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VW MKIII-A3/B4 TDIs This is a discussion about MKIII-A3/MkIII Jetta/Golf (<99.5) and B4 Passats (96,97) TDI's. Non TDI related postings will be moved or removed.

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Old February 9th, 2018, 16:42   #1
Giberish33
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Default Static timing randomly went retarded, lumpy idle out of no where?

Hey guys, fairy new to TDI's but I've owned my jetta for over 2 years now and have gotten familiar with vagcom and have been doing plenty of reading. About 3 days ago now on my way home from work coming up the last hill to my house I noticed that the car was making a louder than normal "ticking" noise, sounded like injector on a cold morning. The noise was a constant pace and only seemed "loud" when above 2500ish rpm. My I initial thoughts were possibly a sticking injector or just getting worn out (245,xxxkms on original bodies and nozzles).

Today I finally got around to hooking up vagcom to see what was wrong. The car drove normally if a little slugish but the main thing was the idle was lumpy to the point of shaking the car like it was running on 3 cyl. Seemingly from one day to the next my timing in basic settings has gone from dead on center to just slightly above red line retarded. IQ voltage is also jumping around like mad.

Sorry I dont have any screenshots right now but injection balance hduring the summer was not great with cyl 1 = 1.38 cyl2 = 1.18 cyl 3 = 0.33.

Now the balance is at cyl 1 = 2.07 cyl 2 = 1.30 cyl 3 = -0.98

fuel filter + oil filter + oil + air filter all have about ~4000kms on them
timing belt has maybe 30000-40000kms

the car starts fine and actually runs better / smoother when cold (im assuming ECU is adding timing) but by the time I get home from work and everything is warmed up its a lumpy idle that can be heard at the tailpipe as well. Anything in particular to look for? How could timing jump from middle to almost bottom of the graph seemingly overnight?
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Old February 9th, 2018, 17:29   #2
Vince Waldon
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There's a couple possibilities, but the first thing I'd recommend is looking very carefully at the harmonic dampener while the engine is running to see if there's any visible wobble.

If so, the car should be parked, crank bolt removed, and crank snout and sprocket checked for damage... the bolt may have worked loose.

Loose timing belt that has jumped would be the next suspect.

Worn IP a distant third, perhaps, but that would tend to cause a gradual shift in timing. A sudden shift, particularly on an older engine, is generally the crank bolt letting the sprocket shift back and forth. If it is allowed to persist valves can meet pistons.
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Last edited by Vince Waldon; February 9th, 2018 at 17:31.
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Old February 9th, 2018, 18:02   #3
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Ok, so there are a few things here that are an immediate thing to investigate.

Timing being the obvious and that "ticking sound"

Get her to TDC and check to make sure the IP lock out pin is still in perfect alignment as well as the cam and so on. Ok if you’re good on that part, you can move onto what Vince Said. While cold engine, check the tensioner for the timing belt is dead on. If it’s not, adjust it with the tool and put a drop of blue lock tight on the threads for the nut and torque it down to 10ftlb I think, check that one for me before you do. Now make sure that the crank bolt is not loose, now check the tightness of the bolts on the top cover and body of the IP, like if you’re doing a hammer mod. If all those things check out ok, you can start the car. Once you start the car, watch your QA on the IQ You need to be somewhere around 3ish, when its bucking or hard idle issue and your IQ is right, move on, if it somehow jumps to something like 1.4 or less then here is your issue. I’m my 1z it has a very rough idle the lower the IQ goes. I have mine at 1.2-1.4 as I’m trying to get as much fuel as I can, don’t do as I do, OK. Now on to that tensioner, while it’s warm and doing its rough idle, make sure it’s not that tensioner. A faulty one will give a bit of slack here and there as it’s not adjusting properly anymore and can cause this issue as well. You’re right to think it’s a timing issue. If that looks good, make sure your 3rd injector is plugged in. Also check to see if the big round wire harness bit by the end of the head over top of the Trans is plugged in all the way and free of water contamination within. Also MAKE SURE THAT IS GORUNDED. I had this exact issue but it never stopped, all the time, the grounding screw on its frame part was snapped off. It must be grounded. Now if you have check everything here that I have said so far and nothing is working or correcting it or wrong, move on to running a purge of liquid diesel molly injector cleaner, with a can, a bit of hose, a inline filter and go to town, consume the entire bottle, it takes a while. In a nut shell, put 2 hose lines into the bottle, one to the IP intake and the other to the IP return and have a cheap clear filter inline on the IP intake.

If that don’t work I highly suggest you start investigating the IP. They do go bad but all the other things I just mentioned are much more likely.
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Old February 9th, 2018, 21:22   #4
Giberish33
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Thanks for the input guys. Ill check what I can tomorrow as there is supposed to be a snow storm coming my way and I don't have a garage to work in. Would it be possible for the IP pressure relief valve (maybe not correct term) part of the reason? In reading about what it does when its "not together" sounds sort of like what I experienced where there is not enough pressure in the IP case at idle / low rpm causing the timing issue then when on the throttle the ECU takes over and there is more pressure in the IP to supply more timing advance. I guess its easy enough to remove that valve and see if the parts have worked their way free, then jam them back together to see if that is a possible cause. Harmonic balancer as well as A/C pulley etc are not wobbling at all I already checked that out, also Alternator pully was changed just before the winter. I have yet to check the timing belt tensioner. I don't think the noise is valves touching anything, it seems entirely fuel related as there is only noise when accelerating, decel there is nothing so not cv clicking and not valves and not lifters. I can replicate the knocking / ticking sitting stationary in neutral(5 speed car if that makes a diff).

Another possible cause I read about is IP bolts working their way loose and allowing the timing to drift off? Possibility? I have new non stretch type bolts and a torque wrench so I could adjust the pump timing if needed.
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Old February 9th, 2018, 22:40   #5
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uuuh, vinces advice come 1st to check. crank bolt being loose is a real possibility. like he posts check harmonic-pulley for wobble, even then the crank gear may be loose. if it gets 'out of play' valves may cross pistons. may have happened, for you.
for ip bolts working their way loose, a 'micro-torque' wrench is used, a 3/8" wrench. ip base bolts about 18ft-lbs, add some more for tightness, not much more. for a 'micro torque wrench' convert inch-lbs to foot-lbs. its 12inch-lbs to a foot lb.
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Old February 10th, 2018, 11:45   #6
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The thing is that the pump pin won't be in perfect alignment at TDC on a 1Z or AHU since the pump lock pin is removed when the belt is tensioned and the sprocket will move. So don't expect it to be.

The cam should be.
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Old February 10th, 2018, 11:50   #7
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Quote:
Originally Posted by KLXD View Post
The thing is that the pump pin won't be in perfect alignment at TDC on a 1Z or AHU since the pump lock pin is removed when the belt is tensioned and the sprocket will move. So don't expect it to be.

The cam should be.
yea i guess it wont be EXACT but it should be very close, a tooth or more off and the holes wont even come close to aligning.
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Old February 10th, 2018, 13:26   #8
Giberish33
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IP pressure relief valve was together as it should be so I guess im going to check the IP sproket bolts next. Any kind of real danger running with very retarded IP timing except for more smoke or poor fuel economy. The car has started just fine and drives fine its just at idle where things get funky. Ill check it out and report back.
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Old February 10th, 2018, 15:26   #9
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Cracked open each injector one by one, each of them made the engine stumble so I guess things are looking ok for the injectors, I bumped the IQ a little from mid 5's to high 3's seems to have smoothed it out a little, I havent experienced the idle stumble / 3 cyl shake. The one thing still puzzling me is how the IP timing drifted off to within spec but retarded when a few months ago it was dead on in the center of the graph. I guess its possible it has been retarding slowly and I only now realized. Any one have any clue after what time period / mileage the "timing belt stretch" comes into effect. I've heard that it is normal for the timing belt to stretch somewhat over its life and slowly retard the timing so its usually best to set the timing slightly advanced to compensate for the stretch. Currently a snow storm with possible ice rain tomorrow were I live so I'll see if I'm able to adjust the IP timing or wait for better weather. Thanks again for all suggestions guys!
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Old February 10th, 2018, 17:51   #10
Vince Waldon
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If timing belts stretch at all it is a very very very tiny amount.

If your timing was good and then suddenly changed something else is going on.

If you're not sure it suddenly changed perhaps reset and monitor is all you can do at the moment.

Unfortunately, on an older TDI like a 1Z, my money's on the crank snout interface. The harmonic damper will wobble when it's really in bad shape, but it starts with things sliding around in line.
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Old February 10th, 2018, 19:05   #11
Giberish33
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Damn ok, thanks Vince. I guess I over estimated the amount of timing can be offset by any stretch. Like I said the last time I checked timing it was mid 40's reading dead on in vagcom, now timing is in the mid to low 30's given the same fuel and coolant temps. Pretty much my plan at this point is to reset the timing and monitor it. I can't seem to see any kind of wobble in the harmonic balancer, should I be looking at first start up when things are cold or when the motor is already warmed up / doesn't even matter there would be wobble at all times?

Also weird to me is that cyl 3 (I know this is really cyl 4 in comparison to cyl 3) is showing negative numbers for injection deviation, this summer all cyl were in the positives. Again all of this could have been progressive and I only realized now but I'm just worried that something is actually not ok. I take great care of her otherwise, consistent oil changes, filters, diesel additive and taking the bi-weekly WOT run onto the highway.

*side note: have not had the same lumpy idle since I tightened down the injector retaining clamps and bumped the IQ a little, maybe unrelated but as of now I'm only trying to figure out the reason / correct the drop to retarded IP timing from dead on center*

Last edited by Giberish33; February 10th, 2018 at 19:10.
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Old February 10th, 2018, 19:27   #12
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lets put it this way, i did a timing belt on a car with 280K on the clock on the ORIGIONAL belt, i marked the teeth on the sprockets and counted them against a new belt, the stretch was only half a tooth off over the top of the cam sprocket to the top of the IP sprocket and the bottom of the crank in that direction. So yea, minimal to say the least.
Unless you verify that the physical timing is correct, your ricking even starting it up. there are a hand full of things to check before you turn that key. Your risking big $$$ to repair a simple check over. the IP bolts just dont back out randomly, if they were worked on before, maybe over a few hundred or thousand miles, i can see that but of the 4 times i have adjusted my IP timing on my 1z its never backed out or changed.

Vince is 100% on point and this is the most likely option of what happened.
Bring it to TDC and make sure your on time.
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Old February 10th, 2018, 19:51   #13
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I didn't not know the MkIII well - just what I have read and I know that the crank snout is a common problem. But something in the OPs last post caught my eye. He said that last summer all three readings were positive. Well, from my understanding, there should be some negative and some positive and if you add them together, they should equal zero, or just about.

So that makes me wonder if there is a problem with the #3 injector sensing. Yes, the crank sprocket is most common, but if that's tight, would it be worth looking into the #3 injector? Maybe even swapping it out with a know good?
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Old February 10th, 2018, 21:54   #14
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Yup, don't get me wrong... there's other possible explanations to a sudden shift in timing.

Just thinking that if nothing else obvious becomes apparent for the cost of a new bolt and some time spent building/borrowing a crank lock it might make sense to inspect the snout, if only to eliminate it as a suspect... and sleep better at night?

Issues with the pump or needle sensor are non-terminal to the engine.... the crank snout unfortunately not so much.
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Old February 11th, 2018, 10:33   #15
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I'm not going to ignore that fact that many vets here are suggesting the crank sprocket as the issue and in doing some reading it seems possible, however I don't see any wobbling on the harmonic balancer and the car has no starting issues even in -15c not plugged in after work. The timing graph starts off dead on when cold starting as I observed yesterday in vagcom and progressively drops off. Wouldn't things be more constant if the crank sprocket bolt did loosen up and things had slipped timing(ie. always retarded timing even when cold starting). As of now I only experienced the very rough idle / stumble once. I don't have the tools or space to do it myself, is there anything I can check by hand or with a socket wrench & cheater bar?

I also read that if the crank sprocket is loose the timing wouldn't stick so do I trying to advance the IP timing and see if it drops off again or just call my local vw/audi shop and ask them to take a look at the crank snout/ harmonic and repair?

Last edited by Giberish33; February 11th, 2018 at 10:54.
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