colfax

Hi all,

I have read of the need to occasionally clear the motor so to speak by going at a high speed for a while?

IF this is a good idea how does one go about doing it without getting a speeding ticket?

Would putting the tranny is S3 in order to raise the RPM's and keep the speed lower do the same trick, and how long should one hold the RPMs at what suggested RPM?

thanks!

Dave144239

Actually, these engines run in port injection mode under normal load, and switch to direct injection under higher load, so flooring the car to clear carbon will actually have the opposite effect.

colfax

thanks for that answer Dave

I asked the question because when I was researching buying my 07 there was a discussion and a couple of posters spoke for the need to "exercise" the motor

if memory serves there were comments about the motor's performance being noticeably improved after doing so........but what you are saying is that it is not true

Dave144239

It could be that the car responds to the higher revs/speeds by relearning driver behavior, which is something a lot of cars do these days. If that's the case, it might feel like performance has improved, but in reality it may just be different throttle mapping. That's just my theory

Either way, flooring it now and again is definitely fun. I was happy to find out that the engine runs in port injection mode most of the time. My previous car was a direct injected Cadillac, and carbon buildup was definitely a thing with those engines.

ibidu1

iTrader: (1)

While on the highway just romp the throttle it will blow out any loose carbon. I would do this after a carbon combustion cleaning with seafoam through the intake manifold. Run a whole bottle through it!

Chuckinnj

JLAWS

This post reminds me of my 1998 Cadillac STS ownership days back in year 2000. The Caddy forum recommended flooring in once in a while to clear the carbon, I was doing that on a regular anyways in my early 20's with a 300hp V8

Oliver Enterprises

I just drive the car normal, and never consider such a thing. Every once in a blue moon I find the desire to floor it, but otherwise I drive like grandpa. Never had an engine issue with any vehicle I own(ed), and don't believe I ever will, at least not related to carbon build-up. I take that back, I did blow off an apex seal on my rotary, but not related to carbon buildup. Personally, coming from an automotive engineer's position, I believe this to be just an old wive's tale (for lack of a better description). I think people see some dark smoke come out of an exhaust from another car when the other car is flooring it, and perceive it an (detrimental) build up. Maybe it's some build up, but I doubt it's detrimental. Of course it hurts nothing to blow it out if one feels so compelled.

I will also add that absolutely brand new cars (Hyundais) would blow out the same nastly black smoke on start up at the end of the assembly line. There was sort of a tunnel / room that a vacuum was drawn on where the cars were supposed to be started. The vacuum would pull the nasty out. And, quite frequently, those vehicles would fail to start within the confines of that room, because the line was moving. And cars at the drag strip who's engines very unlikely have any carbon buildup, blow out nasty smoke. But that is dependent on their state of tune.

The point is, I personally have and never have had any concern for carbon buildup. I've never added any fuel or oil additive, and have had no issues with a vehicle's engine. Just regular maintenance and drive conservative. I did floor the LS a couple weeks ago to get to a traffic light before it was red ... for too long ... before I went under it ... with my fingers crossed. The LS didn't miss a beat and sounded awesome and pulled really strong. I didn't notice any smoke, but I wouldn't be surprised if it choked out a little.

Doublebase

Nospinzone

Yea, enquiring minds want to know.

I remember when I was a kid in the 60's my father said to change the oil on a new car after a 1000 miles to get rid of all the metal filings left over from the manufacturing process. Of course those were the day when you changed your oil at 3000 miles anyway. Now supposedly the manufacturing process is much more advanced that that is not an issue any more. Is it?

Oliver Enterprises

There was a study I read when I was at Toyota. I don't believe it was done by Toyota, but I don't remember exactly. The study took maybe 10 engines and did durabilty testing on them. Some they did only the recommeded maintenance (oil & filter) some did extended, some did recommended but varied some earlier maintenance.

Each time they did service they took measurements. They counted metal in the oil, documented cylinder pressure in every cylinder and various things like that. The engines with the accelerated maintenance had their first oil change at a simulated 500 miles. And every 500 miles until the simulated mileage hit the first service interval. After these engines reached the first recommended service interval they discontinued the acceleration and just stuck with the schedule.

In the end they did some ridiculous amount of miles, like 500,000 miles on the engines. All variables documented all along the way. For the final measurements the engines that did the accelerated maintenance at the beginning had far better cylinder pressure, put out more power, and consumed less oil. Their theory which was backed up by data was that the metal count was extremely high in the first few oil changes. And by getting the metal out of the oil sooner than later prevented microscratching of the cylinder walls ... which pevented wear within the scratches over time, which led to the better results.

i followed that with my Corolla when I bought it new. It has 240,000 miles on it and I swear it runs unbelievably strong. Its just too bad my wife considers it just a mobile garbage can and a door stopper for other parked cars. It's starting to look like something you'd see in Mogadishu.


Jason

Nospinzone

Are you thinking of the test of motor oils that Consumer Reports did?

Oliver Enterprises

It had to be 2001 - 2003 when I read that. I doubt it was CR.

Dave144239

That's a shame There's a house in my neighborhood that always has two or three relatively new cars outside, and all the cars are dented, with bits of trim missing or hanging off them, rust spots where the paint is gone, etc. They must sell them at night in a rainstorm, because I'd laugh if I saw them trying to trade them in for a new car. I figure the maintenance is probably taken care of about as well as the exterior.

Doublebase