Yesterday, the 'Check Engine' message came up in the dash computer of my 2005 Mercedes C230 Kompressor during hard acceleration. I immediatly thought a line might be pinched in the EGR system, but then the engine sputtered and hesitated. I pulled over, turned off the engine for a couple minutes, then restarted. The engine seemed to run smoothly, but I babyed it straight to the dealer and left it with them to check it out. The service manager called to say he would have to keep it over night because he had to order injectors. Injectors! The car only has 8200 miles on it!

Now here's what he says that I'm unsure about. He questioned the quality of the fuel I'd been using. I told him that I had only ever used 1 type of gasoline in the car: BP 93 octane (BP now sells Amoco Fuels, which I have heard is some of the cleanest gas you can buy). He then said that I should be using a lower octane fuel. Like 87 octane or 'regular' unleaded. This is in direct contradiction with the owners' manual. He said that the fuel in the US is so much purer than the fuel in Europe that we don't always need the highest octane, especially in the warmer areas of the country. He said that the high-octane gas is burning too quickly and a residue is building up on my injectors (especially the #4 injector).

OK, I thought higher octane made the gas burn slower to prevent knocking in the colder weather, not faster. And what about his recommendation vis-a-vis my warranty. Manual says 91 Octane and above, he says 87 is OK. He said something about a service bulletin on this topic, which I will ask for a copy of, but what do you guys think? Does thic sound right to you?

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--Craig.

"When you see a fork in the road, take it!"
(Yogi Berra)

That mechanic is an ass. All MB's produced now require Super or 92+ Octane fuel due to the higher compression ratio of most of there engines. The C230K is a Supercharged engine and does require the 92+ Octane fuel. If you use lower octane the engine will Ping and then the ECU will retard the timing! Thus losing power to save the engine. Pinging is never a good thing and the ECU has to detect it first to retard timing, thus meaning that there is a risk to the engine in the long term due to excessive pinging. I would follow what the MB Engineers and Designers suggest not some Mechanic who obviously would like to tell you something diferent than the guy who actually designed and built the damn engines! The M271 engine is pumping 11psi of boost from the factory, not exactly low boost for that 1.8 L engine. Follow what the Boys and Girls in Stutggart suggest!

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~Jamie
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2003 Pewter C230K SC C1, C4, C5, C7, heated seats, CD Changer, and 6 Speed. ContiExtremes on the C7's.

1986 190E 2.3 Black, Auto, Mods to come soon.....

I would suggest your mechanic is fibbing.

Higher octane fuel does not burn faster or slower than lower octance fuel. The octane rating is simply a number that shows how reistant the gas is to burning upon compression. A "93 octane" fuel has the same properties as far as resisting detonation as a mixture of 93% octane and 7% heptane. Octane is much more resistant to detonation and therefore a higher octane number means higher detonation resistance. And why would how fast the fuel burns leave residue on the injectors? This mechanic does have previous experience with motor vehicles, does he?

Follow the owner's manual and find a new mechanic.

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Ali Al-Chalabi

2001 CLK55
1999 Dodge Ram 2500 Cummins Diesel
2002 Harley-Davidson Fatboy
Merlin Extralight w/ Campy Record

The guy is clueless! You probably can use lower octane, but the detonation sensor will retard timing (or maybe even boost) and the car will not feel as peppy. The best course of action is to continue using premium.

I would also question his diagnosis. What engine code was in memory and what does it mean? This is a very important question. What's the basis for changing the injectors. (I'm assuming the car is on warranty.)

You should either go to another dealer service department or ask for a meeting with the Mercedes dealer service rep and ask him to do a proper diagnosis, and then repair whatever is the problem, if their is a problem.

Duke

Yep......he's right, there was a bulliten concerning fuel quality but it was very specific that you must use PREMIUM FUEL in all current vehicles. So you are fine with the fuel you are using.

Ask which cylinder it was if it ever does it again. Cylinder 4 are known for either a problem with the valve seats or carboning up on that cylinder. Also ask them if they checked the fuel pump current draw (7-10amps from memory). If the current draw at idle gets out of that range then you have a fuel pump problem (common).

I'm presuming they are changing injectors because of a fuel starvation/lean running fault code. The fuel pump will do that.

Also ask if they took a fuel sample. This is a very early steep in diagnosing a misfire on these engines (water/contaminents in the fuel).

Sometimes the smooth running sensitivity is too low and needs to reset to the lowest sensitivity to avoid unnecessary cylinder shutoff.

I hope this helps you with your problem. Have comfort knowing that even if you get bs answers from service manager/advisors, the people who work on your car usually know these cars back to front.

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Alex.

MB Tech
Sydney, Australia
Volvo 122S
W201 190D 2.5 manual
W202 C240
W203 C32

I forgot to add that all the loan cars at my dealer are run on the cheapest grade of fuel available in Australia. The C180 (highest compression and lowest boost) is the vehicle that feels the crap fuel the most. Anything over 50% load between 2000-4000rpm is where you can feel the ignition beind retarded. This is a range where the average driver will use often so the old "I don't need performance fuel, I don't drive it hard" doesn't bear relivance anymore.

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Alex.

MB Tech
Sydney, Australia
Volvo 122S
W201 190D 2.5 manual
W202 C240
W203 C32

I see you mentioned that the mechanic in question is an M-B mechanic from a proper licensed M-B dealership, right???

What I have always done in situations like this (when the service manager or a mechanic from the dealer contradicts owner's manual specs), either to justify a work that is NOT needed or to cover for something they don't ACTUALLY KNOW is to have there answer or justification written and handed over to me (preferably using the dealer's stationary) and, of course, signed by all responsible parties.

Then, with this letter, contact your M-B representative or zone offices and inquiere about the issue.

You'll see what there reaction is...

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A. Rosich
CL 500, 1998
S 500 L, 1998
E 320 T, 1995 [Sadly sold ]

Thanks to everyone who offerred their opinions and direct knowledge of my problem! I picked up my car from the dealer yesterday and voiced my concerns (even quoting some of you responders) about the fuel recommendation. This is the only Mercedes dealership in town and I have been extremely satisfied with every department I have dealt with there so far. The service manager is a 20 year veteran at that dealership, a very friendly person and seems to genuinely know what he is talking about. However, he reiterated that MB has told his shop foreman that in certain, isolated cases (where there is carbon buildup on the #4 injector) better results and less buildup can be gained from 87 octane fuel. He says he has had a few cases like mine in the past and this took care of the problem.

He went to the foreman to see if a service bulletin existed that spelled this out, but couldn't find one. He said he knows the instruction was given verbally by phone from MB to his shop foreman. He said I was free to use any fuel I chose, but that he recommended trying the 87 octane fuel. What was done to my car:

Code 8319 Faulty injectors. Performed short test. Performed ME-SFI flash and scn code fuel computer. Replaced all injectors. Replaced ignition coil. Replaced spark plugs. Drained fuel tank, clean air intake system, add BG44K fuel additive to fuel tank.

All work was performed under warranty. Ignition coil was part of the prescribed remedy from MB--service manager didn't feel it was necessary, but followed MB's procedures. Also, injectors were not exact replacements of the stock injectors as the new ones were some sort of upgraded injector. I spoke with a representative from MBUSA's Customer Assurance Center today and told him my story. He was unable to find any written material to support using a lower than 91 octane fuel in this car, nor had he ever heard of such a remedy. He recommended that I continue to follow the fuel guidelines in the owner's manual, so I will. It was suggested to me on one of the forums I posted this issue on to rotate brands of fuel periodically so that I don't always have the same additives in every tankfull and I will try that as well.

Thanks again to everyone who responded to my thread--I really appreciate your collective knowledge!

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--Craig.

"When you see a fork in the road, take it!"
(Yogi Berra)

I could be wrong, but it sounds like the dealer was trying to make some warranty dollars from MBNA.

The "I was told you should use lower octane by phone" excuse sounds fake. They changed all of your injectors and a coil (was this even necessary?) to run up a huge bill with MB. They then blamed the whole thing on fuel.

I guess it's no big deal for you. You have new injectors and a coil. I'd DEFINATELY keep using high octane fuel.. you have a manual printed by experts on what you should use -- don't risk MB denying you a warranty claim in the future based on what some mechanic told you.

This is not an entirely uncommon thing, by the way

Neal

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'83 300SD 335,000km (207k) mi SOLD
'87 560SL 163,000km (101k mi) SOLD
'86 300SDL 356,000km (220k mi) SOLD
'92 500SEL 250,000km (155k mi) SOLD
'90 300SL 140,000km (87k mi) SOLD
'01 S430 260,000km (161k mi) SOLD
'03 SL500 167,000km (104k mi) SOLD
'07 S550 4MATIC 235,000km (146k mi) SOLD
'07 GL320 CDI 4MATIC 348,000km (215k mi)
'13 GL350 BlueTec 4MATIC 170,000km (105k mi)
'14 SL550 72,000km (43k mi)

I have the same engine with 36,000 miles on it and used only 92+ octane fuel for all those miles. I have never had an injector failure or any other ignition related or fuel related problems. But if you search the C Class specific MBKlasse.com forums you will see other had this same type issues. Also I recall this was due to bad coil packs, not the actual injectors. I have learned while dealer with the Stealer that they do what ever it says in the computer, never thinking outside the box. The follow MB like they are gods and never question what they are told. This Service Guy probably got it backwards and was most likely really told that running 87 Octane would do that rather than 92! Of course my car had to go to the Stealer Three times for the Seatbelt Extension to be fixed because two times they left a piece out when replacing it! Both times I asked if they checked the other one in the car and they said yes, but the piece was still missing. Put it on backwards the first time and it was useless, I took it off and flipped it around and noticed the spring clip missing. I do not have faith in anyone who can not put a piece of plastic with a metal spring clip in correctly even after it was pointed out to them on the first try, let alone the second and subsequent 3rd try. They looked at the computer and the computer did not show the piece so they did not put it in! Common sense would tell them to at least look at the one installed from the factory or at least the one they took out to replace to make sure it was done properly! Oh well. I just make sure I check out the car when it is done with service. Last time it was in they replaced the alternator and afterward my Bi-Xenons would not auto level to the appropriate height. They never even verified they aimed when done with the work. It was light out so we did not notice, then I went to go to dinner and notice the headlights aimed as far down as they go. Took them 2 days to figure out what they screwed up. Apparantly you have to remove the anti-sway bar for the alternator removal, the auto level sensor is on the sway bar and takes something like an hour long procedure to set properly. They did not do that procedure and sent it on its way. I had to unplug the sensor so I could drive the car for the weekend, since it was Christmas! So don't take what they say or do as gospel!

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~Jamie
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2003 Pewter C230K SC C1, C4, C5, C7, heated seats, CD Changer, and 6 Speed. ContiExtremes on the C7's.

1986 190E 2.3 Black, Auto, Mods to come soon.....

I'm pretty sure they're out to make money on your car.

I've seen numorous bullitens instructing that ignition coils are not to be replaced unless they are deamed to be faulty by means of osciliscope patterns or physical damage (broken electriacl connectors, corrosion, etc.). Another point is that they used a fuel additive. MB specifically state that additives of any kind are not required.

So they've replaced the injectors, replaced ignition coils, replaced spark plugs, updated the engine ecu software, cleaned the air intake, drained the fuel tank and given you a fuel additive ............How confident do you feel about the diagnosis skills of the people working on you vehicle when you are out of warrenty and you are paying the bill

So they didn't actually pinpoint an exact fault, sounds like they just replaced everything.

Verbal recommendations should never be passed on to customers unless they can be backed up in writing, it doesn't matter what industry you are in.

As long as your fault is fixed, all is well. Just be mindful when you are paying the bill next time.....ask lots of questions!

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Alex.

MB Tech
Sydney, Australia
Volvo 122S
W201 190D 2.5 manual
W202 C240
W203 C32

This happened to me twice. Filled up with 94 octane, check engine light flickering at start up, idle rough and sluggish. Switched back to 91 octane all the above gone.

Coincidence? go figure. I'd say you know what is best for your car.

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joel

Prayers bring forth enlightenment.

The manual recommends 91 octane, so it shouldn't be surprising that it runs well on it!

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1998 C230 330,000 miles (currently dead of second failed EIS, yours will fail too, turning you into the dealer's personal human cash machine)
1988 F150 144,000 miles (leaks all the colors of the rainbow)
Previous stars: 1981 Brava 210,000 miles, 1978 128 150,000 miles, 1977 B200 Van 175,000 miles, 1972 Vega (great, if rusty, car), 1972 Celica, 1986.5 Supra

It sounds like a few around here need to "think outside the box" and not assume the tech or the MB tech dept is trying to ruin/make money off this guy. Very often the techs at the tech center will have info from all over the country on ideas which are "fixing" certain conditions. If the tech at the tech center says to try 87 octane (and the dealer is willing to put this in writing on the work order) then I'd try it. I wouldn't continue to use it if it created problems, and i wouldn't let the dealer say that you now have a code caused by using 87 octane gas.
There was a time when we were advising cusomers to run mid-grade as opposed to premium fuel on mid-90's 104 engines to cure a "false start" condition when cold, it fixed the problem just fine.

Gilly

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When dealing with these such issues, it will say on the customers copy of the repair order: "recommend using 89 octane gasoline". This is the info that MB has given us. This topic seems to get people as fired up as a K&N filter thread. If you want to spend more money to have your car not run as well, by all means do it. The gas pumps at my dealership have had 89 octane in them since the afforementioned 104 issues.