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Misfire on cylinder 5... Please help


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Its on an 05 Boxster 2.7L manual. 26,300 miles.

I got codes P0300 and P0305.

I changed the coils on cylinder 5 and 6 and still got the same codes.

I changed all the spark plugs and changed the coils around on each side and still got the same codes.

All the coils looked good, no cracks.

I checked to make sure they were plugged in all the way and they were.

When I start it, it runs a little and dies. It will start again, and if I rev it it will drive (I had to move it from my driveway), but dies.

I figured it can't be the spark plugs, since they are new. It can't be the coils since they are not in their original spot.

Any help? Anything else I can look for?

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Its on an 05 Boxster 2.7L manual. 26,300 miles.

I got codes P0300 and P0305.

I changed the coils on cylinder 5 and 6 and still got the same codes.

I changed all the spark plugs and changed the coils around on each side and still got the same codes.

All the coils looked good, no cracks.

I checked to make sure they were plugged in all the way and they were.

When I start it, it runs a little and dies. It will start again, and if I rev it it will drive (I had to move it from my driveway), but dies.

I figured it can't be the spark plugs, since they are new. It can't be the coils since they are not in their original spot.

Any help? Anything else I can look for?

Have you checked compression on that cylinder to make sure there is no issues with the valves or cylinder itself?

If low compression -- than check leakdown for source.

If no issue there -- do you get oil or fluid build up in that cylinder?

Lastly -- maybe there is a fuel lnjector probelm.

M

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Have you checked compression on that cylinder to make sure there is no issues with the valves or cylinder itself?

If low compression -- than check leakdown for source.

If no issue there -- do you get oil or fluid build up in that cylinder?

Lastly -- maybe there is a fuel lnjector probelm.

M

Thanks... how do you check compression... will a Durametric tool tell me or is there more work to it?

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Have you checked compression on that cylinder to make sure there is no issues with the valves or cylinder itself?

If low compression -- than check leakdown for source.

If no issue there -- do you get oil or fluid build up in that cylinder?

Lastly -- maybe there is a fuel lnjector probelm.

M

Thanks... how do you check compression... will a Durametric tool tell me or is there more work to it?

Well I'm not an expert -- but basically what you do is to pull the spark plug on one cylinder at a time.

Than you get a compression test kit which uses compressed air through a set of valves.

You put that cylinder at TDC -- i.e. where all the valves should be closed and you turn on the

compressed air with one end of the kit connected to compressor and the other screwed into the

spark plug hole. To get to TDC -- you turn the crankshaft until the valves of that cylinder are seated.

It often ends up being a trial and error exercise.

If the compression is good than you have good seals. That is all the valves have seated properly and

the rings are sealing well.

The absolute value is not as important -- as the test rig will vary. But you want each cylinder to be +/- 5-10% of each other.

If one is out of range low -- or shows no compression at all then you do a leak down test.

Again you goto TDC -- but here you try to determine where the air is leaking. Into the exhaust than the exhaust valve

is not seated properly, intake leak is the an intake valve issue. Neither (which means rings) means the rings are leaking

and probably need a rebuild.

Do some googling -- and I'm sure you can find both a better explanation, and pointers to the equipment you need.

mike

Edited by txhokie4life
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Well I'm not an expert -- but basically what you do is to pull the spark plug on one cylinder at a time.

Than you get a compression test kit which uses compressed air through a set of valves.

You put that cylinder at TDC -- i.e. where all the valves should be closed and you turn on the

compressed air with one end of the kit connected to compressor and the other screwed into the

spark plug hole. To get to TDC -- you turn the crankshaft until the valves of that cylinder are seated.

It often ends up being a trial and error exercise.

Your close txhokie but no cigar for you.

A compression tester (CT) is a air pressure guage that you screw into your spark plug hole. Thats all it is. Remove all the spark plugs. Thread compression tester into cylinder 1. Make sure CT guage is at 0 lbs. Turn over the engine 5 or 6 times. Look at the reading on the CT guage. Write this # down. (((EG)145 lbs.))) Clear the CT reading so its at 0. Remove CT and thread into cylinder #2. Turn over engine 5 or 6 times. Look at the reading on the CT guage. Write it down. (((EG 140lbs))) Do this on all the cylinders. Compare all your results. Each cylinder should be within 10%. A low cylinder will either be bad valves or bad rings . Try this method first . If you have a low cylinder there are additional methods to determine what the problem is.

Compression testers are cheap. Probably about $25 and make sure the CT has the proper spark plug thread that is the same as your spark plug thread. Also. Make sure the CT has a rubber hose with fittings ,that threads into your spark plug hole. Your guage attaches to the rubber hose. It makes your life easier trying to thread a guage into your spark plug hole when its a tight fit. Alot of times with engines there is no room to thread a guage into a spark plug hole due to headers etc so you need the extension hose.

It sounds to me not compression issues or valve issues with so few k on the car.

Question.. When the motor fires up, does it fire up and seem to run normal then sputter and die? Or, does it run like crap from the get go?

Good luck.

Edited by zedex
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It sounds to me not compression issues or valve issues with so few k on the car.

Question.. When the motor fires up, does it fire up and seem to run normal then sputter and die? Or, does it run like crap from the get go?

Good luck.

It starts and runs fine for 15-30 seconds and then starts to die. If I rev it it will stay running, but if I stop it will slowly die. any ideas?

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It sounds to me not compression issues or valve issues with so few k on the car.

Question.. When the motor fires up, does it fire up and seem to run normal then sputter and die? Or, does it run like crap from the get go?

Good luck.

It starts and runs fine for 15-30 seconds and then starts to die. If I rev it it will stay running, but if I stop it will slowly die. any ideas?

Yup. Its being fuel starved. Check fuel filter/replace it or anything related to fuel. I would also dump some methyl hydrate into your fuel tank in case you have water in your fuel. Cold weather water turns to ice and blocks fuel lines etc.

Edited by zedex
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Yup. Its being fuel starved. Check fuel filter/replace it or anything related to fuel. I would also dump some methyl hydrate into your fuel tank in case you have water in your fuel. Cold weather water turns to ice and blocks fuel lines etc.

What is methyl hydrate? Where do I buy it from and how much do i put in it? Thanks for everything... I will look into the fuel filter.

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Methyl hyrate is methyl alcohol. You can get it at hardware stores,paint stores. Its used in the fuel tank and it absorbes water. Its a fuel antifreeze. In a full tank i would dump about a litre in. I have used it since i was a kid to run my toy steam engine. Its a great fuel.

It sure sounds like a fuel problem to me . I would bite the bullet and take your car into a porsche shop. Just get em to find out WTF is going on. Or.. You could buy a fuel pressure tester which is a tester to test your fuel pressure. :)

Since the car is starting up fine but then sputters to a halt its IMO running out of gas. Could be fuel filter,fuel pump. Since all cars now have in tank fuel pumps its expensive replacing them because in most cases you have to drop the tank. Labour costs can get high + fuel pumps in most vehicles are friggin outragously expensive.

Curious. What were the conditions before your problem started. Was it cold? Raining? Just filled up the tank with unknown fuel? Ran you car close to empty? Did it just start doing this out of the blue?

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Methyl hyrate is methyl alcohol. You can get it at hardware stores,paint stores. Its used in the fuel tank and it absorbes water. Its a fuel antifreeze. In a full tank i would dump about a litre in. I have used it since i was a kid to run my toy steam engine. Its a great fuel.

It sure sounds like a fuel problem to me . I would bite the bullet and take your car into a porsche shop. Just get em to find out WTF is going on. Or.. You could buy a fuel pressure tester which is a tester to test your fuel pressure. :)

Since the car is starting up fine but then sputters to a halt its IMO running out of gas. Could be fuel filter,fuel pump. Since all cars now have in tank fuel pumps its expensive replacing them because in most cases you have to drop the tank. Labour costs can get high + fuel pumps in most vehicles are friggin outragously expensive.

Curious. What were the conditions before your problem started. Was it cold? Raining? Just filled up the tank with unknown fuel? Ran you car close to empty? Did it just start doing this out of the blue?

I bought the car used. It sat for a few years without it being driven. When I got it, I replaced the air filter and filled up the fuel tank (It was towed to my house from cross country and there was no fuel it in when it arrived). I drove it around town for a little and it kind of ran rough when I got near home and the check engine light turned on. When I checked the light it was a misfire on cylinder 5... then I changed the spark plugs and moved all the coils around. This is where I am at... a few weeks ago it was freezing here at night.

I might go try to find some Methyl and put it in there to see if that might help... is that all I ask for at a hardware store? If that doesn't work, I'll check all the fuel lines and see if I can figure out why it wouldn't be getting fuel... do you think its just cylinder 5 not getting it or all of the engine?

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Cylinder misfire on 5?? I wish you would have said that at the beginning. I have no idea what those codes are. New fuel injector and you should be off to the races. Probably plugged by crap that formed in the tank due to not having gas for 2 years. I would run good gas and fuel injector cleaner for a few tanks and hope to hell your problems are over.

What exactly are codes P0300 and P0305.

One is injector misfire whats the other one?

Edited by zedex
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Cylinder misfire on 5?? I wish you would have said that at the beginning. I have no idea what those codes are. New fuel injector and you should be off to the races. Probably plugged by crap that formed in the tank due to not having gas for 2 years. I would run good gas and fuel injector cleaner for a few tanks and hope to hell your problems are over.

What exactly are codes P0300 and P0305.

One is injector misfire whats the other one?

P0300 is the general misfire code that's always set whenever there's misfires and P030x is the cylinder specific misfire. If he has access to a Durametric, there should be some "fault type" info for P0300 that could help isolate the problem. There's a whole bunch of stuff to check including electrical related (plugs, coil packs, wiring) and mechanical (secondary air system, valves, exhaust system, fuel injector/supply). Also, if there is any "freeze frame" info from the Durametric tool, there could be some info to help troubleshoot in the way of what the fuel adaptation (fuel trim) was doing when the misfires triggered the CEL. Also, a flaky crankshaft position sensor can be a source even if it didn't trigger a code.

Regards,

paul...

Edited by paulv
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P0300 is the general misfire code that's always set whenever there's misfires and P030x is the cylinder specific misfire. If he has access to a Durametric, there should be some "fault type" info for P0300 that could help isolate the problem. There's a whole bunch of stuff to check including electrical related (plugs, coil packs, wiring) and mechanical (secondary air system, valves, exhaust system, fuel injector/supply). Also, if there is any "freeze frame" info from the Durametric tool, there could be some info to help troubleshoot in the way of what the fuel adaptation (fuel trim) was doing when the misfires triggered the CEL. Also, a flaky crankshaft position sensor can be a source even if it didn't trigger a code.

Regards,

paul...

I do have the Durametric. How do I use it to help me more. I just got it and haven't played around too much with it.

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P0300 is the general misfire code that's always set whenever there's misfires and P030x is the cylinder specific misfire. If he has access to a Durametric, there should be some "fault type" info for P0300 that could help isolate the problem. There's a whole bunch of stuff to check including electrical related (plugs, coil packs, wiring) and mechanical (secondary air system, valves, exhaust system, fuel injector/supply). Also, if there is any "freeze frame" info from the Durametric tool, there could be some info to help troubleshoot in the way of what the fuel adaptation (fuel trim) was doing when the misfires triggered the CEL. Also, a flaky crankshaft position sensor can be a source even if it didn't trigger a code.

Regards,

paul...

I do have the Durametric. How do I use it to help me more. I just got it and haven't played around too much with it.

If your CEL is still on, the Durametric tool will have a lot of info stored -- if it's off, then the tool will only provide "pending code" info. The important stuff to help troubleshoot is the freeze frame data which only gets recorded when the CEL illuminates and for most DTCs (codes). Get as many screen shots as possible and post them here (the DME related screens). Someone should be able to help as there are many knowledgeable people here.

Are you running ver 5.x or 6.x?

Also, you should become a Contributing member here as there is access to TSBs (Technical Service Bulletins) and there's a TSB that describes what all the actual values are on the PIWIS and Durametric tools -- I found it to be a big help.

Regards,

paul....

Edited by paulv
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