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You shouldn't have any black smoke during WOT. You might have a bit of a fuel cloud from running a much richer AFR, as all cars when the ECU runs in open loop for WOT runs. This is something you might see on another car if you viewed it from the back, but you won't see this out your back window from in the car.
Nearly all PAG and VAG turbo cars have oil in the IC or lines from the breather system. Personally, I have not heard of a situation where someone was burning oil because they had so much of it in there. Not saying it couldn't happen, but with the mileage and condition of this car you just bought, I'd suspect something else.
The list of things that could contribute to this is long. So, you're going to have to do some baseline work on the car, and hopefully that will reveal some issues.
Still haven't actually "bought" it, just put a deposit down and verbally committed to buying. I won't/can't actually take possession until end of the month.
That said, given the smoke out the back, I'm thinking a PPI makes sense. I've done a fair amount of digging around for info on black smoke at WOT and there just isn't much out there, which is double worrisome b/c why isn't anyone else having this issue.
There's some literature on smoke at startup, which seems normal, but this was getting onto the highway after 3-5 minutes of warming up on surface streets.
Nobody can look at the color of the exhaust pipes and ascertain whether you have an oil burning problem.
A PPI is mostly a visual and functional inspection. They're not going to remove parts or do troubleshooting for you. It's a 3 hour job just to get at the spark plugs for a compression test. Tack on another hour or so for a leak down. Figure 8-10 hours of labor to pull the down pipes and inspect the turbos.
It's a high-mileage Cayenne that looks like it may have seen a hard life. I don't know what to tell you that hasn't already been said.
I hear you WP and appreciate your input. I wish this was a no-brainer decision; I've bought higher mileage cars before and going in with eyes wide open helps. The thing is the car doesn't smoke until accelerating at WOT (didn't try cruising at WOT), which makes me think it's less an oil burning issue and more something else, but what do I know...
I'm sort of putting this out here so that if I do end up pulling the trigger on this one, it may be funny to come back and try to see whether I was on or off my rocker this whole time.
Originally Posted by wrinkledpants
Nobody can look at the color of the exhaust pipes and ascertain whether you have an oil burning problem.
A PPI is mostly a visual and functional inspection. They're not going to remove parts or do troubleshooting for you. It's a 3 hour job just to get at the spark plugs for a compression test. Tack on another hour or so for a leak down. Figure 8-10 hours of labor to pull the down pipes and inspect the turbos.
It's a high-mileage Cayenne that looks like it may have seen a hard life. I don't know what to tell you that hasn't already been said.
Anytime you have a block or turbo issue on a turbo powered car, they usually smoke at WOT. Turbos are spinning at full boost, crank case is under pressure, cylinders are at maximum pressure. The only time I see cars smoking at part throttle is if the crank breather system is totally fubar, or the block has serious problems. If you are smoking during lift-off and under vac, this is usually a valve issue.
I've always purchased high-mileage cars. The 911 that's my avatar photo had over 200K miles, and I sold it to a guy in Australia for top dollar because of the condition and history. I had an Audi B5 S4 avant with the notorious 2.7t that had over 200K miles when i was T-boned and the car totaled. Because of the condition, color, and trans combination, I sold it to a guy on the east coast who rebuilt it (it was a rare car). Our old B6 A4 had over 200k. Would have not thought twice about recommending these cars to someone if they had over 200K miles.
The CTT I own now had 99K on it when I initially bought it. We've driven the **** out of it - offroad, towing, long road trips, sleeping in the trunk - you name it. While this motor has proved to be the most reliable motor I've ever had (of the 20K in receipts, only 500 is related to the motor itself), I would never want to take on this car at the mileages you're talking about. There is no way to buy cheap, use your own labor and time, and come out ahead.
GT3, air-cooled, or any other car Porsche makes - I'd rock them all over 200K miles all day. My wife and I live downtown, and we both walk to work. The CTT is now our only car, and chances are good if we buy a 2nd car, it's going to be a Tesla as a city car. I'll continue to own the CTT simply because it's in immaculate shape and well sorted at this point. Even in the air-cooled world, the advice was always "every 911 is a 20K 911; spend it now or spend it later" back when they were pretty cheap. If you wanted a project, you were going to spend more money on it then if you had just bought a nice one. For some people like yourself, they had specific needs or desires so projects made sense. But, you're talking about a stock CTT for your wife. No reason to take on a project.
Purely from a fiscal standpoint, you will spend more and stand to lose more with the way you're going. personally, I think you are off your rocker. You're welcome to search M1 0W40 and how crappy it is. There is no way I'd run that oil more than 5K miles, and you're seeing 10K mile oil change intervals on that car. If you smoke a cylinder or blow a turbo, you're either going to be left with a worthless car, or you'll be on the hook for a repair that's the cost of the car. At that point, your total financial outlay is getting dang close to a med-higher mileage 957 CTT. Or a nice 957 CS.
It looks to me like you really want a CTT, and you're trying justify the rational so this one makes sense to you. We're here to tell you that we think your nuts, and most of us DIY all the maintenance on this car.
I would really think long and hard about this purchase. These are rewarding cars to own, hugely capable, even by today's standards. But, if you buy a POS, you're going to be headed down a road of perpetual headaches with a steady stream of cash leaving your wallet. If you're OK spending the purchase price + 5-7K, I have no idea why in the world you wouldn't buy a lower mileage unit that's in much better condition. I've heard your validation, but honestly, it seems thin to me.
It's your money, man. But I personally think you're taking on a huge liability and it makes no sense to me when you're OK spending 15K between acquisition and repairs. That gets you a clean, turn-key, well sorted CTT.
Awesome, this is immensely helpful. I really wanted to know what was symptomatic of smoke at WOT since I still have a free option on the car and can get whatever PPI work I want/need done.
From the sounds of it, if I pay a guy $400 he'll pull my plugs and do a compression test which should give me an idea of what could be causing my issue. If compression comes back fine, either I'm imagining it or there is an issue with the turbos. From the intel I've gathered here both the case and turbos are relatively bulletproof, but not guaranteed with this mileage. Is that about right? How does one diagnose the Turbos?
I have to say, I like doing my due diligence. Despite that, if I hadn't noticed the smoke, this would have been a no-PPI, let's get this done sort of transaction, it's that clean. Excepting the mileage, this car is as clean and babied as any I've ever seen; former CPO, women driven, dealer serviced, 2-owner clean car with no accidents Even at 1.5-2x the purchase price (obv excepting the smoke), the cars I've been seeing have some sort of hair on them (multiple owners, 120+ miles, indie or DIY mechanics, rough physical shape, or all of the above).
Originally Posted by wrinkledpants
Anytime you have a block or turbo issue on a turbo powered car, they usually smoke at WOT. Turbos are spinning at full boost, crank case is under pressure, cylinders are at maximum pressure. The only time I see cars smoking at part throttle is if the crank breather system is totally fubar, or the block has serious problems. If you are smoking during lift-off and under vac, this is usually a valve issue.
I've always purchased high-mileage cars. The 911 that's my avatar photo had over 200K miles, and I sold it to a guy in Australia for top dollar because of the condition and history. I had an Audi B5 S4 avant with the notorious 2.7t that had over 200K miles when i was T-boned and the car totaled. Because of the condition, color, and trans combination, I sold it to a guy on the east coast who rebuilt it (it was a rare car). Our old B6 A4 had over 200k. Would have not thought twice about recommending these cars to someone if they had over 200K miles.
The CTT I own now had 99K on it when I initially bought it. We've driven the **** out of it - offroad, towing, long road trips, sleeping in the trunk - you name it. While this motor has proved to be the most reliable motor I've ever had (of the 20K in receipts, only 500 is related to the motor itself), I would never want to take on this car at the mileages you're talking about. There is no way to buy cheap, use your own labor and time, and come out ahead.
GT3, air-cooled, or any other car Porsche makes - I'd rock them all over 200K miles all day. My wife and I live downtown, and we both walk to work. The CTT is now our only car, and chances are good if we buy a 2nd car, it's going to be a Tesla as a city car. I'll continue to own the CTT simply because it's in immaculate shape and well sorted at this point. Even in the air-cooled world, the advice was always "every 911 is a 20K 911; spend it now or spend it later" back when they were pretty cheap. If you wanted a project, you were going to spend more money on it then if you had just bought a nice one. For some people like yourself, they had specific needs or desires so projects made sense. But, you're talking about a stock CTT for your wife. No reason to take on a project.
Purely from a fiscal standpoint, you will spend more and stand to lose more with the way you're going. personally, I think you are off your rocker. You're welcome to search M1 0W40 and how crappy it is. There is no way I'd run that oil more than 5K miles, and you're seeing 10K mile oil change intervals on that car. If you smoke a cylinder or blow a turbo, you're either going to be left with a worthless car, or you'll be on the hook for a repair that's the cost of the car. At that point, your total financial outlay is getting dang close to a med-higher mileage 957 CTT. Or a nice 957 CS.
It looks to me like you really want a CTT, and you're trying justify the rational so this one makes sense to you. We're here to tell you that we think your nuts, and most of us DIY all the maintenance on this car.
I would really think long and hard about this purchase. These are rewarding cars to own, hugely capable, even by today's standards. But, if you buy a POS, you're going to be headed down a road of perpetual headaches with a steady stream of cash leaving your wallet. If you're OK spending the purchase price + 5-7K, I have no idea why in the world you wouldn't buy a lower mileage unit that's in much better condition. I've heard your validation, but honestly, it seems thin to me.
It's your money, man. But I personally think you're taking on a huge liability and it makes no sense to me when you're OK spending 15K between acquisition and repairs. That gets you a clean, turn-key, well sorted CTT.
Basic smoke color out the exhaust:
Black- fuel (rich condition)
Blue- oil
White- Coolant
If I was diagnosing a car with "black" smoke I'd be looking for an excessive fuel related issue. I have no CTT experience, (but many years of tuning vehicles) so unfortunately I don't have CTT specific things for you to look for. When you get the inspection done have them do a WOT pull and watch the sensors. Does it have any performance and/or other aftermarket upgrades?
Basic smoke color out the exhaust:
Black- fuel (rich condition)
Blue- oil
White- Coolant
If I was diagnosing a car with "black" smoke I'd be looking for an excessive fuel related issue. I have no CTT experience, (but many years of tuning vehicles) so unfortunately I don't have CTT specific things for you to look for. When you get the inspection done have them do a WOT pull and watch the sensors. Does it have any performance and/or other aftermarket upgrades?
Nope it's totally bone stock; the owner drives her sub-10 year old kids to school in this every day and said if she had ever seen anything like black smoke she would have taken it in immediately. The thing is she's not driving it WOT, so I'm not surprised/believe she's being disingenous or hiding something.
*Edit, forgot to ask the obvious: What typically causes a fuel rich condition? Bad injectors? Spark Plugs not firing appropriately? Sticky fuel Valve issues?
There are many things that could that could alter the air/fuel ratio from where it should be. You listed a few of them. Fresh plugs are a good idea if it's been a while. Worn injectors that are not closing properly can have an effect. A maf that's incorrectly reading could cause issues. Faulty O2 sensors. Vacuum leaks. Boost leaks. Incorrect fuel pressure. Again, I'm not familiar with the CTT's and what all the pcm is using to make changes at WOT. Those are just some basic ideas.
I asked the seller to look at the computer for MPG to see if that's below "market" and therefore indicative of a poorly performing engine. For the primarily city driving over the past few months, it's averaging 13.7 as per the computer. Which is helluva lot better than the previous CTT I looked at that also was city driving but getting 11 as per the computer.
Based on what I hear here, that's either right down the fairway or maybe even a little high for 80/20 city/highway.
Why are you fixating on this particular CTT? There's lots of them out there. I agree with WP, as with any Porsche, buy the best one you can afford. If you can afford to buy this car and then spend thousands on it, just buy a better, lower mileage one to begin with.
I think there are fewer of these in similar condition than you think. There are so few 964's because they made few, but more importantly they were so stupidly cheap not that long ago that every Tom Dick and Harry bought one, carved it up or drove it into the ground. I would hazard to guess that the number of 2004-2006 CTTs in the country that conform to the first 3 Pro's below is sub-500 (of ~5,000 built). Of those, how many are for sale?
**Non-sequitor edit** Is it possible that the smoke was simply carbon build-up or something similar being expelled since the PO had been driving like a 40-y/o woman? I/e since it had never been taken to that limit, maybe the boost was enough to clean some built up gunk out of the system?
Pros
Very Clean
Dealer Maintained Since Day 1
2 Owner, CPO car
Alpine Head Unit w/ backup Camera
Well Optioned with Smooth Leather
Local seller
CTT vs. Canythingelse
Cons
High Mileage (175K)
Black Smoke noted from Hard Acceleration
Not a 2011+
Originally Posted by docwyte
Why are you fixating on this particular CTT? There's lots of them out there. I agree with WP, as with any Porsche, buy the best one you can afford. If you can afford to buy this car and then spend thousands on it, just buy a better, lower mileage one to begin with.
06-21-2016, 11:40 AM
