Help, AHU injection timing issue

[Poiuqf]

I’ve recently finished acquired a 1998 VW jetta tdi and it’s been driving fine with little issues, averaging around 40 mpg. I decided to hook it up to vcds to check the injection timing, and instead of seeing a yellow line from the bottom and left side intersect around the three colored diagonal lines, all I see is a vertical yellow line. While in basic settings, group 000, the value for block 2 is 255. Also the cold start valve value bounces between 60%-70%.

I tried adjusting the pump and it has to be advanced as much as I can put it to run decently, and adjusting the pump showed no change in the value 255.

The cam and injection pump are timed correctly, I think, as I can lock the injection pump at the same time as locking the cam with the plate but I could not notice a timing mark on the flywheel.

 

[Houpty GT]

Yellow line usually means timing is too advanced. Does it not say that at the bottom of the screen? The case is possible that you need to move the pump gear one tooth on the timing belt. When timing is way out, "TDI timing" is known to give incorrect information. It's a Timing for Dummies book.
I don't use the group 000 to set timing. I normally set it with cold start and target 3-10% when fully warmed up.
It is curious that your cold start seems to be telling you it is retarded, in contrast with the "TDI Timing" screen. I don't trust "TDI Timing."

When timing the belt, start with the pump and the cam locked. First remove the lock in the pump. Second, retime the belt so the flywheel is marked perfectly. This will knock the pump out of time but we adjust that after. Then lock the cam pulley.

Your flywheel mark is probably there but the pump is moving it out of the window on you.

 

[Vince Waldon]

Gonna be very tricky to time the engine (from both a cam and IP perspective) without starting it all off at a known-good TDC.

Has the flywheel got some rust on it, or are you thinking there's just no mark, period?

 

[Poiuqf]

Thanks for the replies, yes the flywheel does have a little rust on it and it could be possible I was rushing and it was dark and I just overlooked the mark, I’m going to look again when I get off of work. Could these problems indicated a failing cold start valve?

In regards to moving the injection pump gear one tooth, could this cause any sort of catastrophic failure with the motor? If the i.p was timed correctly and me moving it one tooth put it out of time? It’s weird because I’ve driven the car about 2000 miles averaging 40 mpgs. It does blow white smoke on cold start but clears up after driving the car just down the road.

 

[Houpty GT]

The injection pump will not cause any failures. Make sure you don't move the flywheel and cam out of alignment though or it is bye-bye valve time.

White smoke could be timing or old injector nozzles. Fix your timing cam timing, then your injection timing, and last, worry about nozzles.
40 MPG is not so good. I averaged 44 MPG with my old blue 1998 Jetta which had 289,000 miles on it. The best that car ever got was 49 and the worst I ever got was 41. You're getting 10% less which is significant. Fuelly says your average should be 44 or 45.

 

[Poiuqf]

Which way should I attempt to rotate the injection pump gear by one tooth? Clockwise or counterclockwise? I appreciate the information.

 

[Houpty GT]

Check the cam and flywheel timing first!
I would turn the pump way back first before you move the belt. Try it and see if Group 00 block 2 comes down.
My pump got stuck at 27 degrees BTDC the other day and it was loud and smokey and gave me only 36 MPG pulling an empty tow dolly.

 

[Mongler98]

Age of timing belt?
If you dont know... do a timing job NOW.
Your flywheel not aligning up means that the job was done poorly or it's very very old as these belts dont really stretch much and the usual misalignment is with the cam and the crank.
The IP has enough play in it that it will lign up with probably both bit not at the same time.

 

[Poiuqf]

I’ve adjusted the pump both ways, rotating it towards the front of the car, the car starts to idle worse and the number in group 000 block 2, value is 255 and doesn’t change. I will change the timing belt, recheck timing and get back with the results. Thank you.

 

[Mongler98]

If everything is done correct and within spec...... the car should not change idle at reguardless of olthe ips position to either extreem.
I've ran full above and below the line to see what the difference was and only 2mpg difference and maybe a slight less placebo power when at bottom of the graph.
You have something wrong here.
Order a proper belt kit... do the job... then worry about timing.

 

[valvecrusher]

and instead of seeing a yellow line from the bottom and left side intersect around the three colored diagonal lines, all I see is a vertical yellow line.

Timing is off scale HIGH, if you only see a yellow line....

When i was fine-tuning my 99.5 Jetta couple months back after a new TB/Wp install, I could adjust the IP off scale HIGH, to off scale LOW,
adjusting only the IP.(and even bumping IP without seeing it move the sprocket AT ALL)

If you read the TB install process by Runsonbeer(?)'s PDF, you will understand that loosening the IP bolts, and bumping only slightly causes Huge shift's in static timing....you might just need to be more slight in your IP adjustments...

on a different note, very important to align
Camshaft(locking plate into end of camshaft, drivers side)
Inj Pump(locking pin)
Crank(TDC mark)

These ALH's are extremely sensitive to undiscernible IP adjustments, with regard to timing..


I think someone WAY more knowledgeable and experienced than myself said, regarding IP timing after a TB/wp job....:
"If you see the IP sprocket move, it's too extreme of adjustment"


I adjusted mine 10 times before I nailed it...

After installing new TB kit, I was slightly below the middle line.....but I wanted it between middle and upper lines..

9 times I 'bumped it slightly' and it was too high, too low....etc
off scale high....below lower mark, above upper mark etc...



It's halfway between middle and upper line now, but I was super surprised at the precise descriptions by the TDI guru's,
and how they could NOT have emphasized it more accurately..

Also dont' adjust IP on an engine that not FULLY up to temperature(not even 5degrees low F)
It's that sensitive!

Good luck!

 

[Houpty GT]

He has an AHU. If it is stock, then he moves the pump to adjust timing. It is much easier than the ALH and can be done dynamically with bolts snug and the engine idling.

 

[Poiuqf]

I appreciate the information. I’m unaware when the timing belt was last changed so I’m going to do that before going any further. I checked the timing by locking the injection pump and cam at the same time, but I could not notice a timing mark on the flywheel, although its possible I just overlooked it because it is a little crusty looking. Although prior to checking timing, I’ve driven the car for about a month, am I safe to assume the crank is timed correctly because I was driving it with no issues?

Slightly adjusting the injection pump and/or drastically adjusting the pump, while idling, showed no change in group 000 block 2, value being 255.

 

[Vince Waldon]

The engine can be timed such that it runs and doen't smash valves into pistons, but that doesn't mean you're getting full power or fuel economy, and of course the white smoke is a strong suggestion of retarded timing.

I just use the timing graph in VCDS when I time an engine so not familiar with using block 2, but I'd guess that a value of 255 is "meter pinned"... particularly if you can't get it to change when you move the pump.

The other thing to recognize is that the cam-to-crank timing is important as well, and that can't be checked electrically.

I'd sure be inclinded to have another careful look for the TDC mark, so that you can start over and be sure both the cam and the IP are where you need them to be. It's the mark that everything else is set to, including where to lock the cam and IP.

 

[Poiuqf]

I’ve now rotated the motor, over a handful of times slowly watching the crank through the plug hole on the transmission. Cannot seem to see the TDC mark. Gonna go back out there in a little bit to have another look once my flashlight is charged.

 

[Vince Waldon]

Yeah, unfortunately there are flywheel kits out there with out 'em.... one of my cars as this issue as well.

Fingers crossed for ya!

 

[Mongler98]

I’ve now rotated the motor, over a handful of times slowly watching the crank through the plug hole on the transmission. Cannot seem to see the TDC mark. Gonna go back out there in a little bit to have another look once my flashlight is charged.

EASY... put a flat head screwdrivers tip against the flywheel as you rotate it. you WILL find it this way. i marked mine when i did the clutch with blue paint... that turned into blue paint covered in clutch dust like the rest of it and was IMPOSSIBLE to find as the piant had filled the line so it was harder to find. s flat head screwdriver as a feeler works like a charm.

 

[Mongler98]

Yeah, unfortunately there are flywheel kits out there with out 'em.... one of my cars as this issue as well.

Fingers crossed for ya!

WHAT? i highly doubt that! well any more... the writeup clearly states that you scribe the line to a new fluwheel if there is one missing so i know there was some out there but now... im not sure any exist. that isnt to say that OP may have one with no marking... Lukily the crank sprocket has a dimple on it that will indicate what TDI is but its not accurate as the flywheel is. it can be done via a glow plug hole and roap trick but its not exact... the ONLY way to clock the engine with the head ON is to replace the flywheel with one that has the marking on it as it can only be installed ONE WAY

 

[Poiuqf]

After some time of cleaning the crud, and other form postings showing me the screwdriver trick ^
I’ve found the timing mark. The timing mark on the crank is pretty much dead centered with the mark on the transmission housing, at the same time the injection pump pin can be inserted.

 

[Mongler98]

After some time of cleaning the crud, and other form postings showing me the screwdriver trick ^
I’ve found the timing mark. The timing mark on the crank is pretty much dead centered with the mark on the transmission housing, at the same time the injection pump pin can be inserted.

but let me guess. the cam is not!
if it is not... its an easy quick fix by just lostening the cam bolt and locking out the cam manually then tightening it back with a counter holder on the sprocket.
again... if you have no idea when the belt was done... i would not drive it will it IS done

 

[Poiuqf]

Just realized, while inserting the pump pin, after locating the mark on the crank. With the TDC mark lined up on the transmission housing, I was inserting the pin at a slight downward angle without noticing. Lining up the mark for the injection pump perfectly moves the TDC mark out of line with the mark on the transmission. Timing belt job will be done this week. Thanks everybody for the help and information.

 

[Mongler98]

Just realized, while inserting the pump pin, after locating the mark on the crank. With the TDC mark lined up on the transmission housing, I was inserting the pin at a slight downward angle without noticing. Lining up the mark for the injection pump perfectly moves the TDC mark out of line with the mark on the transmission. Timing belt job will be done this week. Thanks everybody for the help and information.

i only ever purchased 1 tool to do the job... the tentioner tool. i have made all the other tools and the tentioner is the one you DO want to have. WAY better than the POS i tried building many times. the rest is saww all blades and a magnet and a bolt the same size as the IP hole.. i used a bolt i had laying around and wrapped it up in HVAC tape. even the proper pin tool does have some play in it as well. the camp on the IP sure wants to make it not strait.
make sure you order a proper kit too. ID parts or German auto parts and so forth. avoid rock auto and anything from ebay

 

[TDIDaveNH]

Poiuqf, here's a little tip for ya on rotating the engine to find TDC on the flywheel. I usually raise both front wheels off the ground, pull off the passenger wheel and stick a screwdriver in the brake rotor vents between the caliper and it's carrier then put the car in 5th gear. This will allow you to rotate the engine by turning the front driver's side tire and be in the best position to be watching for the V notch on the flywheel when it comes around. I don't always, but I've highlighted the V notch with a white paint marker after cleaning it out well then placed multiple arrows on either side pointing towards it with a yellow paint marker to warn me to slow down hand turning the front tire.

Lastly: your Bentley manual will most likely show the cam sprocket torque spec as 33ft/lbs. That is known to be a bit on the light side in this community over the years and has allowed movement of the cam sprocket....not good. I always go to anywhere from 42-45 ft/lbs AND I wipe down the mating tapers on cam & sprocket with some acetone just before installation. do be careful to avoid getting any on the cam seal. If you study the marks on the cam sprocket's taper... I've also found that the fit is not what most would call 'hand lapped' the sprocket tends to fit tight on the cam at the small end of the sprocket taper so the surface area of engagement is far less than what you'd think it should be, hence bumping up the torque spec.

Good luck and just remember, TDC is not only everything, it's the first thing.

 

[Mongler98]

I don't always, but I've highlighted the V notch with a white paint marker after cleaning it out well then placed multiple arrows on either side pointing towards it with a yellow paint marker

I did that... waste of time and more hassle than it's worth. For me anyways... probably because of the 2nd stage clutch!
The paint attracts more clutch dust than the rusty metal surface of the flywheel.

 

[Poiuqf]

After redoing the timing belt, all marks now are timed, checked 5 times. Started up and ran good, little white smoke, When going to check the timing on the graph, it’s still reading 255, showing a vertical line. Attempting to retard the pump still showed no change in the value, advancing the pump as far as I can, to where the bottom of the pump was touching the metal piece for the accessory belt tensioner, the value then changed and fluctuated between 1-6.

Could the cold start valve stuck open calling for to much fuel?The cold start valve value consistently stayed between 70-80.

 

[Mongler98]

The QA should have no change to the timing.
It's not fluctuating is it? Might be a worn crank sprocket. Although its not as common on the AHU as it is the ALH it can still be worn down. But I would check a few other things first...
is the 3rd injector wireing harness in good shape? No corrosion?
Are you sure you have the right graph selected. My old days of vcds remembers that you have to select he ALH as the graph is the same for both engines but for some reason I could never find the AHU selection. But i could be wrong about that. It's been a while...
Since we know the timing on the belt sprockets is correct we should suspect the pump it could be wearing down... if you have not done the IP seals on the QA... go buy a set and take the QA off and inspect the lobes on the head and cam visually. Should be nice and shiny smooth with little to no signs of wear or lines. If there is.... I'm sorry but the IP may be trashed.
They can be rebuilt but I would suggest you swap it to the 11mm pump as the cost is virtually the same. Buy one on ebay and send it out to be redone.
Leta see if somone here can chime in with diagnosing the IP before we start tossing parts at it.
Good job on the belt. It's worth doing... so we know that really was not the issue.

 

[turbodieseldyke]

255 is usually in the Retarded range, even though Vagcom calls it Advanced. Yours probably needs to be advanced more.

 

[Houpty GT]

Waa wah wee wah! I came across this video was I was researching my p00550 code. Kansas City TDI had the same problem you did. The ecu is showing advanced and it had skipped a tooth in the retard direction. When it's too far out, I guess it just gets confused.

Reset the timing and move the gear forward one tooth.

 

[Poiuqf]

Waa wah wee wah! I came across this video was I was researching my p00550 code. Kansas City TDI had the same problem you did. The ecu is showing advanced and it had skipped a tooth in the retard direction. When it's too far out, I guess it just gets confused.

Reset the timing and move the gear forward one tooth.

On the video, he says he changes the cam pulley one tooth, does he mean the injection pump pulley? Moving the cam a tooth would put it out of time with the timing mark on the crank I would think.

 

[turbodieseldyke]

On the video, he says he changes the cam pulley one tooth, does he mean the injection pump pulley? Moving the cam a tooth would put it out of time with the timing mark on the crank I would think.

Correct, the IP is the one you can move. Cam and Crank must always be TDC.