SilverSteel

She has a sexy belly!

SCREEN GRAB.

3-Pedals

Dealer wants $1800 to change the spark plugs of our V8 in GTS. Any DIY instructions that anyone can provide? Why is it so expensive considering the engine bay is massive?

911dude41

Porsche tax

3-Pedals

I know. Thats why I change my own plugs in my GT3RS. But I am not familiar with the V8 in GTS.

chassis

If you change the plugs in the 911 then you can do the Cayenne. I have a V6 but the engine bay layout is the same in principle. The engines are from the same period/architecture and the elements are nearly the same, the V8 just consumes more space in the engine bay.

Air filter housing needs to come off, easy.

Trickier bits:
- dog bone torque strut on pass side needs to come off

- chassis cross brace probably needs to come off for V8, this is not needed for V6. Not 100% sure about this for V8.

- V8 has two oil-vapor separators which means the pass side PCV hose might need to come off on V8. Driver side PCV hose needs to come off for V6 and V8, easy squeeze-to-release tube connector.

- coil electrical connectors are easy to release.

- wiring harness cable duct is secured to the cam cover by a rubber ball/socket connector. It is stubborn to remove and requires some force. Prying tools to get under the plastic duct will help. Apply a dab of dielectric grease on the plastic ball stud when reassembling to help with removal next time.

- after all of the above is done, pulling coils and removing spark plugs is easy.

3-Pedals

Thank you. I used to have a V6 Macan S with the same engine as Cayenne S and the engine oil change on that car would take 30-35 minutes vs 2-3 hours in my GTS. I know, in principal its 2 more cylinders but in practice its a pain in the *** to change oil. The most work in oil change I have ever done in any car. Not saying you are wrong, it could be identical process to V6 cayenne but perhaps similar to oil change, its a bit more involved.

I think in my car, the engine filter stuff needs to come off too, the front brace, so basically identical to oil change. The part I am not sure is if the injector rails have to come off or not. I remember vaguely here someone who did plugs in a turbo saying the injectors were very hard to remove. Maybe thats why it costs as much.

chassis

Injector rails? You mean the gasoline pipes need to be removed for spark plug change? Are you sure?

SilverSteel

I spent some time under the hood this morning, removing the air cleaner etc to expose the area, and there are some definitive differences in the layout of the electrical compared to the 6 cylinder, and they pose some real challenges.

1. They've tied cables via zip-lock to the plastic ECU cable case-no problem, cut them and release the runner for what appears to be a couple of sensors, easy to replace later....
2. Unlatching the plastic housing for the ECU only exposes the cables, it does not release them like it does in the video on the Audi, and...
3. There are four retaining nuts on the driver's side, you can access three with a 7mm wrench, but the fourth remains tucked under what I'll call the mother ECU cable which is partially housed in the plastic housing...
4. Gaining access to the fourth bolt is nearly impossible without undoing all of the sensors, what appear to be injector electrical lines, and releasing the wires that are thermally taped to protect them from the heat...
5. In a two minute run to move the my cayenne from vertical to horizontal in my four car garage, I was shocked how hot the turbo exhaust side became in that short time, it would burn me if I touched it with an arm or hand, so don't warm up your car.
6. Yes, I tried to determine if I could in fact gain access to the spark plug tops without releasing and undoing the cables, and the answer is an absolute "no". You can't even see the closest to the steering wheel plug, let alone gain access to the nut that retains the plastic housing and pins the ECU cable. See photo.

In my opinion, at this point, is that to gain access to all of the plugs, that mother ECU cable and its various tentacles must be released at each cylinder by unplugging, undoing the nut(s), removing thermal tape, removing sensor plugs, and finding a way to release the last nut (closest to the steering wheel) without removing the cables to the ECU itself.

The problem with removing the plugs to the ECU are many, but more importantly, they are incredibly well packaged to stay in place and run under the ECU itself, not plug in the front like you would hope, oh no, that'd be too easy. I need a schematic of the engine exploded to understand the connecting points.

SilverSteel

Front brace does not have to come off in this instance, but literally every sensor, zip tie, retaining nut, plastic housing and thermal taping must be removed to access at least three of the plugs on the driver's side. The plastic housing is literally not only bolted to the engine, but pinned with numerous sensors and injector wires to where there is zero tolerance in there. Looking at the passenger side, it actually looks easier since the only mitigating point is the engine stabilizer when you can break down to nothing with four bolts and nuts thereby totally eliminating that obstacle. The driver's side poses special challenges as that's where all the cables run to the ECU, and they take special care to be sure they do not get anywhere near the engine by adding thermal foam, tape and heat resistant plastic. A lot of thought went into the risk the heat poses.

I watched videos of the 6 cylinder and the previous model 8 cylinder, and they are not the same beast, hence the reason no one has posted it yet, I imagine.

matthewr87

Wow what a PITA. Spark plug change interval is 30,000 miles for the V8?

SilverSteel

Yes it is.

SilverSteel

The challenge is not changing the plugs, it's getting to them. My cat can change spark plugs, but for gosh sake's, it's as if they built the engine to where it can't be serviced by anyone other than those who have the "book" with instructions and schematic. Crazy. I'll keep looking into it...

chassis

You shouldn't have to release the small plastic latches circled in red. When you remove the front nuts, the nut from hell should be more accessible after PCV hoses are removed. I would release the DME from its bracket to gain more wiggle-ability. When the nuts are removed, the entire harness run will come off and the small plastic latches will come along with the plastic cable duct.

Looks like the V8 does not have the plastic and rubber ball and socket retainer to hold the cable duct to the cam cover.

I don't see that the fuel injector plumbing (gasoline pipes) need to be disturbed, do you?

LDT

Same for the V6.........30k miles

SilverSteel

No plastic ball, I wish.

Don't need to move what may be a fuel line.

I circled the latches on the plastic housing as I did unlatch them, but it really didn't matter, as there are so many thermally taped wires running off of it that if you do not cut them the housing will be locked in place anyway, like an "arm bar".

Agree, "IF" I can get to the last bolt near the steering wheel, there "may" be enough room to wiggle to get to the plug wire, but even if you can, unless there is a lot of wiggle room when you remove the bolt that holds the plug wire in place, you are screwed. That area is so tight, you need significant space to wobble the wire out.

The wires are strung like a guitar in there, I was shocked. You will have to literally unplug everything down there to move it enough. It's as if they use an 8 cylinder engine with 6 cylinder wiring. I've never seen anything like it. I have done work on my Ferrari and other 911's I've owned. This is a new level of confounding.

I can tackle it, I just need to know how to gain slack in that mother ECU wire. Oh, and if you don't remove those four nuts, there ain't nothing going nowhere! This thing is built like a nuclear submarine.