Slug-Gunner

Hi, I'm new to this forum, but not to automotive work. I'm a retired ASE-CMAT but NOT FAMILIAR with M-Benz vehicles and systems. About 3 weeks ago, my son was driving my ex-wife's 2000 C280 Sports Sedan, V6-2.8L (98,386 miles) and it 'bogged down' on him when he tried to accelerate into traffic. It had set the CEL lamp and I put my Equus 3160 ScanTool on it and got the DTC codes from it (P0300; P0301; P0302; P0303 Misfire codes). I erased the codes from it and drove it to check it. It seemed to drive 'normally' at low speed and under 'moderate' acceleration..... so I tried to ACCELERATE HARD and see what would happen. Once I accelerated above 3500 rpm, it started to 'misfire', the CEL started flashing, and once it went solid, the engine was in 'limp mode' (cylinders 1,2, & 3 were SHUTDOWN). I pulled over and checked my ScanTool for the codes (see above) and looked at the 'Live Data" at the time the DTCs were set - it happened at 3900 rpm. No other DTC's were set at that time, nor since that time (except a P0410 - Secondary Air-Injection System) as a 'Pending' code, but only during engine 'warm-up' period.

Over the last couple of weeks I've spent several hours reviewing older posts on this forum and another M-B forum about 'misfire codes' and many of them described MAF sensor problems being related to this. Even though I've got TWO rollaway tool cabinets with several thousand $$$ in tools in them, including a wide selection of 'security type bits', I didn't have the "5-POINT SECURITY TORX BIT" needed to remove the MAF element from its housing to clean it properly. I ordered one thru Amazon.com and finally got it a few days ago. During that time waiting for it to arrive, I've been driving the car around with my ScanTool hooked up at all times to monitor 'Live Data' and be able to record it if it failed again. It drives fairly normal, even at Interstate speeds of 70+ mph and accelerates fairly strongly.... as long as I keep the rpm below 3000-3500 rpm. I have deliberately tried to ACCELERATE HARD just before arriving home = and IT ALWAYS DOES THE SAME THING..... CEL first flashes a few times, goes solid, then engine runs like crap since the ECU shuts off the FUEL INJECTORS for cylinders 1,2, & 3. If I pull over, stop, shut off the engine for a minute, restart it again, the CEL is ON, but I can drive it again 'normally' with all cylinders firing normally (unless I accelerate 'hard' again).

I finally got the 5-point TS bit socket set and removed and cleaned the MAF element thoroughly with MAF Cleaner, reinstalled it, and then drove it around again. Everything was 'normal' UNTIL I ACCELERATED HARD ABOVE 3500 rpm. Since M-B parts are ridiculously expensive, and since it NOT MY CAR, I'm a little hesitant to start replacing parts on it without some guidance from some of you MB owners who have more knowledge of these MB vehicles than I have.

I've read these forums quite extensively and have even tried the "ECU Reset" procedures just to see what would happen. I did notice a change in the lower speed shift-points being 'quicker' and more solid and made sure to keep it below 3500 rpm until I got 'close to home'. When I tried accelerating hard again, the misfires codes and CEL returned. The 'Live Data' on my ScanTool always shows it happening between 3800-4200 rpm. Other than this, the car starts and runs quite well.... as long as you DON'T ACCELERATE HARD.

Here's one thing I'm noticing about the 'Live Data' readings I'm getting on my Equus 3160 ScanTool - the 'Advance' is always displayed as '-' (NEG) in front of the DEGREES OF ADVANCE reading. I checked this on two other vehicles and this ADVANCE displayed normally without the '-' in front of the displayed 'degrees advance' readings. Is this an 'incompatibility' with my ScanTool and the M-B ECU or what?

I've bought a set of Bosch +4 Platinum spark plugs for it and am going to replace them tomorrow and try also switching the 'coil packs' from the passenger side (bank 1) to the driver's side (bank 2) and vice-versa, just as an experiment to see if the DTC codes 'switch' with them or remain the same - this WILL CONFIRM WHETHER THE COIL PACKS ARE GOOD OR NOT. I've even purchased an AllDataDIY subscription for this vehicle, but even it hasn't provided much guidance in troubleshooting this problem since I don't have the M-B 'special tools' needed for it.

I've got to try to 'fix it' before my son returns it to my ex-wife in Atlanta or I'll never hear the end to her "B----ing about it being returned 'broken'."

I have all of the basic tools and knowledge (24 years Avionics and 40+ years auto tech background) to check anything out.... I just can't find any info as to what the voltage readings should be at various connection points to test the various suspected components properly.

Any help or guidance in troubleshooting this C280 is greatly appreciated. There seem to be some very knowledgeable people on these forums. I read about a decent $$ source for parts (near AZ, I think) but can't seem to locate it again. The local M-B dealer wants $460 for a new MAF assy, $222 for a Cam Position Sensor, and $243 for a Coil Pack.

ll1l2l1l2lll

okay. finally i find someone with the EXACT SAME PROBLEM as me. i have a 95, c280 with 110k miles. anything below 3.5 rpm is fine when accelerating hard. i can't punch it on the freeway but i could slowly roll up in there. i've been driving with the gear box and holding my gears in order to pick up speed so my cylinders don't bog out and the ECU won't turn them off. what i replaced so far (close to 3k in parts as it is, and nothing) are COIL PACKS, the entire WIRING HARNESS, all SPARK PLUGS, new bosch MAF, SPARK PLUG WIRES and even the CRANK SENSOR (what i was pinging at first) before my mechanic cleared it, it was just the p0300 code.

if accidentally accelerate too hard and my engine bogs out, i would just restart it and i'd be fine. runs strong when not accelerating too hard. it seeems like the engine might be running kinda rich? (not anywhere close to a mechanic but smells kinda rich and my exhaust backfires when i let off the gas sometimes)

however, the thing is, after the mechanic cleared the CEL. i never came back on if it bogged out. wouldn't blink or anything. computer thinks its fine which is really strange. but let me know if you find a solution..... i've been going to the mechanic once a week for the past few months trying to diagnose this problem..

HELP US OUT GUYS!

ll1l2l1l2lll

fuel pressure regulator says some of my searching.. since i replaced everything else everyone suggested.. LOL. stupid. no more money for books for college. ugh.

Slug-Gunner

The "Fuel Pressure Test" was what I'm going to do next.... after I change the spark plugs out with new ones, and the "Misfire Codes" are still present. The AllDataDIY.com subscription has the procedures and parts illustrations to perform that test and I've got the Fuel Pressure Test Set to perform it - if the M-B Schraeder Valve fuel rail fitting isn't an odd size (like everything else on this car).

As a 'preventive maintenance' measure, I'm also going to DISCONNECT AND CLEAN all the electrical connectors for the coil packs, fuel injectors and both the Camshaft Position Sensor and Crankshaft Position Sensor (and maybe remove the sensors themselves and clean them off too) using Electrical Contact Cleaner and Throttle Body Cleaner. Will check closely for any vacuum hose or inlet air tube problems when changing the spark plugs out since I have to remove most of the air inlet tube to even access them.

From what I've read on this and another M-B Forum, the M-B line of cars seem to have 'programmed failure' built into them once they get to the 80-100K mile mark. Many have had to replace the MAF, coil packs, plug wires, and wiring harness components in many of the posts listed. The M-B line of cars look good and drive great, until something starts to go wrong with them - then you need a 'second mortgage' to pay to keep them running right once they get past the 100k mile mark. I've got a '96 Nissan pick-up that has over 240K on it that hasn't had anything other than regular 'preventive maintenance' done on it (other than batteries and brake pads/shoes). I've used Mobil 1 in it since I got it with about 40K on it.

If anything I do in this process 'fixes the misfire problem', I'll probably NOT KNOW WHICH ONE ACTUALLY FIXED IT since I don't plan on testing it after each step and driving it and then having to let the engine cool off again before I can check something else. I'm getting too old to do this stuff all the time anymore.

ZX-6R3235

I would check the temperature of the exhaust pre cats and post cats to see if the cats are clogged. I had the same situation where I was getting miss fire codes and the CEL would come on if the rpms got too high. I cut the cats out and put one high flow magnaflow cat in there place and the problem was solved. I just got my car like 2 months ago and spent countless hours searching though old posts and found one where a guy had the same situation and the cats caused it.

xvvvz

The place you were thinking of is autohausaz.com

Keep us posted. It sounds like you are diagnosing things in a logical manner. The MAF can throw so many phantom codes when it starts to go bad that can throw you off track. What a pain. I am guessing you have checked the resistance of the plug wires to make sure they are OK? How old is the fuel filter? Glad to hear you are checking the fuel regulator too. The fact that the problem happens at the exact same rpm each time makes me think it is more likely to be an electrical type issue but who knows.

fast mayte

i've noticed these symptoms on many other cars with sparkplug wires going bad. i know we have 2 plugs per cyl, could there be wires from teh coil to the plug? i think start by replacing those and plugs if you haven't done so

ll1l2l1l2lll

did the tubes going down, wires, coils and even new plugs...

fast mayte

could also be a cam or crank sensor , hummm

ll1l2l1l2lll

crank sensor was my first code i threw, fixed that and i got others. weird right?

Slug-Gunner

Well, I'm getting both 'discouraged' and 'disappointed' in this M-B C280 "Misfire" issue. Here's what I've done so far with UNSUCCESSFUL RESULTS.

1. Ordered "5 pt TS Security Torx" set and cleaned MAF sensor element = NOT SUCCESSFUL.

2. Replaced all 12 spark plugs with Bosch +4 Platinum (#4418) plugs. While doing this, I switched all of the coil packs from the right bank to the left bank and vice-versa. Cleaned all coil pack connectors with contact cleaner. Checked and cleaned spark plug wires for continuity and/or corrosion = ALL CHECKED GOOD. Results = a little better low end performance and smoothness, but STILL SET SAME "MISFIRE CODES".
(2000 C280 "P0300; P0301; P0302; P0303 Misfire codes " = RIGHT BANK ONLY)

NOTE:
Since I 'swapped the COIL PACKS out from one side to the other and the DTC codes remained the same, this verifies that the COIL PACKS ARE GOOD!

3. Check fuel pressure at fuel rail Schraeder Valve = 55 psi at idle speed. After 1 hr 'at rest' waiting time, fuel pressure only dropped to 45 psi. This means fuel pump pressure IS GOOD and no 'fuel injector' leak-down is occurring. Fuel volume test = 1 liter in less than 30 seconds = GOOD FUEL PUMP and NO OBSTRUCTIONS IN FUEL FILTER.

4. Finally received new MAF element and swapped it out. Low speed performance is ACTUALLY WORSE THAN BEFORE with original installed MAF element (a little engine 'roughness' is noticeable).

Tried doing an "ECU Reset" and no change. Hard acceleration above 3900 rpm = "Misfire" DTC's still present, but added a 'P0304' DTC this time.

Tomorrow, weather permitting (no rain), I will try cleaning the Crankshaft and Camshaft Position Sensors and their respective connectors. It looks like they may be a little difficult to get to, especially the Crankshaft Position Sensor. (Have to remove a couple of access. components to get to them.

Since I had previously gotten a P0410 (Secondary Air-Injection Error) PENDING CODE, I checked the Air Injection Motor and it was running properly during 'warm-up' period. I don't plan on going into this, since this IS NOT MY CAR and only does this DTC 'intermittently'.

Since I'm not 'new' to automotive work or diagnostics, I'm starting to get a little 'critical' of MB's compliance with OBDII standards. There is a DEFINITE LACK OF INFORMATION being provided by the computer DTC codes displayed. When I check out all of the available MB DTC's that are 'available' on the P code charts, there should be a lot more codes available to diagnose this "MISFIRE" PROBLEM. My guess is that you have to have a MB type ScanTool to access them (STAR system scanner???). If the MAF, Camshaft Position Sensor, Crankshaft Position Sensor, Fuel Injectors, or O2 sensors are not providing 'output signals' WITHIN TOLERANCES = I should be getting CORRESPONDING DTC "ERROR CODES", which I am not. Am I wrong in thinking that this "MISFIRE" DTC seems to be a 'catch-all' DTC to SELL A LOT OF M-B PARTS IN HOPES OF 'FIXING' THE PROBLEM (often without being successful)? Maybe, I'm just getting 'cynical' in my 'old age', but MAYBE NOT!

xvvvz

Yeah, MB has its own version of definitions for the codes but the majority of the basic ones are the same as other code sets. An MB Star Diagnostics system would be sweet to own. They come up occasionally on ebay.

ZX-6R3235

P0410 is the code that i has throwing before I changed my cats. I have driven about 700 miles since and haven't gotten that code or any more miss fire codes.

Pecha2010

Did anyone manage to solve the misfire problem.. Ive been getting the same problem. 95 merc c280

BenzMan1

I just fixed this same issue with replacing my spark plug coils. Also this is a great place to get the info you are looking for on codes and repair solutions. I use it all the time and it is worth the $18.00 for 24 hr access http://www.startekinfo.com/StarTek/

aaronirvin67

I am having a miss fire problem on a ClS 550 cylinder PO 302 code piping up. Any suggestion I am hoping I don't need a valve job.