1997 C280 Rough running - Page 2 - PeachParts Mercedes-Benz Forum

Jerzeeshor · #16 10-01-2008, 11:37 AM

I had the identical symptoms and codes on my wife's '98 C-class. To save a few dollars, I replaced the Mass Air Sensor with a rebuild and the car ran worse than ever! It ultimately turned out to indeed be a bad Mass Air Sensor - BOTH the original one and the rebuilt one! I took the loss and bought a factory-new one from the dealer, and it has been perfect ever-since! By-the-way, be sure to change the air-filter regularly to prolong MAS life!

#17 10-01-2008, 11:53 AM

I remember one of the reasons I bypassed checking the coils and that was because the code said random misfire, not pointing exactly to one cylinder.

I called and asked that they rule out the coil packs...

thanks again.

Cysquatch · #18 10-01-2008, 12:50 PM

Quote:

Originally Posted by Madewell

I remember one of the reasons I bypassed checking the coils and that was because the code said random misfire, not pointing exactly to one cylinder.

I called and asked that they rule out the coil packs...

thanks again.

Luckily I had an OBDII reader laying around and it indeed pointed to a specific cylinder misfiring when I had a similar problem. Made narrowing down the bad coil pack easy.

Arthur Dalton · #19 10-01-2008, 03:42 PM

Do you have Plat Plugs in there ????

mbdoc · #20 10-01-2008, 04:23 PM

1st question? Did you purchase a complete mass air flow sensor?? (new) in Bosch
box with Bosch part number 0 280 217 517??

If the answer is yes?? Has the fuel pressure regulator been tested for diaphragm leaks??

#21 10-01-2008, 05:01 PM

Mr. Dalton,

No platinum plugs.
I had a bad experience with them when I first got the car, two weeks after I put them in one burnt out. I have had regular NGK's in the car since November.
the plug wires and connectors I use were Bosch from the ******** AZ.

John

#22 10-01-2008, 05:09 PM

M.B. DOC,

Yes sir, the part was new and in the original Bosch box. I ordered it as well from Auothaus AZ.

I did not check the pressure regualtor, I will verify if the shop has done it yet. I wish I had the tools to make all the necessary checks.

The shop it is in mainly works on Mercedes and BMW's so I thought they were a good choice but they have been unable to chase this one down for the last week.

I know they checked the system pressure while the car was acting bad and they said it checked OK. they were not sure why the O2 sensor was giving them negative readings.

John

Arthur Dalton · #23 10-01-2008, 05:14 PM

I meentioned Plta b/c you described the electrodes as thin..
???

Anyway, the test on the regulator is to simply take the vac hose off and see if fuel comes out the port..if it does , the daiphragm is leaking and feeding unmetered fuel to the engine.
Common problem

OzC36 · #24 10-01-2008, 10:37 PM

The Oxygen sensor readings could be symptomatic of the misfire rather than the cause of the misfire. When the engine misfires the percentage of oxygen in the exhaust varies rapidly depending on the source of the misfire and the engine computer response to try correct the misfire.

The oxygen sensor signal will "trim" the fuel to optimize the mixture to produce the desired level of oxygen in the exhaust gas. However, the amount of authority to trim the fuel is limited and therefore, I do not think that it could cause a misfire.

In one test I carried out was to run the engine and then drive my car with the oxygen sensor disconnected. There was absolutely no detectable effect on the normal operation of the engine.

I think Arthur's comments are always spot on. Copper core non-resistor spark plugs are the only plugs that are happy in the M104 C280 and C36 engines. In line with Arthur's comment, check your NGKs are of the copper core non-resistor variety.

I personally prefer the Bosch F8DC4 plugs. They are getting hard to source but ******** still has them.

I started having problems with my coil just one month after my incompetant Mercedes Dealer put Bosch resistor plugs in my car. I refused to go back to them after that.

It took me over six months to resolve my problem. The independent Merc specialist couldn't determine the problem or fix it, so I had to resolve the problem myself.

1. New MAF
2. New plugs and ignition harness
3. Repairs to the engine wiring harness
4. New engine wiring harness
5. New crankshaft position sensor
6. New fuel filter
7. New throttle body
8. Countless manhours and tests and other parts I can't remember
9. ...and finally fitting the new coil in the last of the three coil positions finally and fully resolved the problem.

mbdoc · #25 10-02-2008, 08:12 AM

Back to the air mass sensor. Was it a complete unit OR an insert?
Does it have tha Bosch number that I listed?

#26 10-02-2008, 10:54 AM

M.B. DOC,

It was a complete unit in the Bosch box. I called the ******** to confirm that it was a new unit. The part number is: 0280218080 as it reads from the invoice and this was what the part that was on the car read. I believe the plug connectors are different, mine has the rectangular plug.

Thanks for the help

#27 10-02-2008, 10:58 AM

OZ,

If they don't get it done today, I am going to bring the car back home and I will try your suggestions. I asked them to verify the coil packs and check the plugs, they might attempt it today.

Thanks for your suggestions and help...I can't believe how frustrating this is getting. I have always been able to work on my own cars, this one is a bit different.

M.B. DOC...I forgot to mention that they did check the pressure regulator and it had no leaks.

#28 10-02-2008, 11:21 AM

M.B. Doc,

I went back and looked at the two Mass Air flow Sensors offered for this and I believe both have the rectangular plug. The one that was on the car was the 0280218080 number so that is the one I re-ordered. should I try the other model number?

John

mbdoc · #29 10-02-2008, 11:50 AM

ON a 1997 M104 motor in a C280, the only correct air mass sensor is MB # 000-094-10-48 OR Bosch number 0 280 217 517!!

OTHER numbers might fit but will not operate correctly!

#30 10-02-2008, 01:52 PM

M.B. DOC

I just verified with the shop and he ordered from Mercedes part number 000-094-10-48. He put it on the car and it ran fine for about 15 minutes and then started it with the same condition. It is not giving any codes except bad brake sensor?

He said the engine is running to lean. All fuel system pressure checks and the fuel system regulator check OK.

The next thing they are going to do is to use a new coil pack and start moving it's position to see if it will have an affect.