'03 TDI cam shaft position sensor

03_blue_jetta

Member
Joined
Sep 3, 2021
Location
Edmonton
TDI
2003 Jetta TDI
Summary and then an update after several weeks of no progress:

Original symptoms: no previous problems, driving along freeway in Sept' 2021 at around 80 km/h (50 mph) and suddenly engine went to 0 rpm. Coasting, I put in the clutch and re-started and ran for only a few seconds then died again. Towed car to my mom's house and put it in her garage.

I paid a mobile mechanic to come to mom's house he did several things wrong: sprayed starter into air intake, and had me crank the hell out of the engine for literally 30 seconds non-stop. This was later discovered to have burned out my starter motor. He also disconnected fuel lines into / out of fuel filter, thus introducing air into the fuel lines.

After getting rid of the mobile mechanic, and with help from this forum the problem was traced to be the high pressure diesel pump had skipped 4 teeth so fuel timing was off.

Got fuel pump timing aligned properly. Tried to start the car, but absolutely no cranking happening due to burned out starter.

Installed a replacement starter (a used one) from a wrecker.

Still no cranking - looks like my battery was very old and no good.

Now we're caught up to today (June 29 2022). A new battery was installed and I was sure the engine would fire up, but nope. Turns over but doesn't fire up. I did think that maybe my belt was old and the pump skipped teeth already while cranking today but after checking the timing again all seems well in that department. My best guess is air has been introduced into the fuel system. I can see air in the fuel line coming into the fuel filter. So what does a guy need to do to purge the air? Or does anyone have other ideas why it's won't start?
 

KLXD

Top Post Dawg
Joined
Aug 22, 2009
Location
Lompoc, CA
TDI
'98, '2 Jettas
I didn't look at all the previous posts but I see the pump skipped. Why? Did the cam? Is it now aligned too? Did you bend any valves?

Do some searching on getting the air out. Easiest way is a vacuum source like a brake bleeder.
 

jokila

Vendor
Joined
Dec 3, 2004
Location
Houston, Texas
TDI
2003 Jetta GLS, Manual
It should start if the injectors are bled. You should be seeing fuel spew out of them if you loosen the nut.

If you don't mind, set the crank at TDC, then take a pic of the injection pump pinned.

Take it from above the pump right over the postage stamp size smooth flat spot on top of the pump and that shows the pin from above as well. There have been many people who get that alignment wrong and a pic will prove you have it correct.
 

AndyBees

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Joined
May 27, 2003
Location
Southeast Kentucky
TDI
Silver 2003 Jetta TDI, Silver 2000 Jetta TDI (sold), '84 Vanagon with '02 ALH engine
I'm sorry, but Injection Pumps don't skip teeth. If the Timing Belt skips teeth, it will be at the Crankshaft. Of the three major components, the Crankshaft Cog has the least number of teeth in contact with the Timing Belt and is the source of power/torque that spins the belt. The Timing Belt has three jobs, rotate the Cam Shaft, the Injection Pump and the Water Pump. Of the three, the Water Pump is the easiest to rotate followed by the Injection Pump.

Take a look at the timing belt in the photo below. The Water Pump locked-up and almost destroyed the Timing Belt. But the Timing Belt did not jump time on the Crankshaft, Camshaft or Injection Pump. The incident happened to the ALH engine in my Vanagon (many of you have see this pic).

I believe you would be ahead to heed the advance that several have suggested, set the engine on Top Dead Center. Then, determine if the Cam Shaft and Injection Pump are "in Time." That "department" is more important than any other. If the Cam Shaft is not "in time" with the Crankshaft, all four Exhaust Valves have kissed their pistons .... Not Good.

 
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jettawreck

Top Post Dawg
Joined
Aug 2, 2004
Location
Northern Minnesota-55744
TDI
2001 Jetta and 2003 Jetta
Agree with Andy.
Unless the belt loses tension (indicating other issues) there is no way just the IP can skip teeth. The IP sprocket has lots of engagement area compared to the crank sprocket, so there will be timing off.
 

Mozambiquer

Vendor , w/Business number
Joined
Mar 21, 2015
Location
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2004 VW Touareg V10 TDI, 2012 Audi Q7 V6 TDI, 1998 VW Jetta TDI. 1982 VW Rabbit pickup, 2001 VW Jetta TDI, 2005 VW Passat wagon TDI X3, 2001 VW golf TDI, 1980 VW rabbit pickup,
Agree with Andy.
Unless the belt loses tension (indicating other issues) there is no way just the IP can skip teeth. The IP sprocket has lots of engagement area compared to the crank sprocket, so there will be timing off.
I had the injection pump jump time once, but I found out later that it was because the lower idler was locking up.
 

03_blue_jetta

Member
Joined
Sep 3, 2021
Location
Edmonton
TDI
2003 Jetta TDI
Hi guys - thanks for the replies!

Yes, I'm quite confident that it was only the injector pump that skipped. The advice from AndyBees was to: "set the engine on Top Dead Center. Then, determine if the Cam Shaft and Injection Pump are in Time." and that is exactly what we did. At TDC the cam and crank were in the correct position but injector pump was off by 4 teeth. We loosened tension and reset injector pump to (what I believe is) the correct position. Jokila, next time I'm back at my mom's garage (where my Jetta is RIP) I'll try to take that pic of the injector pump you asked for. And KLXD, no I don't believe any valves were bent. I say this because: first, when the problem originally happened (freeway driving then suddenly 0 RPMs) there was no noise or vibration of any sort. Secondly, when that mobile mechanic was "helping" he sprayed starter fluid into the air intake and the engine did sputter to life a little and no horrible engine sounds were produced. Lastly, every time I've looked the cam and crank positions indicate they have always been in their correct positions, so no opportunity for valves to get bent.

My best theory right now is air introduced into the fuel lines / pump. So looking for ideas to purge that.

Disclaimer - I'm certainly no master mechanic so take any statements I make with a grain of salt I suppose.
 

AndyBees

Top Post Dawg
Joined
May 27, 2003
Location
Southeast Kentucky
TDI
Silver 2003 Jetta TDI, Silver 2000 Jetta TDI (sold), '84 Vanagon with '02 ALH engine
We loosened tension and reset injector pump to (what I believe is) the correct position. ......... I don't believe any valves were bent.
I sense a little doubt ....

If a lock pin was not used in the Injection Pump Cog, well, it is likely still out of time. With the lock pin in place, the IP shaft needs to be set roughly in the center of the three bolt hole slots in the COG, and, of course, the Crankshaft and Camshaft in time at TDC. The IP can be out of time enough within the range of the three slots that the engine will be hard to start........... that's how sensitive timing is with an ALH engine!

Well, guys, I've been putting Timing Belts on VW Diesel Engines since before I purchased my first VW Diesel in 1980 (Rabbit with the little 1.5). I've never seen an incident where the TB jumped time on the IP cog. I've seen all sorts of things, but never an Injection Pump jumping cog teeth. I'm not convinced at all.

What else did the mobile mechanic do that we are not aware of?

I really hope all is well.
 

03_blue_jetta

Member
Joined
Sep 3, 2021
Location
Edmonton
TDI
2003 Jetta TDI
Thanks for the healthy dose of skepticism AndyBees, no harm in that. I will take the advice of Jokila to include a pic of the pinned IP. And yes, we did pin it when resetting its timing. However, if a photo is requested, I'm happy to provide one. It'll take several days, but I can provide that pic. AndyBees with your many years experience of doing this I'm liable to defer to your knowledge. It could be that I just *think* I've set the timing properly but actually haven't. Will check further into that.

Lastly you ask "What else did the mobile mechanic do that we are not aware of? " I can give a summary of what he did. And even he gave a disclaimer that he is not a TDI expert but more of a 'regular car backyard mechanic'. Anyway, He disconnected the air intake from the air filter and sprayed engine starter fluid into the air intake. Something you can do on a gasoline engine but he thought it was also fine to do it on my diesel. He had me turn the engine over a ton. So much that it eventually ruined my starter motor (ya, thanks Mr. Mechanic for costing another $150). The engine did kick and fire a few times, so he suspected a fuel delivery issue, so he disconnected the fuel lines that run from the tank at the back of the car to where they connect to the fuel filter in the engine compartment. He had me crank the engine some more and when he didn't see fuel spurt out he concluded the pump in the tank was shot. Little did he know that upon my own research there is no pump in the tank upstream of the fuel filter. It's downstream of the fuel filter. Little wonder he didn't see any fuel coming out of the lines at that point. So in hindsight this guy didn't know enough about a TDI engine and his assumptions and techniques all proved to be useless. Anyway, that was about all he did. He left me with this diagnosis that the <imaginary> fuel pump in the tank was not sending fuel.
 

KLXD

Top Post Dawg
Joined
Aug 22, 2009
Location
Lompoc, CA
TDI
'98, '2 Jettas
One wonders if the pump is having issues but I can't imagine what could cause it to lock up enough for the belt to jump but then free up again. Unless the plunger shaft itself seized and it broke. But what could cause that?
 

AndyBees

Top Post Dawg
Joined
May 27, 2003
Location
Southeast Kentucky
TDI
Silver 2003 Jetta TDI, Silver 2000 Jetta TDI (sold), '84 Vanagon with '02 ALH engine
One wonders if the pump is having issues but I can't imagine what could cause it to lock up enough for the belt to jump but then free up again. Unless the plunger shaft itself seized and it broke. But what could cause that?
The plunger shaft doesn't take much force at all to snap. I have one out in the garage from a VE Pump that's broke. The guy installed the pump dry. It had no fuel in it. He called me. I picked up his pump and disassembled it to find the plunger shaft broken and dry pump inside.

But, like you, I do wonder what might be going on inside the IP if it did in fact skip teeth.
 

jettawreck

Top Post Dawg
Joined
Aug 2, 2004
Location
Northern Minnesota-55744
TDI
2001 Jetta and 2003 Jetta
Hi guys - thanks for the replies!

Yes, I'm quite confident that it was only the injector pump that skipped. The advice from AndyBees was to: "set the engine on Top Dead Center. Then, determine if the Cam Shaft and Injection Pump are in Time." and that is exactly what we did. At TDC the cam and crank were in the correct position but injector pump was off by 4 teeth. We loosened tension and reset injector pump to (what I believe is) the correct position. Jokila, next time I'm back at my mom's garage (where my Jetta is RIP) I'll try to take that pic of the injector pump you asked for. And KLXD, no I don't believe any valves were bent. I say this because: first, when the problem originally happened (freeway driving then suddenly 0 RPMs) there was no noise or vibration of any sort. Secondly, when that mobile mechanic was "helping" he sprayed starter fluid into the air intake and the engine did sputter to life a little and no horrible engine sounds were produced. Lastly, every time I've looked the cam and crank positions indicate they have always been in their correct positions, so no opportunity for valves to get bent.

My best theory right now is air introduced into the fuel lines / pump. So looking for ideas to purge that.

Disclaimer - I'm certainly no master mechanic so take any statements I make with a grain of salt I suppose.
When you have a timing "event" at driving speed you won't hear any noises, more lack thereof as the engine shuts down. Plenty of posts to that effect.
Yes, with enough coaxing you can get a damaged engine to fire and sometimes even run a bit. My first TDI project (the original "jettawreck") was so badly damaged inside as to make it unsalvageable even to head guru Franko6, but it ran on the two remaining(?) cylinders briefly, no doubt doing more damage, not that it really mattered.
Any time there has been an "event" where timing is lost the valve cover should come off for a very close detailed inspection of the lifters, cam and all the valve train.
There is/was a reason for a slip/event. It doesn't just "happen" w/o a reason or cause.
 

noob_tl

Veteran Member
Joined
Mar 30, 2012
Location
Central Indiana
TDI
2003 NB
My best theory right now is air introduced into the fuel lines / pump. So looking for ideas to purge that.
The engine did kick and fire a few times, so he suspected a fuel delivery issue, so he disconnected the fuel lines that run from the tank at the back of the car to where they connect to the fuel filter in the engine compartment. He had me crank the engine some more and when he didn't see fuel spurt out he concluded the pump in the tank was shot.
Rereading this thread I don't see confirmation that the fuel system was properly bled. When the filter is disconnected the lines to the tank will empty. Cranking the engine with air in the fuel lines will move that air to the injector lines. The pump cannot clear this condition itself. Whatever other problems you might have, it will never fire until the air is bled from the fuel system (manual vacuum pump on the IP return line) and then the injector lines are bled by loosening the nuts at the injectors and cranking until fuel spurts out. There are several writeups and opinions about the best way to do this, but it must be done. If you can't prime the IP or bleed the injector lines, that may point you to other issues that cause a no-start condition.
 

AndyBees

Top Post Dawg
Joined
May 27, 2003
Location
Southeast Kentucky
TDI
Silver 2003 Jetta TDI, Silver 2000 Jetta TDI (sold), '84 Vanagon with '02 ALH engine
I changed an over due frozen Fuel Filter in a parking lot with the temp 20f and wind blowing .......... I used a 12 volt tire pump to purge the air from the system from the filter to and thru the IP. Then, while the owner cranked the engine over, I bled the injectors. The engine fired up and ran a bit rough as I took the RPMs up to about 1500 and held them there for about one minute! It is not rocket science!
 

Mozambiquer

Vendor , w/Business number
Joined
Mar 21, 2015
Location
Versailles Missouri
TDI
2004 VW Touareg V10 TDI, 2012 Audi Q7 V6 TDI, 1998 VW Jetta TDI. 1982 VW Rabbit pickup, 2001 VW Jetta TDI, 2005 VW Passat wagon TDI X3, 2001 VW golf TDI, 1980 VW rabbit pickup,
I changed an over due frozen Fuel Filter in a parking lot with the temp 20f and wind blowing .......... I used a 12 volt tire pump to purge the air from the system from the filter to and thru the IP. Then, while the owner cranked the engine over, I bled the injectors. The engine fired up and ran a bit rough as I took the RPMs up to about 1500 and held them there for about one minute! It is not rocket science!
Only 20? I did that once when I broke down in Minnesota in January driving my brother's golf. It was -23F and the filter froze. I realized he hadn't changed it in way too long.
That was a fun morning.
 

marcomurabia

Member
Joined
Jul 3, 2022
Location
MADRID
TDI
Mk7
I can't think of anything in the IP that would function as a cam position sensor. There's a crank position sensor and the #3 injector lift sensor that senses the injection event.
 
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Windex

Top Post Dawg
Joined
Apr 1, 2006
Location
Cambridge
TDI
05 B5V 01E FRF
This one is quite the (yet unresolved) saga...

At this stage, given everything tried, and descriptions thus far:

inspect the timing belt from the top with a good lamp and a small mirror - look for anything that would indicate missing teeth or any lack of alignment in the belt system.

If that checks out. Get a 12point 19mm and carefully roll the engine over by hand and note any resistance other than that of normal compression. the engine should go through 2 crank revolutions and one cam revolution and experience 4 periods of resistance and 4 periods of reduced effort as the engine passes TDC on the compression stroke of all 4 cylinders.

... If that checks out, rotate the engine until the crank TDC mark is aligned in the inspection window at the transmission bellhousing. If everything is aligned properly, you should be able to insert the 6mm pump pin (make sure you're not in the "sucker" hole) and you can verify cam by removing the vac pump on the rear of the head and see that the slot in the cam is completely flat and aligned with the cylinder head surface.

If it doens't check out, I would de-tension the belt, slip it off the pump, and rotate the pump by hand clockwise. It should feel the same as the engine on a smaller scale - four pulses of increased then reduced effort for each full rotation. If the pump caused the belt to skip time (doubtful), then something is massively wrong inside the pump and will feel wrong when turning it over by hand.


You need to do all of this, because as others have said, injection pumps on ALHs don't skip time on their own... They just don't. They will hold that belt and cause teeth to rip off at the smallest pulley - the crankshaft as already indicated above.

If all of the above checks out fine, then there is no plausible way the pump could have made itself become "3 teeth off"

Do all the above and report back. If it all checks out, then pull fuel through the pump to prime it, then have an assistant crank the engine while you crack the 17mm nuts at the injectors until they spray fuel, then re-tighten.
 

jokila

Vendor
Joined
Dec 3, 2004
Location
Houston, Texas
TDI
2003 Jetta GLS, Manual
Until he posts a pic of the pump pinned while the crank is at TDC, I am skeptical if the pump is at its TDC position. Wouldn't be the first time this happens while we all are throwing advice at the problem.
 

csstevej

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north nj
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2001 golf tdi 4 door auto now a manual, mine, 2000 golf 2 door M/T son's,daughters 98 NB non-TDI 2.0, 2003 TDI NB for next daughter, head repaired and on road,gluten for punishment got another tdi 2001NB,another yellow tdi NB
I’m thinking he has it pinned in the false hole at the IP ,maybe that’s accounting for the “ 3-4 teeth off “ , and he needs a serious bleed job…..
 
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