Kugelfischer mixture problem

T

tonch504

Member
Fellow Frogger
Joined
Nov 21, 2010
Messages
250
Location
Sydney
Hi all,
My 504 is idling a little rough. When listening to the exhaust note, there is an intermittent but distinct stumble or cough sound. Also, it smells like its running rich.
I have removed the plugs and found 1 and 4 to be dry but quite black and sooty (number 1 more so than 4). Numbers 2 and 3 are silver/grey. They may look wet in the photo, but they are not - it’s just the photo.
I have tested the cold start injector and found it to be okay. When the starter is operated the cold start injector sprays a nice fine cone shaped mist and then stops immediately when the key is released. It does not seem to weep once it stops. So, I think I can cross that off the list of possible causes. And it wouldn’t explain why number 4 plug is black anyway.
I have installed new plugs and swapped injectors 1 with 2 and 3 with 4.
I’ll now need to drive the car for a bit to see what results.
Can anyone suggest anything else I can try?
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tonch504 said:
Hi all,
My 504 is idling a little rough. When listening to the exhaust note, there is an intermittent but distinct stumble or cough sound. Also, it smells like its running rich.
I have removed the plugs and found 1 and 4 to be dry but quite black and sooty (number 1 more so than 4). Numbers 2 and 3 are silver/grey. They may look wet in the photo, but they are not - it’s just the photo.
I have tested the cold start injector and found it to be okay. When the starter is operated the cold start injector sprays a nice fine cone shaped mist and then stops immediately when the key is released. It does not seem to weep once it stops. So, I think I can cross that off the list of possible causes. And it wouldn’t explain why number 4 plug is black anyway.
I have installed new plugs and swapped injectors 1 with 2 and 3 with 4.
I’ll now need to drive the car for a bit to see what results.
Can anyone suggest anything else I can try?
Click to expand...


Try fresh fuel in it?

Which plugs are you running in it?
 
Will do.
Stale fuel affect each cylinder differently?
NGK BP6ES. Gapped at 22 thou.
 
I do notice that the plug that is dark has a different ,colour extension on it compared to the others ,could it be that ,the light coloured one is giving a weaker spark causing incomplete combustion and a fuel smell ,spose you could swap them over and see what happens .pugs
 
Just because the cold start injector shuts off cleanly with the key, it doesn't necessarily mean that it's working properly. Is the car difficult to start when hot? That can be another symptom.
 
BP6ES is the wrong spark plug. BP6ES is for a carby 504. Wrong heat range. I was sure that it is a BP7ES for a 504 Ti but on-line search seems to lead me to a BP8ES.

Anyway, from Haynes, for a 504Ti it's either a Champion N6Y, a Marchal GT34HD or an AC42XL.
 
Cold start injector may behave differently with a vacuum applied to it, as it would have during idle.
 
Thanks for the suggestions.
I'll try replacing the odd coloured plug extension.
The car is not particularly difficult to start when hot.
I'll install the correct plugs. But, would this cause the rough idle even before the engine has fully warmed up?
I'll rig up a vacuum and see what the cold start injector does.
 
Do you have a leaky/incontinent injector?

Given that you have different performance/mixture on different cylinders it is likely to be something specific to one cylinder ( or to three, leaving the fourth affected by compensatory tuning manoeuvres - richening of mixture etc )

A good diesel workshop could test the injectors

Specs are:

Factory opening pressure 30-38 Bar(new)
Minimum acceptable opening pressure 15 Bar

Should be continent ( not leak ) when held at 15 Bar for 5 sec
Good conical spray pattern

They are also susceptible to dirty fuel which fouls up the regulator valves in the pump

Big nasty is camshaft wear in pump due to failure in / neglect of oiling. This caused similar symptoms in my KF2 equipped 404

Full rebuild is eye watering, so I hope that the simple solutions produce an answer

Best Wishes

Andrew
 
tonch504 said:
Will do.
Stale fuel affect each cylinder differently?
NGK BP6ES. Gapped at 22 thou.
Click to expand...

you need to systematically eliminate each variable. For example. rough idle could be stale fuel.

Critical to Ti engines is:

- fresh fuel (95 is good)

- correct "heat" spark plugs

- correct plug gap (0.22" which you already have)

- high energy coil (not Bosch GT40)

- HT leads in good condition


Others may suggest other things like points gap to be 0.16"


Eliminate the simple things before spending money on the more expensive ones.
 
Given No3 plug is showing good colour I would stay at NGK 6 range for your use rather than a colder plug. I think you are on the right track with changing the injector positions to possibly move the problem. Currently I would go with dirty injectors dribbling or with a poor spray pattern. I would say your coil is fine, although leads could affect separate cylinders somewhat.
 
Thanks guys,
The leads are new, so I suspect they are good.

Will certainly do the easy and cheap checks first.

I’m thinking also to remove the cold start injector and plunging the hole and fuel line to see if that may be the cause.

How long, or how far, do you think I should run the car, to get an indication on the spark plugs?
 
Those Jaeger cold start valves are notorious. I've had two fail with exactly the same results you are seeing. The injection pump itself is almost certainly not the problem.
 
There is a kit to fix incontinent cold start injectors. It does involve some cutting and pasting on the old one, but looks well thought out. I have one but have not had to use it ( my problem was tracked down to somewhere else in the system.)

From memory, I think that Serie 04 had it , so if this proves to be your problem, a fix is not too far away

Best Wishes

Andrew
 
Another thing. If you have changed the motor without changing the altitude corrector on the firewall you can get a rough idle till the corrector is re calibrated
 
This morning I have removed the cold start injector and plunged the hole into which it screws (making sure there was no vacuum leak). The idle is exactly the same. So I guess it’s fair to say this is not the problem.

I’ve checked the compression. All cylinders are the same.

The Altitude Corrector is mismatched to the pump. However, I would think this would affect all plugs the same way. Thoughts?

Given that I’m trying to resolve a rough idle, I have assumed that the different coloured plugs is an indication of the idle problem. I guess they could be caused by different problems, but am I’m looking in the wrong place? I guess the odd coloured plugs is something which needs to be resolved anyway. Right?

Also, I have now noticed that even when I increase the engine RPM to 2000 and higher, the roughness, or stumble, is still there.
 
I still think the altitude corrector could be the problem.If you dont have the original one that came with that motor then that one needs to be re set.Im not sure how its done but it might make all the difference. Ive had one reset by a Peugeot mechanic and I think it was a simple job.I had one adjusted by a mechanic once and it seemed a simple job.
 
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