Engine behaving strangely upon startup.

[Stu_CDX]

Hey guys and gals.

As you're probably all aware, me and the Missus drive a Mercedes W124 280.

Here's the story...

When cold, most of the time, it takes a lot of cranking and a touch or two of the throttle to start. When it starts, it'll either be perfectly fine or almost have a misfire, but whatever happens, it's always fine as soon as you put it in gear and drive off. Sometimes, there's a puff of blue smoke, but the manual mentions burning oil.

Mrs has rang me in a terrible state, saying the car today has twice performed the next act:

When the car is started (Never when I've driven it, so excuse the vague details), the engine revs shoot right up to between 5-7k RPM. Now, I know the car wont rev above 4krpm in P or N select, so this has me stumped.

The car drives PERFECTLY, only the other day did I bang it into DR2 and take it to the maximum speed (seventy something MPH).

And when warm, it seems to behave nicely. Fuel consumption is a little high, but it DOES need a service as it's due.

Can anyone shed any light on the above facts?

(No good asking me for chassis numbers and stuff as I'm not with the car).

 

[rpe2]

When getting it serviced:

- ask the garage to check the loom for degridation (sp?) and;

- ask the garage to clean the throttle body.

 

[Stu_CDX]

Anyone got any other suggestions? Do the injectors need cleaning or some redex shoved through?

Stu.

 

[roofless]

vacuum leak could cause the high rev's or if the smoke is only on start up when cold & clears it might be just the valve stem oil seals letting a little oil into the bores overnight common with older cars & the oil+fuel might fuel the car more for a few sec's & make the car rev higher ..only a theory thou

 

[television]

Is it still sticking to 4k rpm in drive

 

[Stu_CDX]

As said in the original post, I can take it right up to the red line limiter in 2nd hold... It only limits itself to 4k when not in gear.

The revving is unusual to say the least.

The hard starting is annoying, but sometimes, priming the fuel pump more than once can solve the problem. Other times, it'll just turn over and over and over until you give it some gas.

 

[television]

As said in the original post, I can take it right up to the red line limiter in 2nd hold... It only limits itself to 4k when not in gear.

The revving is unusual to say the least.

The hard starting is annoying, but sometimes, priming the fuel pump more than once can solve the problem. Other times, it'll just turn over and over and over until you give it some gas.

OK to rev up to 4k in N or P is normal. if it is only hard to start from cold, then this has to be a fuel enrichment device not always coming on

 

[Stu_CDX]

OK to rev up to 4k in N or P is normal. if it is only hard to start from cold, then this has to be a fuel enrichment device not always coming on

But Malcolm, when it does start, it misfires when you rev it, until you put it in drive then it's absolutely fine!

Put it in reverse and you get a nasty surging almost... Very annoying. Takes a lot of skill to get it out of a sloped driveway when it's wet.

 

[roofless]

But Malcolm, when it does start, it misfires when you rev it, until you put it in drive then it's absolutely fine!

Put it in reverse and you get a nasty surging almost... Very annoying. Takes a lot of skill to get it out of a sloped driveway when it's wet.

it would do no harm to check the pressure control cable adjustment for the gearbox it's on the throttle linkage & must have slight slack in it with the throttle closed ?