Vivaldi

Hello,

I am new to this forum and I am also the owner of a 6 month old Cayenne Diesel with 21,000 miles. The vehicle ran flawlessly until 4 days ago when I attempted to start the engine one morning while the ambient temperture was 38 degrees Farenheit. The yellow Diesel Preheater Indicator Light began flashing and did not turn off. I began driving the vehicle because I was thinking it would soon turn off, but then I noted poor acceleration and a slight jerking feeling as though the engine was not getting fuel. So I turned off the vehicle and let it sit a few minutes. When I restarted it, the yellow Diesel Pheheater Indicator Light was OFF, but now the yellow Check Engine Light was ON continuously.

The local dealership told me that for whatever reason, the diesel fuel had temporarily "gelled up" in the fuel line due to cold weather and they asked me if I had used any off brand diesel fuel. I told them I have only used Chevron and Shell diesel fuel. I was also told by my dealership this has happened with other Cayenne Diesel vehicles around the country, according to Porsche, USA. My vehicle is still with the dealer, and I am thinking they are still scratching their heads about what happened. The vehicle ran perfectly as I drove it to the dealership, but the yellow Check Engine Light was still on continuously. The vehicle is supposedly running fine now but I have not yet gotten it back from the dealership.

Interestingly, we have recently had colder mornings where the ambient temperature has been in the low 20's Farenheit and the vehicle has started without any problems. Another interesting fact is that my vehicle had it's 20,000 mile servicing only 3 days prior to this problem, and I wonder if that had something to do with it. Perhaps some type of flushing procedure or something else of the sort?

So, has anyone else with a Cayenne Diesel heard about this problem? Any suggestions on how to prevent this from happening? Fuel additives? Any comments or suggestions would be greatly appreciated.

grohgreg

That's a loada crap, I've never seen diesel fuel gel until the temps got below 0F/-18C. Lower if you put in your own anti-gel additive. Sounds to me as if they didn't even read the fault codes. In my experience with the 958 diesel, the GP icon simply indicates that a minor fault code has just been recorded. They're usually self-clearing. The check engine icon indicates a more serious fault code has just been thrown, and it often has to be cleared via the OBD2 port. But in both cases, they're still in the fault code recent event history. The dealer should have been able to see EXACTLY what triggered each icon.

Regarding fuel additives, I use Power Service; silver jug spring/summer/fall, white jug winter. At normal strength, it's an fuel path cleaner - with emphasis on injector tips. At double strength it's a cetane booster; the higher the cetane rating, the more complete the burn. On our crappy US diesel fuel, that translates into more mpg. When I purchase fuel with a cetane rating of less than 46, I add 12oz of the silver jug to the tank. that supposedly bumps the cetane rating up five points. The white jug contains the anti-jell additive. 6 oz per tank is enough to minimize jelling, but I use 12 to get the cetane boost at the same time.

//greg//

abatis

Sounds like something is not right. On the diesel side just recently I had left my CD at the airport at temps of -12F. It was -12F when I started the vehicle and it started right up. Just Centex diesel with no additive. However after reading Greg's recommendation I have added Power Service to be safe.

Vivaldi

Thanks Grohgreg amd abatis for your feedback. The dealership service department infofrmed me the fault code was P008700 which means "Hi fuel; pressure too low". The service representative was not exactly sure of the meaning of this code, but he told me they replaced the fuel filter and all seems to be running ok now. However, I should note that all seemed to also be running ok when I brought it to the service department, except that the yellow Check Engine Light was continuously on after the episode. I will pick up the vehicle this afternoon. I think the service department folks are still scratching their head on what happened. Any similar experiences or thoughts from people on this forum would be greatly appreciated.

gnat

Part of the 20k service should have been for them to replace the fuel filter. Could be they did something wrong there or there was something wrong with the filter.

pclewis

I concur, sounds like a fuel filter issue, or possibly water in the fuel. Run the tank down and refill somewhere else.

Slow Guy

You need to replace the fuel filter at 20k on these things?

gnat

On the diesels, yes. That is probably on the aggressive side just like I expect draining the water at 10k is aggressive for most people, but as long as its under warranty I'll go by Porsche's guidelines.

Needsdecaf

What was your fuel gauge at the time? There is a recall for running out of gas. Happened to me with similar symptoms.

grohgreg

To the best of my knowledge, that's part of the 20k intermediate service. I have no plans to drain the water (which I'm confident won't be there in meaningful quantity anyway), as it will be done by default during the intermediate service. FWIW, my 2011 John Deere schedule is to change fuel filter at 200 hours, which is the automotive equivalent of 12k miles. So before I leave the Porsche dealer, I will make sure I see a replacement fuel filter on the intermediate service invoice.

//greg//

Vivaldi

To answer the question about my fuel gauge at the time, the tank was 3/4 full.

I picked up the vehicle from the dealer 2 days ago with the tank 1/2 full of the same gas as when the problem occurred, and all seems to be working fine.

This is all still a mystery. But after going back and looking at my recent credit card purchase history, I realized that I filled the tank at a BP Food Mart station the day before the 20 K servicing at the dealership. I normally fill the tank at one particular Chevron station. So perhaps "bad gas" could be the answer. I have never used this BP Food Mart station in the past.

Here is the sequence of events:

12-3-13- Filled tank at BP Food Mart
12-4-13- 20K service at dealership
12-5-13- Drove 60 miles and no problems
12-6-13- Drove 60 miles and no problems
12-7-13- Preheat indicator light and check engine light

According to the dealership invoice, this is what they did:

Fault code P008700 in DME; Create VAL and send; clear fault codes and road test to try and duplicate faults; fault codes will not reproduce; send in p-tech for more assistance; research for more information; found bulletin for diesel fuel jelling in low temperatures; p-tech also confirms this is a likelihood for the low power and CEL codes; 24631999 140
Replaced fuel filter as per service manager

It does seem odd to me the diesel fuel would gel at an ambient temperature of 38 degrees F on the morning of the problem.

Any thoughts?

grohgreg

I have two suspicions. If it never happens again, it is likely related to the 20k service. One of the items is to change the fuel filter. If the lines are not properly purged after the filter canister has been accessed, fuel starvation results if/when that void (air) eventually makes its way to the common rail. Or perhaps when they closed up the filter canister, they didn't ensure an air-tight seal. The brief but rapid loss of fuel pressure instantaneously triggers a P0087. But why they replaced a fuel filter with only 120 miles on it escapes me

If it does happen again, it's possible that either the pressure sensor or an injector is failing. The sensor may be reporting incorrect pressure to the engine control module, or an injector may be randomly extracting more than its "share" of fuel from the rail. Counter-intuitively, a failing injector may be accompanied by higher than expected fuel consumption. But having said that, a failing injector usually throws a code of its own.

So I'm leaning toward human error at the dealership. And at the risk of repeating myself, the "gelled fuel" diagnosis is a loada crap.

//greg//

xc17pilot

I have a 2014 diesel, had rough running this morning after a night of single digits here in PA. After car warmed up it ran fine. Any funnel or other device needed to add the Power Service or can you just pour it into the tank?

Thanks, I'm new to this diesel stuff.

chsu74

Just pour white power service into the tank. It won't hurt if you put too much in. My GL fired right up after sitting for over a month outside this morning at 7 degrees.

grohgreg

I use a funnel so as not to get any Power Service on the paint. Not that it's likely to harm the paint, but it's probably a pretty good wax/polish stripper. Back to the funnel though, you have to get one with a diameter that will be accepted by the safety mechanism that prevents the accidental insertion of a gasoline filler pipe. And make sure you use the appropriate Power Service too. Silver jug is generally for use when there's no threat of fuel gelling. Around here that's March-November. Cold season Power Service comes in the white jug, as it's the blend that contains the anti-gel additive. I've never even purchased the red jug, it's only for use after the fuel has actually gelled up on you.

//greg//