Plug change due? C240 V6, 64K

[AngmarWitchLord]

Ok guys, here's my problem

Just serviced the car myself and whilst I was at it I fitted a pipercross washable filter (because I KNOW I'll notice the extra 0.3 bhp )

Anyway, coincidence or not, the car started acting very strange when I took her for a test run to my parents house 10 miles away.
The engine was behaving sluggishly, and if I floored the pedal, it had the same effect of slamming on the brakes and the engine began to die as if it was choked of air, making me immediately suspect carburation rather than ignition.

I hastily sent off an e-mail to pipercross to see if they had any opinions, but inn the meantime I put my Mann paper filter back in, lo and behold there was no change (I'm expecting to send a very apologetic e-mail to pipercross soon )

I decided to have a look at the plugs as I knew they were due for replacement sometime soon and they do look like the electrodes are covered in groups of tiny pits. and the electrodes look quite worn, not like a new plug.

I only removed one side as everyone here with a V6 knows what I mean about it being one b*tch of a job.

I 'll also describe what happens with a cold start:
Engine will turn over and fire up ok, going to 1500rpm fast idle, but then will reduce over 3-4 secs and eventually cut out after some popping and farting.
After several attempts like this I disconnected the Mass air flow sensor in the air inlet pipework above the air filter compartment and the car then seems to start ok, going to fast idle and not stutering when reducing down to idle (althought this may have been coincidence as I'd attempted about 5-6 times to start)

I removed the mass air flow sensor and with the car at idle, I blew on the sensor, this had a similar effect like the car closing the throttle plate to compensate for the extra air flow and agin the car began to choke.

I think this probably eliminated the MAss air flow sensor from my line of enquiry, so what the hell is it?

Could my plugs really have such a profound effect on my cars' performance or is a trip to the local dealer for the dreaded "diagnostics -but we'll fit a new ignition system for you anyway as its sure to solve some problem somewhere for you sir"??

Someone must have an answer for me here.
I'm loath to fork out my hard earned cash whilst MB charge me to fit parts on atrial and error basis which I'm quite capable of doing myself, and I dont have to pay them a fortune for the privilege!!.

Ps this is getting embarassing as my girlfriends 2.5 Litre X type is top car again at the moment.

 

[Robbo]

Aftermarket air filters have been known to kill MAS sensors. You say the car starts OK with it disconnected but runs badly with it connected. I'd say that's your answer. You could try cleaning it with isopropyl alcohol.

Apparently the pierburg MAS from GSF works well and is a fraction of the cost of a Bosch unit.

 

[stats007]

If you just get the sensor then it's worth removing the whole unit to clean and check anyway. Alternatively most complete MAF sensors can be found on eBay new for £80 odd.

 

[nickmann]

When you say that you serviced the car yourself, what other jobs did you do? (other than the air filter?) The MAS could be red herring. I suspect it is the problem, but it is worth considering all the angles before diving in with the chequebook.

 

[GrahamC230K]

£5 on it being your MAS!

Old MAS + new free flow air filter = Preamturly Dead MAS

 

[Vlad]

I know that this is going to sound like a "OOhh you shouldn't have done that" type comment.....but fitting aftermarket air filters is not recommended on Mercs as they do tend to Bu**er up the MAS sensors.

I know it doesn't help you sadly, but it may help other members reading this posting.

 

[AngmarWitchLord]

hmm

 

[AngmarWitchLord]

When you say that you serviced the car yourself, what other jobs did you do? (other than the air filter?) The MAS could be red herring. I suspect it is the problem, but it is worth considering all the angles before diving in with the chequebook.

nickmann, nothing more than a MB technician would do without plugging in his diagnostic thingy.
Oil/filter change, pollen filter,air filter, fluid top ups, brake pads etc.etc....only thing on the carburation system was the air filter.
I dont want to sound arrogant, but I am loathe to spend my hard earned cash to someone who is no more able to do the work than I am (barring diagnostic thingies and specialist tools I hasten to add - and if I had a couple of grand spare I'd have them too, it'd give me more pleasure knowing that only I touched the car)

I know that this is going to sound like a "OOhh you shouldn't have done that" type comment.....but fitting aftermarket air filters is not recommended on Mercs as they do tend to Bu**er up the MAS sensors.

Yes Vlad, but I havent seen that anywhere except here.
The first place I looked, the pipercross website

http://www.pipercross.com

on the home page states that their replacement panel filters are OEM quality and wont invalidate the manufacturers warranty, they wouldnt post such claims if they were blatantly untrue, it would be tantamount to suicide if they become inundated with repair bills for replacement MAS sensors!.

Ok, the general consensus of opinion is that is my MAF sensor.
I have some Isopropyl alcohol in the garage so I'll soak it in that for a while.

Watch this space, Thanx guys - I'll keep you all posted.

 

[GrahamC230K]

K&N say much the same. I tried to get them to accept blame for my MAS failing about 20 miles after I installed their replacement panel filter. They would not unless MB said the filter was to blame. MB would not commit to this.

You live and learn. I read the warnings and ignored them and bought a new MAS a little earlier than I would have done.

 

[nickmann]

I think you're right, but it was worth asking. I feel the same as you, I really enjoy working on my car, both from a mechanical point of view and also for reducing costs.

Incidentally, it may not be the fault of the filter per se, if the airbox had any dirt it that got disturbed by the change. I think it is a good idea to hoover out the airbox and ducting, and make darn sure there are no loose particles on the new filter when working with a MAS-equipped car.

 

[AngmarWitchLord]

Ok Graham.
I dont think I owe you the fiver yet.

I've cleaned the Mass air flow sensor with no improvement.
So - does anyone have any other thoughts?
What about my initial question about the condition of my plugs.
What I'm not about to do is to go out and buy 12 new plugs AND a new MAS to find it was neither.
Nickmann, I made sure the air filter housing was clear of loose particles, I removed it when I took the plugs out to check them, so I gave it a good shake out.

 

[nickmann]

What I would do next -
There is a vacuum pipe in front of the inlet manifold. Is this still connected?
Re-make all the plug lead connections (check the two leads to each pot are right way round)
Re-make all the coil lead connections
Check the throttle connection on top of the inner wing
Check for blockage (lost rag etc) in the induction path - in the airbox intake snorkel right up to the inlet manifold.
Disconnect MAS and test drive (they don't clean well)

 

[AngmarWitchLord]

What I would do next -
There is a vacuum pipe in front of the inlet manifold. Is this still connected?
Re-make all the plug lead connections (check the two leads to each pot are right way round)
Re-make all the coil lead connections
Check the throttle connection on top of the inner wing
Check for blockage (lost rag etc) in the induction path - in the airbox intake snorkel right up to the inlet manifold.
Disconnect MAS and test drive (they don't clean well)

Cheers nick.

I've already covered what you listed there.
Handy of them to mark on the side of the cylinder head which lead goes where btw. Still no joy.

Waiting for the service department to ring me back now so I can book it in for some diagnostics.
PS I dont recommend MB of Warrington, I've been waiting over 1.1/2 hrs for them to call back, and I told them I was going out today so I need them to call.
Might try the dealer in Altrincham, if my car can get me there without killing me on the way! .

 

[AngmarWitchLord]

Graham
Here's the fiver I owe you.

Looks like it was my Mass Air Flow Sensor, I left it disconnected and the car is significantly more driveable than with it connected.
replacement on order from eBay, cost me £70 inc. postage.
Considering I was quoted £180 +Vat from GSF and EuroCarParts, doesnt sound too bad.


PS The Pierburg meter that GSF sell doesnt have a little temperature sensor which is present on my Bosch.

For reference, all those of you who have a V6 (240/280/320) the Bosch / Mercedes part number is 0280.217.515 / 112.094.00.48

 

[GrahamC230K]

Printing it now..cheers!

Glad your problem is solved. I made same mistake and paid ~£300 for my MAS..there, that made you feel better!

 

[silverarrow]

looks like i ve missed out on the £5 i would have said maf
pls have a look at www.bba-reman.co.uk
maf recon and check service most mafs fail just in spec and thus hard to pin point

 

[AngmarWitchLord]

Addendum:

Mass air sensor arrived today and I've just fitted it.
The difference is just incredible, it looks like it has been losing spec over a long period and I havent noticed it.

It's always been a bone of contention that my girlfriends X type was quicker off the mark and generally perkier than my car.

Not anymore...Its like a new car now, definitely gonna give her a run for her money....you wouldnt believe the amount of teasing I've had to put up with for months.


Now its PAYBACK!!!!

 

[stats007]

Looks like you owe Graham a fiver! Get your money back from Pipercross!

 

[fuzzer]

i couldnt help thinking that it was the mas from the start of the thread.

good result .. id still change those spark plugs tho.