracked according to the dealer, nor was it driven much, only 6,000 miles in 4 years by the original owner and it had the original tires (of course another set of wheels could have been used). I don't track the car, it is a daily driver. If the CEL's continue for this reason I'll get into more detail on the fuel system, the stored data to pinpoint the problem and if necessary, find a dealer (or someone) with a lab scope to check the flywheel. I'm beginning to appreciate my first Porsche, a1969 912 with only 22,000 miles. It was a relatively complex car back in 1971 when I got it but nothing like the complexity and technology we see in these modern cars. I could actually fix certain things on the 69 and keep the valves adjusted properly but don't have the courage to do much with this machine. Thanks again for your thoughtful input.

[spiffyjiff]

When I took the factory tour 2 weeks ago, whilst in the engine assembly line section the guide said that the assembled basic engine unit (heads, cylinders, crank, block before all the add-ons) is mechanically rotated at 10,000 rpm to test for vibrations or other detectable problems. This happened right at a station on the line that our group viewed. So each engine has an unrecorded range 6 even before it leaves the factory. I'm not suggesting that this is equivalent to a mechanical over-rev, but the stress level of this test suggests to me that there is maximum quality engineered/built into the engine and that while it is not wise to abuse the limits, the car is built to tolerate some exuberant driving.

haha, it's like you are i are volleying in tennis because it's so funny you should mention that - i've had 2 techs (one dealer, one indy) say that these engines are more than capable of going past redline and even quoted the 10k RPM you ref'd. they said the problems arise with the immediate spin up of the engine. e.g. when a money shift occurs, the engine spins up incredibly fast. this is what causes the damage. but in a controlled test environment, these things can operate at (much) higher-than-redline conditions.

[luigi007]

krjohnson,

I have a 2005 997 carrera that I am having very similar issues. I have been fighting this issue for about 6 months now. I get the p0300 code "multicylinder misfires" with all the cylinders misfiring "p0301-p0306". I have replaced the spark plugs, mass air flow sensor, and throttle body assembly. I have taken my car to the dealer twice. The first time they told me that the throttle body was the problem. They quote me around $900 dollars to replace. I decided to buy the complete module from Porsche Sonnen for around $300 and took me about 20 minutes to replace. I still have the problem. This week I took my car again to the dealer for the second time and they told me that they will need to inspect the dual mass flywheel. They think that is the problem. I will need to pay $1900 to drop the transmission to inspect the flywheel. I am getting really tired with the dealer. They are never sure about their diagnostics and cost the customers tons of money. Does envy one here on this forum agrees with the dealer recommendation? The local Independent shop does not agree that the flywheel would be the problem. The dealer is quoting me $4,000 to replace the flywheel, change the RMS, and IMS. Any feedback? Anyone?

[luigi007]

One more thing, have you guys ever heard of crankshaft sensor reteach process? I read in youtube of a guy with a Mustang that he replaced the clutch and flywheel and was getting the random misfire codes after the replacement and all he did to fix the problem was to have the dealer recalibrate the sensor using their dealer computer. Can this be done with the Porsches? My car does not make any noise at the flywheel. I believe the previous owner changed the clutch own my car, that is why I was wondering about this easy and cheap fix. Also, the $4,000 quote includes a new clutch assembly.

[Loren]

One more thing, have you guys ever heard of crankshaft sensor reteach process? I read in youtube of a guy with a Mustang that he replaced the clutch and flywheel and was getting the random misfire codes after the replacement and all he did to fix the problem was to have the dealer recalibrate the sensor using their dealer computer. Can this be done with the Porsches? My car does not make any noise at the flywheel. I believe the previous owner changed the clutch own my car, that is why I was wondering about this easy and cheap fix. Also, the $4,000 quote includes a new clutch assembly.

There is no re-calibration process needed for the crankshaft position sensor in Porsches.

[luigi007]

Loren,

Thanks for the feedback. What is your opinion in regards to having a bad dual mass flywheel creating all the cylinders to misfire? The car runs great, just a little rough at idle. Also, no noise coming from flywheel.

[Loren]

Loren,Thanks for the feedback. What is your opinion in regards to having a bad dual mass flywheel creating all the cylinders to misfire? The car runs great, just a little rough at idle. Also, no noise coming from flywheel.

You you monitor the CPS with a scope you should be able to see a consistent waveform. So you can see if it is picking up a consistent signal.

Never seen a bad CPS not give a fault code as the DME usually sees intermittent signals -- but I guess it could happen.

What are your exact symptoms and faults?

[luigi007]

I keep getting the following codes:

P0300

P0301

P0302

P0303

P0304

P0305

P0306

The car idle is not bad at all and runs great. The codes come back after 3-4 days after the computer has been reset. Also, I always get the codes when the engine is cold.

[Loren]

Here is what the service manual says for your faults:

When misfires occur on both banks:- Incorrect/low-grade fuel- Tank empty- An engine-block heater is used- Secondary air- Exhaust system blocked/narrowed- Foreign bodies in intake tract, this can lead to sporadic misfires on changing cylinders.

Any recent changes like cold air kit?

Since it only happens when the engine is cold - that is when the secondary air pump runs. Are their any codes (at any time) for the secondary air system?

[krjohnson]

krjohnson,I have a 2005 997 carrera that I am having very similar issues. I have been fighting this issue for about 6 months now. I get the p0300 code "multicylinder misfires" with all the cylinders misfiring "p0301-p0306". I have replaced the spark plugs, mass air flow sensor, and throttle body assembly. I have taken my car to the dealer twice. The first time they told me that the throttle body was the problem. They quote me around $900 dollars to replace. I decided to buy the complete module from Porsche Sonnen for around $300 and took me about 20 minutes to replace. I still have the problem. This week I took my car again to the dealer for the second time and they told me that they will need to inspect the dual mass flywheel. They think that is the problem. I will need to pay $1900 to drop the transmission to inspect the flywheel. I am getting really tired with the dealer. They are never sure about their diagnostics and cost the customers tons of money. Does envy one here on this forum agrees with the dealer recommendation? The local Independent shop does not agree that the flywheel would be the problem. The dealer is quoting me $4,000 to replace the flywheel, change the RMS, and IMS. Any feedback? Anyone?

Sounds like you are experiencing a very similar situation that I have. You can check the prior posts to see where I am on this but here is the short version. For the last 5,000 miles the CEL would go on and shortly thereafter would go off, all starting while the car was idling. Then after gassing at Costco (10% ethanol, my mistake), it came on and would not go off but otherwise the car ran fine. My independent cked the plugs and ignition but found nothing out of order, reset it and it came on again but went off. I burned off the Costco gas so that is not now a factor. Then while I was in the smog check line, it came on again and could not be smogged. I took it to the dealer who programmed the DME, saying it was out of date and needed to be done (only $176, the cheapest trip ever) and that was a first step to finding out the root cause of the problem, and that it could be the 2-piece flywheel, which is known to be an issue on 2005's. The dealer took only an hour for that and the CEL has not illuminated again in the last week. I think (well, lets say hope) it was too lean of an idle mixture which caused the misfire and it could also explain the occasional stall. My independent said the DME programming probably richened the idle mixture and he cked the idle (not completely smooth) and said if it was the flywheel it would be shaking and possibly making the clicking noise. Today I had it smogged again but it had not cycled to a neutral state, so the car failed because there was still the CEL indicator, even though the CEL was off, the emission values were more than excellent and it passed all the visuals and other tests. You might have the dealer check the programming and if that is not needed go through the cklist that binger suggested. Maybe find a good independent to validate what the dealer is saying, that has helped me out and taught me that the dealer tech reps don't always have the hands-on experience to explain or even understand things clearly. Typically they say "you need this and it costs $x,xxx". Good luck, hope this helps out and you can get back to worry free driving.

[luigi007]

Loren,

I really appreciate your input and support.

1. I always use Chevrone 93 octane

2. No low gas problems. The dealer also checked the fuel pressure. They said no problem with that.

3. I do not believe the car has an engine block heater. How can you tell? I am not the original owner.

4. OEM air intake. Can a non-OEM filter cause issues with the secondary air system? Not sure if the filter is OEM or not. Need to confirm.

5. Problem with exhaust system??? Not sure. The exhaust noise sounds like a little sputting. First Porsche I owned, so I do not have a base line to compare my car. Is that sound caused by small misfires? The sound is more noticible at low RPMs.

6. Foreign bodies in intake systemz? Again, not sure how to inspect for that. I know the dealer did a throttle body system clean up before I replaced the throttle body. Dealer did not mentioned anything about finding foreign objects.

Regards!