Fluctuating Revs

[trainer]

Hi,

For a short period after starting, say 10-15 minutes, the revs are fluctuating quite noticeably.

Any ideas?

Thanks

 

[Dano]

Hard to say mate.

An independent diagnosed similar symptoms as defective coils.
Paid £40 for the diagnosis.

Left it for while. A different garage said, I am paraphrasing, "if you have a misfire, the unburnt fuel may damage the cat"

So I shell out £200 for coils and the labour

Outcome...The guy says there is no misfire, but I can tell you the flucutation on the rev counter is still there!

-- D

 

[lynall]

Might be worth cleaning the throttle body and flap out with carb cleaner and a toothbrush.

Done this on a few of wifes old cars all to cure uneven idle or low speed shunting problems.




Lynall

 

[evdok]

i had this problem with a 406 ended up having a new stepper motor.

 

[BlackC55]

Many things can cause this fault but the most common issue is a vacuum leak.

 

[c200Kompressor]

Many things can cause this fault but the most common issue is a vacuum leak.

Yeahp! On my C200 kompressor that was the problem!!!

 

[lynall]

Good point as when doing my injectors the other day my revs were up and down then i saw i had the plastic hose of the purge valve.

I also noticed a few of the little vacuum hoses at the front of the inlet manifold were perishing, not holed but not good either so i replaced them.

Quite a few hoses at the back of the manifold as well.



Lynall

 

[Dano]

I still have the fluctuating revs on idle. Please can you help me locate the throttle body? (W208.365) Once I know where it is and what it looks like I will have a go at cleaning it!

I have bought one of those service / maintenance manuals (DVD) from ebay. Looking forward to knowing a lot more!

 

[lynall]

If it the v6 motor its at the back of the inlet manifold, when i did mine v8 i unplugged it and it took the car while to relearn the throttle settings so had to put up with high idle for a few days then a long run to dover and back sorted it out.
If i was doing it again i would not unplug it but unbolt it and clean it whilst still attached to the loom, carb cleaner and a toothbrush.



Lynall