1984 Jetta , TDI WE MUST! (1.9 AHU M-TDI)

[8v-of-fury]

PM SENT

I have a weird idle issue. Since well.. installation of the TDI engine LoL. So just so we get up to speed on where my pump settings are. I have throttle lever set up so that the internal throttle is at its most relaxed position (throttle shaft as far CW to the levers CCW orientation as possible). With the external idle setting backed all the way out, I set my idle with the max fuel screw. Then adjusted the max screw out 1/4 turn and brought the idle up with the idle set screw. So my issue is this, If I leave it where it is to get a nice low hot idle I have like a 400rpm cold idle.. (no tach so I am just making a number up). If I raise the idle screw so that I have a cold idle, it is a few hundred rpm higher than I would like when it gets up to temp.

There does not seem to be a happy medium. Just as a note, I have had this weird idle issue forever. With the stock 1.6 pump, with the three different hand built m-tdi pumps, and now with this rover pump as well.

[QuickTD]

 In order for the idle governor to work properly there needs to be a certain amount of preload on the idle spring. This preload pulls the governor lever and increases the fueling as the engine slows and the governor weights retract. Conversely, when the engine speed increases the governor weights push against the spring and decrease fueling. The net effect is a balance based on the spring tension working against the governor weights.

 By setting your idle using the max fuel screw, you effectively take all the tension off the idle spring (1.9TD pump) or the governor capsule which incorporates the idle spring, rendering it useless as a speed governor. You need to allow more room on the low end of the range.

 Best practice is to back off the idle lever stop on a 1.9td pump or the throttle lever stop on a 1.6 style pump and then set the max fuel screw to barely idle or even stall. Next bring the idle speed up using the idle lever stop or the throttle lever stop until you have a satisfactory idle speed. You won't give up much fueling on the high end but you will get a stable idle using this method.

[8v-of-fury]

Ahh thank-you very much sir, this would be the exact reason it seems. I have always set them more or less the same way.. with the max fuel screw controlling idle lol. However, out of the three diesels in my driveway the AAZ is the only one that idles the same speed cold or hot, alternator load or not. It is set the same way, as I set it. The 1.6TD also has a bad cold idle issue, but does not have a throttle bump on the cold start at the moment due to a leaking throttle bushing.

I will try resetting both to the way you described. Thank-you for the advice.

[8v-of-fury]

So I tried and set it the way you mentioned QuickTD, and it did not help the problem at all. Unfortunately.

I reset the M-tdi and the 1.6TD. It helped the 1.6 a bit, but did not help the AHU. It will still idle, just ridiculously low. So I am not quite sure what is up there.

Also check this out! My rover pump is eating shut off solenoid plungers!




I replaced it last night with the one on the right.. and today it has yet again broken. I got a few weeks out of the first one, and it seems the pump ate it. I got 5 or 6 shut offs on the newer one from last night.. and it is yet again not killing the engine. Apparently it allows enough fuel past it still to not hinder running at all.

[QuickTD]

Is there anything about the rover pump that would cause the housing pressure to be extremely high? I can't think of any reason for the broken plunger other than extreme housing pressure causing it to "extrude" into the plunger fill port. I would look for a blocked "out" bolt or plugged return line. Maybe make up an out bolt with a fitting in it to measure housing pressure. Something is fishy there...

[410]

Looks like cavitation to me.I wouldn't be surprised if this is caused by your delivery valves.  IDI delivery valves have a completely different design then DI delivery valves.

[8v-of-fury]

Looks like cavitation to me.I wouldn't be surprised if this is caused by your delivery valves.  IDI delivery valves have a completely different design then DI delivery valves.

I dont't know about that. The DI Rover valves were identical to the 1.6TD valves inside. From what I could see anyway.

[libbydiesel]

It's not from the delivery valves.  The TDI delivery valves are a different design but there are a massive number of DI engines using the earlier style of delivery valve.  I've used them for a long time (a couple years) in my mTDI without any issues and have even swapped between the 1.6 delivery valves and the TDI ones and after making a little max fuel adjustment cannot notice any performance difference whatsoever.  

[410]

What does the seat look like now in the head?  Is it also worn just as bad?  That might be the reason why the second plunger no longer works.  Have you checked the voltage at the stop solenoid when running and when you shut it off?

[8v-of-fury]

It's not from the delivery valves.  The TDI delivery valves are a different design but there are a massive number of DI engines using the earlier style of delivery valve.  I've used them for a long time (a couple years) in my mTDI without any issues and have even swapped between the 1.6 delivery valves and the TDI ones and after making a little max fuel adjustment cannot notice any performance difference whatsoever. 

Yes I saw no problem running them as they looked like an identical valve compared to the DI Rover ones.

What does the seat look like now in the head?  Is it also worn just as bad?  That might be the reason why the second plunger no longer works.  Have you checked the voltage at the stop solenoid when running and when you shut it off?

The seat for the plunger? Or the rubber tip itself? The second plunger worked perfectly for two days lol. Then the same thing again.

I have not checked voltage, what do you suspect is happening?

[8v-of-fury]

So I thought I lunched my k03, it were a sad morning.. It was making a very weird metal on metal sound when higher boost was reached..

BUT when I got to work I found out that I had just broken my EGR cooler! YAY. The two broken pieces of pipe were I guess wiggling on each other when manifold pressures got up there, and causing gnarly sounds. Luckily I have a delete kit I bought anyway, so this is a perfect opportunity.

Pheww.

[8v-of-fury]

Removed my EGR cooler tonight, broke a damn stud off in the exhaust manifold too.. it has definitely been on there since factory.. ~500k kms ago..!

So needless to say it leaks, i was hoping the one may seal it.. but no chance. Now I have to fight with that stud.. some sticking out but not really any room to work vice grips. I also do not own a welder.

Crrrap.

[410]

It might be easier to replace the manifold.  If it were me and I had to save the manifold I would file the stud flat, center punch it, drill and tap it.  I doubt that the stud will come out using any other method.  

[libbydiesel]

Sounds like a good time for a turbo swap.   

[8v-of-fury]

I got about a thread and a half up when it broke off.. I was working it back and forth lots of quality penetrating oil, pisshed.

I honestly really love the k03, and I'm "never gonna give it up, never gonna let it down, never gonna turn around and desert it". Lmao. It is an extremely well suited turbo for 100% of my driving, 90% is like 75km/h and the other 10% is like 120km/h tops. It moves enough air to still have good power when you punch it at 120km/h which for my trans and tires is 3000rpm.

Yes I have been bitten by the nasty animal they call power addiction, but I was hoping to wait until spring.. haha