1.6D Cold Start Bad Stumble/Misfire - MK1

[moclovflop]

Hey All,

Over the past couple days, the temps at night have been in the 40's and 50's and in the morning I've been having a pretty intense stumble/misfire at first start up of my Mk1.

It lasts about 15 seconds before everything is running smooth again, and it's way more intense than the normal little hic-ups it might have if I forget to pull the cold start knob. It really feels like only 1 or 2 cylinders are working, Like "WHOMP.....WHOMP....WHOMP"

With the stumble is a bunch of white smoke. Once the engine finally smooths out (15 seconds later), the smoke is gone as well.

I was thinking it was bad glow plugs, so I've ordered a set and a new relay just in case (not here yet). HOWEVER I'm also thinking they aren't the issue because even though it has a misfire, it starts on the first rotate when cranking. Meaning one turn and everything catches. I'm not sitting there cranking, which would be more of a symptom of bad plugs. This also makes me think compression isn't an issue, and power/idle after this is the same as it's always been.

No issues with speed or smoke, and it starts/idles like normal when engine is warm, or warm-ish (sitting for 4 hours). Seems to only be after a cold night/long sit.

    Notes:

    - This happens with the advance knob pulled out, which is how it has always been started even before this began. Once It is smooth, it will spudder a bit if if push the knob in (if I do it before about 1 minute of warming up.) After 1 minute, nothing changes with knob in or out.
    - I'm leaning more towards stuck injectors. Mainly because it clears after a short time, and the smoke also makes me think fuel isn't burning as it should.
    - No air bubble in the lines. But that doesn't mean the pump isn't leaking at a seal or something that I can't see. Maybe it's full of air and I don't know it?
    - Haven't tried touching the throttle during any of this for fear of something breaking.

I Have a set of injectors I was thinking of having rebuilt, they might be due anyways.

 Anyway, let me know your thoughts. I'm tempted to rotate the pump to get a little advance, but don't want to mess with that until I rule out some other issues.



TL;DR: Bad misfire when cold, white smoke, all clear after 15 seconds. No loss in power. No issues with warm start. No air in lines.

    Thanks!

[theman53]

99% glow plugs, If it was anything else it would not go away as soon as the engine has a 10 degree warm up.

[moclovflop]

Makes sense. Thanks. I'll install the plugs/relay and report back.

[air-cooled or diesel]

your current relay sounds like its good, 4 new glowplugs, some anti seize, should do it for you, i like the flange nuts, the 8mm's for the bar connection.

[theman53]

You have had a diesel before right? It is a diesel, it will smoke, it is not a gas car. You can and will have to live with a little smoke from these cars.

[moclovflop]

Not the smoke I'm worried about. The extreme misfire is the cause for concern. Again, it feels like it's running on 1 or 2 cylinders only.

[theman53]

Not the smoke I'm worried about. The extreme misfire is the cause for concern. Again, it feels like it's running on 1 or 2 cylinders only.

Is this your first diesel?
It can only be a couple of things:glow plugs, compression, air, or fuel. With the rest of what you stated you can probably narrow it down to glow plugs or fuel *ex:timing, air in lines*. Report back with something when you have something.

[moclovflop]

Yeah, first diesel, but not my first experience fixing stuff. I'm no novice, I know when things aren't right, even with a diesel. The symptoms I'm experiencing here go beyond normal "old diesel" clatter and daily mishaps.

Anyways, installed the new plugs and relay. Plug number one had lots of carbon build up, the rest looked fine. However, the new relay seems defective. Test drive went fine but it kept clicking on and off every 30 seconds or so. Multimeter confirms that it keeps charging the plugs on those cycles. It also shows the relay isn't turning off after starter is engaged. This was a Bosch relay so it's a little odd that it's acting up, but anything is possible.

Thinking maybe the plug had bad contacts, but dielectric grease did nothing to help. Disconnected the coolant temp sensor but that didn't help.

ReInstalled the old relay and it worked fine, so I'm leaving that in there for the time being even though it might be a slow-glow relay (no part numbers were visible, but it's something German, and has some age). I'll order a new Bosch one and see if there's a change.

It was too warm today for glow plugs to do much good in initial start up, so the car started up without issue before I even started to work on it. I should get an idea if the plugs helped tomorrow morning. Also might throw a new coolant temp sensor on for some maintenance.

[fatmobile]

 Try advancing your timing a little.
 Or you might have low compression.

[theman53]

Yeah, first diesel, but not my first experience fixing stuff. I'm no novice, I know when things aren't right, even with a diesel. The symptoms I'm experiencing here go beyond normal "old diesel" clatter and daily mishaps.

Anyways, installed the new plugs and relay. Plug number one had lots of carbon build up, the rest looked fine. However, the new relay seems defective. Test drive went fine but it kept clicking on and off every 30 seconds or so. Multimeter confirms that it keeps charging the plugs on those cycles. It also shows the relay isn't turning off after starter is engaged. This was a Bosch relay so it's a little odd that it's acting up, but anything is possible.

Thinking maybe the plug had bad contacts, but dielectric grease did nothing to help. Disconnected the coolant temp sensor but that didn't help.

ReInstalled the old relay and it worked fine, so I'm leaving that in there for the time being even though it might be a slow-glow relay (no part numbers were visible, but it's something German, and has some age). I'll order a new Bosch one and see if there's a change.

It was too warm today for glow plugs to do much good in initial start up, so the car started up without issue before I even started to work on it. I should get an idea if the plugs helped tomorrow morning. Also might throw a new coolant temp sensor on for some maintenance.

What did you accomplish with this? Did it fix it? If not we would like to know if you are to be helped. Help me help you.

Sounds like that relay is messed up, but if it is a newer one it will cycle long after the car is started. The big question is did it ever stop cycling after 5 minutes or so?

If it starts with no glow plugs as you say too warm for them, you do not have a compression issue. Nor is it likely you have air in the fuel. I really don't think you have an issue at all. Stumbling for 30 seconds in a compression engine when it is cold out is normal, so is smoke. If there are no issues driving then I don't think you have issues. I have an idi with lowered compression for boost, it starts fine down to 11f with no block heater, it smokes and stumbles and hates running for 30 seconds or so...then as the engine heats it slowly goes away. When the coolant gets up to 150f or so all issues are 100% gone. I say that to ask, is this similar to what you experience?

[ORCoaster]

Help me help you.

Had a laugh reading this as I saw the vid posted on the other thread and you are right.  I can't offer advice if you don't describe the problem well enough for me to screen some of the possibilities.  All problems start with the key right?  I turned it and nothing happened.

[air-cooled or diesel]

I was thinking it was bad glow plugs, so I've ordered a set and a new relay just in case (not here yet).
 

where did you order these parts from; not all bosch parts from discount places work like 'good' bosch parts, depending on where you bought them from(or other parts as well,,)

[moclovflop]

Parts were bought from AutohausAZ.

More info:

In addition to all the stuff In the first few posts, here's everything I can think of:

-Glow plug light timing hadn't changed - stays on 7-10 seconds.
- checked function of coolant temp sensor for the above. Grounded wire, Everything checks out
- reading full voltage at glow plug bar, so fuse isn't blown
- no air in lines
-running liquimoly Diesel additive every single tank.
- Bought diesel from same station I always have for over a year
- idle hasn't changed after the issue clears itself
- once everything is cleared, no more smoke than it produced 6 months ago.
- No less power than 6 months ago.
- Gas mileage is better than it was 6 months ago
- Starts without issue if it's warm outside.
- no fuel leaks
- no coolant loss or leaks
- no oil loss except normal seeppage
- Not burning oil
- Fuel filter was replaced 6 months ago
- oil was changed 4K ago
- Checked pump mounts and bolts, everything is solid, it didn't move.

I get it, everyone's car runs like crap, and everyone just deals with it, and your weather is colder than mine, and no one should complain about it because "that's just old diesels".But up until now, my car wasn't running like crap, that caused some concerns, so I came here. Last winter I didn't have an issue, last month I didn't have an issue. 2 weeks ago I didn't have an issue. Like you said, it would be one thing if it was -11 outside. But 40-50 shouldn't cause this much of an issue.

What else can I provide that would be helpful?

[theman53]

How many miles have you put on it since it started doing this and in the last year when you said there were no issues?

What is the IP timing set to?

How old are the injectors?

Did it quit since you changed the plugs?

How accurate is your measurement of liquimoly?

Is it the winter blend of liquimoly?

Do you have any moisture in your fuel?

Do you think you have a HG issue?

Are all 4 gp's getting warm to the touch?

Does it go away or get better if you let the gp cycle 2 or 3 times instead of 1?

Did you verify that the glow plug relay quit cycling? I think you stated the gp light is just a timer, which is correct. It does not signify that the glow plugs are working.

[air-cooled or diesel]

but from your 1st post it seems your current problem is solved, you didnt mention any other problem, is you car running like sh*t? it doesnt sound so, as a diesel esp w/o turbo it ll be slow, it only sounded like you had a starting problem, and yes at 40-50dg its a cold start, you need all glow plugs to work and cold start pulled to start, in both my idi's i have to use glow plugs even in the dead of summer, of course as it gets colder i have to use more glow plugs. sounds like you need to return relay for a good one, having a spare can be an easy fix for when the current one goes down. at this temp as long as you have winter blend of fuel and/or add your own, the liquidmoly ive found works real good for fuel lube/conditioning, you will also need anti-gel/winterizer for below freezing temps. if this fixed your current problem i think your ok, for now, the other things listed can be looked into depending of maintenance. excess smoke on colder and colder starts is normal, most smoke should clear up, for me within a mile or two.