I’ve driven many Toyotas and Volvos for extended mileage without changing an ignition coil, but for some reason my ’04 Porsche Cayenne has a real taste for them. Perhaps it began when the first one failed. I thought it was the driveshaft because the vibration in the car was so extreme. So of course I fixed the driveshaft. That didn’t help Ruby’s drivability.
Eventually the check engine light came on and informed me that cylinder #7 was misfiring. A single coil cost about 80 USD plus shipping, and I found that I could buy a set of eight on Amazon.ca for 260 CDN. A vendor on Vancouver Island sent them along in short order. I replaced the #7 coil and Ruby was whole again.
For well over a year the remaining coils sat in the shop in their package until Ruby started to miss a little. I bought a set of spark plugs and resolved to do a tune up. It turned out that #7 is the easiest coil to change on the whole car.
The other bank of cylinders has less room to work. #2 is the worst because of an engine mount which forms a sort of flying buttress from the right fender to keep the engine from twisting under load. The coil fits inside the H-shaped mount, and the electrical lead must thread through it. A critical ground wire anchors to this cast aluminum device, as well.
After her tune-up, Ruby ran very well. Then came little hesitations when accelerating from 1600 rpm to 2000. These occurred primarily in heavy traffic, so I learned to use the fingertip shifting paddles to drop a gear and use the higher revolutions to get over the rough spot on the engine’s torque band.
The big annoyance about a misfiring coil is that it is maddeningly difficult to tell which one of the eight is the problem, because a coil appears only to misfire after it is hot, and only when accelerating after a slight slowdown, and the check engine light only comes on if there is a 2% or higher interruption in the firing process. The oxygen sensor is much more alert than the CEL, though, and leans out the fuel rail on that side of the engine almost instantly to protect itself from an overly-rich mixture. So a single miss creates an engine firing on only four cylinders.
Last April the problem had gradually grown worse until I had trained myself to downshift in anticipation of the misses. Then finally, blessedly, the CEL came on in city traffic. I pulled into a service station parking lot, clapped on the tester, determined that the code was P0302, and scooted home to fix it. Two hours later, Ruby was fine.
Then the miss returned. I pleaded for advice online, but received only a blanket condemnation of Asian aftermarket coils from the moderator.
But then came one of those family emergencies where schedules required that I tow a borrowed covered trailer loaded with a sofa twenty miles down the highway. The increased wind resistance was all it took to cause Ruby’s CEL to pop another Code P0302. That was the newest coil in the car, the one I had “just” replaced. Once I had the information, the repair was simple and Ruby’s drivability was restored.
A Cayenne S is a marvellous car to drive when firing properly.
My take-away from Ruby’s coil troubles so far?
1. Buy the best coils, whether or not you can afford them. This is no place for cost-cutting.
2. When in doubt, replace the coil you put in most recently.
3. Check the tightness of the spark plug when the coil is out. Six months ago the plug had worked itself loose even though I had carefully torqued it. This time it was fine.
UPDATE: 18 October, 2018
4. Another coil failed spectacularly today and I just managed to limp home for repairs. It was #7 and it smelled like a burned computer component when I took it out. See #1 above. I called the Porsche dealer and ordered 8 new OEM coils. $611. with tax and cheap at the price.
UPDATE: See the sequel to this rant at
Ruby’s ignition coils.
The ongoing quest for Ruby’s oil
September 23, 2018
Ruby, our 2004 Porsche Cayenne S, requires fairly frequent oil changes to protect her cylinder walls from ring-scraping. Her previous owner didn’t go over 5,000 km between oil changes, but he drove very limited amounts in downtown Vancouver traffic. I drive on the highway almost exclusively, so a 10,000 km interval seems more reasonable. The only time Ruby has used oil was the time I forgot a washer and didn’t torque one of the two drain plugs to the full 37 foot-pounds. That spilled a litre over 8,000 km.
UPDATE: February, 2019
I did it again, skimped on the crushable washers. I knew when I checked it that it was going to leak, but with 9 litres of oil above the plug, what are you gonna do? So I forgot about it until the computer gave me a stern warning a couple of weeks ago. I added a bit over a litre again, and all was well with the computer.
But the regular oil change requires nine litres of 0W40 Mobil 1 European Auto Formula. It says so in the engine compartment as well as in the manual. That’s two jugs of oil, normally priced at a bit over $50.00 each: double the cost of a normal oil change, just for the oil.
Canadian Tire fortunately has put that particular oil on sale on a regular basis, and my son, Tony and I have been stockpiling it to meet the needs of our various Porsches.
Last Thursday Tony sent a message that CTC had the oil on special again. Then he tried in Smiths Falls and reported that it was no longer offered. I checked the Internet. Nobody seemed to have it except the Division Street store in Kingston. I called and attempted to order six jugs and pay online. Yes, they have 22 jugs of product #028-9441-2, but I have to have a Canadian Tire card in order to buy it online. My moans had no positive effect, so I resolved to drive to the store at first opportunity and make the purchase in the good old-fashioned way, with my bank card.
Sunday morning at 9:00 I was one of the three or four eager souls admitted through the auto parts door. On the oil wall I found three jugs of euro blend, but they were 4.7 litres rather than 4.4, and the price was a bit north of $51.00. The clerk at the auto desk spoke politely to me and then made me wait fifteen minutes while she answered a series of telephone calls. Then she assured me that her store has only three jugs of euro blend and its price is $51.xx, but the Cataraqui store has 22. She implied that I must be mistaken, and she wrote down the number of the auto parts department at the other store.
A friendly guy answered, listened carefully, then put me on hold while he ran out to check his oil wall. He did not return. Fifteen minutes later I ended the call to save on cell expenses, if nothing else.
On my retreat from the Division Street store a sympathetic clerk asked me if she could help. Then she directed me to the customer service desk where the woman in charge gave me access to the Internet. I promptly located the ad, gave her the product number, which enabled her to call Penny and send her to the warehouse for the six jugs of oil.
The unrepentant Penny brought them out and I made sure that the correct price went through at the check-out. I left the store at 10:00 a.m.
What could have been a wild goose chase had been saved by a couple of alert staff at the Division Street CTC. The lesson from this: Don’t try to buy anything on sale at CTC if you don’t have at hand the product number in the ad. Store computers don’t have access to the online ads, and you’ll look like a fool to the Penny’s who also work there.
Cayenne S tows into the wind
May 5, 2018
It was a hell of a wind yesterday evening, but Charlie had to get to Canadian Tire Motorsport Park just east of Toronto to play with his BMW and work as a Porsche Club of Canada instructor for the weekend, so he set off at 6:00 from the farm towing the 20 X 8.5 enclosed trailer loaded with his car and equipment. I checked with him at 9:50. He had just arrived.
The load-levelling hitch evened the suspension out pretty well, but the problem was SW winds were so high they had closed the airports in Toronto, and the Hamilton Skyway Bridge shut down as well because of wind gusts over 75 mph. Headwinds were a minimum of 30 miles per hour, with gusts passing 50 mph.
The 2004 Cayenne S pulled the bulky trailer through it well, according to Charlie. I asked him about the fuel consumption.
28.5 L/100 km. Normal is in the low 12’s for mixed driving. That was a serious pull over a relatively flat road. He did say it was very windy.
UPDATE: 6 May, 2018
This evening Charlie told me that when towing the trailer into in that 60 mph headwind, there was no change in engine effort when going down hills. I insisted that he check the engine oil. No change in oil level from before the vigorous exercise.
Senior moment
April 25, 2018
In the Costco parking lot this afternoon I found myself tightening the left front lug nuts on my Porsche Cayenne. Of course today had been the day I decided to put the summer tires on, so I had Ruby up on the hoist and the wheels switched before 9:00 a.m. Seems the studs were rustier than they looked, and I forgot the torque-wrench stage.
It was fortunate that I had had to back out of a trick parking space at the Rose and Crown (fish and chips to die for) and the studs alerted me to their looseness after the prolonged full-lock maneuver. What astonished me was how many turns it took to make the four loose studs tight again. One was still intact. The studs must have been working themselves loose while I was driving down the 401 at high speed. And there was no warning until I cranked the steering enough to allow the wheel to rattle a bit, fifty miles into the trip.
Initially it sounded like a rear brake spring loose, but over a mile of driving it became steadier and louder. I parked, loosed Bet into the store, and set about with the on-board tool kit.
The tire wrench works, and I couldn’t bend it with the limited brute force I could generate. Later the torque wrench set at 105 foot pounds only tightened one stud any more before clicking. But on the left front, four of those studs had required many turns with the emergency wrench.
Crisis ended, I headed for the lunch bar and a dish of chocolate ice cream. Then came my only inspired moment of the day. My wife habitually vanishes into Costco and I can’t find her until she is ready to come out. Instead, this time I texted: “Chocolate ice cream in dish with two spoons, at the tables.” Very soon thereafter Bet showed up, took a spoon, and helped herself to the bait. She knew I would eat it all, so she had temporarily abandoned her cart to protect my blood sugar. Kind, self-sacrificing woman.
Even kinder, she did not rail upon me for forgetting to tighten the lug nuts, and even offered not to tell Charlie. Oh well, if he reads this he’ll know, and resume clandestinely torquing the wheels on his Dad’s cars.
Do you have any idea how much that hose costs?
April 14, 2018
The sole casualty of my bumbling exploration of the area under Ruby’s manifold was the following little crankcase vent hose. Pelican Parts offers it for $183. USD, plus shipping, exchange, taxes and fees. All for a little crack.
The trouble was that there was no space for clamps.
One contributor suggested gluing a copper junction piece in, but one end needed a regular piece of copper pipe, so I modified it a bit, then cut the end off at an angle to accommodate a slight bend in the hose. The moderator of Rennlist.com warned me in no uncertain terms not to use any product with silicone in it or it would kill the O2 sensors on the engine.
JB Weld is apparently as good as its reputation. A mixture of limestone, steel filings, and epoxy, it works well in engines.
After a couple of hours to set, the repaired hose slid neatly into position. I left it for a day to finish its cure in a warm shop; then it worked fine.
Changing Ruby’s spark plugs, etc.
April 14, 2018
It seemed like an easy job now that I had the beauty covers off the engine, so I bought a set of the correct Bosch spark plugs and had at it. I even laid in a new 5/8″ spark plug socket with the rubber insert to help me pull the loosened plugs out of the long tubes which guide them down into the engine.
Yeah, right. The first plug wouldn’t stay on the wrench, so I recovered it with a magnet on the end of a cable/coil arrangement which allowed me to open a grappler down the tube and grab the loosened spark plug. When I installed the fresh plug, the rubber sleeve from the expensive spark plug socket stayed on it, now torqued into the cylinder head. There was nothing to do but remove plug and all, and from then on use the grappler for the handling of loose spark plugs.
My phone provided essential information: torque the plugs to 22 foot pounds.
As I removed the old ones, most looked to be in excellent condition, but #5 and #6 showed some carbon on them. It was time to do this job. #5, for reference, is the spark plug closest to the driver’s side headlight on a left-hand-drive model.
5 through 8 are very easy to change. 1 through 4 are more of a challenge.
After one removes the beauty panels which surround the engine on a Cayenne, the coils and spark plugs are covered by a pair of decorative plastic fingered things which clip and screw on. They significantly reduce injector noise and protect the wiring harness, so they are not just a frill. The only problem is that on the right side, one of the fingers slides through a complex engine mount, and another doesn’t have quite enough room to slide out from under an air pump at the rear of the engine. First use a 30 torx screwdriver to remove the screws holding the fingers down. You’ll need a tiny ratchet and the equivalent bit for a couple of tight spots, but this shouldn’t be difficult.
Needless to say, if you don’t have access to a set of triple-square male sockets, you can’t go any further. There’s this arm which reaches from the right fender well to the side of the engine. A bolt can be readily removed with a 16 mm socket at the head and a 12mm triple square thing on the other end. Then the fender connection can loosen with the same 16 mm socket and allow the torsion arm to fold out of the way. This becomes a routine operation if one is to spend any time under a Cayenne’s hood, but it’s a non-starter if one has misplaced the triple-square male socket set.
The air pump hanging over the back of the engine, one of two, is easily moved out of the way. Just remove three screws (torx #30) and let it flop loose. It’s not fragile. Unfortunately there is an aluminum frame which holds it. It has a machine screw down into the cylinder head, some sort of strange hex bolt, but an 8mm socket will work on it. Loosen that until the air pump mount can wiggle enough to let the finger out from underneath without shattering. Remember that Porsche plastics do not age well and are prone to failure when stressed. I found over several repetitions that if I removed the oil filler cap it allowed the fingers more room to wiggle without twisting. Stuff a clean rag into the open oil filler, of course.
Once you have removed the finger cover, you’ll discover that the coil for the #2 cylinder can’t come off unless you remove the rest of that engine mount. It is fastened to the right cylinder head with four hex bolts, 10 mm on top, and more of those strange green 8mm things below.
Once these obstructions are out of the way, it’s a simple job to remove the coils and change the plugs on the right side. The coils are freed with a 10 mm socket on a small ratchet to back out the the complex studs which one level up held the screws for the fingers. Once they are out of the way (Don’t lose any!) I found that the upholstery tool, a broad, angled screwdriver with a notch in the centre which comes with most screwdriver sets, is the ideal device to persuade well-established ignition coils out of their dens.
*Triple square is like a 12-point Allen wrench.
Once the plugs are in and torqued, it becomes a matter of re-installing the ignition coils. All of the old ones I had removed had 2″ vertical splits in the side that goes down the tube, but they worked well. I had new ones to install, so I cheerfully clipped them in, fastened everything back together, and fired Ruby up.
Ruby’s ignition missed quite badly, so I put the OBD II meter on. P0308, 301, 302. Ulp! Much fussing led to the conclusion that half of my brand new Chinese coils did not function. This led to an interesting afternoon of chase-the-ignition fault until at long last I had it nailed down to just P0308. With a prayer I replaced the new imported coil with the original, cracked coil which had come out of cylinder 8. Ruby fired up and purred.
I can’t emphasize enough how desperate a misfiring Cayenne V8 appears. My son says it has to do with the O2 sensors. If one detects a richer mixture because of a misfire, it leans out the entire bank of cylinders. So tic-tack-toe with old ignition coils and potentially defective new ones is a real challenge. But once it runs, it runs beautifully. It’s more like computer programming than auto mechanics.
Then it’s just a matter of putting everything back together and testing the car on the road. In my case this step occurred a few times before success. After enough repetitions the engine mount and air pump routines become familiar and strangely comforting.
And that’s how you change the spark plugs on a 2004 Cayenne S.
With the new plugs Ruby averages 12.1 litres per 100 km. That translates to a fuel consumption rate of 23.35 miles per Imperial gallon on 91 octane. That’s about what my Volvo 240’s used to do on regular.
UPDATE: 17 October, 2018. After changing the #2 coil again last week, I re-read this blog entry. Ruby in summer driving averages more like 11.8 litres per 100 km. This could be the effect of summer gas. The new coils sent under warranty were no better than the old coils. They likely came out of the same parts bin. I think it is time to go to the dealer and open my cheque book for a set of new, OEM coils, but still I hesitate.
UPDATE: 2 May, 2018. I notified the Amazon vendor that only half of the coils in the batch actually worked. He sent me another box of eight new coils in short order, so I get to try again.
UPDATE: 3 May, 2018. The vendor sent me eight new coils from another batch. They went in and perform flawlessly. I have become rather proud of my Porsche Cayenne tune-up skills as a result of all of the practice.
UPDATE: Mid-summer, 2018. After a month of intermittent and sporadic missing sessions, particularly while accelerating after braking on the highway, #2 began missing so badly that it popped a code and I was able to identify the culprit. It was quite reassuring to have the CEL reader in the glove box because Ruby acted as if she was dying. We limped home fifty miles and I had at the engine mount coil again. Surprisingly, the spark plug was loose beneath the coil, as well. I had torqued it to 22 lb. not long before. Could the intermittent misses loosen a plug? I labelled the defective month-old Chinese plug carefully and switched in a new one from the set replaced under warranty by the Amazon vendor.
Ruby is once again a pleasure to drive, though I suspect another coil failure is in the offing. It could be my imagination, though, as symptoms are mild.
UPDATE: October 12, 2018. Coil #2 failed again. I got to take everything apart again.
UPDATE: October 18, 2018 Coil #7 failed in a spectacular manner today with the smell of burnt electronics permeating the shop when I removed it. Enough is enough. I ordered a set of Porsche ignition coils from the dealer.
A final word on Porsche coolant pipes
April 3, 2018
After some correspondence with a contributor on Rennlist.com, I decide to satisfy myself that I can tell if a Cayenne has had its coolant plastic coolant pipes replaced with the aluminum upgrade by looking from outside. I take the scope and snake its camera into the back of Ruby’s engine compartment with only a vague idea of what evidence I am looking for, but convinced of the outcome because we have already lifted the manifold and looked at the array of aluminum below.
Eventually I tell myself I see a satisfying flash of aluminum casting just below the elaborate black plastic casting of the intake manifold. The next step is to take this methodology into the engine bay of my son Charlie’s nearly identical car to determine if it has also had the upgrade.
This proves daunting. There is an aluminum casting in the correct location, but things generally look different. After much fussing Charlie and I conclude that on Ruby the tech left out a black plastic component which sits above the pipes running toward the back of the engine. Anyway, the upshot of it is that the gray Cayenne has also had the coolant pipe upgrade, we think.
I find it hard to believe that my surgeon can replace heart valves with a variation on this scope. My hat is off to him. I can hardly find the back end of an engine with mine.
BTW: I have an unused coolant-pipes-kit in the shop with shipping and Canadian sales tax already paid, if anyone in Eastern Ontario would like to take it off my hands at a bargain price.
Coolant pipes diary: Day 2
April 1, 2018
NOTE: The passenger side is right, the driver’s side is left for the purposes of this article.
8:00 a.m. Restless and anxious to get at the project, but must wait for son to arrive. Make work. Build fire in auto shop. Brush the dog. Clean car mats.
Enough of this. I want to wrench. I decide to pull a spark plug to see their condition. The easiest access is the second cylinder from the front on the left. The coil has a 3″ split in the plastic tube, so I pick a new one out of the box and install it, but of course I can’t test it yet.
12:00 p.m. Charlie, Roz and Ada arrive.
1:00 p.m. We start in on Ruby. Charlie scopes and photographs, and we eventually agree there’s little point of further disassembly.
Charlie spends an hour trying to get the rear right screw into the fuel rail.
2:10 p.m. We partially remove the manifold to allow the installation of that damned screw. Now I understand why techs leave the fuel rails on the manifold, and remove the whole unit. The right rear screw is otherwise impossible.
Things go back together well. Charlie understands the strange packages with air running through them on the top of the engine. I content myself with putting on covers and clipping on injectors. Back go the fuel pump fuses, and Ruby fires up. There’s a slight miss which we decide to deal with after Easter Dinner.
4:45 p.m. The OBD reader shows P0202. That means the injector on cylinder 2 is misfiring. That’s the second one from the front. I quickly tear in to the coil I had replaced this morning, second from the front. No amount of abuse of the coil and the injector on what turns out to be cylinder #6 helps the problem.
Eventually I call up a diagram, realize I have been working on the wrong side of the car, take off the right air pump, loosen the air pump holder, remove the motor mount shaft and the notoriously fragile beauty cover which fingers in among these obstructions, only to discover an injector wiring connector which is loose under the fuel rail and an awkward clump of wiring. Ten minutes later it clicks into place. Ruby fires up smooth and powerful. I put the car back together, vowing to post a diagram of Ruby’s engine on the shop wall so I will always know where cylinder #2 is.
6:00 p.m. All better. Test drive is a quick, one mile sprint, and home.
Coolant pipes diary: Day 1
March 31, 2018
8:00 a.m. Fired up Ruby for what may be her last drive for a while. It might as well be an enjoyable road, the trail to Landsdowne, the International Bridge, and Wellesley Island in the middle of the St. Lawrence River where the local Kinek parcel depot flourishes in the back of the Wellesley Island Building Supply.
8:35 a.m. U.S. customs agent took my passport and asked: “Where are you headed today, Wellesley Building Supply or Watertown? You don’t look as though you’re going far.” He was right. I was back through Canadian Customs inside 15 minutes.
8:40 a.m. The parcel with the aluminum coolant pies kit was in, as promised. It felt so light that I opened the box on the spot to make sure it wasn’t empty. All there: aluminum is light, I guess.
10:30 a.m. Home. Removed Ruby’s engine beauty panels and a motor mount. At that point I ran out of the things I’d had practise at doing. Then I realized I wasn’t sure about how to disable the fuel pumps. Read for a while, becoming more confused by the manual.
1:00 p.m. Decided upon the two-fuse method explained by Harkness on RennTech.org. Pulled 13 and 14 and Ruby (Harkness identifies 14 and 15 as the pump fuses but his is a newer model) obligingly refused to start. Released a small bit of fuel from the end of the fuel rails.
Removed the spark plug covers. Then the air handling stuff at the front of the engine. The car is well built, though Porsche plastics are a chore.
3:00 p.m. So far, so good. Ruby’s apart. I’m stuck at the removal of the fuel rail. Don’t know how injectors detach or come out. Must read. Going pretty well. One screw lost from rear right fuel rail. As predicted by Harkness. Apparently those screws are never seen again. I also broke the predicted pvc hose made of desicated fortune cookie dough, also predicted by Harkness. Electrical tape works well on it. The rest is pretty sensible, so far.
4:00 p.m. Back at it after sandwich. Decided to fasten rails back onto the manifold. Lost a second screw in a careless attempt at left rear corner.
Backed out the manifold screws without difficulty. Compared to changing 7 A/C servos from the floor in front of the driver’s seat, this stuff is a cinch!
4:45 p.m. Shifted the manifold forward and up. Peeked underneath… Nothing but gleaming ALUMINUM under there! Hooked up the scope, probed carefully below. Starter and solenoid connections show no evidence of corrosion. A small amount of grass seems to have blown in recently as if it has had one summer only in a leafy area. No evidence of nests and the gleaming aluminum coolant pipes suggest Ruby has had a pampered life in garages in downtown Vancouver before taking over Charlie’s shop at the farm.
5:00. Notify family and associates of bathetic end to the coolant pipes project. General bemusement.
Shall enlist son Charlie on the cleaning and re-assembly. A few years ago he spent a winter’s weekends resealing a 968 engine, and he did a great job on it. He’ll definitely want to have input tomorrow, as the engine in his ’04 Cayenne S is next in line, and the parts are already in stock.
Fuel octane ratings
February 25, 2018
My Porsche Cayenne S has a label on its fuel filler door which sternly warns that this engine requires 98 RON fuel. I have felt guilty giving Ruby 91 octane, but it’s the hottest gasoline I can find in my area.
Then this week on the outskirts of Kingston I saw 94 octane as a choice on my pump. $1.459 per litre was quite a premium over 1.139 for regular and about 1.269 for premium. Nonetheless I decided to try a tank of super-premium and rake in the performance and fuel mileage benefits.
At low speeds Ruby accelerates a bit more strongly with the hotter fuel, and I notice the gear changes aren’t quite as smooth, as if the engine produces more torque. I didn’t notice any difference in performance at highway speeds, though. The Cayenne is pretty strong in the passing lane with its usual premium fuel, in any case.
The surprise was Ruby seems to use a bit more fuel than with 91. I’ll update this when I have more data, but my impression is that fuel consumption is up 1 to 2%.
Wikipedia informed me that the German RON 98 is the equivalent of the North American AKI 91-92, so I wasn’t actually starving Ruby. With the hefty cost increase for super-premium, I can’t see the point of the richer fuel in a Porsche V8.
Tom Stutzman sent along this link:
UPDATE: 1 March, 2018
After a couple of drives on two laner’s in light traffic, I have decided that Ruby’s sparkling performance in the passing lane is rather good. Next fill-up if 94 is available I may try another tank, just to be sure it’s a waste of money.
UPDATE: 7 December, 2018
In my reading about O2 sensor failure, I ran across a couple of Cayenne S owners, one in BC and one in Ontario, who tied their O2 sensor failures to American high test gasoline. They suspected the ethanol in U.S. 91 octane. I was not aware that only in Canada do they keep 91 ethanol-free.
the Walnut Diary 