Help me Mr. Wizard !

SledDawg2

Veteran Member
Joined
Feb 5, 2012
Location
Waterville, Me 04901
TDI
2002 Jetta TDI
Car info: 2002 Jetta 5sp manual
Symptoms:
Engine idles very ROUGH. Driveability is poor as is acceleration.
The engine smokes excessively at idle and under light to moderate acceleration.
I had no DTC's while driving !
Observations:
I checked the injection timing and it is within the specified timing range.
I verified the static timing and with the cam lock installed and pump pinned the reference mark on the fly-wheel is at the bell housing index mark.
The fuel filter was replaced 6K miles ago.
I thought it was fueling problem. I had a known good spare injection pump installed. The pump install was "text-book" but the problem persist !
This morning I performed a compression test.
All of the numbers were good in the mid 400's with a 40 PSI split between the high and low cylinder. (I was impressed with this data as the engine has nearly 250K miles.
The intake manifold is clean (EGR deleted long ago).
My next thoughts lean towards a "clogged cat" but befor I go that route I would like some further opinions.
While I await your wise advice and insights I'll take a fuel sample just to see what is in the tank. (This was advice from my wife :eek:!)

1st update: I removed the fuel filter and drained the contents into a glass sample gar. The fuel is clear and free of visible water.
 
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SledDawg2

Veteran Member
Joined
Feb 5, 2012
Location
Waterville, Me 04901
TDI
2002 Jetta TDI
Does anyone want to take a "WAG" at this problem ?
(WAG=Wild Ass Guess)

This is a shame...My car has been running flawlessly for nearly three years without a single issue.

While I'm waiting ... I'll reinstall the glow plugs, the fuel lines and reprime the fuel pump/ injectors.
Hope to hear some ideas ...?
 
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Mark Dempter

Veteran Member
Joined
Jun 7, 2012
Location
Caesarea Ontario, Canada
TDI
2002 MK4 TDI Golf, 1997 MK3 Jetta
What color smoke? Black / white / blue ?

Possible air intake system problem..? (Mass airflow, boost sensor, can monitor using computer).

I would unhook the mass airflow sensor and see if it makes the situation better, if so maybe clean / replace it.

My car had a clogged snow screen at the inlet for the airbox, could not see light through it. Its worth having a look at it..

I have seen split intake hoses allowing boost to leak out and cause rich conditions.
 

SledDawg2

Veteran Member
Joined
Feb 5, 2012
Location
Waterville, Me 04901
TDI
2002 Jetta TDI
Some more information.
I've re-primed the pump/injectors and have the engine running (again).
I've checked the boost hoses (no cranks or rips) the snow-screen was removed a long time ago. I also disconnected the MAF sensor and there is no change.

However !
There is a distinct rattle noise as if coming from the accessory section (Serpentine belt).
My question is:
Could a binding AC compressor or some other accessory component cause my problem?
I'll remove the serpentine belt and see if this will affect any change.
 

SledDawg2

Veteran Member
Joined
Feb 5, 2012
Location
Waterville, Me 04901
TDI
2002 Jetta TDI
Update #2

Update #2:
Removed the serpentine belt and started the engine.
The odd rattle noise is gone!
The engine does idle a lot smoother however there still remains more smoke than usual.
With the serpentine belt removed I found the alternator clutch is seized. but rotates in both directions.
Would a faulty alternator clutch be the cause of excessive rough idle ? :confused:

The AC clutch feels OK (the AC compressor is less than 2 years old)
The power steering pump pulley feels good (smooth rotation)

And ideas?

I'm still leaning towards a clogged cat... but I'm not 100% convinced.
 
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Mark Dempter

Veteran Member
Joined
Jun 7, 2012
Location
Caesarea Ontario, Canada
TDI
2002 MK4 TDI Golf, 1997 MK3 Jetta
The rattle noise could very easily be caused by the shock absorber that is part of the serpentine tensioner assembly. I had to replace mine as it made a annoying rattle. If you have a bad alternator pulley clutch you will cause the shock to get beat up faster than normal. Grab alternator pulley and spin it back and forwards quickly and you should be able to feel it spin the alternator internals one way and freewheel the other way. If not then it needs replacing.

Smoke Thats a big topic.. Fire up VCDS and have a look at the Injection quantity (search on here for the procedure). If your number is down around 1.5-2.8 then it is on the rich side. The engines like to run 3.5-5.0 which is leaner. It shouldnt really change on its own unless you fiddle with the pump (re-sealing leaks will cause the pump to need VCDS to tweak it back).

These cars dont report a Code for "Exhaust Too rich" like gas cars do. If the pump is set to run a certain fuel it will.. there is no O2 sensor or nothing looking at exhaust gases. I could be wrong but I dont think the engine can tell if an injector has gone bad (except the #3 with the lift sensor internal)
 

SledDawg2

Veteran Member
Joined
Feb 5, 2012
Location
Waterville, Me 04901
TDI
2002 Jetta TDI
update #3

The rattle noise could very easily be caused by the shock absorber that is part of the serpentine tensioner assembly. I had to replace mine as it made a annoying rattle. If you have a bad alternator pulley clutch you will cause the shock to get beat up faster than normal. Grab alternator pulley and spin it back and forwards quickly and you should be able to feel it spin the alternator internals one way and freewheel the other way. If not then it needs replacing.
Smoke Thats a big topic.. Fire up VCDS and have a look at the Injection quantity (search on here for the procedure). If your number is down around 1.5-2.8 then it is on the rich side. The engines like to run 3.5-5.0 which is leaner. It shouldnt really change on its own unless you fiddle with the pump (re-sealing leaks will cause the pump to need VCDS to tweak it back).
These cars dont report a Code for "Exhaust Too rich" like gas cars do. If the pump is set to run a certain fuel it will.. there is no O2 sensor or nothing looking at exhaust gases. I could be wrong but I dont think the engine can tell if an injector has gone bad (except the #3 with the lift sensor internal)
I should mention:
I have the Power-Plus 520 nozzles
The replaced injection pump is an 11 MM upgrade
I'm running a stage 3 tune
There is a way to test for a "dead" injector. With the engine running "crack" open the injector B-nut to vent fuel from the top of the injector. This will cause the engine to noticeably jolt/ stumble as the open injector is no longer providing fuel to that cylinder. As you tighten the B-nut the engine will smooth out as fuel supply returns to normal for that cylinder. If you open the B-nut and notice no difference in idle then you have a "dead" injector assembly.
Tomorrow I'll install a new alternator w/ new clutch pulley (it's the original alternator so it isn't long for this world anyway (I do not want to re-visit this problem again during winter weather).
I will certainly look into serpentine belt tensioner.
As for the I.Q. with this inj. pump and these nozzles my I.Q. is running at about 8.5. I did the hammer mod and kept the default value.
 

kiwibru

Veteran Member
Joined
Sep 21, 1999
Location
Distant island in WA. state
TDI
Golf 2-door, 2k Silver. Red RTDI now gone but not forgotten!
Did you happen to actually look in the fuel tank under the back seat? You have any really cold snaps lately? Fuel pick-up may be blocked? You idle rough though so that doesn't make much sense unless it's really bad and fuel starved at higher rpm. Just throwing out ideas here...
How about pressure relief valve plug on the IP? Has the plunger walked out?
What does VCDS show for injector balancing for each of the units when running? Forget the actual channel, maybe it was 13?
 

SledDawg2

Veteran Member
Joined
Feb 5, 2012
Location
Waterville, Me 04901
TDI
2002 Jetta TDI
@UhOh
The MAF has just over 20K miles. With the engine at idle disconnecting the MAF made no difference in smoke or idle behaviour.
@Kiwibru
The check-valve in the fuel sender was removed years ago.
But thank you for the insight and pointer.
 

SledDawg2

Veteran Member
Joined
Feb 5, 2012
Location
Waterville, Me 04901
TDI
2002 Jetta TDI
Update #4

The new alternator is now installed.
Amazing difference ! I just can't imagine a defective alternator can have such a negative impact on the operation of this engine!
The engine idles much better but the smoke problem is still excessive (not nearly as bad as yesterday).
I've dialed the I.Q. to 5.5 and kept the default value at 32768.
The cat is going to be replaced. I've made up my mind. I've had the replacement unit on the shelf in the shed for some time. Waiting for a reasonable excuse to install a "Gutted Cat" and now I have my " Reasonable Excuse" at hand. :D
 
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