Confounded - misfire problems continue......2006 TT

[PKN]

I installed the new latest rev plug packs and plugs, checked that all plug pack connectors are undamaged and I am still getting serious misfiring on cylinder 5 - over 100 in a couple of minutes running - but the Durametric is not showing any error codes. I can see the misfires when I look at the misfire counter. If the injector is the problem, would it throw an error code? Not sure what to check next

Steve

[binger]

Hi Steve,

Can you please give us some history on the car? Did you have any codes before you changed the coil packs and plugs?

[PKN]

Binger - its in the thread below - "P2320 error code and bad misfire/backfire.....help! "

The difference now is that the problems moved to cylinder 5 and on the last test run, I got no codes at all but cylinder 5 is still getting a lot of misfires. I think my next move is to run some injector cleaner through the fuel system....unless anybody has a better idea

Steve

[binger]

You say you looked at the wiring? Did you trace all the wires or do any voltage drop testing? You changed the coil packs so check that off the list. I would replace the fuse even if it look ok. If that dose not work you have 3 other possibility's listed in red below.

Possible causes:

- Short circuit to B+

- Short circuit to ground

- Open circuit in line

- Fuse F 07 faulty (fuse carrier in plenum panel E-box)

- Bar ignition coil faulty

[PKN]

This morning things went from bad to worse...below are the error codes I got on the Durametric. It sure feels like a short in the wiring harness ! I am thinking about removing this part of the harness and stripping off the insulation to check it out....Any other thoughts? So far we have new fuses on 7 and 8, new coil packs (latest revision), new plugs and even some injector cleaner in the tank

P2320:

- Upper limit value exceeded, test conditions are not-completed, fault is not currently active and is not causing a DTC light

P1132:

- Value below lower limit value, test conditions are not-completed, fault is currently active and is not causing a DTC light

P2228:

System Off Idle Bank 2 - Value below lower limit value, test conditions are not-completed, fault is currently active and causing a DTC light

P0300:

Random/Multiple Cylinder Misfire Detected - Value below lower limit value, test conditions are not-completed, fault is currently active and causing a DTC light

P0306:

Cylinder 6 Misfire Detected - Value below lower limit value, test conditions are not-completed, fault is currently active and causing a DTC light

P0305:

Cylinder 5 Misfire Detected - Value below lower limit value, test conditions are not-completed, fault is currently active and causing a DTC light

P0307:

Cylinder 7 Misfire Detected - Implausible signal, test conditions are not-completed, fault is not currently active and is not causing a DTC light

P0301:

Cylinder 1 Misfire Detected - Value below lower limit value, test conditions are not-completed, fault is currently active and is not causing a DTC light

P0307:

Cylinder 7 Misfire Detected - Value below lower limit value, test conditions are not-completed, fault is currently active and is not causing a DTC light

P0308:

Cylinder 8 Misfire Detected - Value below lower limit value, test conditions are not-completed, fault is currently active and is not causing a DTC light

[PKN]

Today, I disconnected all coil packs, injectors and associated sensors and unwrapped the insulation, cleaned off the wires and closely inspected them as well as all of the connectors. I found only two small areas where the cable cover had split and one of those was a ground wire. The other was to a coil pack - number 7. I could not see anywhere it might have grounded. I wrapped the problem areas and reconnected everything. Testing the motor with the Durametric I got no misfires over a 5 minute run. I re insulated all of the wiring and retested. No errors. Put all of the covers back and retested - no errors.

She is running very smoothly now which leads me to believe that either a connector wasn't seated right or the insulation break caused the problem. I will put some miles on her tomorrow and report back. Cant say I am happy that I didn't discover a definitive cause for the problems but will take the result and hope it stays fixed. A good day. I even got the chance to finish reassembling the rear windows and hatch on my Jag XKE....

Steve

[PKN]

The problem is apparently fixed. I plan to remove the insulation on the other bank soon to look for similar issues before they become a problem. 100,000 miles seems to be time for a few more inspections than I had planned. Changing out the problem harness is not an option as Porsche does not list "part harnesses", only the bits that attach to it. Maybe its time to look at adding some extra airflow under the hood via a scoop or something. It is getting monotonous, changing out vacuum tubes, cooling tubes, coil packs and now wiring.....

Steve

[binger]

Looks like that harness is available. I would call Andraya at sunset Porsche to confirm 800-346-0182. See the link below parts diagram.

http://www.autoatlanta.com/porsche-parts/hardparts.php?dir=9PA-03-06&section=902-09