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TDI 101 Got a simple/basic TDI question? Are you a newbie (new to the forums). Feel free to post your question here.

View Poll Results: what do you think?
I wouldn't bother - not worth it 3 7.32%
It's OK but not required 5 12.20%
Strongly Recommended 14 34.15%
Absolutely a must! 15 36.59%
No - just clean it when it gets dirty 4 9.76%
Voters: 41. You may not vote on this poll

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Old October 28th, 2004, 14:45   #1
snorksca
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Prevent Intake Cleaning
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Old October 28th, 2004, 22:13   #2
Ed's TDI
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Not trying to rain on your parade but you may get more replies on this in the "PD (Pumpe-Düse) TDI's" section. Just a thought. Cheers.
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Old October 28th, 2004, 22:50   #3
nicklockard
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This issue gets beaten to death here on Fred's.

My take: clean it if/when it noticeably affects performance. Mine's at 77K miles...has 3-4 millimeters soot. Runs damn fine and returns great mileage.

Drive the dang car.

I think it's a hugely overblown non-issue for most of us.
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Old October 29th, 2004, 04:20   #4
keywestbob
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Perhaps this is an "overblown issue" perhaps you can answer this question.
In the 3000 miles since my last oil change the ProVent has removed over 1.5 ounces of Motul 505.01 oil which ended up in my Provent drain line, where would this oil have ended up if not for the filtering of the ProVent? Floating around the intercooler? Attaching itself and egr soot to the intake? Over time the removal of what I consider excess oil is a good thing but that is my opinion and you are entitled to yours and I do not wish to start a flame war but want to state the facts. 1.5 ounces of oil removed in 3000 miles, I have just over 13,000 miles on the car. That would amount to almost 1 pint of oil removed so far. It does add up and should not be there, the TDi is not a two stroke.
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Old October 29th, 2004, 04:51   #5
dr_canak
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"I think it's a hugely overblown non-issue for most of us."

Here is the intake of a car not properly maintained

http://pics.tdiclub.com/showphoto.php?photo=14056

Someone just helped me clean my intercooler and we dumped a good half cup of oil onto the driveway

As far as I'm concerned, anything to prevent intake clogging becomes part of general maintenance for the car. My intake obviously looked worse than most, and maybe a testament to the engineering that the car even ran (although not well)despite how gummed up things were. I'm sure there are others out there with intakes backing up, and it just seems like a smart thing to do given the cost and ease of preventive maintenance vs. fixing the above.

just my .02
jeff
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Old October 29th, 2004, 08:02   #6
compu_85
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Remember: Shift @ 3k, Shift @ 3k, Shift @ 3k, Shift @ 3k...

Also, when the engine is warm, run it all the way to 4k.

My 99.5 has been driven most of it's life this way, and with no mods at all, there was only a light coating of paste on the intake at 145,000 miles. These card beg to be driven

-Jason
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Old October 29th, 2004, 08:41   #7
DIESELprogrammer
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Quote:
My 99.5 has been driven most of it's life this way, and with no mods at all, there was only a light coating of paste on the intake at 145,000 miles. These card beg to be driven -Jason
You removed your EGR valve housing to verify this?
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Old October 29th, 2004, 09:05   #8
keywestbob
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From day 1 I have driven using DBW suggested methodes, so I am running the engine up to about 3thou cold and higher warm. My daily commute is about 4 miles to the Interstate than about 40 on the Interstate with another 4 or so off the Interstate. While crusing at 65 or so I will run it up to over 80 once in awhile. I would be interested to hear how much oil other ProVenters are finding and at what mileage interval.
No I have not pulled the EGR yet, is the EGR the device that hangs over the valve cover more on the passengers side of the engine with one wiring connector on it?
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Old October 29th, 2004, 09:42   #9
Kabin
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Could someone explain the logic for shifting at 3k rpm. The soot index has a low at about 1800 rpm and increases as the rpms increase, wouldn't that suggest short shifting would be better? Also, the soot index at 1000rpm is lower than the soot index at 2500rpm.
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Old October 29th, 2004, 10:21   #10
scotthershall
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I think the underlying theory is that higher RPMs moves more air though the intake and sweeps away the new soot deposits before they can mix with oil and bake on to the intake. So, even though the soot index is lower at 1800 RPMs, most of that soot is landing on the intake and clogging it.
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Old October 29th, 2004, 11:11   #11
HopefulFred
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Much of the rationale for shifting at higher RPM is to ensure the turbo is producing boost for two reasons: moving the turbo vanes so that they don't become stuck with this or similar gunk; and providing sufficient pressure to seat the rings properly.

I wouldn't disagree with the idea that later shifting will increase airflow and minimize the rate of build-up (though I'm not convinced it will help), but I don't think that's the reason for DBW's recommendation.

As a side note, I haven't come across anything other than anecdotes to suggest a ccv filter is really going to be effective. Are we certain that it's actually crankcase vapors collecting and gumming up the soot? What about unburned HC also in the EGR? H2O in the EGR? (Is this stuff water soluble at all?) My point is: it's been argued contuinuously and persuasively that EGR + CCV = clogged intake, but how can we be sure?

If it's only EGR doing it, then we need to account for the absence of (or locate) these deposits downstream in the exhaust system.

Just a thought.
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Old October 29th, 2004, 11:19   #12
jddaigle
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Quote:
As a side note, I haven't come across anything other than anecdotes to suggest a ccv filter is really going to be effective.
Here's a thread in which I asked that very question.
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Old October 29th, 2004, 14:35   #13
DIESELprogrammer
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Quote:
As a side note, I haven't come across anything other than anecdotes to suggest a ccv filter is really going to be effective. Are we certain that it's actually crankcase vapors collecting and gumming up the soot? What about unburned HC also in the EGR? H2O in the EGR? (Is this stuff water soluble at all?) My point is: it's been argued contuinuously and persuasively that EGR + CCV = clogged intake, but how can we be sure?

If it's only EGR doing it, then we need to account for the absence of (or locate) these deposits downstream in the exhaust system.Just a thought.
I did my first EGR cleaning a few weeks ago:
EGR Post

I removed and inspected the exhaust delivery tube to the EGR and inspected inside the exhaust manifold where the tube connects. There was no clogging and the thin layer of soot inside the tube and the exhaust manifold was dry. However, the air intake to the EGR valve housing from the IC was wet with an oily film and the area inside the EGR housing post EGR valve had a thick/oily soot buildup.

My conclusion from what I have seen with my car is this: Mostly dry sooty exhaust mixes with oily intake air at the EGR valve. The exhaust soot becomes oiled post EGR valve and builds up on the intake walls. Anyone that has removed the EGR valve housing and the exhaust delivery tube have any other conclusions?

As for rpm shift points, as noted in my previous post, I almost never shift below 3k when warm and at least once or more daily, I shift to redline. That is why I asked Jason if he has taken off the EGR housing to prove his point.
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Old October 29th, 2004, 14:57   #14
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Quote:
I think the underlying theory is that higher RPMs moves more air though the intake and sweeps away the new soot deposits before they can mix with oil and bake on to the intake. So, even though the soot index is lower at 1800 RPMs, most of that soot is landing on the intake and clogging it.
This is one theory. There is also the theory that at higher RPM's the EGR does not open as much, thus less EGR to begin with? I have not logged the EGR duty cycle to confirm this though. Maybe someone who has can chime in?
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Old October 29th, 2004, 17:19   #15
jddaigle
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Quote:
There is also the theory that at higher RPM's the EGR does not open as much, thus less EGR to begin with? I have not logged the EGR duty cycle to confirm this though. Maybe someone who has can chime in?
Arthur did some logging for this thread over in the PD Forum:

Quote:
Here is a bunch of PID data and the conditions:

July 27, 2004
2004 Jetta TDI, 5 spd
28000 km
B20 biodiesel fuel
Motul 505.01 oil
16 C outside temp
Light rain
Rel humidity 95%
101.52 kPa barometer
using Snapon Microscan.



AT IDLE: EGR UNPLUGGED / EGR PLUGGED IN

Abslt TPS - 95 / 24
Engine rpm - 899-912 / 899-903
Calc Load - 15-18.5 / 28.2
MAF - 12.56 / 6.02
MAP - 102 / 98
Coolant temp - 88 / 88
IAT - 42 / 38
O2 Voltage - 2.06 / 1.563
EQ RAT - 0.44 / 0.189
(Commanded O2 sensor equivalence ratio)


02 value of EGR UNPLUGGED / EGR PLUGGED IN in 3rd gear at 1500 rpms crusing.
1.93 / 1.03


Some (O2 sensor values / EG Rat value )with EGR plugged in

Wide open throttle: (0.7 - 0.9)/(0.097 - 0.89) <---- The 0.097 may be a writing error on my friends part who was helping me with this because it didn't match the pattern but I am not fudging results.

Foot off throttle in gear (injectors not firing) (2.5/1.99)
4th gear at 2000 rpm steady (0.4/0.087)
3rd gear at 2000 rpms steady (0.75/.105)
1st gear at 1000 rpm steady (1.5/0.185)
1st gear at 2000 rpms steady (1.4/0.18)
1st gear at 3000 rpms steady (2.0/0.330)

If I'm not mistaken looking at these numbers it looks like its gonna burn significantly more fuel with the EGR unplugged depending on how hard the ECU will try to compensate. I agree that the car feels way better with it unplugged. Feels smoother and less surgy. Also you can clearly hear more turbo which is not necessarily a good thing. A few of the numbers above don't make sense and it may be a fault in the scanner reading the PID such as the abslt throttle position of 97% while idling.

My next step is to run a tank through with the EGR unplugged and see what happens to the fuel economy, if its really bad I'm plugging it back in.
Looking at the Equivalence Ration ("EQ Rat") from the O2 sensor, it looks like the EGR system is most aggressive at idle (until it shuts down after ~90 seconds of idling), and increases with RPM.
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