starts hard after resting; timing changed to zero

000utback

Well-known member
Joined
Mar 12, 2010
Location
VA
TDI
96 Passat sedan; 03 Jetta sedan; 04 Jetta sedan
96 Passat TDI at 495,000. 1 yr / 20,000 miles on timing belt done by professionals. Then VAGCOM said timing = 50 at 164 fuel temp; 840 idle / 5.4 mg/stroke / 1.34v. This was about midway between the center blue line and the top green line.
Past 2 weeks car is getting progressively harder to start after sitting overnight. Cranks great, but takes 20-30 seconds before it starts to fire 1 cyl, and more cranking to get enough firing to run. Lots of white smoke.
I rechecked the timing graph this morning after driving to work, and it shows 0, idling at fuel T 159. How can that be? Car runs ok, but for years I have been plagued with a light load shudder issue. Fuel consumption seems normal, over 800 miles/tank.
So, why would the timing show zero? and does that relate to my hard starting problem?
I know I should also look for air leaks into the fuel line, but still concerned about this timing question. Thanks for any comments.
 

pdq import repair

Veteran Member
Joined
Nov 6, 2016
Location
idaho
TDI
09 Jetta
The early cars had a soft lower crank sprocket that could wear the key away and timing could change due to that. I always inspect or update the lower sprocket.



Or something may have been left loose on the belt install. Either way it needs to be looked at before damage happens.
 

garciapiano

Veteran Member
Joined
Feb 12, 2018
Location
Southern California
TDI
1997 Jetta TDI (1Z)
Have you tried adjusting the pump position and seeing if that affects timing? It’s entirely possible for the pump to shift by accident, although the car will usually start even if the pump is not timed dead-on.

Other thing to check would be timing, period. It is entirely possible you are off a tooth or more on your belt due to slippage. If that has happened you really want to address it quickly. Several members have experienced similar symptoms when the timing belt has slipped.

Long crank before start could indicate your pump losing prime, but that would be the last thing I would check after confirming timing is correct.

Oh, and I would take it back to these “professionals” before messing around with it yourself. Even out of warranty, it should be in their best interest to at least take a look and potentially keep you as a customer.
 
Last edited:

Steve Addy

Top Post Dawg
Joined
Aug 7, 2002
Location
Iowa
TDI
97 Mk3
If it is a lower crank sprocket issue you should be able to see it in VCDS on the timing graph. The variability will be all over the place instead of confined to a specific small range around where it's been set.

Steve
 

000utback

Well-known member
Joined
Mar 12, 2010
Location
VA
TDI
96 Passat sedan; 03 Jetta sedan; 04 Jetta sedan
Thanks for the responses. It got so bad that it wouldn't start this afternoon after work, so I'm waiting for someone to come help jump start it. First things I'll look at will be a visual on the timing belt to see if it's coming apart, then see if the fuel pump has loosened up and shifted. Main thing I still don't understand is why it can run so well while after I get it started. How can it even run if the timing is buried at the bottom of the graph? Much to learn.
 

BigAndy

Veteran Member
Joined
Apr 19, 2002
Location
Northern BC
TDI
99 A3
Once the car starts - the ECU takes over and adjusts the timing as best it can. Prior - it relies on things being mechanically close. Another note, it takes the engine turning over a certain RPM to start as well - somewhere around 300rpm if I recall.

This is why folks who have a battery on it's last legs can have a car slowly becoming miserable to flash up.

Your problem sounds timing related. I'd pull the valve cover - and line up the mark on the flywheel, pop the pin in the IP and slide the plate in the cam before going too much further.
 

Steve Addy

Top Post Dawg
Joined
Aug 7, 2002
Location
Iowa
TDI
97 Mk3
I should also say that if timing is way off it might not show on the graph....

As a side note, be careful about jump starting. If your voltage drops too far it can have adverse consequences on the instrument cluster...aka kill it.

Steve
 

000utback

Well-known member
Joined
Mar 12, 2010
Location
VA
TDI
96 Passat sedan; 03 Jetta sedan; 04 Jetta sedan
Visually the timing belt looks fine. I adjusted the injection pump position a lot, and on the first try the car started immediately and ran smooth as silk. Fiddled with the pump position and left it just a hair below the blue (center) line. Numbers say timing 38 at fuel T 154. The data cloud feature shows a variation of 5 units. Checked the IQ and it's at 5.6 mg/str, very close to last year's check. Overall I moved the fuel pump about 3/16 inch.
So, after the last tb I drove, say, 18,000 miles with steady performance, and then 2000 miles of degrading performance until I moved the pump 3/16 inch to make everyone happy again. Seems like something is changing. Does the crank sprocket seem the most likely culprit? I'm going monitor the timing weekly for now.
Thanks for all the advice; and all the other info I found on the forum while going through this.
 

000utback

Well-known member
Joined
Mar 12, 2010
Location
VA
TDI
96 Passat sedan; 03 Jetta sedan; 04 Jetta sedan
still getting worserer

So, when we last talked Jun 20 I said I moved the fuel pump and got timing lined up and everything ran good. Then I took it to my shop, with photos of the timing graph from last year and after the timing changed and asked what's going on. They said "the timing is right on". Well, duh, that's because I changed it. So, no help.
Aug 3 the timing is again at 0 and the car almost impossible to start. Left it at the shop. They said it starts really hard. Said they don't think it's the crank sprocket because the car runs so well when it IS running. Which is true. Smooth and powerful. They recommended a mass air meter change. I did that, finding that the air filter had a hole in it, there was debris on the old mass meter, and the snow screen was plugged. Totally removed the snow screen, installed new mass sensor, and started / ran / off / started a few times. The value at the bottom of the timing graph changed from 11 to 14. Still very hard to start. The CLOUD variation is 7 yellow dots. Is that excessive?
What does it take to get a visual on the cam sprocket? I have seen references on pinning it to keep in position, but I'm not sure how involved it is to get to it. Thought if I could see for myself if it's loose (or secure) that would help me guide my mechanic. Could it be something slipping in the fuel pump?
thanks again for all the help.
 

Abacus

That helpful B4 guy
Joined
Nov 10, 2007
Location
Relocated from Maine to Dewey, AZ
TDI
Only the B4V left
It is your crank sprocket, I guarantee it. I’ve done a ton of these and you describe it perfectly.

Whatever you do, when you find it is the crank sprocket, DO NOT have your ‘garage’ replace it. They sound like they have no idea what they are doing when it comes to these cars.

It is very easy to check, and there are lots of posts on here about it, I have also included ones with pictures. Just remove the valve cover, and the opener timing belt cover, then the little plug over the flywheel on the other side of the engine. There are marks/pins that all line up and I guarantee they do not, which means your crank sprocket has moved. It’s a common thing and an easy fix, so long as you know what you are doing and take no shortcuts, which I bet your garage will.

Checking the static timing is the first thing anyone should do when diagnosing a hard start condition on these engines. What you have checked is the dynamic timing, not the static. Unfortunately to do this job the timing belt has to come off and the crank sprocket and bolt replaced. Any shortcuts and you’re back in there redoing it again. I have done a few due to them being done improperly by garages and even VW dealerships. It’s important to make sure anyone working on your TDI knows the TDI engine, just knowing gassers isn’t good enough.
 

KLXD

Top Post Dawg
Joined
Aug 22, 2009
Location
Lompoc, CA
TDI
'98, '2 Jettas
If the sprocket's moving this isn't a trivial thing you want to keep compensating for by adjusting the timing. You need to consider that the crank is getting mangled too.

Is it moving far enough for the valves to be hit?

Is the bolt backing off along with the sprocket so the whole thing comes off?
 

Steve Addy

Top Post Dawg
Joined
Aug 7, 2002
Location
Iowa
TDI
97 Mk3
I'm in agreement, this is serious enough that you need to have it addressed now. I wouldn't want to risk my engine if it's loose enough to result in the timing changes you're seeing.
 

000utback

Well-known member
Joined
Mar 12, 2010
Location
VA
TDI
96 Passat sedan; 03 Jetta sedan; 04 Jetta sedan
CRANK SPROCKET
As suggested above, repeatedly, the crank sprocket was the issue. The 3rd time I took it to my mechanic, I said, look just check the crank sprocket. You charge me labor by the hour, and I'll gladly pay you. Just check it for me. When I picked the car up, they said the timing is definitely changing, but it can't be the crank sprocket, so they didn't check that. No charge. So, it rested in the driveway for awhile, until SUDDENLY I got a phone call from ninedee_golf_tdi. Just like that. It was like Santa Claus. Or an angel. "Hey did you ever get that car straightened out?" He's back in Stafford, and I was his second or third customer. I trailered the car over there, being too afraid to drive it any more, and while he was checking the timing noticed the crank pulley bolt was barely snug, so he got the crank sprocket off and yes it is a little banged up, but not as bad as some pictures. Put it back together with new sprocket and new bolt and timing belt kit.
I should have posted then, early December, but I really wanted to run the car for a thousand miles and give glowing reports of how wonderful it is. Well, I was kind of nervous about the May expiration on state inspection, and knew it needed pads all around, but when I went to do the brakes, a front caliper piston wouldn't retract, so I was looking for my CarQuest lifetime warranty receipt (third warranty replacement), and looking, and finally after 2 weeks ordered a new, quality caliper, but then I had to take the last few days of deer season. So, here I am logged in and figured I'd go ahead and settle the mystery of the timing retarding off the graph on its own. I'll give another update when I get it back on the road. (driving the daughter's 03 with stage 2 and heated seats also impacts the priority list...)

THANKS A MILLION, TOM!
 

Mongler98

Top Post Dawg
Joined
Mar 23, 2011
Location
Northern MD (HAGERBUSH)
TDI
98 Jetta TDI AHU 1.9L (944 TDI swap in progress)
The jackassery of mechanics never fails to me to facepalm. The bolt was loose? Lol guess your not going back to that shop again. Not doing what you asked upon request..... epic fail.

Anyways glad she is running again. You did the right thing.!
 
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