8R 8S

Just wanted to start by saying thanks to everyone here once again. I posted about attempting a Jimmy Fix about 2 years ago and got outstanding responses and was able to fix the cardan shaft myself, this forum is truly amazing.

Unfortunately, my Cayenne has accrued multiple problems and I am looking for advice on which route to take. I live in Minnesota, and about a month ago we had a week of -15 to -20 F temps. Before this winter I bought a brand new battery to prepare for the cold temps (Drove all the way to Minneapolis to the Porche Dealer and they sold me an Interstate Battery). I had no problems until temps started hitting about 30 F degrees. Around the first snow of the year (Maybe 2 months ago) I was driving and accelerating to 45 MPH, at which point the check engine light came on. Went and coded it at Oreilly's (Porsche dealership is about 1.5 hrs away from me so don't have access to a Durametric), and had misfires on multiple cylinders. (I should also add the Cayenne now took about 5 seconds of cranking before it'd finally fire)

I searched Rennlist and everyone recommended getting new ignition coils from Suncoast Porsche as they'd guarantee they'd be the new version, and to replace all of them, not just the misfire coded ones. Simple enough fix I thought. I followed one of the excellent tutorials on here and changed out all 8 Ignition coils. Of the old ones I pulled out, 4 of them appeared to have a crack. I thought my problems were solved. I drove to Oreilly's to reset the codes, and after hitting 45 MPH I got a dragging and almost skipping feeling from the motor. I figured the computer still thought the cylinders were misfiring so didn't think much of it. I successfully cleared all the codes, and all the dash indicator lights were off. It still started pretty rough, and at the time I thought maybe there was just unspent fuel built up. I started driving home, and once I hit 45 MPH, the check engine light once again came on. I thought maybe I didn't install one of the ignition coils correctly, so I drove back to Oreilly's to code it again.

Imagine my surprise when the code reader showed cylinder misfires on 4 cylinders again. I was even more surprised that the SAME exact cylinder banks that were coded in the first place, were coded again. The spark plugs didn't look bad, but I really had no other explanation. I couldn't find the recommended Rennlist Bosch spark plugs anywhere in town, so I just bought whatever Oreilly's had in stock to see if that would at least solve the problem until I could get some quality plugs from Suncoast Porsche. All codes cleared, I drove off, and low and behold at the magical 45 MPH mark, the check engine light again came on.

Back to the Rennlist Research Center. I took a picture of all the codes I scanned this time, and there was one code that the code reader didn't have a definition for. The codes I received AFTER I installed the new ignition coils and plugs are as follows :
P1026 - NO DTC Definition Found
P0301 - Cylinder 1 Misfire
P0303 - Cylinder 3 Misfire
P0300 - Multiple Misfire Detected
P0304 - Cylinder 4 Misfire
P0308 - Cylinder 8 Misfire
P0421 - Warm Up Catalyst Efficiency Bank 1 Below Threshold
P0431 - Warm Up Catalyst Efficiency Bank 2 Below Threshold


After researching the unknown P1026, I inferred that I had a problem with the high pressure fuel pump. Further research would lead me to a post about the motor going into "Power Reserve Mode," which shuts down 4 cylinders when the fuel pressure drops. Another symptom of the fuel pump was extremely rough starts. I had completely drained the battery trying to start my Cayenne one morning when it was about -20F. I even attempted to jump start it, it auto-cranked three different times for about 10 seconds each time, and it would not fire. This was all making more sense now, and I only came to this conclusion about a week ago. I haven't drove the Cayenne at all in the past week, as I have been weighing the options of buying a Re-manufactured fuel pump or a brand new one.

Fast forward to this week. I charged the battery and went to start my Cayenne. The first warnings I was met with on the dash indicator after charging the battery was :
"System Fault Headlamp"
Ok, least of my worries. Next I receive :
"Coolant Level Low"
Keep in mind I haven't even attempted to start the Cayenne yet, I only inserted the key and this was shown on POST.

Sure enough, I was leaking coolant. From where, I wasn't sure, but the reservoir was below the "Minimum" line. After researching and many advising not to mix different types of coolant (again I don't live close enough to the Porsche dealer to get a gallon quick), I added some distilled water to see if I could examine where the leak was occurring. There appears to be a gouge/crack/hole on the underside of the motor. I cannot definitely say that this is where the leak is occurring, but there is a leak in that area, and the hole does not look like it belongs there. I'm not very familiar with what part of the motor I'm actually looking at on the underside but it appears to be where the motor and transmission (should be) bolted together. I say should be, because it is clearly leaking coolant and not transmission fluid, so I don't think I'm looking at the transmission joint. There are also a few obvious factory holes in the area of the suspected crack, but the one of concern is right on the bolted "joint." I could also be paranoid and the leak could be higher up on the motor and simply dripping down to this possible pre-existing hole. Is there common problem area's on the Cayenne to check for coolant leaks?

Questionable hole on joint

Location of suspected hole


I went from replacing ignition coils to possibly having a hole in the motor in the course of about a month in attempting to diagnose and fix the Cayenne.

My main question is,
do I keep putting time, money, and effort into this Cayenne?

Or is this just a giant snowball on a steep mountain that will inevitably roll down to the bottom? (Is it worth it just to sell to someone for parts)

If the coolant leak is easy enough to fix and not as big a problem as it appears on the surface, is the High Pressure Fuel Pump the most likely culprit for the multitude of codes being thrown as well as rough-start, post-45 MPH symptoms?

Thanks again to everyone for the help. I wouldn't have got this far without you guys. Already eyeing my next Porsche.

95_993

First, it sounds like you have honed in on the fuel pump as the cause of misfires.

As for the coolant leak, it could be coming from higher up on the engine. Do you know if your coolant pipes were ever changed? That is the first place to start. The original coolant pipes (under the intake) were plastic and fail. Replacements are aluminum. When they leak, it's usually down the back of the motor by the transmission.

Mark7000

Will let one of the folks who know more about 1st gen v8 coolant leaks to chime in on that.
It could be a normal spot for coolant to drain from if the coolant tee/pipe has broken?

Oahni

This is an ‘09 so not the same coolant pipes as the 4.5L which is good news. Could be your coolant “T”? I don’t know enough about the 4.8’s, but remember something about the T needing replacement.

As for the misfires, I had a similar issue (and ultimately why I got rid of the cayenne). I was pulling on the highway entry ramp around 45 - 60 mph when the check engine light started blinking. Got right back off and to my Indy. He pulled codes and it was misfire 3, misfire 4. Coilpack 3 was cracked and fuel injector 4 was clogged. He did a fuel injector service and replaced coilpack 3, charged a few hundred dollars and she was good to go. I got rid of her 5 days later. Death by a thousand paper cuts is still death.

8R 8S

Thanks for the replies everyone. I now see the overfill/overflow tube for the coolant leads directly to the wheel well. I'm wondering if I didn't drain some coolant into that overflow tube, which dripped down to what I'm pretty sure now is the transmission casing. I can't imagine the casing I'm looking at retains fluid when there is clearly two factory holes next to what I thought was a puncture. I will be re-investigating today with some daylight available.

I'm not sure if the previous owner ever changed the T's or coolant piping, but will examine it today.

It is about 35F today so there is quite a bit of water dripping off the undercarriage but there is no definite puddle of coolant, and the reservoir is around the MAX line I filled it to yesterday. (I added about 3/4 gallon of distilled water to get it to the MAX line.) I think I read on another post the Cayenne holds about 6 gallons of coolant, although I'm not sure if it was the same year/model.

I will let it run for a while and see if the problem shows itself. Thanks again to everyone that has replied, it is definitely much appreciated in an emotional time!

8R 8S

So I got it started, left it run for maybe 20-30 mins. I couldn't physically see the back of the motor coolant T, but was able to stick my phone down and get a picture. It is plastic, but there's really no evidence of it leaking at that point. There is a noticeable amount of buildup around the water pump and where the coolant block mounts to the motor, but there is no leak big enough that it is dripping constantly or spraying out.

Plastic T (No evidence of leaking)

Coolant Block Buildup

Water Pump Buildup

Additional Water Pump Buildup


What is the consensus on adding stop-leak / do you have any recommendations on additives? I am somewhat convinced that the coolant has been teetering on the Minimum Line for a while and it finally threw the code. The coolant has to be coming out somewhere however small the leak might be.

I am hopeful that the coolant leak is not as bad as I had anticipated.

Thanks again to everyone and hope you're all having a Happy Holiday.

Ericson38

No stop leak, that will wreak havoc with today's cars. Good for an old tractor, or a 1963 Falcon with the inline 6. You have a nice car, don't be the only one in the US driving around with stop leak in it. We just had the HPFP go out on our 2010 Cayenne base with 130K miles. Code reader told me fuel pump, and dealer confirmed once in their shop. Flatbeded 100 miles to Richmond Va. Got a 2019 Cayenne loaner.

2010 Cayenne Base
2006 Carrera Base C4 Cab, manual trans

TRINITONY

P1026 is HPFP, at least in my case.

Wisconsin Joe

The coolant pipe issue is for the 955s.

The pipes under the intake on the 957 are not a problem.
There IS a junction near the back of the motor that has a fitting that is known to leak. I believe it's called the 'coolant manifold', but could be wrong on that. I think it's mentioned in the 'thinking about buying' sticky.

It's not a new car. It's 10 years old.
Stuff wears out, stuff breaks.
Stuff will continue to break.

Overall, it's usually cheaper to keep & fix it than get another one.

ScootCherHienie

957s still have some issues with coolant pipes, though its not as bad as 955s. Vacuum pipes are trouble at 8-10 years or so too. The thermostat housing, rather than being a single cast metal part that would never fail and would cost $25 or so even after Porsche's 5x markup, is multi-hundreds of dollars and is equipped with glue that fails to hold the 2 metal pipes in the composite housing after 8-10 years or so. That leads to the pipes being able to spin in the housing where leaks start. There is nothing special about German engineering any more. Every friken automotive engineer trainee I ever ran into in 5 years (while I was one too) knew you had to key a glued pipe so it cannot rotate in the hole because glues don't have enough shear strength at 200+ degree working temperatures to hold un-keyed pipes in position reliably. That was 50 years ago! Of course, I suppose if all the parts were as reliable as they could be, there would be no reason for the precipitous depreciation that allows us to enjoy these beasts... when they are running right.

deilenberger

The "hole" in your first photo looks like the bell-housing (where the torque converter for the transmission lives) weep hole. It's there to let fluids that get into the bell-housing out so the thing doesn't fill up. What I see looks more like engine oil.. of course it could be engine oil and coolant mixed together.

The photos upfront - there appears to be oil leaking going on behind the crankshaft pulley. To really track this leak down - the entire area should be cleaned and then observed after something like 100 miles or so - and see where the fresh oil appears to be coming from.

In all cases - some cleaning up of the engine will make diagnosis a lot easier.

Pillow

This! Clean it and then see where the fresh leak is coming from.

NBsharky

so did you ever track down the cause / solution? especially to what looks to be a bad oil leak?

ElSpoon958

I know I'm commenting on an ancient thread, but I too am curious about a hole/crack that "doesn't look like it belongs there" (hilariously well put!). But I'm not leaking anything that I can tell, and my weird spot isn't on the engine, although it looks strikingly similar to the OPs. Mine is further back, on/near the transmission housing. Kinda weird both our strange looking "holes" look similiar but are in different areas. FWIW, I am also currently tracking down an intermittent strange coolant issue. Sometimes I'll get that Check Coolant Level / Coolant Level Low warning, and when I check the reservoir it's usually fine. It does seem to go down slightly, but I never see any leaks on the ground nor do I smell the unmistakable burning coolant scent. I think I've isolated it down to a bad thermostat or sensor of some sort. Coupled with the fact that my temp gauge will sometimes be sitting pretty in the middle, then the needle will jump up and peg itself at the highest possible point for a few seconds and freak out and then settle right back down to the normal, middle position.

Anyways, mostly just commenting because I thought it was interesting we have a similar looking hole albeit in different areas: