Idle surge and ten second start
 

HI all, Im hoping someone can help me with two problems. I have a '93 SL500 73K on the clock.
First problem: No matter if the car is hot or cold it takes about ten seconds to start. Always starts smooth and always about the same time. Only time it starts quicker is if i turn it off and start it straight away again.

Second problem: The car surges in idle and has stalled on me a couple of times in traffic. seems to run a little smoother when cold but the moment she warms up she surges. Surging seems to disappear at about 1800rpm.

any help would be appreciated, been to two people already and just by the look on their faces i can tell they are guesing. Handy enough with a tool box but a little lacking on the electrical side of things.

Please anyone????

Similar problems with the surging and occassional stallin on my 190e. Most likely caused by the Idle control valve or the Over Voltage protection unit. Not sure why the starting thing is happening. Sounds like it may be ECU related though if you can shut it off and then it starts right up.

Any Master Techs out there with any other thoughts????

Same Problem
 

I cleaned the Throttle Body Actuator on my 93' 500E with 67K miles and stalling issues and cold start resolved.

No need to remove the TBA, only intake pipe and carb cleaner.

Do you have efi or mechanical injection?

sounds like a fuel pressure problem (for the starting issue at least) If you have EFI then check the fuel pressure reg for leaks. If you have mechanical then the leak could be the fuel accumulator.

You'll need more time and some gauges for the mechanical system to accurately find the leak without replacing alot of things.

Idle surge pattern developing
 

Hi guys and thank you all so far for your suggestions.

not sure about efi or mechanical inj but think mechanical.

i have started to notice a pattern to the idle surge problem. when the tank is full and all the way down to 1/4 tank the surging still exists but not too bad. still stalls from time to time but bit serious. when the tank drops below 1/4 tank then the car runs seriously rough, shakes and judders. if i pull away too quick good chance of stalling. oil pressure gauge also moves alot more.
then when i fill her up she continues for another twenty miles like that and then all disappears to a mild surge. have checked fuel pressure and stays nice and constant. but thing that puzzles me is the power delivery over 2000rpm seems to be unaffected by this surge and there is absolutely no hesitation or shake above this engine speed. something else i have noticed is when i accelerate mildly she seems to be a little sluggish unitl 2k rpm and then almost feels like a turbo kicks in and she starts to seriously deliver. is this a tw stage fuel delivery system or is this part of the fault?

will updateif i can assymilate further paterns.

again thanks for the suggeestions, keep them coming. if i ever solve this one i will let you all know in minute detail.

regards

D