stuttering idle and judders as pulling away - 190 auto

[kintyre]

Hope you can help I am pretty new at this game -

When I start up my 190 auto, (G reg, 71k) no problem, but as it idles every now and then the car judders as if it has missed a beat, (the oil pressure fluctuates as does the rpm with each judder.) Then when I pull off the car now judders, lacking acceleration, until I get some speed up (20mph or so) and then things calm off. The acceleration isn?t smooth as it used to be, but jerks as it pulls away.

If the car is left for a period, over night say, no problem for first 20 mins or so of driving, then the fault is back.

The engine appears to vibrating more vigorously than normal. I am not very good at the diagnostics game - let me know what more info would help. I have searched the forum but can?t find any comments with the idle and acceleration combination - any comments, however straightforward would be very greatly appreciated.

As always - Jack K.

 

[Spike]

Two thoughts spring to mind here. Firstly what RPM is the tickover...and secondly, have your engine mounts ever been changed?

 

[Rick 190E]

Snap

Had my 190E 2.0L Auto for 6 Months. Mine is doing exactly the same. Mine ticks over @ 700RPM at Tick Over, Engine Mounts Changed 18 Months ago.

Rev the car in neutral doesn't miss a beat. When things are warmed up and when moving off Judders and stutters (like its misfiring) unless you stamp down and the Rev's pickup. Have checked my Gearbox oil level (Engine Cold) sitting halfway between max and min, the oil appears clear (not coloured red as I have rear elsewhere) and doesn't smell burnt.

Don't want to be sold a Chocolate FireGuard by my local Dealer / Garage. It really would help if I had some inclination as to what was faulty.

 

[leicesterboy15]

It sounds very similar to the problem I am experiencing but mine is a manual. It doesn't happen on idle or when revving while standing still so people find it very hard to diagnose.

I have been told it could be the fuel filter being clogged up which is why its erratic and theres no real pattern to it. A new one is about £15 from german sweedish so it won't break the bank even if it turns out not to be this. I have a new filter but I don't think I'll have time to fit it any time soon. When I have done, I will let you know the outcome.

I have posted a message about this which has more details about my problem and there are some responses.

http://forums.mercedesclub.org.uk/viewtopic.php?t=4137

Raks

 

[ChrisOnline]

Throttle housing?

Hello all. I dont yet have a MB at all, but the symptoms you suggest sound very much like what I had on my 97R volvo s70 and the cause was found to be crud/grime in the throttle housing. Clean that - problem was solved. Just a thought.

Chris

 

[dieselman]

Possibly an air leak into the inlet manifold. This will be most noticeable when the throttle is closed and after the engine is warm due to being on choke when cold.

Check all vacuum pipes leading from the inlet manifold.

 

[mezza]

Ignition parts would be my suggestion, esp ignition amplifier

check rotor, cap, leads ign amp and plugs - replace if necessary

check coil also

you can find dimply diagnostic test in a workshop manual

http://shop.mercedesclub.org.uk/acatalog/MBOA_Club_Store_Workshop_Manuals_5.html

good luck

 

[blue190E]

Mine did this a while ago.

Cleaned and sealed all the electrical connections in the engine bay, and hey presto, running fine ever since. I also changed some of the small dia. vacuum pipes as they were perished. I guess a leak in one of those could cause a dodgy signal to the ECU.

The car had just had a full service including plugs, leads and fuel filter. The symptoms you describe could quite easily be caused by any of those items being faulty though.

It cold be anything really (or even a combination of things) which is why I took the blunderbuss approach.

 

[Rick 190E]

Keep them ideas coming guys ..........

 

[jaques2k]

I assume you´ve checked the plugs as mezza said - but what brand are you using, and how old are they? Mine (a 6-cyl engine) got about the same symptoms, jerky acceleration, bad idle, almost shaked the whole car when running, and so on. Changed a faulty spark plug from NGK to Champion as is recommended for most Merc. motors, and the motor was smooth as ever! Now I have a mixture of both NGK and Champion, but will replace them all with correct ones asap.

 

[Rick 190E]

Update ......... since last posting.

On a motorway run, noticed blue smoke pouring from the car. Pulled over to discover oil dripping onto the exhaust. Noticed Gearbox pan was wet, everywhere else dry. Spoke to a couple of people who suggested that first of all I stop crying and secondly check the gearbox oil level (when at normal temp) if high it could well be oil being out of the gearbox breather.

Checked the oil level, bugger me it was that high the box was drowning. Popped underneath and drained away the excess.

Q) While I had the time I carried out a minor 6000 mile service. I Also took off the Air Box, diconnected some of the hoses from around the airbox and rocker cover to the discover that some of the inline fittings we're blocked. I've cleaned them up as best I could. But, a fitting mounted to the block secured by a allen bolt needs to come off to give it a proper clean. Access is hindered by an overhanging blue female electrcal connector attached to a metal pipe to the Air Mass Unit. Is it with disturbing the metal pipe to turn the connector that will give me access to remove this clogged up fitting?

Car no longer judders / stutters from standing and after a 40 mile run down the motorway the underneath appears dry.

However, the idle is as lumpy as a rice pudding, the plugs were sooted up (NGK) with No. 3 looking as if it had been plated in calcium / carbon. So they're out, after just doing 6000 miles, for a set of Champions.

Q) Cold start - everytime I start the car I have to sit with my foot on the gas waiting for the car to warm up before I can succesfully move off in D without stalling it. Stupid as it may sound do I need to service / replace the illusive cold start valve?

p.s. I am seriously considering having my car shipped to Andy in Birmingham for him to work his magic. The guy seems like a top bloke and certainly knows his onions.

As always - Cheers

 

[babybenz]

Could be the cold start valve or the CIS engine temperature sensor on the block.

 

[Rick 190E]

Thanks for the feed back .......

Just treated the car to a nice set of Champion XON Plugs and it seems to have done the trick - rough idle has disappeared, no more misfire and in general is a far livelier beasty. A little damp around the Gearbox pan seal. Have tightened to MB recommendations but still seems damp around the aft OS joint. Doesn't seem to be tracking from anywhere else.

p.s. anyone got any recommendations of how to remove oil stains from block paving, other than swapping bricks! Driving the Merc is great but causes domestics when it bleeds onto the driveway.

Cheers Again