Color of turbo

[DJ Kill]

Today I change downpipe and remove cats from my RS2 and find that turbo wheel completely white.

I suppose that white color of turbo hot wheels point on the extremely lean mixture.
But I cant find any problems with the engine.
All parameters looks exactly as in manual (erwin RS2 workshop manual part for motronic ignition).

Can you give any suggestions what should I check?

[mike74]

Is there any fault codes stored?
Are you losing any coolant? Have you run any sort of fuel additive through the engine lately?
Might be worthwhile pulling a spark plug out to see what condition/colour its in for comparison sake

[DJ Kill]

Is there any fault codes stored?

It was checked first of all. No.

Are you losing any coolant?

Yes. But it goes through secondary coolant pump (new pump is going).

Have you run any sort of fuel additive through the engine lately?

No. Only 98 unleaded fuel.

Might be worthwhile pulling a spark plug out to see what condition/colour its in for comparison sake

Do it as soon as possible. But color of spark and turbo iы the consequence of any problems.
But on the first look everything looks good... And I didn't hear any detonation at all (lean mixture -> detonation). That confused me.

[SteveH]

Typically a normal mixture will leave the wheel pale brown. White would suggest it's a bit lean. Have you checked the plugs?

AFR gauge would confirm what's happening.

At least it's not burning loads of oil!

[diesel des]

Put an afr gauge on. Hard to go by just colour

[JariP]

I don't know what brand or blend of fuel you're running, but here white turbine blades only mean that the car is running on unleaded pump fuel. The color comes from the additives on fuel, it has nothing to do with running rich or lean. Maybe you can ask around other people running turbo engines in your town, what colors are they seeing.

[quattrostyle]

The turbo I've had were the same, would make sense if it's due to unleaded fuel.

[DJ Kill]

I've got also 1.8T engine and turbo looks different.

So, today I've got the problem on the road: it look like one cylinder stop firing fuel.
Engine tremble on the moving. After a few kilometers got a lot of smoke in exhaust.
It looks like one cylinder misfire.

But after few km all problems gone and then I come home and got VSCD everything on engine was Ok....

[DJ Kill]

So, the problem looks more deeper as I expect.

After a long idling (more then 3-5 minutes) there is a lot of smoke from the exhaust. And this is a fuel smoke not the oil.

I check all idling parameters and all looks fine.
The only one parameter that lays above limits it's the "Idle speed stabilization operating range"
Workshop manual says that on idling must be 121...135 but I've got 145-150.

Then I replace oxygen sensor.
"Idle speed stabilization operating range" downs to 136-138.
Nothing else changes.

What should I check next?
I suppose (but I'm not sure) that car losses the power.
And fuel consumption looks little bit higher then normal.

Also I've got problem with MFTS: temperature on dashboard stays about 110 C. But this problem stays more then 5 years and all works fine.

[simon20vq]

Might sound stupid but have you checked the spark plug and coil for that pot? Sorry re-read!! However I would swap the plug and coil to another pot and see if the problem 'moves' to that cylinder

[DJ Kill]

The problem didn't applied at any cylinder. I can't hear any missfire.

But I planed to change spark plugs, spark wires (small rubber tubes) and MFTS. Just in case.

Also I've got manual "Motronic ignition" and it's possible to check ALL thing that described in this manual, but it's quite a lot of work. Maybe someone can point me o the possible problem?