83 Jetta Coupe Turbo Diesel Build Thread

[fatmobile]

Absolutely not. You should not mess with the injection pump if you don't know what you are doing. It has nothing to do with the wastegate. If you turn your fuel screw up too much you risk a runaway.

Too much fuel left over after the burn can cause the RPMs to hang but won't cause runaway.
That's when engine is running on it's own oil and shutting the key off won't stop it.

In other news. noticed yesterday had a little fuel leak on the number four injector. tightened the line and saw bubbles coming up from the threads. so decided to see how many might be leaking. 1 and 4 appeared to be letting pressure out. then i used brake clean to clear what I used to check for bubbles.... found out number 2 is sucking A LOT in than it is letting out. revs jumped really HIGH. engine isnt' damaged but definitely have some leaks.

An injector won't pull fuel in. You sprayed too close to the intake.

20psi at idle is realy good.
If a buzzer is going off at idle; check you low oil pressure switch. It's going off too early.

[GTIVWMK2]

An injector won't pull fuel in. You sprayed too close to the intake.

20psi at idle is realy good.
If a buzzer is going off at idle; check you low oil pressure switch. It's going off too early.

No I don't think I sprayed to close to the intake. Intake is different than the NA diesels it's off to the left infront of the tire. I swapped the sensor's from a 1.8L Hydro block I have and the low switch off the orginal head and still buzzing. Maybe I'll buy new ones instead, also could be possible that the sensors are different.....

[GTIVWMK2]

Just looked it up. high is 1.4bar (20.58 psi) and low is .3bar (4.41 psi). Same on all models. also thought that when low oil pressure is not met oil light flashes when high isn't met it buzzs. Am I wrong?

[foxygrandpa]

There should be a "My oil warning relay is buzzing or oil light is flashing thread" with all the info one needs to fix haha.

Mine still is coming on too and even after changing all the oil pressure switches to brand new ones. I'm thinking at this point it has to be the relay because my engine runs fine and yet my relay doesn't seem to agree. And it's weird, mine doesn't come on when you start the car only after you rev it a little bit.

Anyway, sure hope you get it figured out soon. That buzzer sound haunts my dreams. I'm glad you are still plugging away at it. love this car.

[8v-of-fury]

Too much fuel left over after the burn can cause the RPMs to hang but won't cause runaway.
That's when engine is running on it's own oil and shutting the key off won't stop it.

It is not fuel left over after the burn, it is fuel still being injected at the right time. Rpm hang is not caused by l"left over fuel". Rpm hang is caused by the internals of the pump not being allowed to work properly due to frigging with tehesettings improperly. It will not cause an oil fueled runaway, but it will cause the engine to possibly reach unsafe rpms where it could destroy it self.

[GTIVWMK2]

There should be a "My oil warning relay is buzzing or oil light is flashing thread" with all the info one needs to fix haha.

Mine still is coming on too and even after changing all the oil pressure switches to brand new ones. I'm thinking at this point it has to be the relay because my engine runs fine and yet my relay doesn't seem to agree. And it's weird, mine doesn't come on when you start the car only after you rev it a little bit.

Anyway, sure hope you get it figured out soon. That buzzer sound haunts my dreams. I'm glad you are still plugging away at it. love this car.

The relay you speak of is inside the gauge cluster behind the speedometer. My friend said take it out... I think he's nuts because it's telling me something is wrong and that I need to fix it...

[GTIVWMK2]

It is not fuel left over after the burn, it is fuel still being injected at the right time. Rpm hang is not caused by l"left over fuel". Rpm hang is caused by the internals of the pump not being allowed to work properly due to frigging with tehesettings improperly. It will not cause an oil fueled runaway, but it will cause the engine to possibly reach unsafe rpms where it could destroy it self.

Agreed. Unfortunately after thinking of how the mechanics and the boost setup works if the throttle is not allowed to go back to it's proper idle position the pump thinks you are still on the throttle. the run on only happens when boost hits. so the pump thinks I'm giving it throttle and the diaphragm from the boost is hit by said boost and increases fuel mixture and with no load it just keeps climbing/stays steady.

[8v-of-fury]

Agreed. Unfortunately after thinking of how the mechanics and the boost setup works if the throttle is not allowed to go back to it's proper idle position the pump thinks you are still on the throttle. the run on only happens when boost hits. so the pump thinks I'm giving it throttle and the diaphragm from the boost is hit by said boost and increases fuel mixture and with no load it just keeps climbing/stays steady.

Sort of.

The LDA doesn't exactly work they way you describe. It only moves a limiter out of the way when given boost, it does not have any effect on off throttle fueling however.

When you are on the pedal before boost, the internal throttle hits a limiter. This limiter then moves out of the way directly relative to boost.

[GTIVWMK2]

LDA? Not sure what the part is actually called. Maybe I'll get the bentley for christmas. Not sure though Just thought of how awesome a gift that would have been when I was asked what I wanted for christmas...

[8v-of-fury]

The part with the boost pin and diaphragm in it. That is what the LDA, not sure what it stands for. But the boost enrichment is what it does.

[Ceepo88]

Gonna have to watch this thread, got a 84 Jetta myself i just picked up sadly it has low compression

[RabbitJockey]

The relay you speak of is inside the gauge cluster behind the speedometer. My friend said take it out... I think he's nuts because it's telling me something is wrong and that I need to fix it...

is it? on my 83 rabbit it was under the dash, i had the same problem i just took the relay out i checked pressure with a mechanical gauge a few times and it was always ok, don't know what the problem was i sold it like that and just gave the buyer the relay and told them what was up. i realize tho that an 83 rabbit has a totally different electrical system, but i have torn apart alot of instrument clusters and i've never seen a buzzer or anything inside.

[GTIVWMK2]

It is on my 83

[RabbitJockey]

perhaps a turbo diesel only thing. that 83 rabbit i had was an automatic and it had alot of the td specific stuff on it like cold air shrouding around radiator and the headlight for a cold air intake, oil water heat exchanger, coolant level sensor.

[GTIVWMK2]

Some of that stuff is pretty specific. Were you the first owner?

[XXX008XXX]

take that stupid buzzer out. you tested it with a guage and its 3 psi lower then what is supposedly "in spec" you also thought it had a spun bearing and it didnt... your making a big deal over nothing. the car sat with the window open for how many years? its all corroded inside there causeing these stupid electrical gremlins... the car runs and drives fine... you know it does... just because a weather beaten electrical 30 year old buzzer came on doesnt mean the whole engine has to come apart....

[RabbitJockey]

No I believe I was the 4th

[GTIVWMK2]

Well then it could have been changed. Although not sure how. Or perhaps they changed wiring setups. But I do know that most of those gauge clusters where all the same.

[GTIVWMK2]

So after much arguing with my friend. going to put the car back together and put a oil pressure gauge in the car and pull the buzzer

[RabbitJockey]

[fatmobile]

It is not fuel left over after the burn, it is fuel still being injected at the right time. Rpm
hang is not caused by l"left over fuel". Rpm hang is caused by the internals of the pump not being
allowed to work properly due to frigging with tehesettings improperly. It will not cause an oil fueled runaway, but it will cause the engine to possibly reach unsafe rpms where it could destroy it self.

What setting do you change to get the RPMs to quit hanging?
Due to these settings; the governor won't keep it from over-revving?

When the coller is removed from the max fuel screw and fuel turned up too high;
All the fuel can't burn and some is left over for the next cycle,.. in addition to the fuel added then.
This can cause RPMs to hang,.. fuel left over after the burn. Black smoke.

A poorly spraying injector can also leave fuel in the cylinder that builds up and burns on the next cycle,
causing RPMs to hang, from fuel left over after the burn. White smoke.

[rallydiesel]

Left over fuel doesn't make any sense. I believe Jeremy is correct. When the max fuel screw is turned up too high, the angle of the internal throttle lever is pushed "past the point of no return" and the spring isn't able to bring the lever back to the idle position.

[8v-of-fury]

What setting do you change to get the RPMs to quit hanging?
Due to these settings; the governor won't keep it from over-revving?

You need to slacken up the governor springs pull so they can accurately do their jobs. This is why you get hang when you rotate the throttle lever a spline or two to slacken the governor cage, and then raise the idle back up with the max-fuel screw.

When the coller is removed from the max fuel screw and fuel turned up too high;
All the fuel can't burn and some is left over for the next cycle,.. in addition to the fuel added then.
This can cause RPMs to hang,.. fuel left over after the burn. Black smoke.

[b]How can you believe that? Changing how much fuel you send in at injection time does not change the injection pressure of the fuel pump, or the break opening pressure of the injector. On a properly working injector, injection only happens right before TDC. Exactly enough fuel is burnt to maintain near Stoich A/F mixture, and the rest is expelled as black soot ie. half burnt fuel[ from the tail-pipe./b]

A poorly spraying injector can also leave fuel in the cylinder that builds up and burns on the next cycle,
causing RPMs to hang, from fuel left over after the burn. White smoke.

Seems to me you are also a small 2-stroke mechanic. Fuel getting built up for the next cycle? Are we going to foul our plugs from this rich mixture?? Kidding, but seriously. Now when you say poorly spraying injector, do you mean one that has a poor spray pattern? Or one that dribbles after injection has stopped? A bad spray pattern will do nothing more than hurt economy and performance. A drooling injector could melt a piston crown. RPM hang from left over fuel? Again, 2-stroke references? The engine can only sustain combustion with an ignition source, TDC of compression stroke is when this happens. As soon as that piston gets to BDC and the exhaust valve opens, that cylinder is done contributing to the turning of the crank until next compression. However neither a bad spray pattern or leaking injector will cause white smoke.

Left over fuel doesn't make any sense. I believe Jeremy is correct. When the max fuel screw is turned up too high, the angle of the internal throttle lever is pushed "past the point of no return" and the spring isn't able to bring the lever back to the idle position.

Yes, the governor springs get "over loaded" and can't hold the assembly back. As RPM's pick up this force becomes stronger, and the springs have an even harder time.. which is usually also why the rpms will hang and then start to sky rocket if you don't help them back down with engine braking.

Just a Little note;

White smoke is usually a sign of burning water, ie. Coolant, not usually ever fuel related.

Black smoke is always a sign of fully un-burnt fuel, ie. Rollin' COALS. Not timing related, and not A/F mixture related.. despite popular belief.

Blue-Grey smoke is a sign of improper combustion, ie. retarded injection timing. The fuel is not given enough time to fully burn in the cylinder, so it burns on its way out the exhaust valve but not fully.. thus the colour.

ps. It worries me to see such false information spewed around the web.

[RabbitJockey]

mine have smoked pretty white before with very retarded timing, just putting that out there.

[8v-of-fury]

mine have smoked pretty white before with very retarded timing, just putting that out there.

Probably, but not as white as coolant burning. Therefore it is Grey. An off white with a hint of dark.

[rallydiesel]

I would say that raw fuel smoke is as white as coolant smoke. But you can easily smell the difference. And raw fuel smoke will be associated with a poorly running engine at idle with an obvious misfire.

[GTIVWMK2]

It's still parked for the winter. My daily got rear ended so I have had to put all my attention and money in to making another daily. Although the 83 is not being dailied right now because of the salt and snow on the roads periodically. I plan on getting antique plates for it and Hagerty's insurance. so it will be able to be driven when needed. It is started multipule times a week as I have to pull it out in order to work on the 90 I'm putting together. Put the manual oil pressure gauge in and when it's cool out oil pressure stays at about 22 pounds but I'm willing to bet if I was driving it around and not just idling it would drop lower than that. as I have had to start it shut it down and then try and start it again 5 minutes later I have found that the injectors are definitely bad as I thought they were. hopefully I have enough money left over after putting the 90 together for new injectors. $310 before cores.

[fatmobile]

This post is very hard to reply to,.. because of the posting inside the quotes for my posts.
I'll try to address your [B] comment first.
"[b]How can you believe that? Changing how much fuel you send in at injection time does not change the injection pressure of the fuel pump, or the break opening pressure of the injector. On a properly working injector, injection only happens right before TDC. Exactly enough fuel is burnt to maintain near Stoich A/F mixture, and the rest is expelled as black soot ie. half burnt fuel[ from the tail-pipe./b]"

Where did I say it changed the injector pressure? Or the breaking pressure?
Sounds like you made up something I said so you could argue in favor of something everyone agrees with.
You know removing the collar and turning in the max fuel screw will increase fuel?
And you can't possibly think increaseing the fuel increases the pressure somehow because I
don't know anyone who thinks that. I certainly can't believe it and wouldn't/didn't make that statement.

Oh wait you do know it adds fuel because you know it creates black smoke out the tailpipe.
And it sounds like you think you can have half-burnt fuel out the tail pipe but no left over fuel after the burn.
That doesn't make sense at all to me.

Next point:
"Seems to me you are also a small 2-stroke mechanic. Fuel getting built up for the next cycle? Are we going to foul our plugs from this rich mixture?? Kidding, but seriously. Now when you say poorly spraying injector, do you mean one that has a poor spray pattern? Or one that dribbles after injection has stopped? A bad spray pattern will do nothing more than hurt economy and performance. A drooling injector could melt a piston crown. RPM hang from left over fuel? Again, 2-stroke references? The engine can only sustain combustion with an ignition source, TDC of compression stroke is when this happens. As soon as that piston gets to BDC and the exhaust valve opens, that cylinder is done contributing to the turning of the crank until next compression. However neither a bad spray pattern or leaking injector will cause white smoke."

Alot of stating the obvious but missing the point.
If you are saying a bad injector won't cause the RPMs to hang,.. I know that's not true.
I know just saying so or saying I have the credentials to make it the truth won't convince you,
nor should it.
Neither should a rant about how long I've been pulling pumps apart, we've both resealed
pumps for a long time. Probably can both pull the mainshaft bushing and ream it to size too.
,... but you know burn your money. I believe he worked at Gile's shop for awhile. Maybe both of us telling you bad injectors cause RPMs to hang might convince you:
"Check that you aren't pulling in lots of air in the fuel line, and then get your injectors tested. Bad injectors will cause hanging RPMs."
In this post:http://www.vwdiesel.net/forum/index....seen#msg112974

If we are jumping from RPMs hanging to white smoke.
It should be mentioned air in the fuel is a common cause of white smoke.
I was sure that was common knowledge but you instead say it,
"White smoke is usually a sign of burning water, ie. Coolant, not usually ever fuel related".
Joking but seriously; not a confident statement usually ever, ha.

While injectors with a bad spray pattern will also cause white smoke, I'm not sure I can prove it to you.
I thought it was common knowledge.
You don't have to believe it now but some day you'll figure it out.

What do we agree on: setting the max fuel screw too high
(and maybe setting the accelerator lever back a spline) can cause unburnt fuel, dense black smoke
and hanging RPMs.
You think none of the unburnt fuel it is left over in the cylinder for the next burn and
you might have changed my mind a little on that,..
I still think it contributes but might not be the main factor to hanging RPMs.
Though I still don't understand how the governor springs can be relaxed (foot off the accelerator)
basically sitting at idle and the lever it attaches to still won't be shoved back by the flyweights.
I have experienced hanging RPMs at idle, pull up fast and put the clutch in and the RPMs hang.
They don't go back down on their own but don't increase.
That can't be explained by left over unburnt fuel burning on the next cycle.
It isn't spewing out black smoke so there isn't lots of unburnt fuel left over for the next cycle.

I have experienced hanging on a stock 1.5 without the max fuel screw "floored".
On my first VW diesel back in the 90s, before I even knew how to change a belt or mess with the max fuel screw.
I believe that was poorly spraying injectors, something you say doesn't happen but Burn,
I and many other have experienced.

If disinformation worries you so much you should check your posts better before hitting Submit Reply .
I often find your posts informative and sometimes comical. Keep up the good work.