bigbuzuki

It was running smooth before you changed the plugs.

You changed the plugs and it now runs rough.

You changed the coils and now your getting misfires on 5,6,7.

Try interchanging plugs 5,6,7 with 1,2,3 and see the results.

ArmyRover

The starter was done at the same time. Previous to the starter and plugs I didn't have all the misfires, electrical systems warnings.

I will try swapping the plugs for fresh ones tonight after duty.

ArmyRover

I left the battery on the charger over night to make sure it was good to go. I was able to start the Cayenne 3 times it would die shortly after starting I couldn't keep it running long enough to decide if it was still missing on the same cylinders. It now is stalling out pretty quickly. After the third start the battery no longer had the ability to turn it over. I had to add the jump pack. I checked voltage and it was at 11.86. I pulled the battery and have it on the charger overnight and will have it tested again tomorrow.

ArmyRover

Battery came up good, on volts and cca

ArmyRover

So I did a check on the fuel pressure since it would barely stay running. Key on it jumps to 77 lbs than it bleeds off to zero in 4-5 seconds.

When started it bounces between 70-78 but is only steady briefly when given gas then it drops and nearly stalls/stalls

Petza914

That could be the HP fuel pump but I'd also check for leaking injector(s) as that would be another way for the pressure to decrease quickly and that's not good as it's flooding the the cylinswr with fuel and washing away the oil from the walls. Do you have a scan tool that will let you see live values, like a Foxerll or Durametric? If so, hook it up, go to the engine module and select the misfires for all the cylinders, then start the car and when it starts stumbling see which cylinders are logging the misfires. Are they all on one bank, are they random on both banks, etc.

ArmyRover

I have the Launch it should have no issues doing live values. The bigger problem will be keeping it running long enough to get any real data


I will check the oil for a fuel smell tomorrow when I get back out the shop.

Currently it's not recording any misfire codes. It was 3 out of 4 on the driver's bank, last time and 1 before. Going back further it was on both banks randomly.

I thought from my reading there was only two standard electric pumps on the 05 CTT

bigbuzuki

There are only 2 fuel pumps in the fuel tank for the 4.5 litre Cayenne.

High pressure fuel pump was introduced with the DFI 4.8 litre engines.

Your low fuel pressure issue needs to be addressed.

What fuel pressure reading do you have with key on and off? They both should be similar and have nil decay with key off.

Refer to the first 3 posts in this Link for excellent fuel system troubleshooting.



ArmyRover

I had screen shot the 2nd and 3rd posts of that same thread last night.

Key off I am getting 0 psi the system loses pressure after a few seconds. When the pump primes or key is turned to position 2 I get 77 psi which is nearly 5.5 bar. That dumps to 0 after a few seconds. When running I get fuel pressure bouncing between 70-78 psi.

I will run the tests outlined in the second post today and report back

ArmyRover

I am currently awaiting a second opinion on the smell of the oil

ArmyRover

Group decision is it has a fuel smell to the oil

ArmyRover

While I was troubleshooting the fuel system the battery went flat. I noticed that as soon as it had a battery cable on it it would drop 4-5 volts immediately even with the key off. So I had it tested again and it failed the load badly. So a new battery will be a thing tomorrow and I'll start trouble shooting again.

cdk4219

Clogged fuel filter

MM951

I was chasing a similar problem for way too long on my CTT and when i went to my 944 roots and decided to inspect injector wiring, coil wiring, etc I found many many cracks in the insulation and quite a few areas where the insulation had disappeared entirely - I never had any injector circuit / coil circuit codes but my god was the car transformed after I repaired all of that.


edit: i just read you did a starter etc and I would suspect the wiring even more now

ArmyRover

I will run down the wiring and see what I find thanks!