MY87 5 speed running issues

In September 2010 with a help of friend I replaced the following oil pan gasket, motor mount, upgrade to Delrin rack bushing and replace power steering line. Since doing this project my car has the following issue high idle (1200), difficult to start (when engine hot), erratic idle, Engine hesitation (leaning out) and it turns off while driving. I have done some LH Diagnostic Troubleshooting using the WSM Vol1 D24-9. Check the following based on the following test point Engine will not start, Engine hard to start, irregular idling and Engine hesitation. This is what I tested supply voltage, idle speed contact, engine temp sensor II, air mass sensor, idle speed control activation, ground and plug connection and they came up normal. I’ve swapped MAF and LH ECU which I borrowed from Andrew Olson and Tim Murphy (great thanks to both).
I’ve replaced spark plugs and check compression. Install fuel pump pressure by permanently install a Install fuel gauge to fuel rail to have a visual when engine will not running or when it decides to stop running. Inspect fly wheel ring gear by removing the cover. None of this solved the problem.
2012 I had a Porsche mechanic R&R intake manifold and replaced all necessary hoses, TPS and gasket. I Check and adjust the timing belt. I bought an idle valve per mechanic suggestion but he has not installed it. Check and adjust the timing belt. All issues disappeared except for the high idle. After R&R of intake majority of my issue disappeared except for high idle 1200RPM. Four months have past hesitation issue returns not as often but a few times I noticed while driving.
Three weeks ago my starter failed and I had R&R starter. After replacing the starter I took the car for a drive low and behold all the issues are back except for the hesitation thus far.
I hope I didn’t confuse anyone with my rumblings. It’s been a frustrating 2 yrs. I can’t enjoy a drive fear that it will stall and will not start back up.
Thanks in advance
Ariel Trajano

rluvsporsche;11267 wrote: In September 2010 with a help of friend I replaced the following oil pan gasket, motor mount, upgrade to Delrin rack bushing and replace power steering line. Since doing this project my car has the following issue high idle (1200), difficult to start (when engine hot), erratic idle, Engine hesitation (leaning out) and it turns off while driving. I have done some LH Diagnostic Troubleshooting using the WSM Vol1 D24-9. Check the following based on the following test point Engine will not start, Engine hard to start, irregular idling and Engine hesitation. This is what I tested supply voltage, idle speed contact, engine temp sensor II, air mass sensor, idle speed control activation, ground and plug connection and they came up normal. I’ve swapped MAF and LH ECU which I borrowed from Andrew Olson and Tim Murphy (great thanks to both).
I’ve replaced spark plugs and check compression. Install fuel pump pressure by permanently install a Install fuel gauge to fuel rail to have a visual when engine will not running or when it decides to stop running. Inspect fly wheel ring gear by removing the cover. None of this solved the problem.
2012 I had a Porsche mechanic R&R intake manifold and replaced all necessary hoses, TPS and gasket. I Check and adjust the timing belt. I bought an idle valve per mechanic suggestion but he has not installed it. Check and adjust the timing belt. All issues disappeared except for the high idle. After R&R of intake majority of my issue disappeared except for high idle 1200RPM. Four months have past hesitation issue returns not as often but a few times I noticed while driving.
Three weeks ago my starter failed and I had R&R starter. After replacing the starter I took the car for a drive low and behold all the issues are back except for the hesitation thus far.
I hope I didn’t confuse anyone with my rumblings. It’s been a frustrating 2 yrs. I can’t enjoy a drive fear that it will stall and will not start back up.
Thanks in advance
Ariel Trajano

I am a bit confused but I will give it a poke. Since the starter replacement,your issues have returned? I am not sure why you haven't replaced your Idle speed valve because if that is bad or at least intermittantly bad it can cause some of your issues as well.
I would check your basic 928 things so that we can get a baseline of what is good.
Check all the known grounding points for good contact.
Check to see you have a good strong battery
check the wires and connections at the starter and the alternator as well as the jump post on the right front fenderwell and make sure they ar clean and in good shape.
Make sure your alternator is properly charging the battery when at idle as well as cruise because voltage variations can screw up how your ecu functions.
Then get back to us with what you have. My .02 cents anyway.

My Porsche mechanic didn’t think its bad at the time. He did think the TPS was the culprit that was replaced but did not resolve the issue. I've cleaned and inspect power and ground just to rule out the possibility of that. The alternator and starter wires have also been inspected no visual issues and charging tested.

my car had some issue which caused it to rev HIGH when idle and even throttle higher up to 3k rpm at times. once i had turned it off and it wouldnt start back up until it cooled down from normal temp. One night i went to the market the car was off for about 1.5 hrs. when i got back it would crank but not start. i ended up flooding it while trying to start it. in the end took it to the mechanic, he took a glance at the starter, and wrote that off as the problem. after starting it a few times and testing. he found that the RPM sensor that goes by the clutch was faulty and had it replaced. After that the car felt like new. as i havent done my own work im not sure of the real names of the parts... hope that helps pin point the issue.

emmanuelli;11529 wrote: my car had some issue which caused it to rev HIGH when idle and even throttle higher up to 3k rpm at times. once i had turned it off and it wouldnt start back up until it cooled down from normal temp. One night i went to the market the car was off for about 1.5 hrs. when i got back it would crank but not start. i ended up flooding it while trying to start it. in the end took it to the mechanic, he took a glance at the starter, and wrote that off as the problem. after starting it a few times and testing. he found that the RPM sensor that goes by the clutch was faulty and had it replaced. After that the car felt like new. as i havent done my own work im not sure of the real names of the parts... hope that helps pin point the issue.

emmanuelli

Did you experience any other symptoms? Like the car would stop running while driving and it would be difficult to get the car to run again.

Thanks in advance.
Ariel Trajano

the car never shut off on me. the main issue i ran into was the trouble starting the car right after turning it off and the throttling going up on its own from time to time when i was standing still. i was glad i have a 5spd with an auto i would have rear ended some or ran so many red lights!