300SL-24 R129. Sluggish on take-off

[Unsound Methods]

Hi all.

At the end of last year i had an intermittent misfire, which became less intermittent. After 15 minutes the car would start to cough and splutter and then grind to a halt - and not start until cold. It took a while to diagnose, but the original issues seem to have been cured

(Ive read numerous similar accounts like this, and when i originally took the car to a local Mercedes specialist I mentioned that there would perhaps be a good chance the cap would be the issue, but i was informed the cap was fine. After a couple of large bills the cap was replaced and the issue was sorted, mostly. Heres the history so far...

Heres a list of parts replaced by garage:
crankshaft sensor
fuel filter (fuel cleaner 44k)
fuel pressure - all ok
ignition coil


received the car back from garage, car still cutting out, back to garage:

distributor cap
cross rotor arm


received the car back from garage, car not cutting out, but sluggish from standstill, so after some research:

replaced suppressor housing (behind dizzy cap)
Now using Redex for a while, cant hurt..

So the car no longer dies. However, i still get a laboured / sluggish acceleration from a standing start - i notice it at junctions and traffic lights. But once the car gets going, it runs fine, and its absolutely fine right up to motorway speeds. I think it only happens once the car is up to temperature. And it doesnt seem happen all the time.

Does anyone have any ideas on what the problem might be? I could take it back to the garage and they could chuck some more parts at it, but then again i could probably do that myself (up to a point ! ).

any suggestions would be much appreciated.

cheers, Dani

 

[LostKiwi]

I'll ask the obvious first....

What year is the car?

Are you in 'S' mode on the gearbox? If not the car will always start in second. In S mode it will start in second unless you press hard on the throttle to kick it to first.

 

[Unsound Methods]

Sorry, its 1991.
the car is in E mode.

 

[LostKiwi]

In E mode it will only ever use second to start off.
Try it in S mode and see if its better.

 

[Unsound Methods]

ok i'll try that tonight, thankyou.

tbh it doesnt just feel slow - its like it stutters and coughs a bit..

 

[LostKiwi]

Ah ok - thats a bit different then.

Has it had new ignition leads and plugs?
Given you fitted a new distributor and rotor that would almost complete the ignition side.
You should then be able to forget about that side of it for some time ahead.
Also when the shield behind the rotor was fitted did you smear the engine side of the shield with silicone grease? They are prone to getting condensation which causes misfires and this will fix the issue.
Was the cap and rotor genuine? If not what brand? These cars are very picky about ignition components.
Does it run ok at higher RPM?

 

[Unsound Methods]

• spark plugs replaced january 2015

• leads, not replaced, and i cant find any mention of them in the meticulous service history i have..

• i didnt smear the engine side with silicone grease when i replaced the shield. thats something i can do this weekend.

• cap and rotor directly from mercedes

• it runs well at higher RPM - although there seems to be a slight rasping sound on acceleration, difficult to tell where thats coming from, i was going to get the exhaust checked out....

 

[Unsound Methods]

Hi all
Thought I'd quickly update this post. The car has been fixed! It took a while but the fuel injectors were replaced, and the metering unit was sent off to be re-furbished and the car is now running really very well.

Thanks again for the above help LostKiwi, much appreciated
cheers
dani

 

[LostKiwi]

Glad you got it sorted.

 

[robparker]

Hi all
Thought I'd quickly update this post. The car has been fixed! It took a while but the fuel injectors were replaced, and the metering unit was sent off to be re-furbished and the car is now running really very well.

Thanks again for the above help LostKiwi, much appreciated
cheers
dani

Where did you send your fuel distributor?

 

[Unsound Methods]

Hi Rob
I didnt actually send it off myself. Nigel at NJS sent it somewhere in Germany i believe. Perhaps you could drop him a line.

http://www.njs-solutions.com
Email: info@njs-solutions.com

cheers
d