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Could be any number of things. Dx check of codes and parameters would be my essential first step. Given the cost of parts/labor on these cars, the shotgun approach is uneconomical.
I have had a few batches of bad fuel over the many years of ownership. Bad low grade fuel can make your engine feel like it's a bucking bronco and really gum things up. Sounds like a lot of guys chimed in on the most common issues, but these have been my experience too..
After bad fuel or lack of power in upper rpm's
1. Strong Fuel System Cleaner... Chevron Techron concentrate fuel cleaner for a couple tanks and only fill up tank with Chevron Techron premium 91-93 octane fuel or something similar
2. Cleaning Maf Sensor with CRC Maf cleaner
3. Maybe a fouled spark plug
4. Bad coil
5. Dirty intake filter.
6. clogged/dirty fuel pump
Now this I experienced personally a couple of times over the years.
7. Recheck vacuum lines... Especially to variable intake manifold plenum flap. This really affects the "surge" from 5000-7000 rpm. I had the vacuum lines accidentally disconnected and pop off during some routine maintenance at a shop. The surge was gone from 5000-7000. Once they reconnected the vacuum line to the actuator and a bit of crazy glue to keep the vacuum lines attached all was back to normal. You need to visually see this actuator arm rotate/swing open around 5000 rpm. Have someone rev the engine while you keep an eye on this small arm in the engine bay. It's behind the 2nd cross plenum. It will be a bit hard to see because it sits deep inside our engine bays, but worth an inspection. I included some pics from a 987 setup, but it's the same idea on our cars. you will see an actuator arm swing up and down were those yellow arrows are in the photo.
Hope you find a easy solution. I absolutely hate when my Porsche's are not performing 100%
I have had a few batches of bad fuel over the many years of ownership. Bad low grade fuel can make your engine feel like it's a bucking bronco and really gum things up. Sounds like a lot of guys chimed in on the most common issues, but these have been my experience too..
After bad fuel or lack of power in upper rpm's
1. Strong Fuel System Cleaner... Chevron Techron concentrate fuel cleaner for a couple tanks and only fill up tank with Chevron Techron premium 91-93 octane fuel or something similar
2. Cleaning Maf Sensor with CRC Maf cleaner
3. Maybe a fouled spark plug
4. Bad coil
5. Dirty intake filter.
6. clogged/dirty fuel pump
Now this I experienced personally a couple of times over the years.
7. Recheck vacuum lines... Especially to variable intake manifold plenum flap. This really affects the "surge" from 5000-7000 rpm. I had the vacuum lines accidentally disconnected and pop off during some routine maintenance at a shop. The surge was gone from 5000-7000. Once they reconnected the vacuum line to the actuator and a bit of crazy glue to keep the vacuum lines attached all was back to normal. You need to visually see this actuator arm rotate/swing open around 5000 rpm. Have someone rev the engine while you keep an eye on this small arm in the engine bay. It's behind the 2nd cross plenum. It will be a bit hard to see because it sits deep inside our engine bays, but worth an inspection. I included some pics from a 987 setup, but it's the same idea on our cars. you will see an actuator arm swing up and down were those yellow arrows are in the photo.
Hope you find a easy solution. I absolutely hate when my Porsche's are not performing 100%
Thanks a lot! I probably will have to do all of the above.
May I also know what mods have you done to your car? It looks really nice in the picture.
Update: Just got the car back. Huge bill, thanks Porsche tax.
Not sure what the actual problem is, my mech said that he found a leak in my TB pipe. He has ordered a new one but for the time being, he has sealed the leak. He also replaced the "oil filler neck", as that too was also leaking. On the drive back, seems like the Bosch ECU is still learning so there was some hesitation at lower RPM. I'll keep everyone updated as I go along.
Another update: Drove the car for about a month, the Bosch ECU took a few days to learn but afterwards the power in the mid range and low end was amazing. The torque literally was capable of tearing my face off. So much so I actually think my car was previously modified with a chip tune. Tested it against other 997 manuals and my car felt way, way more powerful. Especially in the mid range. Was really happy for a while. The top end power was still slightly lacking but with the better than ever low and mid range power, it wasn't so bad. Notice everything is in past tense?
Because it did not last, new problems have emerged. Went on a PCS (Porsche Club Singapore) drive and got my *** torn by a new 718 S, was depressing but more worryingly, a couple of days after, I noticed some new issues. Firstly, the complete lack of top end power. The power curve literally flattens suddenly after 6k RPM. It is really noticeable, even my first time passenger noticed it.
And there is some new hesitation at lower RPM and the mysterious disappearance of that previous awesome low end and mid range power/torque. There is still some power and torque but it seems deflated back to previous above in the thread levels (pre-vacuum line fix). I'm getting a little bit frustrated. Just a little bit.
Seems like there is another Vacuum leak somewhere. Seems like there is a quiet hissing noise at idle, though I cannot be sure. Could be the other problems mentioned earlier in the thread. I just hope its not engine related like a head gasket or something... that's gonna be expensive.
Anyone have any other ideas?
Just thought I update everyone and add my experiences to the database.
04-19-2018, 02:34 PM
