I am not sure where to begin with a situation that has developed with my car. I am hoping that some of the gurus on this forum can offer some advice. I apologize for the length of this post in advance.

About two months ago I took my car in to a local Porsche dealer in San Diego. I decided to try a different dealer in San Diego than I usually go to see how Supercharger friendly they were. I had a 30k mile service done on the car. The car has been running perfect with the supercharger installed, once I got some initial issues worked out with the supercharger install, I have not had any problems in probably 15k miles. About a week later I started receiving check engine lights periodically and they would go away. I was scheduled to have a set of PSS9's installed from a respected local independent shop in the San Diego area that is a EVO authorized dealer, so I decided I was going to wait to have the check engine lights looked at by them to see if something might of been wrong with my 30k service. I also asked them to look at all the supercharger components because this was something the dealer would not do. The weekend before my PSS9 install I went up in the San Diego hills like I usually do so that I could give my stock suspension one last run. During this drive I began noticing that the exhaust sounded different then it usually does. At first I thought I drove by someone mowing their lawn. After the third time of hearing the lawn mower sounds I realized that there was something wrong with the car. The exhaust sounded like it was puttering. I have the stock sports exhaust on the car and it now sounded kind of like an old WV beetle. I quickly stopped the car and looked at the engine to see if I could see anything wrong with the vehicle. I was not sure what I was looking for but I was looking for oil, checked the belts and also looked under the car to see if I could spot anything abnormal. After about 10 minutes of looking around and not spotting anything I got back in the car and started to drive. I was going to just take the car home because I knew something was wrong. Once I gave the car some gas the car started vibrating moderately and the check engine light was now blinking instead of being solid which tells me that there was a more serious issue possibly going on. I was about 15 miles from my house and I felt like I could make it without any more issues or further damaging the car. I noticed that the vibration was worse going slower and as I accelerated it did not happen as much. At this point I was guessing a transmission problem or maybe a possible broken motor mount.

The next day I had the car towed to the place I was going to have the PSS9's installed and informed them of the problems. When they called back the indicated that they were able to reproduce the problem and they were going to get the car on the lift and check it out. I asked them to look at the computer codes to see what they said. When they called back again they stated that the transmission was shot and when they looked at the transmission oil and that it was coming out grey from the metal shavings. They gave me a quote on a new transmission and I decided to look around myself hoping to find a better price. I was able to find one for $4k + core and had it shipped to them. Unfortunately it would take about 10 days to get it to them however. The labor was going to be a reasonable $600 for the install. Once they received the transmission they promptly installed it and gave the car back to me. I had them do the PSS9 installed while the car was waiting for the transmission so I thought everything was set and I would be good to go.

Shortly after getting the car back I was driving around 30 mph and all of a sudden the car started vibrating again and the check engine light started blinking. I thought that maybe I received a bad transmission and that I had the same problem again. When I called the shop I asked if I should tow the car in again and they stated that I should be able to drive it to them. I mentioned that I thought the transmission went out again and explained the symptoms. They said it might not be the transmission and to just bring it in for them to take a look at it. Once they got the car they looked at the computer and said that my 4th and 5th cylinder was misfiring and the computer was shutting them down. To me it appeared to be the same issue as before with the same vibration and exhaust sound so I found this odd. After they looked at the car further they said that the spark plugs were extremely fouled up and that I needed a new set. Initially I was questioning this because I just had the 30k service done but I was informed that Porsche recommends that the plugs are changed every 60k miles. They said that the supercharger puts extra load on them and that I should probably have them changed much sooner. I had them install the new plugs and they looked at the coils also and said they were working properly. When I got the car back again it was only a day or so until I again received the check engine light with the vibration and puttering exhaust sound. This time I noticed that the problem is happening either at slow speeds or at idle. When I accelerate hard the car did not have any issue. The check engine light came on and off a few times before I was able to take it to the shop. When the light was off the car acted completely normal. When the light was on or blinking I would have the symptoms. When I got the car back in to the shop they fussed with it for a few days and said that they did not feel it was the coils because they were swapping around the spark plug wires to different cylinders and it acted like it should. They also did a compression test and said that the engine was not loosing any compression. They felt the problems were not the valves because the problem was happening during low load on the engine. They finally looked at the air filter and said it was completely plugged up and that they were going to clean it and reinstall it. They ended up tearing the filter so the put a new one in place for me. They said the dealer should have looked at this during the 30k mile checkup but I was never told about anything.

When I got the car back I ended up having the same issue and taking it to them again. This time we got EVO involved. The local shop said that they feel it was a computer programming issue and that the car was mechanically sound. They wanted to have the car reflashed with the latest supercharger program to see if this helps. It was suggested to me by the local shop and by one other individual that the Porsche dealer may have adjusted my computer programming without informing me during the 30k service. I guess they sometimes do some warrantee and recall work without informing the customer. This sort of made sense in the timeline of problems so I was hoping to have some luck with this. I was worried about the programming however because of the issues we had during the initial install of the supercharger. I was concerned I would open up a new set of problems by loosing the program that we had on the car. I called EVO to see if they could locate my program and they said they would look into it. EVO was suggesting that we change the mass air flow sensor. The local shop did not feel this was the problem but we had no where else to go so I authorized them to do this. When I got the car back everything appeared fine again. I even went on a test drive with them and it was working fine. About 20 miles from the shop the problem resurfaced again while the car was at idle for a few minutes while I was at the bank.

This brings us up to where we are at now. I have spent quite a bit of money on this and the transmission problem together. I have also had a lot of downtime with the car and this is my daily driver. Not to mention I have a new suspension I am hoping to play with. To me the symptoms are the same as when I brought the car in for the initial transmission issue. I am not even sure that car had a transmission problem at this point. I am not sure what to do about this at all. I am going to bring the car back in on Tuesday and I am going to try and have a conference call with the local shop and EVO. I am considering shipping the car to EVO possibly or even having the dealer look at it although they won't be able to deal with the EVO programming.

To sum things up:

- Computer is indicating misfires on the 4th and 5th cylinder.
- The problem starts happening at idle or slow speed with very little load on the engine
- The local shop does not feel it is mechanical problem. They feel it is related to the supercharger programming.
- The problem may go away and come back again. When the check engine light is not on the car acts normal.
- A transmission, spark plugs, air filter, and mass airflow sensor have been swapped out.
- The car has received the latest flash program from EVO
- I am practically going bankrupt over this.
- I am going crazy not having my car working. I can't handle not having a supercharged 911.

If anyone can offer any advice I would appreciate it.

 

DrivItLkUStolIt #77

 

hopefully 1999 will read this. he's probably the closest thing we have to a porsche tech on this thread. although my problems haven't been as severe (or as expensive knock on wood), i totally feel your pain with something being wrong and the techs scratching their heads

 

Steve; They did not install platinum plugs, did they? Also, wereLL plugs fouled or just #5 and #6? Plug wires switched on #5 and #6? No other codes except for the cylinders? Car a TIP or 6th speed?

Spend $200 or so and get a scanner that will show your sensor readings.

 

Man I hear you. I was just told by the Toyota dealer my Tundra vibration was the rear diff, 1500 to fix and 2 weeks. I then took it to an indy who fixed the rear u joint for 100 the same day and problem solved. I had even suggested it was the u joint to the stealer. SteveL, I'll bet the transmission was fine, can you have the old core looked at now or is it too late? Dog, how is your car running now? Will

 

The old transmission is gone now. Because of the core charge we were unable to open it. I actually never even looked at the transmission because of time constraints. I want to believe that there was a problem, but the symptoms are so similiar. What upsets me is that I asked them to look at the fault codes and when they were done with the transmission they kind of glossed it over when I asked them about it. I didn't really push the issue because I was happy to get the car back and just wanted to move on.

The car is a 6 speed. They claimed that all the plugs were really fouled up. They showed me one of them and they were seriously black and corroded. I forget the name of the new plugs that were installed, but they made a comment about how good they were. I want to say they were HNK? The porsche (I think it was porsche) part was 999-170-207-91. My understanding is a little unclear, but they have been switching the coils and/or plugs on the 4th and 5th cylinder to see if the problem reproduces itself on a different cylinder and each time the problem stays on the 4th and 5th cylinder. I forget which cylinder but one of them is intermittent with the problem and the other is always showing up in the fault codes. Listed below is the list of codes that I know about:

P0304 - Misfire, cylinder 4
Pxxxx - Misfire, cylinder 5
P1371 - Valve life control, checksum error

I don't have the correct code for the misfire on cylinder 5. It is my understanding that the P1371 code has only appeared once in all of the times the codes have been checked.

 

Looking at your description of the problems they all center on a misfire and the whole transmission swap was just a result of metal shavings found in the transmission oil. Just thinking of the basic things to check aside from the programming would be the fuel pressure regulator and check how much vacuum the engine is pulling/the pattern. Of course making sure there are no potential leaks in the intake tract is another important consideration. The “P1371 Valve Lift Control checksum error - Above Limit� code has me scratching my head though.

 

I am going to get my fault codes looked at in a few hours. I will post the results. They say I do not have any vacuum leaks. I am not sure if this is what you mean by 'how much vacuum the engine is pulling/the pattern'.

 

When I said vacuum pattern I was referring to the pattern of the vacuum gauge needle when it is connected to the engine while running. If the vacuum gauge needle waves quickly back and forth that can indicate something mechanical is wrong. I might have missed it in your original post but do you have a boost gauge installed? If so is the car boosting normally?

 

There is no boost gauge installed. The car does feel normal when driving and everything is working correctly if that says anything. I drove the car about twenty miles today and twice I was able to feel some vibration and then about two seconds later the check engine light went from solid to blinking. This lasts about 15 seconds and then turns solid and the car acts normal again. Each time this happens the car is neither accelerating or decelerating. It almost appears a minute or so after some moderate acceleration but I can not say for sure this is always the case.

 

you forgot me, I don't know what # I am, but Alex might.

 

It would be easier to diagnose with a boost gauge to see if everything is acting normally. My first thought is that your car has a leak in the intake that only occurs under boost, which makes the car idle fine and behave normally if you stay out of the throttle. Here is why this makes sense to me, you hit the gas and the boost builds which is being vented. The vented air is after the flow meter which makes the computer go very rich and fouls the plugs. Try driving around under light throttle and see if the car does anything strange.

 

Have you checked the s/c hoses?

 

I had the codes checked in the computer earlier today and right now only the 5th cylinder is misfiring. We did not see any codes from the 4th cylinder this time. I have put about 100 miles on the car since the latest time the fault codes were scanned (Friday). I am not sure if replacing the air filter of mass airflow sensor helped with this or not....

The repair shop still feels it might be a computer issue. They called EVO today and ask if we could swap the DME unit out for testing purposes. We found out the the computer is tied to the keys so this will not be possible without going to the dealer. EVO is supposed to call back tomorrow with some more recommendations. The repair shop mentioned a few things that had me a little startled. They suggested that we check the hydrocarbons as close to the problem as possible. They first suggested unplugging the O2 sensor and running tests. After that they suggested drilling a hole in to the area of the engine where they could test the hydocarbons for that specific cylinder. I have never heard of this and asked how they would repair this. He said they would mig-weld it and then smooth it out. Somehow this doesn't sound good to me. I am hoping EVO has a better suggestion.

Todera - The problems I have all seem to occur at little or no boost. For example, last Friday when I picked up the car from the shop I had a problem about 20 miles later. The car was parked at idle for a couple of minutes while I was at my bank. My buddy said he felt some vibration but he didn't know there was anything wrong until I told him when I got back. It may be coincidence but it seems a few times the problem actually went away when I stepped on the gas. THe problem has probably happened about 30 times or so now. Each time it has been at either idle or little or no acceleration. It does seem to happen a few times when I have been pushing the car hard and then the car is coasting or maintaining a slower speed (less that 30mph) for a minute or two. I also found out that the vacuum tests did not show any wavering. They also have done a few other tests such as a smoke test and I think some type of ozone test or something like that.

Viper501 - All hoses have been checked as far as I know. I am going to bring up the boost issue tomorrow. EVO asked how much boost I was running as well.

 

You are number early one that won't change his injectors or computer over to a flash <g>!!! I don't know but I could try and find the old invoices from XXXXRAT and it'd show the number?