W123 300 emmissions tips?

[dazdread]

Hi there,

MOT time again and I was wondering what tips you all have to get smoke levels down. After fixing all the issues from the first MOT it missed the retest cut off and so 140 miles later failed its second full test on emmissions.

It failed at 4.93 M -1 with 3.00 M -1 being the target, it's an 1983 (visual smoke test until 1979) so does need a metered test

My plan is

Adjust tappets
Change air filter
Moly diesel purge through engine

Is there any way of limiting the fuel injector to reduce the fuel input, is there a rev limiter?

 

[krimat2005]

italian tune-up will do the trick, just give it some beans for a while, injector cleaner and filters will help too.

 

[Vlad]

As above...can't add any more to what's been suggested.

 

[dazdread]

Thanks guys, not sure how to Italian tune up now it is not legally allowed on the road!

 

[DSM10000]

Thanks guys, not sure how to Italian tune up now it is not legally allowed on the road!

If you have an appointment at an MOT Station you can legally drive it to the station for the purposes of re-testing.

 

[krimat2005]

put it in 3rd gear and take it to national speed limit and keep it that way for 15-20 mins. add a couple of brisk accelerations with kick down - "pedal to the metal".

 

[maxypriest]

Italian tune up all the way – used to have the same issue with an old mech FI golf diesel. I would give it the beans out of every junction and thrape it down the local dual carriageway, straight into the testing bay and bingo – it would pass. By miles.

 

[SilverSaloon]

is it running on pump diesel only? if not and its WVO or SVO put some diesel in the tank so its approx 50/50. i do this now every mot to bring the smoke test down. the wvo can get smokey varying based on quality

 

[ricardo62]

Sorry to hijack thread , but will thrashing a engine ie driving at high revs damage it? im a bit worried to abuse my old 320 cdi , in case i damage it , i drive it gently , prob the reason why my egr needs cleaning ,

 

[DSM10000]

If you are driving within the red line then you will not damage it by occasionally extending the engine.

 

[esox]

If the Italian tune-up doesn`t work try this -

Run the tank down to the lowest point you dare.
Put in two bottles of Comma Diesel Magic.
Retest.

I used to use this trick on my old Fords, one test was off the scale on emissions - 9.99 on a tester with a scale up to 9.99 - and they used to fly through after the application of the injector cleaner.

It`s one of the very few `snake oils` or cure-alls-in-a-bottle that actually seem to work.

 

[a111r]

Easiest way to pass is to run a tank of B100 (biodiesel).
Although at that level of 'fail', you really ought to fix the cause(s)!

 

[isobars]

Change your testing station to one that's not afraid of a little jiggery pokery.

 

[tim.100]

If the Italian tune-up doesn`t work try this -

Run the tank down to the lowest point you dare.
Put in two bottles of Comma Diesel Magic.
Retest.

I used to use this trick on my old Fords, one test was off the scale on emissions - 9.99 on a tester with a scale up to 9.99 - and they used to fly through after the application of the injector cleaner.

It`s one of the very few `snake oils` or cure-alls-in-a-bottle that actually seem to work.

Surprised no-one's mentioned paraffin, which was a farmers' favourite way to get old Series Land Rovers through the smoke test.