GuilhermeRocha

About MAF, I got the chance to buy one used very cheaply (30 euros) working fine. The part number is: 000 094 05 48. Is it the correct one?

Also, I am going to buy a error code reader for my Merc out of Ebay, they are quite cheap and I thought I give it a go.

You guys know a specific one thats any better? Any personal opinions?

Thanks for all the support

optimusprime m1

Check out the OVP relay.It can bring a multitude of problems if its faulty. Sits at the back of battery ,at the rear of plastic cover.Look for one relay with fuses or fuse , on the top .Check the fuse to see if its not blown

GuilhermeRocha

The relay is good. Just took some photos of that area of my engine bay.

http://imageshack.com/a/img922/1939/tXCVF5.jpg

http://imageshack.com/a/img923/4030/ezW6d7.jpg

http://imageshack.com/a/img923/7708/YwFN2w.jpg

I also recorded two videos of my engine compartment, one with engine running:



FINALLY recorded the problem I got:


0:12 Shift it into Gear
0:19 Full gas
0:19-21 Backfires
After 2500 rpm-3000 rpm is perfect. I also notice that in almost every situation on those kinds of rpm, the car backfires just to continue at the same speed.. In the freeway, doing 60 mph with cruise control in a uphill section, it backfired twice in a row like in this video and then I brake just to turn off cruise control and it stopped.. And as we all know 60mph is nothing to this engine and transmission.. It's making my life driving the car quite impossible..

ALSO: after "playing" with it a little, I can guarantee the car shakes in the moments before backfiring.. I cant explain it well. In steps would be: I give it a little bit of gas. Shakes the whole car. If the situation gets worse, backfires until i got off the gas or the car eventually could manage that section of road by itself.

optimusprime m1

Yes as it missfires you engine is running out of balance .So then just as happens your engine will shakes about from the centre to the left and right looking from the driver seat.So it may need new engine mounts also. Keep reading up on this problem on the forum ,the engine is breathing in unwanted air form some place. I do think its i need of fuel as you put you foot down ,but is sucking air instead so then it will back fire...

optimusprime m1

Guil i think you need to read this....Google Search and put in -
Mercedes W124 300e Backfires. Then read the post its in Pelican Parts. He talks about lambda sensor in silencer down pipe being faulty.

GuilhermeRocha

Just read it, great info thank you. My friends in the Portuguese Mercedes-Benz Club also say it might be this little fella

http://imageshack.com/a/img922/294/w0UVGM.jpg

Just next to the MAF sensor..

Great info and help from you all really thankfull, I will spot driving it for a while since my other w124 came back from the shop. In a few days the MAF sensor will arrive. I also noticed that I have to clean the error on my car (if it has any). Anyone knows how to do it?

optimusprime m1

Thinking you may need the code reader to do this. Just do the same with google put qustion on there and read away, thats if you get no replies on the forum.Yoiur car is newer than mine . As my car is a w124 is a 1989 2.6. And the test sheet i sent you will be of no use to you. It is for the one i have an M 103.

GuilhermeRocha

No problem on that case, I got one from Mercedes Club Portugal. I would put it here but dont know how

GuilhermeRocha

UPDATE

Got the error reader working. Bad MAF sensor. Just replaced it. The car runs alot smoother now. Unfortually after gets hot the problem gets back again. This time, all the shaking went away under low acceleration, but while driving and under heavy load backfires like it did before. If I do the same in lower temperatures (40-60º C) it does not occur. Finnaly, I used the error reader again. Shows me I got a bad lambda sensor. Could be this the problem after all?

Either way, my MAF sensor was not working properly, because I can feel the car alot healtier now!

P.S. - just got a leak from my transmission cables that run to the radiator for cooling, no big deal, will fix it soon

GuilhermeRocha

Well my friends, just started on the car again. I look at the state of the spark plugs and I did not like it. Here, take a look:


http://postimg.org/image/8voejzre9/

http://postimg.org/image/j43k3ys8h/

http://postimg.org/image/o3imsy4c1/

http://postimg.org/image/ulbn6orch/

http://postimg.org/image/5lxkufdyp/

http://postimg.org/image/ws6p34hv5/

http://postimg.org/image/o1dwxgjn5/

http://postimg.org/image/hukwg9hf5/

I noticed that spark plug wires Nº1 and 3 were quite humid, maybe oil. Do you guys think this might be the problem for all the hesitation and lack of power in the engine?

Thanks,
Guilherme Rocha

optimusprime m1

Guil i think for the year that it looks normal to me .And in good condition .Lets see what other members have to say .

GuilhermeRocha

hope someone answers me, hoping to get some help in here. A friend from Mercedes Club said i should take off the spark plugs metal cover, and run the engine in a dark place, and see if any sparks come out. If that happens, might be some cable that lost it's insulating properties..

Thanks

optimusprime m1

Put one old plug in to one lead .The others need to be conected Hold it with insulating pliers . Watch out thousands of volts in the plug lead your holding .You will see it spark if you have voltage, as you put it close to the plug thats in the engine. If you are not sure how to do it ,then get further advice.

GuilhermeRocha

Well, got the problem sorted finally. 6 Really bad spark plugs were the cause.. replaced them by myself, runs like a champ now!
Some photos for you guys to check it out.

These were the old ones:

http://postimg.org/image/f5i0zfmt7/


And this the new ones from Bosch:

http://postimg.org/image/attvtswu3/

http://postimg.org/image/8tzygjfaz/


And there you have it, running fine now, very smooth like it always should be.

Thank you everyone for helping me out, all the way in Portugal!

optimusprime m1

The engine will shake if it is not sparking on one cylinder .And the back fire is due to unburnt fuel in the exhaust manifold or silencer
What type of spark plugs heve you in the engine ? ,some dont like resistor type plugs.

GuilhermeRocha

Here you have it:

http://postimg.org/image/djt13js1n/

Bosch FR8 DC+