W124 Ignition Timing & Emmissions

[MJK 24]

1991 H reg 230e automatic.

Can someone advise what's the best setting for the ignition timing with regard to obtaining optimum fuel economy?

Also, what should the emissions be? Mine were 0.67% at the MOT a few weeks ago which I thought was a little bit lean.

Finally, do these engines benefit in terms of economy by using super unleaded?

Thanks for any advice or assistance. I'm currently trying to improve fuel economy as its only doing 27mpg on a very gentle motorway cruise. I'm thinking there's another 5-7mpg to be found!

Thanks again

 

[grober]

http://www.startekinfo.com/StarTek/outside/11832/Resources/201Create/PDF/30010.pdf

 

[Sp!ke]

27 mpg is bang on what I was getting in my 230 regardless how it was driven throughout the 150,000 miles I drove it for.

I don't think you'll find much improvement if any. Just check the timing is correct with a strobe, some tippex and the marks on the flywheel.

 

[MJK 24]

Thank you very much! Some bedtime reading to be done!

 

[grober]

While Spike is bang on with his overall MPG of 27mpg I would expect slightly more on a gentle motorway cruise--- 30-33 and less in city driving 20-23. Things that might effect mpg slightly-- check the lambda sensor and its associated heater is working correctly----- if the car has an old catalytic converter these can partially collapse causing a bit of exhaust back pressure---- make sure your car is operating at optimum temperature- a new thermostat is quite cheap----- and make sure you still have that plastic engine undertray in place which aids aerodynamics at speed- perhaps worth a couple of MPG

 

[MJK 24]

The car has recently had the head gasket, radiator, water pump and thermostat replaced. The thermostat is from Mercedes. Seems to warm up quickly and runs at a smidge past 80
on the guage.

There's no cataltic converter fitted. Will it still have a lamba probe? Emissions seem to low to me at .67%? Wondering if a raise to 1% may help?

Undertray is all present and correct. Just fitted new Continentals and running them at 30psi.

 

[grober]

No catalytic converter probably means no lambda probe either. You seem to have covered all the bases. Only other things I can thing of are transmission losses or binding brakes. Probably a reflection of you driving style- are you using the E setting on the gearbox?

 

[Sp!ke]

As I said earlier - 27mpg is all I ever achieved in mine and it didnt seem to make any difference whether it was motorway driving or not - tank to tank it remaned almost constant.

If I recall it was 330 miles from full until the reserve light came on. Mine was also a coupe and a manual gearbox so in your bigger saloon with an auto box, 27mpg is probably as good as it gets.

 

[MJK 24]

As I said earlier - 27mpg is all I ever achieved in mine and it didnt seem to make any difference whether it was motorway driving or not - tank to tank it remaned almost constant.

If I recall it was 330 miles from full until the reserve light came on. Mine was also a coupe and a manual gearbox so in your bigger saloon with an auto box, 27mpg is probably as good as it gets.

God help me! Being serious, it sounds like its running fine then. I'll still have a check over when I get a chance.

Brakes aren't binding but the gearbox oil could do with a change. I always have it in 'E' unless pulling out of a busy junction or onto a busy roundabout etc. Gearbox seems to select 4th at 28mph when driven gently.

I think part of the problem with 4 speed W124's is that they're quite low geared. 60mph isn't far off 3,000rpm. The engine has the torque to pull a taller top gear in my opinion.

 

[MJK 24]

Another full tank through the system. 27.4 mpg!