Juddering Idling - MBClub UK

KillerHERTZ · 16-06-2012, 09:46 PM

I have noticed over the past week when I stop at traffic lights etc my idling revs are just above 500 RPM on the dash when normally it should be just below the 1000 mark?

Also, it seems to be fluxuating up and down slightly (you can feel the car almost juddering ever so slightly).

The performance of the car has not been effected at all, I havent noticed any changes and I have done the best part of 400 miles this week.

Any ideas? it had an A service 2 weeks ago.

Dieselman · 16-06-2012, 09:51 PM

HT leads or MAF would be the first thoughts, followed by and air leak.

KillerHERTZ · 16-06-2012, 09:55 PM

Cheers, MAF is 4 years old, so hopefully its not that...

DRBC43AMG · 16-06-2012, 10:06 PM

May be an idea to see if you have any fault codes. That could/should point the way to solve the problem

Pendragon · 16-06-2012, 10:18 PM

Quote:

Originally Posted by KillerHERTZ

I have noticed over the past week when I stop at traffic lights etc my idling revs are just above 500 RPM on the dash when normally it should be just below the 1000 mark?

Also, it seems to be fluxuating up and down slightly (you can feel the car almost juddering ever so slightly).

The performance of the car has not been effected at all, I havent noticed any changes and I have done the best part of 400 miles this week.

Any ideas? it had an A service 2 weeks ago.

Snap !...I have the same car with the same problem and I have spent over £600.00 on parts but still the same.............so, if you find out what it is please post back so I can check mine out without wasting any more money.

No fault showing on diagnostics by the way, so totally baffled.

Keith

KillerHERTZ · 16-06-2012, 10:29 PM

Quote:

Originally Posted by Pendragon

Snap !...I have the same car with the same problem and I have spent over £600.00 on parts but still the same.............so, if you find out what it is please post back so I can check mine out without wasting any more money.

No fault showing on diagnostics by the way, so totally baffled.

Keith

Can you let me know what avenues you have already explored?

Pendragon · 16-06-2012, 10:41 PM

I run a diagnostics business so I did my own. I replaced: Plugs, all coil packs, both o2 sensors, MAF, HT leads. I also did a thorough engine flush, a engine decoke, compression test all good.

I did find that the oil breather pipes and air inlet (pinholes) were filthy and pinholes blocked and cleaned them out and it did run slightly better but it is still the same as yours is now.....very frustrating as I have checked every possibility for air leaks. I have run another diagnostics test and it is showing absolutely nothing wrong. Have spent over £600.00 so far and no closer to solving the problem.

Keith

Pendragon · 17-06-2012, 12:23 PM

Just to also add, had the injectors checked and tested....all fine. Had the engine apart just in case it was a burnt valve....all fine.

Petrol and Match is now springing to mind ! 8-)

Let me know if you find out exactly WHAT the problem is.

This seems to be a common problem on a lot of pre 2001 C class models with shed loads of members on here posting about the same symptoms yet I have not found one that has cured it.

Keith

Mr B. · 17-06-2012, 11:57 PM

what are the most common faults on the 1996 c 200 sports?

KillerHERTZ · 18-06-2012, 12:00 AM

Quote:

Originally Posted by Mr B.

what are the most common faults on the 1996 c 200 sports?

Please create a separate thread rather than make this one go off topic.

martyz · 18-06-2012, 12:04 AM

Have you done a fuel rail pressure test,if the fuel pressure regulator is not holding true,you would have some form of spluttering that would be more evident at idle.

KillerHERTZ · 18-06-2012, 12:06 AM

Quote:

Originally Posted by martyz

Have you done a fuel rail pressure test,if the fuel pressure regulator is not holding true,you would have some form of spluttering that would be more evident at idle.

Not done anything at all yet, will get it down my indy in the next week or so.

Just done another 300 miles today, seemed to run better than ever aswell

DRBC43AMG · 18-06-2012, 07:48 AM

Particles in the petrol which managed to get by the filter or come from elsewhere in the fuel line, perhaps

Could be just a morning touch of blues

**WG M-B** · 18-06-2012, 09:08 AM

If there are no faults except for a slightly lumpy idle [ and no faults logging on star] then you need to check the actual values screen at idle. You may find the only value out of spec is air intake temperature which could be raised. If this is the case then the egr valve is not sealing off correctly.

I have had this little bugger of a fault a couple of times now.

Hope this helps guys

Pendragon · 18-06-2012, 09:57 AM

I doubt its the petrol, well not on mine anyway, since I run on LPG.

Just been outside on put my Star on it and still no faults showing.

Keith

16-06-2012, 09:46 PM	#1
KillerHERTZ Executive Staff Join Date: May 2003 Location: Cambridge Car: W209 CLK270 CDI With AMG bits Posts: 10,574	Juddering Idling I have noticed over the past week when I stop at traffic lights etc my idling revs are just above 500 RPM on the dash when normally it should be just below the 1000 mark? Also, it seems to be fluxuating up and down slightly (you can feel the car almost juddering ever so slightly). The performance of the car has not been effected at all, I havent noticed any changes and I have done the best part of 400 miles this week. Any ideas? it had an A service 2 weeks ago. __________________ 2003 CLK270 CDI 'AMG' (W209) \| 1999 C240 Sport (W202) \| 1968 280S Ex-Diplomat (W108) FOR SALE \| 1995 C180 Elegance (W202) R.I.P.

16-06-2012, 09:55 PM	#3
KillerHERTZ Executive Staff Threadstarter Join Date: May 2003 Location: Cambridge Car: W209 CLK270 CDI With AMG bits Posts: 10,574	Cheers, MAF is 4 years old, so hopefully its not that... __________________ 2003 CLK270 CDI 'AMG' (W209) \| 1999 C240 Sport (W202) \| 1968 280S Ex-Diplomat (W108) FOR SALE \| 1995 C180 Elegance (W202) R.I.P.

16-06-2012, 10:41 PM	#7
Pendragon Hardcore MB Enthusiast Join Date: Apr 2012 Location: Cardiff Car: 2000 Mercedes C240 Elegance (W202) with Multipoint Romano LPG Injection System Posts: 247	I run a diagnostics business so I did my own. I replaced: Plugs, all coil packs, both o2 sensors, MAF, HT leads. I also did a thorough engine flush, a engine decoke, compression test all good. I did find that the oil breather pipes and air inlet (pinholes) were filthy and pinholes blocked and cleaned them out and it did run slightly better but it is still the same as yours is now.....very frustrating as I have checked every possibility for air leaks. I have run another diagnostics test and it is showing absolutely nothing wrong. Have spent over £600.00 so far and no closer to solving the problem. Keith Last edited by Pendragon; 16-06-2012 at 11:01 PM.

17-06-2012, 12:23 PM	#8
Pendragon Hardcore MB Enthusiast Join Date: Apr 2012 Location: Cardiff Car: 2000 Mercedes C240 Elegance (W202) with Multipoint Romano LPG Injection System Posts: 247	Just to also add, had the injectors checked and tested....all fine. Had the engine apart just in case it was a burnt valve....all fine. Petrol and Match is now springing to mind ! 8-) Let me know if you find out exactly WHAT the problem is. This seems to be a common problem on a lot of pre 2001 C class models with shed loads of members on here posting about the same symptoms yet I have not found one that has cured it. Keith Last edited by Pendragon; 17-06-2012 at 12:48 PM.

16-06-2012, 09:51 PM	#2
Dieselman Hardcore MB Enthusiast Join Date: Jul 2003 Car: Peugeot 403 Convertible Posts: 28,787	HT leads or MAF would be the first thoughts, followed by and air leak.

16-06-2012, 10:06 PM	#4
DRBC43AMG Hardcore MB Enthusiast Join Date: Mar 2010 Location: Switzerland, Locarno (TI), the canton of merlot grapes, wine, grappa and fine food Car: 98' C240T, 99' C43 AMG "T Rex" Posts: 950	May be an idea to see if you have any fault codes. That could/should point the way to solve the problem

17-06-2012, 11:57 PM	#9
Mr B. Hardcore MB Enthusiast Join Date: May 2012 Location: norwich Car: c 200 sport Posts: 107	what are the most common faults on the 1996 c 200 sports?

18-06-2012, 12:04 AM	#11
martyz Hardcore MB Enthusiast Join Date: May 2011 Location: New Forest Car: '99 S202 '91 W201 Posts: 1,003	Have you done a fuel rail pressure test,if the fuel pressure regulator is not holding true,you would have some form of spluttering that would be more evident at idle.

18-06-2012, 07:48 AM	#13
DRBC43AMG Hardcore MB Enthusiast Join Date: Mar 2010 Location: Switzerland, Locarno (TI), the canton of merlot grapes, wine, grappa and fine food Car: 98' C240T, 99' C43 AMG "T Rex" Posts: 950	Particles in the petrol which managed to get by the filter or come from elsewhere in the fuel line, perhaps Could be just a morning touch of blues

18-06-2012, 09:08 AM	#14
WG M-B Auhorised Forum Sponsor Join Date: May 2011 Location: N/W london Car: ML 55 and others Posts: 595	If there are no faults except for a slightly lumpy idle [ and no faults logging on star] then you need to check the actual values screen at idle. You may find the only value out of spec is air intake temperature which could be raised. If this is the case then the egr valve is not sealing off correctly. I have had this little bugger of a fault a couple of times now. Hope this helps guys

18-06-2012, 09:57 AM	#15
Pendragon Hardcore MB Enthusiast Join Date: Apr 2012 Location: Cardiff Car: 2000 Mercedes C240 Elegance (W202) with Multipoint Romano LPG Injection System Posts: 247	I doubt its the petrol, well not on mine anyway, since I run on LPG. Just been outside on put my Star on it and still no faults showing. Keith

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