w202 won't idle (tickover)

[abbos]

w202 now ticking over but bad idle

Hi Everyone,

My car has been standing for a while (again) and I had problems starting it. I spoke to a friend who said that the battery needs replacing as there is not enough power to feed the ignition.

So I listened to him and bought a brand new battery today. Got it home, fitted it and the same problem!

I start the car but as soon as I let go of the pedal after reving it a little it dies.

Any ideas?

 

[Shude]

Water in the fuel tank? My old vauxhall astra had a batch of bad petrol or something that meant under a certain rpm it just stalled. I figured the thing was dead but after another tankfull it was fine.

 

[abbos]

Thanks Shude, off to the petrol station it is then!

 

[Shude]

Thanks Shude, off to the petrol station it is then!

Petrol can separate if it's allowed to sit for a long time. Also condensation can form in empty tanks - try to keep the petrol tank as full as possible if the car is going to be left for any period of time. I know this probably goes against thoughts about security etc but if the car is stolen I suspect the amount of fuel in the tank makes little difference.

 

[abbos]

Ok I have just added a whole carrier full of petrol to the car and I seem to still have the same problem.

One other thing that I just noticed which I didn't before is that unless I give it a push on the pedal the car won't actually start which is strange because I recall it used to fire up on it's own.

I have taken the air filter out and given it a little knock and put it back in.

Anything else I can check to try to diagnose the problem?

Got petrol all over my hands too, smells good!

 

[Shude]

How does it drive when is *is* going? Is it as expected?

I wonder if a blocked fuel filter or failing fuel pump or something would have a similar effect to what you have described.

Let's wait for someone who knows something about engines shall we? I know basically nothing

 

[abbos]

Hehe, same as me!

When the car used to run it was fine. The last thing replaced was the coolant pump. Checked water level and seems fine.

I don't know whether so squirrel has decided to make a new home in my exhaust or something?

Will wait for the "engine people" to get back from work.

Help..

 

[abbos]

Anyone home from work that can help?

Could it be the spark plugs?

 

[mmc]

re won't idle

I had the same thing happen on my v class, started fine but no tickover, it ended up a my local Merc Dealer and they reset the ECU and it was fine, the mechanic didnt really go into much detail, i would try disconnecting the battery for half an hour and see what happens.
Good luck

 

[abbos]

Pretty sure it's not the ECU that needs resetting as I also bought a brand new battery for the car today and left it unplugged for about an hour before fitting the new one.

Anyone?

 

[Rumble]

I had exactly the same problem, thought it was my battery (as coincidently it happened after i installed some illuminated sills) so i charged the battery and even had the friendly Halford guys test the battery and it was absolutely fine.

I ended taking my car to a merc specialist who hooked it up to a fault reader which diagnosed it as a problem with the throttle body. He quoted a new oone for around £300 including labour. I refused thinking i'd shop around. Then i went on the net and found out its best to clean out the throttle body first with Carb Cleaner. Worked a treat, the car fires up without toouching the accelerator and no more erratic idling, sits nicely at 1000revs in park and around 7000 to 8000 in gear.

Its easy to do, buy yourself some carb cleaner, a can cost be about £4.

If you have a Haynes manual it will guide you on how to get to the throttle body (i didnt remove mine just cleaned it in situ). After spraying it with the carb cleaner and wiping it down and putting everything back together i started the engine up first time.

HTH

 

[abbos]

Thanks for the reply Rumble.

I followed your advice today and the car is now ticking over.

I removed the box between the inlet manifold and the air filter cross pipe, can't remember it's name.

I cleaned it out with carb cleaner and also sprayed some into the inlet manifold. I then put it all back together and it's ticking over.

Issue I have still is that I still have to push the pedal a little to get it started and it idles between 900/1000rpm.

When I put the car into reverse the revs drop and sometimes cause the car to stall.

Any ideas?

Note: The car also is due for a service but I a, unsure wether that will impact on the above issue. Need to be cautious with the pennies at the moment.

Thanks,

 

[Dieselman]

Check the vacuum pipes to the inlet manifold. This sounds like an air leak.

 

[abbos]

Is there anywhere I can find a picture of the vacuum pipes? Maybe in the Hayes manual?

I'm not sure what I'm looking for but will go ahead and try to check all the pipes I can see around that area in the engine bay anyway.

Thanks,

 

[abbos]

Checked all the pipes I could see going into the inlet manifold this morning and couldn't feel any air leaks.

The only thing I did notice is that at the front of the air flow meter but down slightly there is a black bracket which has a thin but long spring attached to it. Does anyone where this goes to and what it is for as it has broken and was just swinging freely.

I am planning on changing the spark plugs, leads, oil & air filters and a engine flush with oil change to see if this helps things.

Any other advice before I push forward with things?

Also where is the cheapest place to buy some decent oil? Not to keen on Halfrauds. I am buying all my other parts from EuroCarParts.

 

[KLee]

Show us a picture of the spring.

 

[tamrsoft]

I had an identical problem with my 1998 C180. As in the previous post suggestions it was caused by carbon build up in the throttle body by the butterfly valve, instead of using carb cleaning solution, I removed the throttle body (simple job) and made sure all deposits were very carefully scrapped away from the inside of the body around the butterfly valves closed position. Car would now start without touching throttle and would idle at about 700 rpm.

 

[abbos]

Car is running much better.

I serviced it yesterday with new leads, plugs and air filter. Need to change the oil filter and oil today.

The car now idles at about 900rpm and when in D or R is at about 600rpm. I do still have to touch the throttle to get the car started.

One small thing though is when I have the steering on full lock and am in either D or R the revs drop even lower and sometimes stalls.

Anyone know what this could be?

 

[Shude]

One small thing though is when I have the steering on full lock and am in either D or R the revs drop even lower and sometimes stalls.

Anyone know what this could be?

Nearly all cars with power steering do that - please don't try it again!

 

[abbos]

Didn't know that but do now

Thanks Shude!

Next thing on the agenda, head gasket needs changing!