MB200E/W124 Intermittent Misfire

[julianps]

Hi,

I'm new here and tried a search but it returned nothing.

I have 4cyl/1999cc 1992 model W124 that might have a Bosch CIS-E (KE Jetronic) fuel injection system. Whilst it runs okay normally at slow speeds it has a misfire that might become more pronounced with temperature.

Also, once warm, it has a pretty rough tickover that feels a little like starvation but as there's no evidence of that at speed I'm not sure what to think.

Is this scenario it any way common with this model of fuel system and could anyone suggest whether the cause might more likely be fuelling or ignition.

Thanks for any thoughts.

Jules

 

[Cole@MBS]

When was the last time it had a set of plugs??? sounds plugish the way you wrote that!

Maybe a new set and leads and cap would be somewhere to start!

Welcome to the forums

 

[julianps]

Hi,

Thanks for that. The plugs and leads were replaced at the last service a year ago.

As a simple description I ran the car yesterday and it was fine. I pulled into a side-street to turn and as I accelerated to pull away the car feels like it dies then suddenly picks up.

It feels like there's some vacuum, advance thing going but in fairness with so many hoses, valves and components it's hard to know where to start with diagnosing it.

J

 

[julianps]

Update

I removed the petrol cap this morning and took the car for a run; a lot better!

Is it normal for the tank to build up a vacuum - i.e. to suck in a lot of air when the cap is opened? Mine really goes nuts which seems to suggest there's no breathing mechanism and the pump is always working against itself.

Maybe the problem is as simple as a new petrol cap?

J