Medevack1

Ok so here is the story on my 911. I have a 2004 Jahre 40th Ae with 152k miles. The car is great the problems are as follow. Sometimes the car will run PERFECTO no issues at all, pulls hard and drives great,. other times it will only throw a 0302 check engine light, which is a misfire #2 cyl. I have changed the coil and sparkplug, the Indy and the Porsche dealership have both tried to fix this problem, they have done a leak test, compression test, smoke test, im sure they have done every test and nothing, The car will go days, weeks and sometimes months without any issues no CEL's at all. But when The car gets a wild hair in the tail pipe, I will get a CEL 0302 about 5 to 10 times a day but it only happens when im on a dead stop. the car will shake and the CEL light will blink and eventually go solid, if I rev the car pass 2k RPM and leave it there while is blinking the CEL will go away with in 5 seconds. around the same time this issue started my drivers side seat doesn't heat up, the cruise control only works when it feels like, I know those might not have anything to do with it but is worth a shot, If anyone has this issue please I need help. the car have been doing this for 2 yrs now.



Thank you all in advance.

roadsession

a battery that's not healthy will throw all sorts of weird codes and behavior.

Macster

Whenever I read of a car with a number of problems like in your car's case misfires, a seat heater not working, cruise control intermittent I always think of rodent damage.

If the car is left unused for some period of time -- and this can only be a week or two -- rodents can get at the car and gnaw hoses, wiring and what have you.

If one assumes the symptoms are unrelated and they very well may be then the misfire reads like a problem with the low/high lift feature of at least one intake lifter of cylinder #2.

A "test" that may or may not be conclusive is to at a cold start let the engine idle for a few minutes at least until the cold idle RPMs drop.

If the engine runs rough (at least rougher than normal) and if the CEL comes on and the error code is P0300 and with one or more other cylinder specific misfire error codes, this can be a sign one or more cylinders have "bad" lifters their low/high lift feature isn't working right. In this case -- well, at least after a high confidence diagnosis is made -- lifter replacement is the only cure.

Some things you can try that might possibly help (provided the intake lifter or lifters are not at fault). Try a bottle of Techron. Use according to directions on the bottle. Well, almost. The bottle I buy treats 20 gallons of gasoline but I just dump the entire bottle into the fuel tank and fill the tank.

The general rule is if one notices any improvement in the engine to run a 2nd bottle when the fuel level of the tank with the first bottle of Techron is low, below 1/4 tank.

I'd suggest even if there is no improvement you still try a 2nd bottle.

Afterwards arrange to change the oil and filter.

Regarding oil: Be sure you are using an approved oil and one that has the right multi-viscosity grade for where you live and drive. 0w-40, or 5w-40 or even one 5w-50 are all available to you but only 0w-40 is suitable if you drive in cold (Porsche says -25C) weather.

Be sure you don't run the oil too long. I have found 5K miles to be a good change interval for my usage.

You can try two bottles of Swepco 502 oil improver. (Two because one just treats 5 quarts IIRC while the engine carries nearly twice that much oil.)

dporto

A blinking CEL is not good. That's a "flatbed it to the nearest shop" type of indicator - and is often associated with bad timing/cam deviations or other potentially damaging engine problems. I'd say if your battery checks out, stop driving the car until you figure out the problem. Good luck

Medevack1

[QUOTE=Macster;14020473]Answers

[QUOTE]

Whenever I read of a car with a number of problems like in your car's case misfires, a seat heater not working, cruise control intermittent I always think of rodent damage. I don't think is Rodents since I drive the car everyday

If the car is left unused for some period of time -- and this can only be a week or two -- rodents can get at the car and gnaw hoses, wiring and what have you. The car was on a lift and no signs of rodents and the car is driven 98% of the time

If one assumes the symptoms are unrelated and they very well may be then the misfire reads like a problem with the low/high lift feature of at least one intake lifter of cylinder #2. could that happened randomly like 1 day and not for another week or month?

A "test" that may or may not be conclusive is to at a cold start let the engine idle for a few minutes at least until the cold idle RPMs drop. I do that every morning I let it idle until the RPM drops

If the engine runs rough (at least rougher than normal) and if the CEL comes on and the error code is P0300 and with one or more other cylinder specific misfire error codes, this can be a sign one or more cylinders have "bad" lifters their low/high lift feature isn't working right. In this case -- well, at least after a high confidence diagnosis is made -- lifter replacement is the only cure. the only code ive had is P0320 for the past 2 yrs
Some things you can try that might possibly help (provided the intake lifter or lifters are not at fault). Try a bottle of Techron. Use according to directions on the bottle. Well, almost. The bottle I buy treats 20 gallons of gasoline but I just dump the entire bottle into the fuel tank and fill the tank. I used seafoam in the tank

The general rule is if one notices any improvement in the engine to run a 2nd bottle when the fuel level of the tank with the first bottle of Techron is low, below 1/4 tank. I will check on that this weekend.

I'd suggest even if there is no improvement you still try a 2nd bottle.

Afterwards arrange to change the oil and filter.

Regarding oil: Be sure you are using an approved oil and one that has the right multi-viscosity grade for where you live and drive. 0w-40, or 5w-40 or even one 5w-50 are all available to you but only 0w-40 is suitable if you drive in cold (Porsche says -25C) weather. Yes I use Mobil 1 euro 0w40 only

Be sure you don't run the oil too long. I have found 5K miles to be a good change interval for my usage. im guilty of that I was running the oild for 10k then chaging it. that's what the dealership told me.

You can try two bottles of Swepco 502 oil improver. (Two because one just treats 5 quarts IIRC while the engine carries nearly twice that much oil.) Ok ill make a note and get it at the store for this weekend.

Thank you for all the help!!!!

Medevack1

The car has been like this for over 2 years, I have an onboard CEL reader and everytime the CEL comes on I know what it is and erase it and the car runs fine until the next time.

thank you ill get that checked out.

Medevack1

I did noticed the battery a little weak when cold starting but my electronic volt meter reads 14.0 when initial start (cold) then it drops to 13.8 when the RPM's go to normal idle.

Ill get it checked out ty

johnireland

Does this relate to when you have bought gasoline? We have had recent issues here in Los Angeles with bad gasoline causing cars to completely break down because of engine misfire. Just curious if it could be caused by buying gas at a contaminated source.

Medevack1

Is not the gasoline and is funny you say that because I usually put 93 in it and sometimes it throws a code but on long trips I have put 89 and the CELL doesn't come on for weeks... lol And im in NC

Imo000

If those shops did an accurate diagnosis then the issue isn't mechanical but electrical. You need to hook up Durametric or something advanced like it and drive around until the problem resurfaces again. Then see what the heck is actually happening.

Medevack1

Does the dealership or the Indy have that Durametric?

rolex11

What about the infamous ignition switch?

Medevack1

replaced it with a new one already.

Ahsai

So in summary
- This is a condition on Cylinder #2 only
- This condition has been there for the past 2 yrs
- Oil is M1 0w-40 and change every 10k
- This condition is intermittent

Since you have already replaced the coil and plug on that cylinder, they are unlikely to be the culprit. What's left? Cylinder, valves and injectors. Cylinder should give consistent issue. So that points to the valves and injectors.

10k oil change is very long. I would inspect the oil filter for debris, check the oil filter canister spring valve is intact. Also drop the oil pan and see what you find. Any magnetic drain plug?

If everything looks good, your options seem to be injector replacement and then valves.

jhbrennan

A weak or failing battery can cause all sorts of issues. I've had a battery start the car with no issues and then 30 minutes later not have enough juice to do anything but click the solenoid. Replacement is a $200 "possible" fix - try it.