Injection timing beyond the range of adjustment via rotating the pump

donbo2000

Member
Joined
Aug 24, 2019
Location
Stockton, CA
TDI
1996 Passat Wagon
I have a 1996 Passat that I bought a couple years ago and while it worked fine initially it started to become harder to start. It finally got the point where it wouldn't start at all and being new to the TDI engines, I wasn't able to troubleshoot it at the time. I ended up leasing a car and mothballing the Passat as I was tied up buying property and moving and just needed something reliable in the short term. So after a year of non-op I turned my attention back to it now and having researched it more I was thinking maybe the timing belt stretched and that threw the timing off. I was able to rotate the injection pump and finally got it to start, I hooked up the vag-com I had bought (but hadn't used before) and the mechanical timing is off the graph, overly retarded. The problem is the pump is rotated as far as it can go towards the engine but it needs more rotation. Since the history of the car is hazy (it was "worked on" at least once by the NiceCars place) I decided to replace the timing belt. I bought the Metalnerds toolset and got everything lined up (crankshaft at TDC with a lockplate installed, cam lockplate in place with both lobes of cylinder #1 up and the lock pin in the injection pump), replaced belts and tensioners and tried to start it but still the same issue, I had to max out the rotation and was able to get it to start but it is still way off. So I'm thinking my only option is to loosen the timing belt and rotate the injection pump a couple of teeth so the pump would have a range of rotation that would allow me to dial it in with the vag-com.

I was looking for any thoughts/advice/guidance on this, as there is a good chance there is something I'm overlooking or screwed up (although the problem rose up without me doing anything other than driving it) or maybe there is another explanation of what is going on and how to fix it?

Thanks in advance for any help!
 

Steve Addy

Top Post Dawg
Joined
Aug 7, 2002
Location
Iowa
TDI
97 Mk3
Sorry to hear you're having difficulty with this.

When you initially used VCDS to check the timing was the engine completely warmed up? It always needs to be at least 80c to provide a reliable timing graph.

When you installed the timing belt were you sure you the crank remained at TDC while the belt was fitted at the IP and that there was zero slack in the belt between the two sprockets on that side? I have found that this is often where a problem is introduced into the mix. The IP sprocket sometimes needs to be rotated slightly by pushing down a bit on the IP lock pin, in order to engage the belt with zero slack between that and the crankshaft.

The evidence for this happening is that once you the manual turning of the engine two times, and back to crank TDC, the cam and IP sprockets don't line up with their starting points; the pin does not install and the plate cannot be inserted.

If you're finding this happening then there's likely slack in between the IP and the crank.

Steve A
 

donbo2000

Member
Joined
Aug 24, 2019
Location
Stockton, CA
TDI
1996 Passat Wagon
Yes, I waited for the engine to warm up (um, well, I checked and VCDS gave me an error that the engine wasn't warm, so I waited it out to warm up after that). I put a lockplate on the crankshaft once I had it at TDC so that wouldn't have moved but I didn't make an effort to get the crankshaft-to-pump side of the belt tight, the whole thing was tight during install even with the tensioner relaxed. I did the two manual rotations of the engine and once I got it back to TDC I could slide the lockplate onto the end of the camshaft again and the injector pump pin fit in. But that said it seems like there is some leeway with the pump pin, I verified I had it in the right hole but was still able to rotate it slightly (maybe this is normal?). But it would seem most likely the belt wasn't tight on the pump side so I will go through the process again and see if it makes a difference.

Thank you for the feedback!
 

ToddA1

Top Post Dawg
Joined
Aug 3, 2011
Location
NJ 08002
TDI
'96 B4V, '97 B4 (sold), '97 Jetta (scrapped)
I’ve had to advance the belt, as you’ve described, on a couple cars. Others have stated the same. I’ve only needed 1 tooth.

-Todd
 

Vince Waldon

Top Post Dawg
Joined
Apr 25, 2009
Location
Edmonton AB Canada
TDI
2001 ALH Jetta, 2003 ALH Wagon, 2005 BEW Wagon
Was the camshaft sprocket broken loose and able to rotate freely as you were tensioning the belt with the cam lock and pump lock in place?

Not being able to get the pump setting within range is a classic sign of forgetting this particular step, because without the sprocket free to rotate slack in the belt has to be taken up on both sides of the sprocket, putting the pump out of time.
 

Steve Addy

Top Post Dawg
Joined
Aug 7, 2002
Location
Iowa
TDI
97 Mk3
Whether it's advancing the belt one tooth or pushing down on the IP sprocket to engage at the right spot it's all the same thing. It just means eliminating all slack between the IP and the crank sprocket when you install the belt.

This belt diagram shows the problem area that I've denoted in red. The arrow at the IP sprocket is the direction you need to move the IP sprocket to engage the belt properly, eliminating all slack. Be sure and maintain TDC while doing so.



Steve
 

donbo2000

Member
Joined
Aug 24, 2019
Location
Stockton, CA
TDI
1996 Passat Wagon
I have it all torn down again, lock plate is on the crank at TDC, lock plate in the camshaft slot, cam sprocket loose and injector pump rotated about a tooth clockwise from where the pin can be inserted into the hole. I got a late start this morning so now all metal objects are the temperature of the surface of the sun, so I will wait until later to run the belt and test it out without getting 3rd degree burns. Thanks for the diagram Steve!
 

donbo2000

Member
Joined
Aug 24, 2019
Location
Stockton, CA
TDI
1996 Passat Wagon
Okay, second time is a charm, got it dialed in now. It started right up from the rough setting and I was then able to adjust it to slightly advanced (48-50) with VCDS, which sounds like it gives better fuel economy and performance. Thanks so much for everyone's help, I really appreciate it!
 

Steve Addy

Top Post Dawg
Joined
Aug 7, 2002
Location
Iowa
TDI
97 Mk3
Okay, second time is a charm, got it dialed in now. It started right up from the rough setting and I was then able to adjust it to slightly advanced (48-50) with VCDS, which sounds like it gives better fuel economy and performance. Thanks so much for everyone's help, I really appreciate it!
Glad to hear it's up and running again.

As for the temps, we finally got past our hot humid spell today, the sun was blocked by smoke from the wildfires so temps stayed in the mid-70's. Finally got some rain tonight and should be in the 80's here all week I guess.

Steve
 

donbo2000

Member
Joined
Aug 24, 2019
Location
Stockton, CA
TDI
1996 Passat Wagon
I thought California had cornered the market on wildfires, at least we are still the leaders in droughts! Looks like we are done with triple digits for a while, should be in the low to mid 90's for the next week or so. Thanks again for the help, this was my first time posting but the site has been a huge help in learning about my car for a couple of years now.
 

Tdijarhead

Top Post Dawg
Joined
Nov 10, 2013
Location
Lawrenceville PA
TDI
2003 TDI Jetta Daughters Car, 2001 TDI Beetle, Wife’s car, 2005 Golf TDI Mine, all 5 spds
You do have a corner on that market. I think Steve means that the California wildfires are spreading smoke and haze across the entire continent. I know we had a day that was hazy a week or so ago (PA) which was attributed to your wildfires. The constant rain took care of that however. Maybe we could send some of our over abundance of rain in your direction.
 
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