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Old April 5th, 2011, 16:10   #1
kiva822
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Default First time diagnosing low power / 1x/limp

Greetings

***NOTE: For those that don't like long-winded, detailed posts, skip to the numbered questions below** but, for context...

OK, the sedan is being quirky and I'm taking my first shot at diagnosing the low power issue. First, background:

A few months ago, the only symptom I was having was, occasionally, if I really got on it in 1st gear (e.g. did not roll into the throttle @ 1800rpm or so, just went WOT), it would sputter, go nowhere, and spew a huge cloud of black smoke. I would then let off the pedal and it would go along it's merry way. This happened maybe 4-6x. I was pretty good about rolling into the throttle instead of stomping on it.

Then, in the last 2 or 3 weeks, it's happening more often + the car seems underpowered. It is especially bad when it hits about 140 degrees on it's way up to 190 (e.g. that zone where it's ok, to start driving it normally, but isn't fully warmed up yet). I'm noticing a general lack of 'pull' and, when going WOT in 2nd-4th, it will even rev up and then start pulling a bit more after 3500rpm. Just really inconsistent power and never full power, as I can tell. It went into limp mode 1x, but I can't replicate it, even on a hill.

Unplugged the MAF and it runs somewhat better, but the problem doesn't resolve itself completely. With the tune, the MAF unplugged defaults to, I think, 1275 (see logs).

Right now, my hand is pretty banged up from racquetball, so getting deep into it will have to wait a week or two and I can update the thread then. However, for now..

(1) when unplugging the MAF, an *improvement* in power is indicative of a MAF problem, or, if the MAF is the issue, unplugging it should resolve it altogether? With the MAF unplugged, it still sputtered, just not as bad.

(2) the vacuum hose from the N75 to the actuator is the cloth braided type. Other hoses have been replaced, it appears. Should that one be replaced as well, as a matter of course? Do most replace the actuator hose with a high temp silicone rather than the cloth braided?

that's it for now. After getting the MAF question answered, I'll move on to the hoses and then testing the actuator and N75 (per the diagnostic thread).

Here are the logs i've taken. If anybody wants to see any different blocks, etc., let me know. It's my first time posting logs, so let me know if I do something wrong:

MAF plugged in:

http://pics.tdiclub.com/data/500/LOG-01-003-011-004.pdf

MAF unplugged:

http://pics.tdiclub.com/data/500/2LO...03-011-004.pdf

any tips on to properly read these things would be great....

Sorry for the long post..I tend to be thorough...

matt
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Old April 5th, 2011, 16:32   #2
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The turbo output looks good. It's a larger unit, ie VNT17, right?
The MAF output looks good (close to maximum -1275).

A default of 1275 mg/H means your tune has MAF delete.
A spec MAF = 850 mg/H means you have an EGR delete. You probably knew both of those things already.

*** The IP looks good, but could use a little more advance in the basic setting. What's it set to now?

Check the group 007 readouts when stone cold and when warm. What's the IAT and fuel temperature readout? Include these values in a log. There is plenty of requested advance, so the values should be OK.

The bogging could be caused by a sticking advance piston. I don't see any egregiously late delivery in the log. With the MAF plugged in, output looks good.

***I can't tell what your requested IQ is. Replace group 004 with 001 and make a recording. Check the IP inlet for air ingestion if you have poor output despite good indications.
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Old April 5th, 2011, 18:40   #3
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jcrews, thanks for the feedback. In order to list the specifics of my vehicles in my sig, I had to delete my disclaimer, which explained how much of a idiot i am

So, I didn't know that a "MAF delete" was the reason it defaulted to 1275. I knew that was part of the tune as a default when you unplugged the MAF.

I didn't not know that 850 = EGR delete. I know I don't have an EGR, but didn't know that 850 number indicated so.

I will check the 007 readings as well as do a new log w/ group 001.

I'll have to look up the basic setting IP advance, as I don't totally understand how to look at that / read it. I'll get back to you.

A wrinkle: when I got this car, it had just had a pump swap done by a trusted mechanic in Sacramento. However, they left it with retarded timing (below the bottom line, but on the screen). I adjusted it to right on the middle line. Now, when I checked it the other day, it's at 33, about 1/2 way between the middle and lower line.

When I cracked the cover to adjust the timing, I saw the dreaded paint marks for a mark and prey. I called the previous owner who assured me those were there when he bought the car and did a dieselgeek tb right after purchase (I have the receipt for that TB kit). Sooo....part of me still wants to confirm mechanical timing, but need a camshaft lock tool to do so, as I understand.

So, perhaps first re-adjust the pump timing mechanically to between the middle and top line? Then move on to the other items?

matt
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Old April 5th, 2011, 18:46   #4
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Matt, for $3000 I will take your car off your hands and later will tell you what is wrong with it!
I hope you get to the bottom of this.
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Old April 5th, 2011, 19:00   #5
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You will need a cam setting plate to confirm the cam timing.

However, you can check the tensioner: Push on the belt with your thumb. The indicator on the tensioner (about 4 or 5 o' clock as you look at it) should displace. When you remove your thumb, the indicator should return to the adjusted position (indicator bump is opposite the notch). The belt should have good resistance, and should not be loose immediately after you relieve the pressure.

You can also increase your confidence by setting #1 to TDC at the flywheel mark, and seeing if you can get a drill bit in the lock pin hole (or at least confirm you can see the hole in a mirror).

I've replaced timing belts on 3 engines with previous paint marks, and I didn't attempt to remove them. I just put a note of it in the maintenance record.

Your basic timing setting should be at about 60-65 @ 140 (just use the graph) in order to reach the tuned advance points. I can't think of a good reason for drift right now other than IP sprocket slippage (3 bolts not tight enough - 25 N-m is standard). Drifting towards advanced over a long time normally indicates nozzle wear due to opening early.
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Old April 5th, 2011, 19:08   #6
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ok, so some confirmation (thanks for patience)

re: confirm timing: remove valve cover, look for "v' on #1, TDC should be at flywheel mark, then try and get bit in hole at IP. Correct? Or are you speaking of something where I don't remove the valve cover, just find TDC via flywheel mark and look for IP hole?

basic timing = "TDI timing" in VCDS, adjusted by rotating the IP, correct? Love those mini, mini, mini adjustments

thanks again for your time
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Old April 5th, 2011, 19:16   #7
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You can leave the valve cover on, because the IP hole won't be aligned (around 1 o' clock as you look straight at the sprocket) if the cam is in the wrong position. This will only increase your confidence a little because there's only a weak connection between the cam/crank timing due to the adjustable sprocket. It may not be worth the effort at all.

Basic timing settings refers to using the TDI timing graph.
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Old April 5th, 2011, 19:28   #8
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well, just went to set timing, and now it's at 21 @ 162. WTH? Appears to be some drift...adjusting now...
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Old April 5th, 2011, 19:32   #9
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It should never drift in that direction, so that's bothersome. Let me know if any bolts felt loose, and if any are single use (not gold, with a narrow "neck" near the head).
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Old April 5th, 2011, 19:54   #10
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ok, none of the bolts were loose. These appear to have some blue-ness to them and, interestingly enough, there is a bit of blue 'paint' or something on the IP sprocket. I kind of remember that last time I was in here, but can't be 100% sure.

bolt:



IP bolts / sprocket (am I saying that right, 'sprocket'?):. Bolt missing is the one I took out for pic; yellow paint marks are the ones I referred to:



In a thread a while back about adjusting the IP timing, I thought these bolts were OK. Are they single use and I didn't know it? If so, WTH are they doing in there? Ugh.

re: the tensioner test...i'll have to dig into that one a bit more. I can't seem to move this belt by pressing the top more than 1/4 inch, if that..

matt
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Old April 5th, 2011, 20:11   #11
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That bolt doesn't appear to be single use, although the new style is typically gold colored.

The blue paint is a little weird.

The toothed belt won't have much give, which is good, just make sure the tensioner moves and springs back.
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Old April 5th, 2011, 20:13   #12
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ok, so, for now, I will check the tensioner, re-tighten the IP bolts and see what kind of timing I get. I'll also go ahead and get some new bolts. I have an 11mm IP to install and, heck, maybe i'll be looking at a TB job at the same time...though there is supposed to only be 20k on this belt/tensioner, etc.

any ideas on drift that direction? Would a failing IP do that?
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Old April 5th, 2011, 20:21   #13
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Other than slippage, possibly invalid basic settings caused by an intermittently stuck advance piston (which would explain bogging/stalling).
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Old April 5th, 2011, 20:22   #14
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Jesse and Matt:

Do you suppose someone put locktite on the IP sprocket bolts? That color looks suspiciously like the non-permanent (low strength?) type blue locktite.

Dan
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Old April 5th, 2011, 20:43   #15
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Locktite blue is usually a few shades darker .. could be that Matt used a flash to take the picture and that is a whole lot of Locktite ...
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