98 TDI excessive smoke

alanack

Member
Joined
May 10, 2022
Location
Rhode Island
TDI
1998 Jetta
First post here....

So i bought this car in October 2021 because the price of fuel was killing me in my long owned and beloved 12v Cummins diesel Rams.... i commute 90 miles a day. Its 1998 Jetta AHU 5 speed

Anyways the car smokes like a friggen freight train..... since i got it. Normal throttle its grey-ish smoke, heavy on the foot its dumps out black smoke like an old mack dump truck.... car is a baby, has just over 150,000 miles on it.

When i bought it the PO replaced the pvc system, turbo, rad, some sensors.... and I further went through it, new vacuum lines, change over valve, glow plugs+ harness full timing belt service with WP, coolant& thermostat everything. Just changed the fuel filter with a filled with liquid moly diesel purge.

Timing verified using my scan tool a few times, ive put over 10,000 miles on the car and it doesnt seem to burn any oil, oil analysis reveals a slight fuel dilution (0.5% and sootly oil) poor combustion?
Other than smoke the car runs great, starts in single digits with ease, and has consecutively given me 48-52mpg US gal.... What gives?

On a side note i bought another one a 98 tdi that the engine was blown, so i had that swaped to a 1z by a reputable VW guy. because the original ahu dropped a valve... that car will not smoke no matter what you do, slight haze of idle on a cold start, but barely.
Im no stranger to diesels but this car has me stumped!
Thanks!
 

garciapiano

Veteran Member
Joined
Feb 12, 2018
Location
Southern California
TDI
1997 Jetta TDI (1Z)
Smoke is usually a fueling related problem. You're going to want to check that

A) your quantity injection value is within standard value range
B) Your turbo is actually providing full boost and your piping hasn't sprung a leak (usually this throws a code for an underboost condition)
C) Your injectors are not worn, clogged or outright failed. They could also be the incorrect injectors for the car, but unless the car is obviously modded I would not suspect that off the bat.
D) The boost sensing line to the ECU is good and not frayed or broken (also can - but doesn't always - throw a code.)

Since the car seems to run, I wouldn't suspect the injection pump. However there are a couple other sensors that also control fueling, including the coolant temp sensor and the fuel temp sensor on the inside of the pump, which I also wouldn't suspect.

All of these have been covered in extensive detail in other threads. I recommend searching the forum for the various procedures to check.
 

alanack

Member
Joined
May 10, 2022
Location
Rhode Island
TDI
1998 Jetta
I had a temp boost installed and the car would build about 12psi quick... every single vacuum line has been replaced. I swapped ECMs temporarily to see if there was a tune on it, no dice there. Coolant temp sensor was replaced when i did the glow plugs.

What is correct injection quantity? I do not have a vag com, but a friend with access to one.


Now im familiar with old diesels, mechanical injectors like these usually have a nozzle, an small indexing piece, spring and a shim. What is there to fail? I've seen the nozzles wear the holes out to a larger size on old diesel engines with literally 400,000 miles. Mines a baby with only 150 on it.

Something wack is going on that im missing, that fuel iq has my interest though
 

garciapiano

Veteran Member
Joined
Feb 12, 2018
Location
Southern California
TDI
1997 Jetta TDI (1Z)
Injection quantity and timing would be the first thing to check. If the timing belt was installed but the calibration was not set, the car could have the incorrect injection timing which can cause smoking.
 

alanack

Member
Joined
May 10, 2022
Location
Rhode Island
TDI
1998 Jetta
Timing is currently set at *57, target value according to my snap-on scanner, well within the limits....

Also the car smoked before i replaced the belt, so that leads me to believe its not a timing issues. Im thinking iq or injectors
 

Rig

Veteran Member
Joined
Apr 14, 2010
Location
New Mexico
TDI
1998 Jetta TDI, 210k miles
Yes, i would agree on the injectors, after everything you described.
 

burpod

teh stallionz!!1
Joined
Nov 27, 2004
Location
cape cod, ma
TDI
82 rabbit vnt ahu, 98 jetta vnt ahu, 05 parts car, 88 scirocco.. :/
take a log with VCDS - 011 + 001 + 004 all together, just make sure to keep pedal planted in a few various positions/rpms for a good 5 seconds each time. since logging 3 channels at once sample rate is low
 

alanack

Member
Joined
May 10, 2022
Location
Rhode Island
TDI
1998 Jetta
I have an AHU on the floor in my garage that has a messed up valve/ lifter im going to pull the injectors out of that and try and swap it....

Hopefully it didnt drop a valve and smash the tip off
 

burpod

teh stallionz!!1
Joined
Nov 27, 2004
Location
cape cod, ma
TDI
82 rabbit vnt ahu, 98 jetta vnt ahu, 05 parts car, 88 scirocco.. :/
next time car is hot, also check 001 + 004 and see what IQ and pump voltage shows at idle as well as actual timing.
 

alanack

Member
Joined
May 10, 2022
Location
Rhode Island
TDI
1998 Jetta
So the timing was so far retarded it didn't even show on graph. It was very difficult to time, literally had to push the pump as far forward as it would.... just to get it in the middle...

Next time i do the timing belt im going to advance the pump a few teeth on the belt...

Iq was at 2, hammer mod'd the pump and got it to 5.5. Car has was more power, much cleaner, and starts much more easily.

Still smokes if you are hard on the go pedal, but it just barely hazes at mid throttle instead of throwing a thick cloud all the time...

Also my spare motor has some issues i guess :)

Is #4 still a good core?
 

burpod

teh stallionz!!1
Joined
Nov 27, 2004
Location
cape cod, ma
TDI
82 rabbit vnt ahu, 98 jetta vnt ahu, 05 parts car, 88 scirocco.. :/
did you check cam/crank timing with lock tool for cam? that's really necessary to do! :)
 

alanack

Member
Joined
May 10, 2022
Location
Rhode Island
TDI
1998 Jetta
Yeah i bought the whole metalnerd kid to do the belt.

Cam lock, timing pin for the IP ect ect.

I read on line that some AHUs need the IP advanced on the belt otherwise you have very little to no adjustment left with rotating the pump.

My IP does leak the slightest amount when its extramly cold so maybe ill play with that next belt interval
 

Mongler98

Top Post Dawg
Joined
Mar 23, 2011
Location
COLORADO (SE of Denver)
TDI
98 Jetta TDI AHU 1.9L (944 TDI swap in progress) I moved so now i got nothing but an AHU in a garage on a pallet.
Sounds like the belt was not timmed properly. It's very common if you dont have a loos cam sprocket and a firm IP pin. The IP pin out is easy to be a bit off and if you dont have the cam sprocket loose while you tdc the engine it will all be off time in the retarded direction.
Easy to check by TDC the engine. If it's all correct then your IP is failing. But if it's off just a bit on the crank well you did the job wrong.
 

ToddA1

Top Post Dawg
Joined
Aug 3, 2011
Location
NJ 08002
TDI
'96 B4V, '97 B4 (sold), '97 Jetta (scrapped)
I still think it’s fine. Call whomever you’re sending them to, and ask.

-Todd
 

alanack

Member
Joined
May 10, 2022
Location
Rhode Island
TDI
1998 Jetta
Sounds like the belt was not timmed properly. It's very common if you dont have a loos cam sprocket and a firm IP pin. The IP pin out is easy to be a bit off and if you dont have the cam sprocket loose while you tdc the engine it will all be off time in the retarded direction.
Easy to check by TDC the engine. If it's all correct then your IP is failing. But if it's off just a bit on the crank well you did the job wrong.
I tell you i most certainly had a one hell of a time, getting this engine timed right.

It kept jumping on the flywheel.

The only way i got it on correctly, was to slide the belt on all the pulleys at once. Then when i tensioned the belt it stayed in time.

I recheck several times before running the engine.

I checked the the belt again after 5,000 miles and everything is still lined up. Crank/flywheel pointer, cam shaft lock tool, and the timing pin. Again i used the metal nerd kit which seems to be well made...

I think i scan see witness/ tool marks on the injectors so nozzles are my guess.

The car smokes very little now so im going to call it fixed.
 

burpod

teh stallionz!!1
Joined
Nov 27, 2004
Location
cape cod, ma
TDI
82 rabbit vnt ahu, 98 jetta vnt ahu, 05 parts car, 88 scirocco.. :/
When the crank moves when you tighten it, my experience has been the IP pulley usually is catching. Need to make sure it moves freely on the hub, after you loosen the pulley bolts, give it a tsp with hammer and make sure it rotates in hub easily
 

burpod

teh stallionz!!1
Joined
Nov 27, 2004
Location
cape cod, ma
TDI
82 rabbit vnt ahu, 98 jetta vnt ahu, 05 parts car, 88 scirocco.. :/
the cam pulley needs to be loose and locked, as well as the IP pulley loose and locked when you tension the belt, else they will move. if you managed to get the cam/crank timed without the pump pulley loose that's fine, just harder to do.

EDIT - this is only for ALH pumps, i keep forgetting this is a stock AHU, so no loosening of pump pulley... :oops:
 
Last edited:

Mongler98

Top Post Dawg
Joined
Mar 23, 2011
Location
COLORADO (SE of Denver)
TDI
98 Jetta TDI AHU 1.9L (944 TDI swap in progress) I moved so now i got nothing but an AHU in a garage on a pallet.
No. On the ahu there is no lossening the IP sprocket. It is either on or off. The ALH or a 11mm pump swapped ahu you can lossen the IP sprocket.
 

burpod

teh stallionz!!1
Joined
Nov 27, 2004
Location
cape cod, ma
TDI
82 rabbit vnt ahu, 98 jetta vnt ahu, 05 parts car, 88 scirocco.. :/
oops my bad - all my AHUs have been 11mm ALH pump swapped for a while, i keep forgetting! :) technically i think you're supposed to loosen the injector line nuts a bit when adjusting the timing on the AHU, else it might be possible that the stress can crack the pipes, at least from what i've read
 

turbodieseldyke

Veteran Member
Joined
Jun 6, 2010
Location
Free Mustache Rides
TDI
98 jetta
the cam pulley needs to be loose and locked, as well as the IP pulley loose and locked when you tension the belt,
Even though you can't loosen the IP pulley, you do need to remove the locking pin before tensioning. If the IP was still pinned, that may be why his flywheel was moving during tensioning. The belt is pulling on things, and something's going to want to move with it.
 

Mongler98

Top Post Dawg
Joined
Mar 23, 2011
Location
COLORADO (SE of Denver)
TDI
98 Jetta TDI AHU 1.9L (944 TDI swap in progress) I moved so now i got nothing but an AHU in a garage on a pallet.
Yep. You must have the IP sprocket fully locked when installing but it must be free when mentioning. This is why there is a manual adjustment for timing. It's best practice when having issues like this to put the IP as far down as possible (retard) then when doing it you will have the most room to get advanced.
Look. Everything ligns up... its within the graph... good enough.
You cant loosen the lines because you must do the job while running at operating temps.
You can if you have to set it all the way but typically it's not a lot of movment you get anyways.
 

alanack

Member
Joined
May 10, 2022
Location
Rhode Island
TDI
1998 Jetta
I always losen the lines after moving the pump to ensure they arent binding or under stress.

I did pull the the pump pin.

So next timing belt job.... pull the belt and with the pump pinned in place.... losen mounting hardware and set the pump as far back towards the radiator as possible?

And doing that should give me more room for advance? Or should the pump pin be out?

Right now all the way forward is pretty much dead center within the graph.
 

turbodieseldyke

Veteran Member
Joined
Jun 6, 2010
Location
Free Mustache Rides
TDI
98 jetta
On my most recent belt job, I pinned the IP in the right place, then unpinned, and after tension it ended up retarded. The pin wouldn't fit at TDC, it was hard to start, and smoky.

So I detensioned it, advanced the pump one tooth, then tensioned, and the IP ended up in exactly the right place, where the pin would go back in the hole at TDC. It was actually about 7-8deg too advanced, and throwing a 0550/p1248, so i had to retard it a hair by loosening the pump.

Your primary pump positioning should be done with the belt/pulley. Save the loosening trick for fine-tuning the timing.
 

alanack

Member
Joined
May 10, 2022
Location
Rhode Island
TDI
1998 Jetta
To be clear routating the pump towards the fire will advances timing....

So to advance timing on the gear/belt I would have to rotate the gear towards the radiator? Moving the timing pin below the hole?
 

ToddA1

Top Post Dawg
Joined
Aug 3, 2011
Location
NJ 08002
TDI
'96 B4V, '97 B4 (sold), '97 Jetta (scrapped)
Looking at the IP sprocket face, rotate the sprocket clockwise, to advance. 1 tooth will be all that’s needed.

-Todd
 

krook

Active member
Joined
Jan 13, 2021
Location
Hungary, Europe
TDI
AFN
oops my bad - all my AHUs have been 11mm ALH pump swapped for a while, i keep forgetting! :) technically i think you're supposed to loosen the injector line nuts a bit when adjusting the timing on the AHU, else it might be possible that the stress can crack the pipes, at least from what i've read
off topic, but what did you need to swap to 11mm ALH pump onto the AHU?
 
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