Yet another 996 Cylinder 1 misfire thread
02-24-2016, 03:33 PM
#76
[QUOTE=DrMEMS;13047488]"Martin and Agnes:
Thanks for your helpful posts. I have some questions.
What is the problem here? The engine was fully warmed up and as you can see, the measured temperature did not change during revving.
I revved it up to 6800 rpm; redline is ~7200 rpm. The time at high revs was less than 10 seconds. Dyno runs are done every day all over the world on stationary cars with high revving for much longer times. "
Every dyno test is done when car is in gear, never in neutral. Engine has to be under load while revving it up, meaning it has to be in gear same as while driving on the road. Factories started to limit engine (especially high rpm motors) revs to 3000-4000 rpms while in neutral to prevent engine from blowing up. You should never rev your motor while in neutral over 3000-4000 rpms max.
It so happens that I'm a motorsport professional, I ride engine which turns 14000 rpms. I have seen my competitors revving their motors for no reason. Later effect is their engine blows up.
Once again, there is a difference when engine is loaded, meaning in gear, and in neutral. If you would like to diagnose an engine you should always rev it from 1000-2500 max. You can hear and feel what is going on inside the motor, revving it up all the way doesn't give you anything and causes more harm than good.
"Both Macster and ChicagoSpeed996 suggested that the Variocam Plus could be stuck in high lift mode.
Also, I still have the tick-tick-tick sound at the same frequency as the camshaft rotation. I hear it much of the time (and it does not correlate with rough running). Three out of three mechanics surveyed say this sound is a sticky valve lifter. "
If you really suspect stuck valve lifters it's easy to diagnose. Remove the muffler, cam shaft cover on bank one and you can see the lifters. You have easy access to tensioner on b1, remove it, disconnect timing, remove cam shaft and you have lifters in your hands. 4 hours job max for SKILLED PORSCHE TECH including putting it back together. I cannot speak for other shops, I know most of them have no idea about Porsche engines, they call themselves Porsche techs because they can install and remove the engine.
You should have called me right away when the problem started instead of waiting 2 months trying to solve this yourself.
Has anyone you spoke with ever suggested doing the simplest thing? Starting your motor for 10 seconds in the morning when it's cold and running rough? You have to do this only when it runs rough and manifolds are cold. Then, after 10 sec shut it off and check your exhaust manifold on bank 1 to see if all 3 pipes are the same temperature. Be careful not to burn yourself. Do it and let me know what you find out. Do not hook up any computers, don't do anything else, just do it the way I told you. You have to have the motor running rough and exhaust manifolds have to be cold, otherwise it won't be able to feel the difference.
Could you also tell me if you have replaced all ignition coils and all spark plugs? Have you replaced #1 injector? Have you replaced maf sensor like Jake suggested? Let me know about these things and do the test I described above.
"This is bad. How am I slowly damaging my engine?
Did you notice that this is an intermittent problem? I have to run it to see the problem."
Problem diagnosis is not done when engine is in neutral and being revved to 7000 rpms. Like I explained above it can only do damage and doesn't let you hear and feel the engine. If you keep driving the car everyday with this problem you will eventually cause a mechanical problem inside. Never drive the car for 2 months with even intermittent misfire.
Simple example, lets assume injector is good, fuel gets into the cylinder, fuel (which doesn't burn) flushes out the oil and in effect cylinder becomes scored. This fuel gets into the oil and everywhere else. If you have a misfire you SHOULD NEVER DRIVE THE CAR UNTIL CAUSE IS IDENTIFIED. This is only 1 example, there are number of things that could be happening inside the motor due to misfire.
"Which shop near San Jose, California is this? As I said earlier, I don't trust the dealer. I've talked to the indy who installed the motor and he can't think of anything more to look at than what already done. There have been several posts about similar problems that other drivers had that took many different shops and a lot of money to nothing. "
That's all other shops, I know exactly what you mean. This is why you have to go to a specialist when you have a complicated problem, doesn't matter where he is located.
"It may or may not be related to something inside of the engine. I hope it's not.
But simply declaring "it's not related to the engine" doesn't make it true. And because it's intermittent doesn't "prove" it's not related to the engine internals."
Easiest way to find out is to perform the test described above and answer all my previous questions.
BTW, picture below shows a 3.8l Carrera s motor and what happens when you drive constantly revving it up. Those motors do not like high revs even under load (in gear).
Thanks for your helpful posts. I have some questions.
What is the problem here? The engine was fully warmed up and as you can see, the measured temperature did not change during revving.
I revved it up to 6800 rpm; redline is ~7200 rpm. The time at high revs was less than 10 seconds. Dyno runs are done every day all over the world on stationary cars with high revving for much longer times. "
Every dyno test is done when car is in gear, never in neutral. Engine has to be under load while revving it up, meaning it has to be in gear same as while driving on the road. Factories started to limit engine (especially high rpm motors) revs to 3000-4000 rpms while in neutral to prevent engine from blowing up. You should never rev your motor while in neutral over 3000-4000 rpms max.
It so happens that I'm a motorsport professional, I ride engine which turns 14000 rpms. I have seen my competitors revving their motors for no reason. Later effect is their engine blows up.
Once again, there is a difference when engine is loaded, meaning in gear, and in neutral. If you would like to diagnose an engine you should always rev it from 1000-2500 max. You can hear and feel what is going on inside the motor, revving it up all the way doesn't give you anything and causes more harm than good.
"Both Macster and ChicagoSpeed996 suggested that the Variocam Plus could be stuck in high lift mode.
Also, I still have the tick-tick-tick sound at the same frequency as the camshaft rotation. I hear it much of the time (and it does not correlate with rough running). Three out of three mechanics surveyed say this sound is a sticky valve lifter. "
If you really suspect stuck valve lifters it's easy to diagnose. Remove the muffler, cam shaft cover on bank one and you can see the lifters. You have easy access to tensioner on b1, remove it, disconnect timing, remove cam shaft and you have lifters in your hands. 4 hours job max for SKILLED PORSCHE TECH including putting it back together. I cannot speak for other shops, I know most of them have no idea about Porsche engines, they call themselves Porsche techs because they can install and remove the engine.
You should have called me right away when the problem started instead of waiting 2 months trying to solve this yourself.
Has anyone you spoke with ever suggested doing the simplest thing? Starting your motor for 10 seconds in the morning when it's cold and running rough? You have to do this only when it runs rough and manifolds are cold. Then, after 10 sec shut it off and check your exhaust manifold on bank 1 to see if all 3 pipes are the same temperature. Be careful not to burn yourself. Do it and let me know what you find out. Do not hook up any computers, don't do anything else, just do it the way I told you. You have to have the motor running rough and exhaust manifolds have to be cold, otherwise it won't be able to feel the difference.
Could you also tell me if you have replaced all ignition coils and all spark plugs? Have you replaced #1 injector? Have you replaced maf sensor like Jake suggested? Let me know about these things and do the test I described above.
"This is bad. How am I slowly damaging my engine?
Did you notice that this is an intermittent problem? I have to run it to see the problem."
Problem diagnosis is not done when engine is in neutral and being revved to 7000 rpms. Like I explained above it can only do damage and doesn't let you hear and feel the engine. If you keep driving the car everyday with this problem you will eventually cause a mechanical problem inside. Never drive the car for 2 months with even intermittent misfire.
Simple example, lets assume injector is good, fuel gets into the cylinder, fuel (which doesn't burn) flushes out the oil and in effect cylinder becomes scored. This fuel gets into the oil and everywhere else. If you have a misfire you SHOULD NEVER DRIVE THE CAR UNTIL CAUSE IS IDENTIFIED. This is only 1 example, there are number of things that could be happening inside the motor due to misfire.
"Which shop near San Jose, California is this? As I said earlier, I don't trust the dealer. I've talked to the indy who installed the motor and he can't think of anything more to look at than what already done. There have been several posts about similar problems that other drivers had that took many different shops and a lot of money to nothing. "
That's all other shops, I know exactly what you mean. This is why you have to go to a specialist when you have a complicated problem, doesn't matter where he is located.
"It may or may not be related to something inside of the engine. I hope it's not.
But simply declaring "it's not related to the engine" doesn't make it true. And because it's intermittent doesn't "prove" it's not related to the engine internals."
Easiest way to find out is to perform the test described above and answer all my previous questions.
BTW, picture below shows a 3.8l Carrera s motor and what happens when you drive constantly revving it up. Those motors do not like high revs even under load (in gear).
02-24-2016, 03:42 PM
#77
Agree 100%, m96 and m97 are made for cruising only
This is exactly why I'm in business. It's a ticking bomb, you have to treat it with superior caution and be gentle to it at all times. Even if you maintain it properly and baby your motor, it can still break on you, that's how it's designed.
02-24-2016, 04:02 PM
#78
Nordschleife Master
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Originally Posted by MBMotorsports
You might want to watch if our 2x4's are straight instead of "servicing" my customers. You should leave more complicated stuff to the wiser people.
02-24-2016, 04:18 PM
#79
Instructor
Thread Starter
Has anyone you spoke with ever suggested doing the simplest thing? Starting your motor for 10 seconds in the morning when it's cold and running rough? You have to do this only when it runs rough and manifolds are cold. Then, after 10 sec shut it off and check your exhaust manifold on bank 1 to see if all 3 pipes are the same temperature. Be careful not to burn yourself. Do it and let me know what you find out. Do not hook up any computers, don't do anything else, just do it the way I told you. You have to have the motor running rough and exhaust manifolds have to be cold, otherwise it won't be able to feel the difference.
The pipes on each manifold felt the same to my hand. I applied a thermocouple to each for a more accurate measurement. The pipes for cylinders 1, 2, 3, 4, and 6 were 102-103 deg F; cylinder 5 was 99 deg F.
The cold roughness is much less severe than the hot roughness I posted about yesterday, so there may be different sources.
Could you also tell me if you have replaced all ignition coils and all spark plugs? Have you replaced #1 injector? Have you replaced maf sensor like Jake suggested? Let me know about these things and do the test I described above.
* All six spark plugs and coils replace 2/10/2016 at 97,640 mi. Didn't solve misfires.
* MAF sensor replaced 2/17/2016 at 98944 mi. Didn't solve misfires.
02-24-2016, 04:25 PM
#80
Cold start. Ran 10 s. Engine feels smooth.
The pipes on each manifold felt the same to my hand. I applied a thermocouple to each for a more accurate measurement. The pipes for cylinders 1, 2, 3, 4, and 6 were 102-103 deg F; cylinder 5 was 99 deg F.
The cold roughness is much less severe than the hot roughness I posted about yesterday, so there may be different sources.
* Cylinder 1 fuel injector replaced 1/10/2016 at 97,413 mi. Didn't solve misfires.
* All six spark plugs and coils replace 2/10/2016 at 97,640 mi. Didn't solve misfires.
* MAF sensor replaced 2/17/2016 at 98944 mi. Didn't solve misfires.
The pipes on each manifold felt the same to my hand. I applied a thermocouple to each for a more accurate measurement. The pipes for cylinders 1, 2, 3, 4, and 6 were 102-103 deg F; cylinder 5 was 99 deg F.
The cold roughness is much less severe than the hot roughness I posted about yesterday, so there may be different sources.
* Cylinder 1 fuel injector replaced 1/10/2016 at 97,413 mi. Didn't solve misfires.
* All six spark plugs and coils replace 2/10/2016 at 97,640 mi. Didn't solve misfires.
* MAF sensor replaced 2/17/2016 at 98944 mi. Didn't solve misfires.
Ok, thanks for the info. It still doesn't tell me anything since engine was running smooth. This test has to be done when engine runs rough, you will have to try to catch it in that moment and then let me know what you find. Just please don't rev the engine any more.
02-24-2016, 04:40 PM
#81
The motors certainly have some issues that can make your day go to hell quick and with little warning, but they do not need to be treated like they are made of porcelain. It certainly sucks when you roll craps and the motor goes **** up, but the vast majority of 996s have not experienced such failures.
I do agree that running the revs up on an unloaded motor when you know that the motor is not healthy is a bad idea.
02-24-2016, 05:25 PM
#82
Cold start. Ran 10 s. Engine feels smooth.
The pipes on each manifold felt the same to my hand. I applied a thermocouple to each for a more accurate measurement. The pipes for cylinders 1, 2, 3, 4, and 6 were 102-103 deg F; cylinder 5 was 99 deg F.
The cold roughness is much less severe than the hot roughness I posted about yesterday, so there may be different sources.
* Cylinder 1 fuel injector replaced 1/10/2016 at 97,413 mi. Didn't solve misfires.
* All six spark plugs and coils replace 2/10/2016 at 97,640 mi. Didn't solve misfires.
* MAF sensor replaced 2/17/2016 at 98944 mi. Didn't solve misfires.
The pipes on each manifold felt the same to my hand. I applied a thermocouple to each for a more accurate measurement. The pipes for cylinders 1, 2, 3, 4, and 6 were 102-103 deg F; cylinder 5 was 99 deg F.
The cold roughness is much less severe than the hot roughness I posted about yesterday, so there may be different sources.
* Cylinder 1 fuel injector replaced 1/10/2016 at 97,413 mi. Didn't solve misfires.
* All six spark plugs and coils replace 2/10/2016 at 97,640 mi. Didn't solve misfires.
* MAF sensor replaced 2/17/2016 at 98944 mi. Didn't solve misfires.
Since you have accurate temperature reader you can also do it a different way. When you drive and engine starts to run rough, park the car and leave it running for a few minutes. If it starts to run smooth shut it off, engine has to run rough to get accurate reading. Then measure the temp on all muffler pipes and let me know what you find out.
02-24-2016, 05:52 PM
#83
That's a load of horsesh!t and I'm pretty sure you know it. There are plenty of examples of tracked and non-babied cars out there that are approaching and beyond 100k and still running strong.
The motors certainly have some issues that can make your day go to hell quick and with little warning, but they do not need to be treated like they are made of porcelain. It certainly sucks when you roll craps and the motor goes **** up, but the vast majority of 996s have not experienced such failures.
I do agree that running the revs up on an unloaded motor when you know that the motor is not healthy is a bad idea.
The motors certainly have some issues that can make your day go to hell quick and with little warning, but they do not need to be treated like they are made of porcelain. It certainly sucks when you roll craps and the motor goes **** up, but the vast majority of 996s have not experienced such failures.
I do agree that running the revs up on an unloaded motor when you know that the motor is not healthy is a bad idea.
Gnat, I have not seen another poorly designed motor in the whole world. It's very complicated compared to other engines, there are too many parts inside which are not very well thought through. Too many things inside are unnecessary, which in effect brake more often. It's too complicated and the result is not adequate to the design. Porsche overcomplicated the design and production not getting anything in return. 89 hp from 1000cc is not impressive. Completely wrong design of ims, timing chains, cylinders (cracking and scoring), etc... I really don't understand what is so positive about these motors. I personally drive a 3.8l Carrera S, 30k miles, have it since very low mileage, never even touched a screw in this car (except for oil changes). I'm afraid to step on a gas in this car. Every time my wife comes back from shopping I listen for cylinder scoring sound. I also have 2 turbos and 1 993 which are a completely different story. Those motors are totally worthy of Porsche cars. I have to get rid of my Carrera S before it blows up because I don't feel like rebuilding my own motor. I would not be surprised if cylinders start to score pretty soon, I only drive it on the street, normal everyday driving nothing extreme. Newest Porsche engines are a lot better because 60% of faults have been eliminated, however, they still have some issues. Porsche is supposed to break, that's how it's designed by marketing and financial departments. New turbo and gt3 are also examples of Porsche's failed design. Same parts, new models, budget cuts but charging fortune for new cars...That's how me, Jake and others will stay in business for a while, but pretty soon it will not be worth it to fix these cars anymore (I mean m96 and m97). Most of you love your cars and probably don't want to hear it but those are the facts. Maybe you'd rather hear me saying those are the best cars in the world and fix them for 30k or more, but I'm not that guy. Don't get me wrong, I love Porsches, especially turbo, I really enjoy driving it but m96 and m97 engines never even had a right to be in those cars.
02-24-2016, 06:15 PM
#85
Regardless, however, the majority of the motors are still running strong with the average example countering your "you have to treat it with superior caution and be gentle to it at all times" nonsense.
I don't think it's the best motor in the world, but it doesn't need to be treated as you suggested in that post.
Most of you love your cars and probably don't want to hear it but those are the facts.
I'm sorry you are so paranoid about your own car. Sell it and move on with your life. Seriously. Life is too short to live like that. I know you see the result of these flaws on a regular basis, but you are only seeing a small fraction out of the total number of cars built.
They aren't the greatest car in the world, but they are far from the worst as well.
02-24-2016, 06:38 PM
#86
I don't know about that, but I agree some poor choices were made that led to some significant and catastrophic flaws.
Regardless, however, the majority of the motors are still running strong with the average example countering your "you have to treat it with superior caution and be gentle to it at all times" nonsense.
I don't think it's the best motor in the world, but it doesn't need to be treated as you suggested in that post.
Saying "you have to treat it with superior caution and be gentle to it at all times" is not remotely based on any facts.
I'm sorry you are so paranoid about your own car. Sell it and move on with your life. Seriously. Life is too short to live like that. I know you see the result of these flaws on a regular basis, but you are only seeing a small fraction out of the total number of cars built.
They aren't the greatest car in the world, but they are far from the worst as well.
Regardless, however, the majority of the motors are still running strong with the average example countering your "you have to treat it with superior caution and be gentle to it at all times" nonsense.
I don't think it's the best motor in the world, but it doesn't need to be treated as you suggested in that post.
Saying "you have to treat it with superior caution and be gentle to it at all times" is not remotely based on any facts.
I'm sorry you are so paranoid about your own car. Sell it and move on with your life. Seriously. Life is too short to live like that. I know you see the result of these flaws on a regular basis, but you are only seeing a small fraction out of the total number of cars built.
They aren't the greatest car in the world, but they are far from the worst as well.
I have sold quite a few used engines for m96 and m97 and I never give any warranty for them, it's supposed to work after installation, that's it. I can bet you that if you bring any "good running" engine to Jake he would find something wrong with it. With his precise eye I'm sure he would find something failing in each of those motors.
02-24-2016, 06:51 PM
#87
I have sold quite a few used engines for m96 and m97 and I never give any warranty for them, it's supposed to work after installation, that's it. I can bet you that if you bring any "good running" engine to Jake he would find something wrong with it. With his precise eye I'm sure he would find something failing in each of those motors.
Its all a gamble in the end, but the odds show that the cars can be driven "like Porsches" and the majority will not have problems.
My only problem with what you've said is your hyperbole about how fragile these cars/motors supposedly are. The actual numbers simply don't bear that out.
02-24-2016, 07:03 PM
#88
Rennlist Member
Yeah, gnat, my '99 C4 only had 133,000 miles on its engine when a semi-truck tire tread knocked off the oil filter housing on the highway and starved the engine of oil. I'll bet that crappy engine wouldn't have lasted much past 150,000 miles or so before it would've needed a rebuild. I mean, really, if a high performance engine won't last longer than that, the car is a complete piece of ****.
Plus, the headlights aren't even round.
Plus, the headlights aren't even round.
02-24-2016, 07:13 PM
#89
Of course he would and so would you. I'd be shocked if any competent engine builder could take apart a "healthy" 15 year old motor with 50-150k on it and not find things wrong. The question is if they were actually going to fail any time soon if left otherwise unmolested.
Its all a gamble in the end, but the odds show that the cars can be driven "like Porsches" and the majority will not have problems.
My only problem with what you've said is your hyperbole about how fragile these cars/motors supposedly are. The actual numbers simply don't bear that out.
Its all a gamble in the end, but the odds show that the cars can be driven "like Porsches" and the majority will not have problems.
My only problem with what you've said is your hyperbole about how fragile these cars/motors supposedly are. The actual numbers simply don't bear that out.
02-24-2016, 07:39 PM
#90
Rennlist Member
Yet another 996 Cylinder 1 misfire thread
I, for one, am glad we can finally have a discussion of the relative merits of the 996 in this forum. Finally!