ALH newbie needs help / advice

Something interesting (and unexpected) was noticed when scanning:
Mass Airflow (Actual) at idle sits at about 300 mg, right about where the Mass Airflow (Requested) is.
As the accelerator pedal is pressed the requested goes up (expected), but the actual goes DOWN.
Is this worth investigating, or is this (like the cam and turbo bearings) just another item to worry about AFTER the main problem is solved?

If the air flow is dropping the allowed fuel is dropping.
Is the EGR sticking open?
This will limit your air flow and available oxygen.

Slip a block off plate in temporarily?

On the IQ, reading from L-R, the WOT from block 1.5 to block 3 is different than the WOT from block 7 to block 8.25. (I hope that makes sense) Were you doing something different those two times, or am I misunderstanding your explanation?

Nothing different. The graphs should have looked more alike.
The EGR actuator hose can be removed from the diaphragm and plugged, keeping the EGR valve closed, and the engine still does not go above 1800~2000. The EGR was connected and functional while the charts were produced.

But if the EGR valve is LEAKING...

True.... It didn't leak while being bench tested. I have some sheet gasket I can slip in between flanges to try.

Dead pedal

Could a bad wireless pedal do this?

It could reduce the maximum requested power, but it wouldn't cause the smoke.

He already said the the pedal returns a full 0-100%. I've had 1-2 AHU ECUs fail to provide throttle input to the pump while still registering on VAG com but he also claims no codes and ALH ECU failures almost always result in a whole passel of codes

Blocking the EGR flow with a hole-less gasket did not improve the condition. If anything it is worse, only 1200 rpm max.
Now that may be because the engine is cold. I'll leave the block in place and try more thoroughly tomorrow.
Or it could signify that the EGR is running the engine and the fresh air is being starved. Blocking the EGR further reduces the air and produced an even lower max rpm.....
So I pulled off the rubber hose between the intercooler piping and the anti-shudder valve, leaving atmospheric, but unrestricted, air available to the intake manifold and still had 1200 max rpm just now.

I have another DBW pedal (B4, though), but if the INPUT to the ECU shows a smooth 0 to 100% then I don't think swapping would be more than a waste of time.
The OUTPUT from the ECU? It seems to work OK (until the immobilizer shuts everything down) when my ECU and pump are in her Golf. Her ECU and pump produces the same low max rpm, max smoke in mine as my ECU and pump do.

Lug_Nut said:

Nothing different. The graphs should have looked more alike.
The EGR actuator hose can be removed from the diaphragm and plugged, keeping the EGR valve closed, and the engine still does not go above 1800~2000. The EGR was connected and functional while the charts were produced.

Click to expand...

I wish I knew what that meant and if it was relevant.

Ok, I've troubleshot other diesels with these kind of symptoms. I think it boils down to two possible causes: Late fuel or lack of air.

You've swapped pumps and checked timing, so IP internal fault causing late fuel is off the list. Timing is controlled dynamically by IP cam positioning piston, with inputs from #3lift sensor and crank position sensor. Starting to think like Dan...Maybe something up with crank sensor as dynamic timing control COUNTS on that being right. An o-scope look at that might be worthwhile. Maybe a quick swap of the sensor.

With head off did you check tdc fw mark accuracy relative to actual piston tdc? Sure is easy with head off.

Air: When head was off did you pop out intake valves and verify no buildup?

With aftercooler outlet hose off egr, does air blow out of the hose?

Thinking aloud..

Eric

Ski in NC said:

Maybe a quick swap of the sensor.

Click to expand...

That's what I said, it seems like a very easy thing to try anyway. One bolt and out it pops.

With all that sludge, could the followers be stuck in a collapsed position? This would cut down on air flow.

dodgediesel said:

With all that sludge, could the followers be stuck in a collapsed position? This would cut down on air flow.

Click to expand...

This seems plausible. Valves not opening would also result in the low compression readings.

from 1st post:Compression is a bit low, but for 250k miles it isn't bad at 330, 345, 345, 330.

Click to expand...

dodgediesel said:

With all that sludge, could the followers be stuck in a collapsed position? This would cut down on air flow.

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I like it too.

I doubt collapsed followers would do it. Easy to check though. Pull cam cover and pick a follower with cam lobe not pushing valve open. Try shoving say a 0.020" feeler between cam and follower. No go means no collapse.

re: post #41, relevant, only based on an earlier post inquiring about the EGR valve seal integrity. I probably shouldn't have replies to two posts without identifying them.
post #42: TDC does coincide with the flywheel marks.
post 42~46: The valves were not removed from the head, but the cam was left in place the second time and it was rotated to assure that all the valves opened to permit visual inspection of the soot buildup condition on the stem side of the valves.
I don't hear the tappetty-tap of the lobes that I'd expect with followers that don't pump up, and .020 would make noise, but wouldn't reduce the air flow all that much. I had flushed the followers as best I could the first time the cam was off (submerged in 5w20 and stroked to displace crud oil and draw in the 5w20). None of the followers failed to exchange the oils. I believe all are functioning and holding pressure.

Aftercooler: That is where I'm heading today. The complete obstruction of the EGR air flow last night resulted in a reduction to a maximum 1200 rpm (maybe because the engine was cold, but maybe not).
Maybe the issue isn't air not getting in the intake (excess fuel smoke, low max rpm, but good idle) but may be air not getting OUT the exhaust. I've cleaned the turbo from the vanes out and from the head down as far as I can, but a restriction at the scroll could reduce air flow through the turbo just prior to the vanes.
This would be consistent with a number of clues:
Good idle and slow speed smoothness,
Excess smoke at higher rpm,
Lower rpm when EGR is blocked
Nearly stalls when EGR is open
I hadn't thought that last one was more than a 'red herring', but now it may make sense in the continually evolving theories.

Here's this morning's theory and the evidence on which it's based: So much restriction getting into the turbo that there is high back pressure even before the down pipe. So much restriction that high rpm isn't possible.
Air can't get out, so no room for air to get in (Excess fuel can also be insufficient air).
Blocking the EGR air flow prevents another path for exhaust to get out.
Opening the EGR when there is high back pressure before the turbo, puts too much O2 depleted air in the intake.

I'll write back within the hour with the report if leaving the EGR cooler pipe completely off made a difference.

Take the manifolds off entirely, block the turbo oil feed, make sure all your neighbors are gone, and start it up?

Symptoms could point to blockage in manifold/turbo scroll. Maybe take it off check for blockage. Maybe a torch cleaning?? Cast iron will tolerate the heat better than Al intakes, and they live through torch cleaning!!

Aftercooler can be checked for blockage with a shop vac.

Still could be some other turbo issue, as these things will not run right at all if turbo is dragging or otherwise not working.

Lug, I haven't installed that turbo I got from bloc. I could send it up to you if it turns out that you need it. It has a bit of drag but it will at least flow air.

Removing the EGR cooler to valve pipe did nothing but discharge about 1/2 the smoke under the hood.
As incongruous as it sounds, I think I'll try 'toofing' as suggested in post 49.

There apparently a market for Emperor's* brand TDI replacement parts, first introduced with the lightweight injector fork supports, now intake and exhaust manifolds are available. They are as expensive as the originals, but the savings on shipping these svelte components will save a lot.
If I don't get power back, at least the weight reduction will help performance.

* registered trademark of ToofTek

This thread is pretty interesting. I see many things have been tried. How about more bizarre then? Given how much sludge was in the engine... What about checking oil pressure while running? I like the collapsed cam follower idea, but maybe at idle it's ok. Possible worn oil pump?

All hail the Emperor!

bhtooefr said:

I'm kinda wondering what happens if you remove both manifolds, block off the turbo oil feed line, and try again, actually.

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bhtooefr said:

Take the manifolds off entirely, block the turbo oil feed, make sure all your neighbors are gone, and start it up?

Click to expand...

A replacement exhaust manifold gasket from the ToofTek "Emperor's" brand line of lightweight products has apparently been the solution. With the exhaust separated from the head by the 1/4 inch thickness of this miracle gasket that only those with good taste can see, the engine runs freely (and sootily) up to redline.
Now to pull the exhaust manifold yet again and find out where the restriction is.

I appreciate all the advice and moral support all have given to keep me progressing.
And Toof, your check, written in "Emperor's" brand ink, is on it's way.

I'm looking forward to the pictures.

Perhaps a BIG GTG at the Ho5g with BHTOOFR & Lug_Nut swilling "Emperor's" brand ink beverages....

Keep going Lug we need to see the A4 at second Friday!!!!

My guess is a mouse nest in the exhaust (now with a dead mouse) or a banana...an old banana....

Phew! I'd like to hear a diagnosis from you about what's going on with your exhaust manifold. Please.

The manifold and turbo look fine. I pulled the vane assembly and the backing plate out to confirm that the scroll is clear and unobstructed. A puzzle.
I'll just put things back on the engine one-by-one and try after each addition until I find the cause.

I think the compression is a bit low. It should be higher and even across the cylinder bank. Your experiance is far above mine, I need more turbo hands on. I think all that sludge did compression ring damage by restricting oil flow through the oil gallys. Low compression will cause those symptoms. I saw on a 2001 1.9 ALH Beetle it would only idle at 900 RPM, compression was shot. When attempting to actuate accelerater to 10% black smoke no higher revs black smoke. It was 300 psi 275 psi is dead limit Volkswagen says that their diesels needs rings and inserts. (Kaput) ( great for gasser @ 275)Pump timing advanced? Your very experianced and analysis humbled me. I hope you find the problem. Perhaps ECU issue, but seems VCDS is showing parameters