940 lambda and catalyst replacement
 

The emission warning light came on on my 1991 945 with the 2 litre non-turbo engine. I was a couple of hundred miles from home so I drove back with a slightly lumpy running engine.
The exhaust and plugs are very sooty black so I am certain the engine was running very rich after the warning light came on (running perfectly beforehand).

So my question is: Will all of that carbon in the combustion space and exhaust give me any problems if I just replace the lambda sonde and the catalyst? (I am assuming that the cat will be damaged by all that sooty carbon so intend to replace it).

My concern is that the sooty carbon in the combustion space and the exhaust upstream of the cat will simply ruin any new lambda sonde and cat that I fit. Do I need to do any cleaning up (if that's possible?) to remove the carbon?

Thanks for any informed advice!

Best regards

Ian F

p.s. I've also posted this request for advice on the US Brickboards forum

I would NOT just replace the lambda sonde and the catalyst. That is starting a process of spending money speculatively. And so far as I have noticed, forum members don't seem to usually find those items are the cause of problems....

To begin, which specific engine has your car got? That will help the informed people to advise.

Informed people will be able to give you further and better diagnostic advice. But as a start, does your car have a built in code reader? Possibly a little black box in the engine compartment with a built in probe? Or. Would one of Loki's code readers suit your car? Either way I would start by reading for any codes.

B 200F 2 litre non-turbo

OBD readout is 2-2-1 "Fuel supply is too weak in part-load stage"

Not sure what else might be the best starting point........

Helpful?

Ian F

Thank you.

I think informed people might find tht interesting. I hope so.


I have a simple understanding of what that readout wording might mean. I shall keep my trap shut at least for now because gut instinct can be a bad mistake. ;)

I am no expert on this subject, but 2-2-1 is a non functioning lambda light, i.e. a problem with the engine management systems somewhere. So what's the cause? Looking at the Volvo 'Green Book' (TP 31361 for the LH 2.4 fuel system on a 240 B230F which will be the same for your engine, and is freely available for download on the internet) the problem is associated with air leaks on the intake system or fuel pump/pressure regulator. The Green Book takes you through how to make detailed technical checks. For what it's worth, my betting is it may well be a pressure regulator valve problem, but who knows. Best of luck ... Bob :)

Thanks for the reply Bob. Can you post a link to the "Green Book" please? I am very wary of downloading unvalidated manuals from the internet as have had problems in the past.

Ian F.

Looking on my search engine pretty sure it came from Scribd at: https://www.scribd.com/doc/126885359...anual-Complete

I d/loaded it and printed it some years ago now. As far as I am aware Scribd is an OK site which I have used in the past (you may have to register but can't remember now). My security set-up gives it the OK.

Bob.

Thanks Bob, will take a look,

Ian

I have a pdf of what looks like exactly that publication. Ian I don't know what the copyright position is. Maybe send me a pm telling me your email address.

It is for the 2.3 engine and I think for USA. It should be basically suitable for the 2.0 UK market engine.

Mine was downloaded from Scribd this year. I had to register and give a monthly payments authority and one has to remember to cancel the payments authority. ;)

EDIT: Cancellation looks to need two steps. Cancelling in PayPal ... and ... cancelling at the Scribd website.


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Thanks Stephen. That would be very helpful. I will send a pm this evening (after I have finished cooking dinner......)

Ian F