Engine Miss-Fire

[mercmatt]

Hello all,

Hoping to get a bit of insight into a problem with my SLK. It is a 1997 (230k) Auto and has done around 105k.

About 4 months ago I was coming up a hill on a duel carriage-way and put my foot down to go round a van ... when I put my foot down the car just stuttered and was popping and all sorts. I originally thought there might be some crud in the fuel as the problem went away on the way home.

Then last week, put my foot down and the same thing happens again ... only this time the problem will not go away. If I rest lightly on the accel pedal and hold it in say 2nd it will go up to 6000 revs smoothly. In 'D' it will go up the gears smoothly if I only press the pedal gently. But in any gear if you floor it, it starts stuttering.

Now it gets interesting, because having been on here for a look through the threads I see that the MAF would usually be the probable cause. So I got a new MAF and Spark Plugs. On the way home from the garage .... same problem again!!!

Anyone got any ideas as to what else is worth changing?

Any help would be very much appreciated

Matt

 

[jibcl500]

New air flow meter, if local to cambs I have one you can have at cheap cheap money.
jib

 

[mercmatt]

Thank you for your response and the offer however a new Air Flow Meter was the first thing I did ... along with Spark Plugs, so my dilema is that I do not know what else would cause this problem

 

[jibcl500]

Where did you get the MAF from and how much did it cost.

jib

 

[mercmatt]

My Mechanic that I take my car to got it from his supplier. It is a brand new part (Bosch). It cost £140 (which seemed much better than what MB wanted).

Why do you ask, could the source / cost have a bearing on the fact that it has not rectified the problem?

 

[Ron Palfrey]

jib will be concerned that it may be a fake Bosch one. The cheap ones are often this.

I'd be suspecting a coil pack myself if it's not the MAF.

Ron

 

[mercmatt]

Thank you for your reply.

Would the fake ones be in a Bosch box? I actually happened to be there by chance when it was delivered (along with some Wipers for the MOT) and both items were in Bosch boxes ... in addition to this the mechanic is well known to my family and trusted.

If t was the coil pack would the problem not be constant instead of intermittant?

Thanks,

Matt

 

[jibcl500]

Coil pack and MAF failure tend to go hand in hand, a duff coil can take out the MAF.

Your MAF should have the Bosch numbers on it, search my postings about MAF there will be some pics to show fake and real Bosch.

jib

 

[star]

get it checked before buying anymore stuff. Guessing is costly and sometimes a waste of money.

 

[idz92]

missfire 230k

Hi This happened to my CLK230k 1999 the mechanic changed the coils/spark plugs and air flow meter but still the same then he cleaned the throttle houseing and used higher octane petrol and its been alright for the last 2years

 

[mercmatt]

Hi All,

Thank you for the info. The car seemed to be running fine but on the way home tonight it seems to have lost all power (different to miss-fire), the auto gearbox does not know what gear it wants to be in ... It feels like the Kompressor is not cutting in

Gone from being the most reliable car to having all these different issues in one week ... problem is with all these different issues it is hard to pin down he problem ... gonna have to dust off the visa me thinks

 

[BlackC55]

Is there any oil in the inlet tract?

 

[mercmatt]

Thanks for your note. I am not sure if there is oil in there as I am unsure what that is!

I have now had all the breather system cleaned out as per this thread

http://forums.mercedesclub.org.uk/showthread.php?t=34036

My mechanic said it did not seem that dirty so is not convinced it is the problem ... he has also said that the oil contamination could be because the car is 'breathing heavy' and the piston rings are going ... sounds expensive.

One other thing I have looked at is that the oil seemed to be a bit over-filled on the dip-stick ... The problem only ever happened when the car was being pushed very hard (I do not do this often) ... is it possible that if the car had too much oil in it, when I thrashed it the pressure built up and sent a load through the system into the MAF?? I am just guessing here but just trying to look at any brighter alternative to tired piston rings.

Many thanks

Matt