97 C230 cold start issues

[mks2005]

Hi all just a quick question really.

My mum has a 97 c230 estate but it has issues when first starting in the morning.. when pulling off it literally has no power at all, once its warm there are no issues at all.

How are cold starts handled with these engines ? is there are cold start valve I can replace or is it managed in a different way ?

Thanks in advance.

 

[silestanix]

Not good with petrol engines however it sounds like some sort or restriction... Is it hesitant or just lethargic?

Cold start is controlled by the ECU and coolant sensor, as with most modern petrol engines the ecu runs the car a tad rich on start up and once the engine reaches a certain temperature the engine relaxes fuelling a bit.

I'm hoping someone will come along and help you out...

 

[mks2005]

Its hesitant and it does not appear to be revving a bit higher as you would expect when the car is cold.

So maybe a sensor that triggers the ECU to inject more fuel is not working.. hopefully someone will be around to point me in the right direction hehe

 

[Steve@Avantgarde]

Usually a failing MAF on these engines is the only thing that gives trouble with power delivery.

Have you had the fault codes checked?

 

[mks2005]

Engine warning light is not coming on.. so guess there wont be any codes logged.. tho I can check.

As for the MAF I replaced it last year.. only an ebay one but the issue was there before and after I replaced it.. Main issue is I live in Spain and original merc parts are silly expensive so went with the ebay one.

Saying that I could pick up a bosh unit from Eurocar parts.. guess that would be a better option then a no make ebay one.

 

[Steve@Avantgarde]

I would say that there would be codes stored. You need to check. I would also say your MAF is the cause of all your problems especially with the cheap unit on there. A bosch one is the best way forward as they are the same as the genuine units.

Not always, but sometimes you have to readapt the ECU. It gets so used to running with a failed MAF that the base settings become corrupt and even if you put a new unit on there, it won't always run to spec. You need to reset everything down.

 

[ajlsl600]

sensor that controls cold start fuel time qty.

 

[mks2005]

Thanks for the advice Steve I think your right I should get rid of the cheap Ebay thing and get the Bosch unit as a starting point and also get everything reset.

Ajlsl600 do you happen to know the part number for it ?

 

[ajlsl600]

I would say that there would be codes stored. You need to check. I would also say your MAF is the cause of all your problems especially with the cheap unit on there. A bosch one is the best way forward as they are the same as the genuine units.

Not always, but sometimes you have to readapt the ECU. It gets so used to running with a failed MAF that the base settings become corrupt and even if you put a new unit on there, it won't always run to spec. You need to reset everything down.

will the fueling not revert to a stored map if the maf fails and run like that,at times fairly well .i think even the cheaper code readers will give a code for failed,failing MAF if i remember even a 30 quid ebay job did that on my clk which ran a little rough after it did not like a starter battery change

 

[LostKiwi]

will the fueling not revert to a stored map if the maf fails and run like that,at times fairly well .i think even the cheaper code readers will give a code for failed,failing MAF if i remember even a 30 quid ebay job did that on my clk which ran a little rough after it did not like a starter battery change

I think the issue isn't so much with the MAF having failed but giving incorrect values back to the ECU.

 

[Steve@Avantgarde]

will the fueling not revert to a stored map if the maf fails and run like that,at times fairly well .i think even the cheaper code readers will give a code for failed,failing MAF if i remember even a 30 quid ebay job did that on my clk which ran a little rough after it did not like a starter battery change

It runs on base adaptation data. But if that adaption data is so far out of spec then when it gets its new MAF it still can't correlate. You need to readapt everything. Had an ML320 do exactly the same this week.

 

[ajlsl600]

It runs on base adaptation data. But if that adaption data is so far out of spec then when it gets its new MAF it still can't correlate. You need to readapt everything. Had an ML320 do exactly the same this week.

got you, would have been handy had ecm stored origional maf,and other settings and rebooted to those when the cars ...brain..? realised that such a component was replaced.like , for example on some engines ,electronic injectors of say 5 plus yr ago the ecm stored the values and if you replaced them it would actualy run fine on those values,however newer types will not and require coding ,or trim files update.as far as i can make out ,makers ,frankly,deliberatly design difficulty and independent repair restistent features into their products. 70 percent of my day is spent overcoming this, with ,limited success

 

[Steve@Avantgarde]

Nothing is easy in life mate, especially with cars.