..a bit tough in the UK since there is next to no one who knows how to work with and diagnose KE-Jetronic issues...
If looking for Jetronic expertise, don't limit oneself to Mercedes dealers or independents. Check for shops that have older Porsche, VW, Audi customers as well.
The rubber manifold was part No. 59 in the digram below.
We noticed it because there was a strong smell of fuel and using a mirror you could see drips when the engine had been run for about 1 minute from cold.
Hard to detect if the engine is warm.
So, from your exhaust analysis it seems that the problem at high revs is you are too lean and the problem and at low revs too rich.
a) Perhaps your fuel pump cannot handle maximum flow.
There are tests you can peform to check fuel flow
Remember, messing around with fuel is dangerous. Follow proper procedure.
b) Perhaps your idle mixture is very rich and reducing the differential pressure
balances it for low revs.
With the EHA back where it was or even a bit more clockwise you would need
to balance with much more lean idle mixture to resolve the mix for low revs
I looked and the 16v does indeed have a fuel pressure regulator thing, comes off the distributor and has a really short vacuum feed from, oddly, the air pipe going to the idle control valve?? I can't imagine that a lot of vacuum is created in here (?) so don't imagine it does a huge amount. I disconnected the vacuum pipe and went for a drive; made no difference. Could be that mine is bust in which case disconnecting the vacuum would do nothing - anyone tried this before to confirm?
I am keen to chase this one up since it's fuel pressure related and fuel pressure change made such a difference to the car.
When the engine's cooled I'll check for splits/blocks in this and other vacuum pipes.
I also noticed while there that the black rubber pipes on top of the injectors - 2 of them each feeding 2 injectors - have slight splits in them. Not split right through from what I saw, but I want to remove/inspect them as an air leak here would be unmetered.
PaulE I hear you on the poorly fuel pump - will log it up as an option. I have the afternoon off so may go play now, bit low on energy with it as I'm going to China for 2 weeks on Thursday..!
If it is any help, I have checked the economy guage at idle and
- Idle cold in neutral revs 1,000rpm economy about 8-10% of max
- idle warm in neutral revs 1,000rpm economy 0% of max.
This is an automatic so if you put it in Drive but stopped engine warm
- revs 800rpm
- economy 8-10%
The vacuum hoses get really hard and brittle so I found it was easiest to replace absolutely all of them.
Crumbs that's rather different to my vacuum setup. Looks like an 8 valve motor that one?
Mine has:
front of engine: double pipe fitment, one pipe to throttle body (connector hidden), one pipe to front wing T-piece. That then comes back to the carbon canister too in a thicker black vacuum pipe.
Back of engine: Y-split piece - one goes off to headlamp high adjustment passing by brake booster. Other goes to ignition ECU.
Also very short vacuum lead from idle air control valve to what I believe to be a fuel pressure regulator.
Think that's it!
Just checked it all and doesn't appear split/blocked. Did drive with vacuum pipe disconnected from ignition computer and seemed to make no difference. It does suck your finger if you put it on it!
Linear Mode
