Rough idle 1.6td

[Wltrc]

Got my 1.6td swapped into the zuk and running, but it is idling poorly almost like it's missing.
This engine has unknown mileage and is a 1989 I believe according to the casting numbers on the head.
Before I stuffed it in I did the following:
Timing belt
Intermediate shaft bearings and seals
Replaced miscellaneous leaking gaskets and seals
Set injection pump timing to 1.00mm

Seems to run very well off idle all the way up through the rpm range. Took it for a short run up the road and has good power, not billowing smoke of any color, just a light grey haze when I lean into the throttle.

Troubleshooting steps I have taken so far:
Triple checked cam, crank, injection pump timing. It's bang on.
Triple checked injection pump timing, also bang on(I've got the proper adapter and dial indicator)
Cracked all the nuts on the injectors to bleed out air.

Now when I cracked the 2 center injectors the idle stumbles and drops. But when I crack the 2 outside injectors the idle does not change. However, with the nuts on the 2 center injectors cracked the engine won't rev up. With them tight it will.

I'll try and upload some videos

https://youtu.be/_deCljLQDaQ

https://youtu.be/n2T8R8R6s9U

[rabbid79]

Very strange that when when you cracked #1 and #4, idle does not change. Based on that, and being that it's unknown mileage, I'd be suspicious of the condition of those injectors.

[libbydiesel]

Indeed, injectors are the next thing I would test.  With the injectors out I would also check compression. 

[Wltrc]

Small update, when I move the throttle and raise the the idle a few hundred rpm and crack the injector nuts it stumbles, all four of them. Going to order a compression tester and check all 4 cylinders. While the injectors are out I'll see if I can find someone to test them locally. It was also suggested that I run some diesel purge through the fuel system, so I'll do that tomorrow

[ORCoaster]

I am hoping that the diesel purge takes care of the rough idle.  The IP internal pressure might be low as well.  There is a regulator for the pressure on the front of the pump.  Pull a hose from the OUT bolt to a can or jar and measure the amount of fuel you get in 90 seconds at 1,000 RPM.  Should be about a liter IIRC.  The old IPs were designed to run on thicker fuel with sulfur in it.  You can't buy that now so perhaps your internal pressure is low and the injectors are struggling to pop correctly at idle. 

Seems like you got the right response from the engine by raising the RPM a touch and cracking the nuts.  That reduces the pressure and low and behold it stumbles. 

[Wltrc]

Ran a bottle of diesel purge through her this morning. It seemed to help smooth out the idle some but I'm still hearing something, not as bad as before but still there. But now when I crack the nuts the idle drops so that's something.

Waiting on a compression tester to arrive this afternoon and I'll check that box. In the meantime I pulled the injectors out but have no idea what I'm looking for in terms of damage haha

Seeing as how the diesel purge did help the problem I'm really hoping it's just an injector problem and not a compression problem. Will know soon enough I guess

Found a place semi local that will pop test the injectors for $40 so I'll line that up for next week

[Wltrc]

Compression numbers are as follows, starting at the timing belt side:
Cylinder 1- 330psi
Cylinder 2- 340psi
Cylinder 3- 330psi
Cylinder 4- 330psi

Not great but not terrible either? At least they are really close to each other so that's good. Next step is to get my injectors up to the diesel shop to get tested and possibly rebuilt.

[fatmobile]

 Turn the crank over by hand,
with the injectors in.
 How hard does it turn?
 Does it try to push itself backwards near the top of the stroke?
 I don't trust compression testers because of the extra space they create.

 Try advancing the timing.
 1mm might not be enough.

[Wltrc]

It's really tough to turn over by hand, almost rips the ratchet out of my hand, it does get and go backwards at the top of the stroke. What's a recommended advance?

[fatmobile]

 If it tries to go backward there is plenty of compression.
375 or more.
 If it was truly 330 it would be easy to turn.

 Got white smoke?
 Try advancing the timing.
 Make sure the cold start lever isn't out when you do it.
 Just change it a little. Then see how it works. Maybe 1.05mm.
The dial indicator just gets you in the area and let's you know where it's at.

[Wltrc]

Well getting the injectors professionally looked is quickly becoming an expensive endeavor, nearly $200 just to have them pop tested. I did find a set of new nozzles at a local European specialist shop but they are for an eco diesel. He could not confirm that they would work with my engine. Does anyone know if the nozzles were different between the two?

Very affordable at only $28 a piece

[libbydiesel]

The ECO nozzles will work fine. 

You might be aware, but it bears mentioning that the nozzle is only the one part of the injector.  It then would need to be installed into the injectors, pop tested, and breaking pressure set for a proper rebuild of the injectors. 

[Wltrc]

Definitely. I'll order the nozzles and build a pop tester while I wait for them to arrive, doesn't look too difficult. I'm a welder/fabricator by trade. Have a lathe at my disposal as well, had to build an extra long socket yesterday to get the injectors out.

[ORCoaster]

Kind of what I have experienced.  Buy new ones and trade in the old as cores.  Don't look back.  Yes, you can build your own if you have the right tools.  But getting them is like a one in 150,000-mile need.

[libbydiesel]

15 or 20 years ago I built a pop tester from a bottle jack.  I have used it quite a few times since then and it is still working fine.