Diagnosing Poor emission result W124 Petrol

[tjamesbo]

Hi Last year my 1993 220TE just scraped through on emissions so am looking to avoid a fail this year ,It gets an " italian tune up" on the way to the MOT centre which is 35 mins away so its plenty hot and had a good high rev clear out on the way Current thoughts ;
1 I have used dipetane in the past cant remember whether any was in last time or not but some will be going in this time for sure
2 perhaps a dose of cataclean would be a good pre measure not expensive
3 run some injector / fuel cleaner now well before the test ( due 11th Feb )
not done many miles since replacment cat was fitted and same for lambda sensor
4 Clean Throttle Body ?
5 New Air filter ( oils is fresh only done a 1-2000 since changed in august )

Any clues from the readings ? i know there are some that can read these and tell what needs doing and how far away from what it should be it is

It seems to be the Hot Idle thats the problem (Fails on first ) and the CO level , any other concerns / indications from the readings/ measurements attached ?
and no it is not a CLA shooting brake LOL
Thanks Boyd

 

[190]

It's possible to get down to 0.5 % on a car without a CAT so the 0.52% CO on the first test suggests the CAT might not have been working properly at that point. Why worry about if it's had a new CAT and sensor since then.

 

[ray_hennig]

Hi Last year my 1993 220TE just scraped through on emissions so am looking to avoid a fail this year ,It gets an " italian tune up" on the way to the MOT centre which is 35 mins away so its plenty hot and had a good high rev clear out on the way Current thoughts ;
1 I have used dipetane in the past cant remember whether any was in last time or not but some will be going in this time for sure
2 perhaps a dose of cataclean would be a good pre measure not expensive
3 run some injector / fuel cleaner now well before the test ( due 11th Feb )
not done many miles since replacment cat was fitted and same for lambda sensor
4 Clean Throttle Body ?
5 New Air filter ( oils is fresh only done a 1-2000 since changed in august )

Any clues from the readings ? i know there are some that can read these and tell what needs doing and how far away from what it should be it is

It seems to be the Hot Idle thats the problem (Fails on first ) and the CO level , any other concerns / indications from the readings/ measurements attached ?
and no it is not a CLA shooting brake LOL
Thanks Boyd
View attachment 107677

If emissions are getting worse, I would suspect the engine temperature sensor as a starting point. Or other sensors that control fuel delivery.

Mine has the Bosch CSI injection and separate ignition and yours is an integrated fuel/ignition system so I reluctant to say more.

Others will have a better idea.

Your measures may just be addressing the symptoms rather than the cause.

Good hunting.

RayH

 

[tjamesbo]

MOT coming up soon any experts on reading these values
(Cat and lambda sensor was changed a few years ago...... not since that reading nothing has been done since that reading last year)

1 Got the injector cleaner in at the moment definitely feels like its running better whatever is in that stuff
But am struggling to get through half a tank as not going anywhere ! Im going everywhere in 2nd gear to drop the MPG
2 bought some MAF cleaner probably needs doing ( original at 235K never cleaned ) cant do any harm will do that next week
want to put some cataclean through it 1/4 tank required / 3 gallons but got to get through the injector cleaner first its a nightmare when i m not going anywhere I ll have to drive round and round the town till I'm dizzy
Air filter will be changed (only a few quid )
I'll be looking at how to check my O2 lambda sensor not done many miles since that was put in although a few years ago
May look at putting an Oil catch can in seeing as I'm on 235K probably some oil blow by going back through the breather system which wont be good for the cat anyway
Clean the plugs but shes running smoothly and not many miles done since last changed
beyond that its a struggle
Last ditch is the doctoring the petrol with 15% acetone which i'm told will make it pass (only going to do last 3 gallons in tank )
MOT due 10th Feb work to do also includes checking my headlamp alignment after last years bump broke some mountings
Boyd

 

[optimusprime]

Good luck MOT time is like going in to the hospital for some of us. Me included ..

 

[grober]

beware of damaged lambda sensor leads that are clipped to the cam cover being damaged by heat. obvious other component is the MAF itself depending on age- beware cheap immitations on Ebay

 

[zipdip]

Well I have said before about MOT's now you have to have a appointment and give the car a good run,get the car very hot,if the car is not going in to the MOT straight away run the car outside until it is,in alot of cases a hot car will pass the emissions as long as nothing is very wrong,and looking at the MOT report you are not looking for much to pass.

 

[tjamesbo]

It does get a spirited drive on the way to the garage goes straight in and the MOT guy there is very good knows me,as i take the other 3 mercs there I could hear him trying again and again revving it up so many times i thought it was a fail but he must have just got lucky on one of the last ones