I noticed in one thread you stated a new battery was installed. Yet you have low voltage at times. Your problems might stem from something as simple as a bad ground connection. Start where you intially replaced parts. New battery may have damaged, loose post. Ground wire dirty or loose. Check for negative cable fault. Check resistance through cable while bending same. Ground points for coils are on cylinder heads. Ground points for injectors are under dash, driver's side.

 

+1

 

going to take a look at those because the mechanic did say cyl6 was getting power but no ground. It seems as if somewhere theres a loose connection that needs to be tightened. Might take a look at the fuses too

 

Ok so the mechanic did the diagnosis and you are doing the work?

 

mechanic did the diagnostics and it led him to believe the issue was the ecu. Cyl6 got power, but no ground. He said the ground is from cyl6 to the ecu. He suggested replacing the ecu. He wanted to try to program another one and swap it out, i told him i will have the ecu tested and i went and got the car. I had the ecu tested and there were no issues. Im currently getting p1317, p0306, p0740. The maf was replaced with the correct non electronic throttle maf and those maf codes are gone.

 

Ok, I understand now. Did you check the ground or #6?

 

the mechanic says he checked the harness and tested the connection. Thats how he discovered the ground issue. After research here and renntech heres my thoughts as soon as i get time:
-check ground by coil where cyl6 is at
-check engine ground strap by rear passenger wheel
-check the wire harness that connects from alternator to starter(Hear this usually has to do with voltage drops)
-check cats
Open to any more suggestions

 

You don't need more suggestions since already have too many. Time to get your hands dirty and start testing the conductors.

 

Any resolution to this mystery?

 

got the wheel off
checked ground strap - good connection
checked battery - good
checked plug by cyl6(behind the wheel behind that plate) good connection
pulled coil pack and spark plug, coil pack looks fine, spark plug smelled like fuel but looked normal other than the white part where it says bosch, above the words is was brown like it was burnt? Or is it just normal wear? Cleaned and put back in, drove great. Took it to mechanic he believes his diagnosis was true and that it’s possible the no ground was due to me having the wrong maf in(the e gas, 99 996 uses non egas) which still doesnt address the misfire. He did say he swapped 5 and 6 to see if it was an issue with the coil pack or plug but same problem. Drove home, no cel but rough idling came back, and a slight voltage drop on the way home. Called porsche to get the plug/coil pack, back order will take 5-6 weeks. Called auto parts stores in the area and they can get bosch parts on order within a day. Im thinking swap out all coil packs/spark plugs, and replace. But heres another thing, my mechanic said it was the injector that had the bad ground, is it possible that needs to be swapped and the coil/spark plugs are fine? Im also going to connect those brown wires under the seat, havent got to it yet, not sure if that has anything to do with it but im sure they probably shouldnt be cut. I also will check the wire behind the alternator.

 

Don't buy any parts unless you are 100% sure it needs replacing or this will get stupid expensive really fast. Put a noid light in the injector connector that you are suspecting to be an issue. Since the coils were swapped and the problem remained at the same cylinder, the problem isn't a coil. Also, since the spark plug is wet, is has no spark or it gets very little fuel from the injector. There is a way to test this too. Start properly testing and stop guessing.

 

Took my car to euro motors and they did a smoke test. The smoke test lead them to believe the issue is with the oil separator. While taking the car apart they noticed the air pump outlet was previously damaged and it was glued to keep it together. Guess the previous owner was buying time. Unfortunately this pump is $1700. The oil filler tube was also split. Found the part 99660510301 on ebay with a 1yr warranty. Will post update.

 

So sorry Dex996, can't believe someone would sell a car with critical parts glued back together. Only good news is car should be fine with new parts.

 

feels good to find the problem, only downside is i cant believe i didnt see it, and i really cant believe the mechanic that has worked on it before hasnt noticed. The air pump is literally right there in front on the left side of the engine.

 

How long have you been on the planet? You'd have to very young to find that not believable.