Help with economy gauge

[optimusprime]

Don't know if this is posted in the right location .But as it may have some electronics involved, here it is. Car Mercedes W124 260e .The speedo binacle as inside on the left bottom , this economy gauge .Well it will not work properly, just about moves as you rev up the engine . Can some kind member give any information as to what I am to look at to solve this idle needle. Thank you for looking.

 

[hotrodder]

The economy gauges on these are pretty crude, they just display intake manifold vacuum. http://www.w124performance.com/service/w124CD2/Program/Chassis/54-0255.pdf covers things

 

[optimusprime]

Hotrodder thats great, and thank you for that, as it takes me futher. I now i must go and inspecting the vacuum line ,now i know its location. Looking like oil in the system as its sluggish to operate. Would you think its any thing to worry about?.

 

[grober]

More likely to be a leak- classic spot is a perished rubber joint or elbow where the nylon pipe is attached to the manifold or to the indicating instrument at either end.

 

[kth286]

You need to fix it as the engine mixture will be faulty due to too much air being inhaled and therefore week.

 

[optimusprime]

economy

Hi as hotrodder as sent a link in his post .And in it it said ,if you have air leak that the economy guage pointer will be in the black part of the guage,ie right hand side . This one is working but slow.

 

[optimusprime]

gauge

Dont quote me on the last post i am still confused over the diagrams .

 

[optimusprime]

pointer economy

Hi just checked the economy dial, and at its rest it sits on the right stop, thats when engine is not running. Then as you start up it moves to the left stop ,as you rev it up, it then moves 1/4 ,but dont think it will go much further .

 

[hotrodder]

Right hand stop with engine off is correct as there's no manifold vacuum for it to respond to. With the engine idling manifold vacuum is high hence it swinging to the left, from memory* blipping the thottle with the car stationary won't be enough to get it to swing back over to the red side, the engine will need to see some load for that to happen say accelerating in top from lowish rpm. If the needle makes it all the way to the left stop i would have thought it's vacuum signal is sound?

Found a vid where you can see the tacho as well as the speed and economy gauge. Unfortunatly you can't really hear the engine note due to some really bad music! https://www.youtube.com/watch?v=3WaVQfXRtA0

* no economy gauge in mine and i've not driven an MB with one for a good few years

 

[optimusprime]

econo

Hotrodder nice video.Looks as if it may be ok.But the car wont go on the road till next year.I dont want to ues it in the bad weather. On a sorn at the moment,so a drive out is out of the question.Ony drove it once ,and that was to put it on the drive.Thank you once again. Your all very helpful.