EGR, vacuum leak, rough idle m112

[mattuk]

Could anybody point where is voltage regulator located? Is there one in the car?

 

[bob13]

Hi again
Just thinking out loud here but would the size of the battery matter? I ask because when I brought the car it had been standing and needed a little help to get started.

At the time I noticed it had a big Merc battery, not sure on amp's etc but a big battery. After getting the car home a short time after having the car you start prodding and poking your new toy I found a standard size battery.

At the time though that's nice a new battery, but thinking on it and reading the forum etc Mercs can get temperamental when the voltage is not quite right.

So could it be the battery not up to the job now it has given its best over the past year. Poor thing been working to hard. I will however check my voltages just to see what's going on here.

Cheers Rob....

 

[bob13]

Hi again
Checked voltages tonight, when car first started 14v after a long run 14v. So something not right there. Both of these voltages were with not lights on etc.

Rob....

 

[mattuk]

Hi again
Checked voltages tonight, when car first started 14v after a long run 14v. So something not right there. Both of these voltages were with not lights on etc.

Rob....

What read with engine off and ignition on?

So 14V remains all the time? Any fluctuation?like 13.9, 14.2? Have u tried to put load on idle?(radio blower?)

 

[Alex Crow]

I cannot see why we now have this voltage fascination, and there are no problems with the voltages being reported here, although 14v at rest is hard to believe.

 

[mattuk]

I cannot see why we now have this voltage fascination, and there are no problems with the voltages being reported here, although 14v at rest is hard to believe.

I think that voltage fascination could give a clue what to look at.

As you said 14v at rest is hard to belive - if this is wrong so what does it say to you? You are MB specialist so you should know what read is correct!

Alex I wish to see you in your garage and I'd like you to sort out my issue but driving 150-200 miles to see you is pointless for me that is why I would like you to help if you can via internet
Thanks

 

[bob13]

What read with engine off and ignition on?

So 14V remains all the time? Any fluctuation?like 13.9, 14.2? Have u tried to put load on idle?(radio blower?)

Battery at rest 11.5 ish so that looks ok. I didn't play to much as i was going out and just had a quick prod when i went out and when i returned home. It may be something of nothing but i have never had a car where the voltage at the battery appears to be at a constant 14.2 ish. It never dropped below 14v when i had my brief look.

I know its not really over charging just on full charge rate, but I would have expected it to at least drop to 13.5v ish after a run.

This may not be the root of our little problem, but could it be a concern ?

cheers bob...

 

[mattuk]

I don't know Bob

Hope Alex and/or other members will help

 

[bob13]

just been doing a internet search, and 14.2 v seems to be the norm.

 

[mattuk]

just been doing a internet search, and 14.2 v seems to be the norm.

That's good

What is suspicious that when air pump turns on interior lights and cluster dim like there is too high or too low voltage and revs become smooth(no hunting) maybe bad ground somewhere or as Alex said it could be something to do with alternator, now again when car running shows 14V. That means alternator is charging. I will try to run car and check current voltage when air pump turn on.

 

[mattuk]

Has it been checked with the polybelt off?
I'm wondering if it could be an alternator load problem.

Alex - with belt off how to check pulleys? Do I have to spin and see how hard it goes?
For example - alternator pulley spin arround. If is easy to do what does mean good or bad? If hard to spin is it ok or no ? I am correct or how I should do it?
Thanks

 

[Alex Crow]

All I suggested, was that variable loads on some ancillary component driven by the belt (eg alternator) might give the uneven idling issue.
Running with the belt off will confirm or exclude this theory, assuming the symptoms are consistently repeatable.

 

[mattuk]

All I suggested, was that variable loads on some ancillary component driven by the belt (eg alternator) might give the uneven idling issue.
Running with the belt off will confirm or exclude this theory, assuming the symptoms are consistently repeatable.

My manual repair book says I have to undo belt tensioner to drop the belt. do I have to take it off compleatly or unbolt enough until belt is loose?
Also I read that this is "autotension" tensioner so no worries about overtightening?
Thanks

 

[Alex Crow]

Sorry, I am not sure you are up to this.
Fixing cars is hard enough, but without proper diagnostic tools and basic knowledge your chances are too slim.

Releasing the tension on the belt is childs play, just use a 12 point 17mm socket to rotate the tensioner arm aginst its spring.
Do NOT unbolt anything.

 

[mattuk]

Sorry, I am not sure you are up to this.
Fixing cars is hard enough, but without proper diagnostic tools and basic knowledge your chances are too slim.

Releasing the tension on the belt is childs play, just use a 12 point 17mm socket to rotate the tensioner arm aginst its spring.
Do NOT unbolt anything.

No worry I am only asking how to correctly get tensioner off , my knowledgeable friend( repaired few cars - head gaskets, pistons etc) will visit me at the weekend if his plans won't change

Ps. I don't touch things which I can't fix or I don't know how to fix

Thanks

 

[icky]

Hi

Due to mud in "fluctuate revs again" thread here is fresh one

My car c320 petrol 2001, 95k miles


Car runs faultless apart hunting/fluctuate revs on idle and sometimes vibrations

I checked all vacuum hoses few times - good condition
Also cleaned throttle body, maf, sealed breather cover leak, checked everything! Car pass MOT without problems, car feels powerful and accelerate without problem, no codes on diagnostic tool , i/m readiness shows that everything works correctly, o2 sensors work in correct values, no oil leaks

Today I was checking EGR valve.
- disconnecting does not indicate check engine light However was pending code. All clear now
- with correct engine temp vaccum supply was disconnected, no difference on idle, still fluctuation, no vaccum in hose.
- engine revs at 2000- 2500 rpm, disconnecting vacuum supply does not make any difference to engine, there is vaccum in hose.
- with engine off vaccum was applied directly to the valve. Valve holds the pressure.
- engine on, idle - valve is hot but it's tube which goes to manifold is cold.
- engine on, revs at 2000-2500rpm - valve is hot but tube(pipe) only slightly warm.
- also I hit valve by screwdriver few times on idle but no changes.

Egr pipe(tube) - how hot it has to be ?

I would be very thankful for help

This could be the problem. check out this video.