1989 300e intermittent running problem

[Paulmerc]

Hi every one hope your all keeping well. I love my 300e but its breaking my heart and may be my bank account if I cannot sort its problem, Just got the car back from my mechanic earlier. He said the car was running fine. I was happy , then after driving for an hour the problem came back, The revs hunt at idle and can fluctuate when reversing which is dangerous, When waiting at traffic lights the revs go down and engine labouring and has stopped in the past, then a bad missing when i drive it, new plugs , new leads done , i have a new dis cap and rotor to replace, any ideas Thanks.

 

[Habil]

OVP relay?

 

[Paulmerc]

OVP relay Hi did you have a similar problem,

 

[slade1]

Many years ago had had similar problem 1986 BMW E23, new air mass meter.

 

[Habil]

No, I've got a diesel. The revs would steadily increase until the engine was hot, I opened up the OVP relay and resoldered the joints. There cold solder joints that are known to fail.

Ps. I also rebuilt the turbo at the same time, it might have been leaking oil

 

[grober]

These cars with the M103 engine are susceptible to breakdown of the HT ignition components. they are also plagued with condensation problems inside the distributor altho your symptoms don't sound to have the correct time line When replacing components best to stick with standard MB PARTS-- plugs, leads, distributor cap, rotor arm , coil as pattern parts often break down after a short time.
OTHER possibility might be the EZL ignition unit is on its way out--lots of info on the forum about these problems

 

[SkegVegas]

Does the car run better when it is cold. If so this may be a problem with the fuel system running too lean. If the idle is fluctuating or hunting if the car drives ok on acceleration there will not be a fault with the ignition as on accel the ignition system is under more load and more likely to fault. It could easily be an air leak either an injector seal or a split air hose. These can normally be detected by spraying an accelerant like WD40 or brake cleaner with the engine idling. If the speed increases or engine dies it will indicate a leak