Injection Pump Timing Adjustment **Please Clarify**

Hey Everybody,

I just completed my first timing belt change (A4/ALH - followed DBW's how-to). Replaced fuel filter at the same time. The car runs well however it feels slightly more sluggish than before. My CEL is on and software tells me it is "Injection Start Control Deviation." I suspect my injection timing is not ideal following the TB change; which I intend to check/adjust tomorrow when my new Vag-Com arrives.

Before I go about adjusting the injection timing, I'm looking for a bit of clarification regarding which direction to turn which part in order to advance/retard timing.

DBW's write-up (A4 Timing Belt Change) says on page 110, #5 (Vag-Com Timing Procedure):
I read "pump" to mean the hub/shaft/center bolt...am I wrong in reading it that way?


rocketeer928 has a great write-up on How-To: Replace...Injection Pump without Changing the Timing Belt and in that procedure it states:

• Rotating the center hub (shaft) counter-clockwise will retard the timing, and rotating the center hub (shaft) clockwise will advance the timing.

So this contradicts DBW.

The manual refers to rotating the "sprocket":
In summary...to advance timing:

DBW: pump...counter-clockwise=advance timing
rocketeer928: hub/shaft...clockwise=advance timing
manual: sprocket..."right"(clockwise?)=advance timing

So I'm left confused.

As I currently understand it, rotating the hub/shaft clockwise has the same effect as rotating the sprocket counter-clockwise...but is the effect to advance or retard timing. If my understanding is correct, then rocketeer928 and the manual would be saying the same thing. When DBW says "pump," is he referring to the "sprocket"?

Anyone feel my pain?

Sure, I can wait for the Vag-Com and play around with turning things in different directions to see what the actual effect is...but I would be so appreciative if someone could help me settle this in my mind beforehand, I will sleep much better tonight.

Thanks in advance (no pun intended)

When you adjust the pump timing, the sprocket stays stationary, held in place by the timing belt. So what you are adjusting is the actual pump shaft relative to the crank of the engine.

The engine rotates clockwise, so if you turn the actual shaft of the pump clockwise, that will advance the timing.

The DBW writeup is backwards. its been known for a while, but no one has fixed the original writeup.

Rotating the hub of the Injection pump clockwise (top of wrench handle toward front of car) will advance the timing and raise the number on the timing graph (say from 40 to 65)

pushing the top of the wrench handle toward the firewall will retard the timing and lower the number from say 85 to 60.

best of luck.

gquenstedt said:

When you adjust the pump timing, the sprocket stays stationary, held in place by the timing belt.

Click to expand...

Right. I realized that which is why I was surprised to see the manual's instructions as they were.

Growler said:

The DBW writeup is backwards.

Click to expand...

That's good to know.

Growler said:

Rotating the hub of the Injection pump clockwise...will advance the timing. pushing the top of the wrench handle toward the firewall will retard the timing

Click to expand...

Got it. Plain English and confusion resolved.

That was what I expected but it's always great to have some verification/validation. Thank y'all for the quick responses!

And.... it's a very sensitive adjustment. Just a "hair" movement (rotation) of the IP shaft relative to the outer sprocket... produces a BIG change in timing. The gurus can often get it where they want in one or two tries. Greenhorns like me occasionally get lucky, but several tries to get it where you want... isn't out of the question. Fortunately, the process is fairly easy & quick.

What Corsair said, times about 10.

Prior to receiving the Vag-Com, I actually played around with advancing/retarding timing (making micro adjustments) and taking the car around the block just to see how the car responded. too much advance and the car starts sounding different and performance nosedives. I adjusted one last time back to where I thought it would run best until the Vag-Com arrived.

Corsair said:

Greenhorns like me occasionally get lucky

Click to expand...

Vag-Com arrived today...software downloaded, installed, and running in less than 5 minutes. Hooked it up to the vehicle and low and behold...injection timing within spec but (slightly) advanced (57-60 @ 131 degrees). I guess I'm one of the lucky ones this time around. I cleared the DTC and the CEL has not returned. The only stored code was the P1248.

The car still feels just a bit sluggish though. I'm new to both the diesel and turbo worlds. I've read about "limp mode" but I can't say I know for certain what that feels like or if my car is entering limp mode at all.

Can anyone point me in the right direction regarding next steps to take to diagnose/troubleshoot performance issues. The engine is stock with 260000 miles.

Thanks!

Make sure you have selected your car from the pull-down menu in the Timing graph.
Based on your signature, it's engine code ALH, pre-2003.

And make sure the engine is up to temperature.


There are some great threads regarding TDI Timing that are worth a read once you've understood the physical adjustment you're making to the injection pump.
It's interesting reading the different opinions of the "elders" of this forum.


As Corsair said, the adjustment on the injection is tiny! If you see the wrench move more than a hair, you've probably gone too far! It's not abnormal to 'chase' the timing up and down the graph the first few times you're doing this.

There is a significant difference in how the car feels between top and bottom of the graph. Bottom of the graph is retarded and you may notice better low end power. Top of the graph is advance and you may notice more top end power at the sacrifice of low end. It's a give and take. Get it to where you like it, and what matches your driving style.

I have a feeling that parts of Drivbiwire's otherwise superb How-To were copied from a procedure for an earlier vehicle (AHU/1Z motor) where one actually rotates the pump to set/adjust the timing...

Yuri

As a tip for any newbies reading this - the longer the wrench the more accurate you can be while fine tuning the static timing at the pump. I have a method I use that puts me dead in the middle between the green and blue lines almost every time. When I miss (in the lower half of the graph usually) I can usually hit it on the first adjustment because I use a very long wrench so I have a wider swing for a smaller adjustment.

Here is a trick I use when adjusting the pump.

I use a regular 22mm open/box wrench, about 12" long.

If I just grab the wrench and pull or push on it, I'm using the big muscles in my arms which aren't good at fine movements.

Instead, I place my elbows on the core support, then reach up with both hands and put them both on the wrench. You end up looking like you're praying.

I then use only my hands to move the wrench. The hands have smaller muscles and are better suited to small, fine movements.

I pull or push the wrench in the direction I want until I feel the slack is taken up. I look directly at the top of wrench so I see how much movement I get. A gentle push or pull is enough. If you can see the wrench barely move, that's enough. Tighten the three bolts and check timing in VCDS.

The sprocket has 44 teeth so 8 degrees per tooth. If you eyeball the wrench handle against the sprocket teeth you can easily see a half tooth of movement.

That's 4 degrees of shaft movement giving 8 degrees of actual timing adjustment.

Unless I've got it backwards.

Sorry to dig up an oldie, but we are having a heck of a time timing this engine. I'm thinking the pump moved internally as we have run out of adjustment. It is too advanced, and we have the timing mark right on, the pin in the pump, and the cam locked.
Is it possible the pump moved internally, so that this would be possible?
Our start of injection can only get down to 7.8, at the other end of the adjustment, the measuring block reads almost 28.
Any help appreciated.

Bdtc is the numbers to clarify

Never went by the numbers. I've always used the graph. Sometimes it gives an error message the opposite of what's actually going on if the timing is way off. I suppose it might do the same with the numbers since the data must be coming from the same sensor.

Any internal wear would tend to retard the timing.

The other possibility is the sprocket moved on the shaft. It's unkeyed on a tapered shaft like the cam sprocket. Is the paint on the sprocket nut intact?

Either way I adjust the pump sprocket the line is "too far advanced to be plotted" [/URL][/IMG]
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Gotta ask these:

The pump was pinned in the hole behind the sprocket, not the side of the boss the hole is drilled in?

Belt tensioned as follows:

Pump pinned
Pump sprocket bolts loose
Cam locked
Cam sprocket loose
Crank at TDC
Install belt
Tension belt
Verify Crank position
Tighten cam and pump
Verify crank position again

Everything still lined up after rotating engine an even number of turns?

I'm wondering if you had a tooth's worth of slack and the crank moved when you tensioned it.

Again, sorry for the newb questions but gotta make sure of everything since I wasn't there.

I don't think that error would cause your problem I think it would cause it not to advance when called for if it's real.

I replyed not sure where it went. Turns out it was the n108 comencement valve on the bottom of the injection pump. Swapped it over and reset the timing belt and it was spot on. Thanks for the help.

Ryan_m83 said:

Sorry to dig up an oldie, but we are having a heck of a time timing this engine. I'm thinking the pump moved internally as we have run out of adjustment. It is too advanced, and we have the timing mark right on, the pin in the pump, and the cam locked.
Is it possible the pump moved internally, so that this would be possible?
Our start of injection can only get down to 7.8, at the other end of the adjustment, the measuring block reads almost 28.
Any help appreciated.

Click to expand...

If this is following a belt change, simply start the timing bit over. TDC, cam up, pump pinned with slots basically centered. The center nut on the pump should never be loosened, otherwise the pump doesn't loose time. Likely something moved when you tensioned. Usually you will catch this when you rotate the engine twice by hand. Just do the belt again, you can jamb a screwdriver to hold the crank if you don't have a proper lock.

When setting the initial timing, you actually get a chance to zero-in everything just after setting the tension on the tensioner... before tightening the camshaft and pump sprockets, you can still rotate the cranckshaft a tiny bit to get it precisely in place (using the center bolt)... once it's lined up, then you can tighten the cam and pump bolts...

Yuri

BobnOH said:

If this is following a belt change, simply start the timing bit over. TDC, cam up, pump pinned with slots basically centered. The center nut on the pump should never be loosened, otherwise the pump doesn't loose time. Likely something moved when you tensioned. Usually you will catch this when you rotate the engine twice by hand. Just do the belt again, you can jamb a screwdriver to hold the crank if you don't have a proper lock.

Click to expand...

Nope I did the belt about 6 months prior and set it spot on the graph. I always rotate it 2x+ just to make sure as well. I have all the tools so nothing could have moved. It's been 1k now and still running like a top