MR Turco

Hi Rennlisters

I recently bought a 2008 GTS w/60k miles. Car is great, I love it. I have noticed the infamous "longer to start" now that the weather has dropped off in Mass. I did test the voltage via a generic OBD reader during crank and it does drop low but i ALSO noticed there was a P1023 code (but no CEL?).

Question: Knowing a weak battery can throw weird codes, the P1023 seems to not be one of them - could this be attributed to a weak battery or do i need to dive into the fuel system? I read a handful of threads around P1023 none seem to be rooted back to a weak battery.

As seen with others, only the first start seems to be weak. I was away for a week and it took about 10-15 seconds to start on first try but did start. If the car has even been remotely driven it seems fine on warm or hot starts.
I've only have the car a month so if it's a battery, it is what it is and I'll replace it. If it's the pump I'm inclined to go back to the dealer and try to get them to replace it.

Thanks in advance for all the help!

Kirill

Do a simple thing - look at the battery and find the manufacturing date - if older than 4 years = replace.

deilenberger

OBD-II Codes fall into two kinds: P0001 to P0999 are "generic" meaning the same code number means the same thing on any car it occurs on. A standard OBD-II code reader can read and display these correctly. These are all emissions related. P1000-P9999 are manufacturer specific. Each manufacturer can assign one of those numbers to any failure in any module they want to. P1023 is a Porsche specific code - and to figure out what it means you should google on "Porsche Cayenne P1023 code" When I did this - it turned up a lot of references to the high-pressure fuel pump, being low on pressure at startup. That appears to agree with your symptoms - and my guess is a new HPFP is in your future. They weren't supper reliable in the early implementation and there may actually be either a service campaign or recall involving your pump..

VulcanGrey

Slow to crank = battery
Cranks but slow to start + P1023 = low fuel pressure most likely. Try turning the key on then off a few times to get the fuel pump to prime the rail as much as possible. If it starts easier, then the fuel pump is having trouble getting to the right pressure. Also if the car is harder to start after sitting awhile (more than 1/2 hr) then the fuel pressure might be decreasing in the rail due to a bad pump.

deilenberger

That diagnostic unfortunately won't work with DFI (Direct Fuel Injection - ie - squirts right into the cylinder). The pump that's failing is the camshaft driven DFI pump - turning the key on/off a few times will do nothing for the pump. Typically these do have a bleed-back problem when they fail. Meaning it takes some cranking of the engine to get the pump to push high-pressure fuel down to the fuel rail and to the injectors.

VulcanGrey

thanks for the clarification. I'm mostly used to Lotus and Acura...
However, doesn't the Porsche use an electric pump to supply the mechanical pump with fluid?

Rossi

P1023 = low fuel pressure

Petza914

I believe the Cayennes actually prime the pump when you open the driver's door, as odd as that sounds, not when you cycle the key.

Wisconsin Joe

955s do. You can hear the pump prime when you open the door, if you are in a quiet spot.

There are also warnings in writeups on removing the fuel rail to either disable the pump, disconnect the battery or just don't open the driver's door while the fuel line is off.

Not sure about the 957s.

deilenberger

Yes - actually two electric pumps, but the symptoms given don't point to those as a problem. They point directly to the DFI mechanical pump.

CaptainGSR

I would invest in a good CTEK charger and let it do its thing for a while. That could help you solve the problem, or at least help you rule out the battery...
I think it is a must have for any car not daily driven.

MR Turco

Update, so i ruled out the battery, it was changed right before i bought the car by Porsche. I definitely think it is just early signs the HPFP is dying. I'll let it sing it's swan song and change it when it crokes.

mhead

I have a 2010 with 110K on it...If it seems like the starter is struggling to turn the engine over or doesn't the first few times it may be your starter is beginingg to fail. Mine exhibited a slow crank...charged the battery and checked it several times...dealer did the same and we found that the starter was failing...

New starter($$$) and all is like new.

Andy E.

A defective new battery is not uncommon; particularly with the MOLL brand that PAG uses on all their vehicles.

I had the exact same symptoms and went through two Moll batteries within 2-1/2 years. I finally went the route of an aftermarket AGM H8 battery and the starter problem was solved.

MR Turco

Wow, good to know. Haven't read that anywhere. I'll keep that in mind. Obviously battery is the cheapest starting point.