Occasional rough-running condition
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From: Cave Creek, AZ
2012 Mercedes S63 P30, 2015 Mercedes GL550, 2009 BMW 650i Convertible
Occasional rough-running condition
Happy holidays, everyone! This issue has occurred twice and under basically the same conditions. 2012 S63 with the P30 Performance Package, 67k miles. Driving for a few hours on the freeway at speeds ~75-100mph (in Mexico on a closed road, of course!). Car runs extremely strong, and then all of a sudden, the check engine light will flash, and the car will act like it's running on 7 cylinders, with consistent, stuttering throttle response. Get off the freeway (still stuttering), turn it off and then on, and everything's fine. CEL is no longer illuminated or flashing. Any ideas? Oil/water temps were normal (less than 200*F), all fluids at proper levels.
Bill
Bill
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'06 MB S55 AMG; '04 Audi Allroad 4.2; '05 BMW M3 Conv.; '92 MB 500E
Happy holidays, everyone! This issue has occurred twice and under basically the same conditions. 2012 S63 with the P30 Performance Package, 67k miles. Driving for a few hours on the freeway at speeds ~75-100mph (in Mexico on a closed road, of course!). Car runs extremely strong, and then all of a sudden, the check engine light will flash, and the car will act like it's running on 7 cylinders, with consistent, stuttering throttle response. Get off the freeway (still stuttering), turn it off and then on, and everything's fine. CEL is no longer illuminated or flashing. Any ideas? Oil/water temps were normal (less than 200*F), all fluids at proper levels.
Bill
Bill
maw
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From: Phoenix
222 S-65
OP describes a misfire... Perhaps consistent with a failing ignition coil. I've not got to fiddle with one of these and am thus not aware of pattern failures... I'd be surprised if this vintage of them never has coil issues. The ECU pulls fuel from a cylinder it knows to be misfiring and will not try again until the key is cycled off and back on. All about protecting exhaust kittahs.
Lack of fuel will recover as soon as he is out of the throttle and leave codes for multiple random misfire or some such.
OP pull codes from the ECU. The flashing check engine light says that the ECU is aware of the problem and will have a treasure trove of useful data for diagnosis. Expect it to say which cylinder is misfiring.
If one cylinder is misfiring.... Swap ignition coils from the hole having a problem with a cylinder not having an issue. If the problem moves you know what to replace. Good opportunity to pull spark plugs to have a look and replace with fresh.
Lack of fuel will recover as soon as he is out of the throttle and leave codes for multiple random misfire or some such.
OP pull codes from the ECU. The flashing check engine light says that the ECU is aware of the problem and will have a treasure trove of useful data for diagnosis. Expect it to say which cylinder is misfiring.
If one cylinder is misfiring.... Swap ignition coils from the hole having a problem with a cylinder not having an issue. If the problem moves you know what to replace. Good opportunity to pull spark plugs to have a look and replace with fresh.
Last edited by JohnLane; Dec 28, 2018 at 05:21 AM.
Thread Starter
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From: Cave Creek, AZ
2012 Mercedes S63 P30, 2015 Mercedes GL550, 2009 BMW 650i Convertible
I ran the codes (the CEL has been off), and the only one that appears is P2270: "P2270 is an OBD-II generic code for the O2 sensor signal stuck lean on bank 1 sensor 2 to the engine control module (ECM). This means that the O2 sensor in bank 1 sensor 2 indicates either too much oxygen in the exhaust stream, an open circuit, or a defective sensor which causes a lean signal to the ECM." Not sure what the correlation between that and the stuttering/rough running would be, but I'll replace the sensor, and it's also time to replace the plugs.
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Bill, your “rough running” was my “running lean”. You can change the sensor if you want. But if the CEL went off and that’s a stored code, my sense is your sensor is still good. I would first change the plugs. While I’m at it, because it’s cheap and non obtrusive, I would change the fuel filter. Then I’d wait and see if the condition occurs again. If so, then I’d move to the sensors and fuel pump. But for now, it seems the sensors are functioning properly. Plugs are plugs, no mystery there. But what you describe is a failing fuel pump. They’ll sporadically run lean before failing altogether. If the condition returns after plugs and fuel filter (good to do no matter what), then I’d next suspect the fuel pump.
On my S55, he failing fuel pump was even more subtle. There would be periodic extended cranks before she would turn over. Every now and again, nothing constant or repeatable. I threw a crankshaft position sensor at it — no dice, same thing, still every now and again. This went on for years, but nothing to bother about. Then, I was driving the car, I hit the gas for acceleration and it sputtered and muttered, but kept running. Light fuel pressure was fine, and the car would cruise, but as soon as I put my foot into it, sputter and mutter. Lean condition, fuel pump. Changed it and filter, no problems since. So I’m just ruling out the things that it makes sense to do on yours, to isolate the fuel pump. New plugs and fuel filter never hurt, so I’m not advising against that. But from the beginning I suspect the fuel pump, based upon my experience.
GL and pleas keep us posted.
Cheers,
maw
On my S55, he failing fuel pump was even more subtle. There would be periodic extended cranks before she would turn over. Every now and again, nothing constant or repeatable. I threw a crankshaft position sensor at it — no dice, same thing, still every now and again. This went on for years, but nothing to bother about. Then, I was driving the car, I hit the gas for acceleration and it sputtered and muttered, but kept running. Light fuel pressure was fine, and the car would cruise, but as soon as I put my foot into it, sputter and mutter. Lean condition, fuel pump. Changed it and filter, no problems since. So I’m just ruling out the things that it makes sense to do on yours, to isolate the fuel pump. New plugs and fuel filter never hurt, so I’m not advising against that. But from the beginning I suspect the fuel pump, based upon my experience.
GL and pleas keep us posted.
Cheers,
maw
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From: Cave Creek, AZ
2012 Mercedes S63 P30, 2015 Mercedes GL550, 2009 BMW 650i Convertible
Bill, your “rough running” was my “running lean”. You can change the sensor if you want. But if the CEL went off and that’s a stored code, my sense is your sensor is still good. I would first change the plugs. While I’m at it, because it’s cheap and non obtrusive, I would change the fuel filter.
maw
maw
Bill
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From: Cave Creek, AZ
2012 Mercedes S63 P30, 2015 Mercedes GL550, 2009 BMW 650i Convertible
Well, I had the plugs changed, and the CEL stayed off for a few days and then came back on with the same code. Now I'll change the fuel filter, just to be safe.
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'06 MB S55 AMG; '04 Audi Allroad 4.2; '05 BMW M3 Conv.; '92 MB 500E
maw
Thread Starter
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From: Cave Creek, AZ
2012 Mercedes S63 P30, 2015 Mercedes GL550, 2009 BMW 650i Convertible
It's too hard to replicate, since it's only done it twice, and it was on the freeway after a prolonged 80-100mph. It'll all of a sudden run terribly like it's on 7 cylinders, pull off the freeway, still misfiring at all speeds, CEL flashing. Come to a stop, turn the car off and on, and the problem goes away completely. I cleared the codes yesterday, and the CEL has yet to come back on. We'll see how long that lasts. Car runs strong.
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'06 MB S55 AMG; '04 Audi Allroad 4.2; '05 BMW M3 Conv.; '92 MB 500E
It's too hard to replicate, since it's only done it twice, and it was on the freeway after a prolonged 80-100mph. It'll all of a sudden run terribly like it's on 7 cylinders, pull off the freeway, still misfiring at all speeds, CEL flashing. Come to a stop, turn the car off and on, and the problem goes away completely. I cleared the codes yesterday, and the CEL has yet to come back on. We'll see how long that lasts. Car runs strong.
I give that to you as added data, but the choice is still yours. I generally don't like throwing parts at cars, unless I have a really good idea about it. But I've observed over time that my guesses are as good as anyone else's, and a lot less painful than the stealership's learning on my dime. If the guess is going to be wrong, it's gonna be my guess (my car, my money), not someone else's.
GL, please keep us posted.
maw
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222 S-65
OP a flashing check engine light only happens for a severe misfire. The ECU should be eager to tell a proper scanner which hole is/was dead. It will remember this for a long time. Start there.
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maw
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222 S-65
Maw a flashing check engine light will happen where there are multiple cylinders that are dead dead deadski long enough for the ECU to pick them out.... However; OP describes one dead hole. This is the easier scenario for the ECU to pick which hole it is.
Random multiple misfire can easily be an issue with just about any and all.
Certainly before condemning a fuel pump I'd have OP hook up a gauge and drive it with that gauge clearly visible such that we can see 'while making multiple awful misfires fuel pressure is low.'
In my E-55 I got to deal with many issues of driving along... Load it up and it cuts the supercharger... Is misfiring... No check engine light. That was really annoying and got fixed with ultimately replacing all plugs, coils, wires + screwing around with coil connectors.
Does the TTbent eight use air mass meters or is it speed-density? E-55 and my 275 are speed density.
Random multiple misfire can easily be an issue with just about any and all.
Certainly before condemning a fuel pump I'd have OP hook up a gauge and drive it with that gauge clearly visible such that we can see 'while making multiple awful misfires fuel pressure is low.'
In my E-55 I got to deal with many issues of driving along... Load it up and it cuts the supercharger... Is misfiring... No check engine light. That was really annoying and got fixed with ultimately replacing all plugs, coils, wires + screwing around with coil connectors.
Does the TTbent eight use air mass meters or is it speed-density? E-55 and my 275 are speed density.
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Agreed on the gage. The problem with these pumps is they go slowly over time, triggering faults that are difficult to run to ground. Mine took years of mild annoyance before it got bad enough that it was easy to replicate, trace and fix. Short of that, as you know, it becomes a series of guesses.
maw
maw
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From: Phoenix
222 S-65
Agreed on the gage. The problem with these pumps is they go slowly over time, triggering faults that are difficult to run to ground. Mine took years of mild annoyance before it got bad enough that it was easy to replicate, trace and fix. Short of that, as you know, it becomes a series of guesses.
Intermittent issues are are the most annoying of all! Currently the S-65 shuts Command off intermittently. Grrrr
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'06 MB S55 AMG; '04 Audi Allroad 4.2; '05 BMW M3 Conv.; '92 MB 500E
Misfires in the E-55 were especially annoying. At first it did it..... Dead hole. No codes. Cycle key and it was fine for weeks to over a month. Predictably it got more consistent over time but was still unwilling to share it's secrets. Finally narrowed it down to a coil. Replace it... Month or so later another fails. Rinse repeat. Especially fun is when a new coil decides to make for yet another new/exciting drivability issue. Been there. Done that. Half of them never make a check engine light flash. It had to run really bad for that.
Intermittent issues are are the most annoying of all! Currently the S-65 shuts Command off intermittently. Grrrr
The point is, these cars do NOT like to run lean. Basic air, fuel and spark. If you have air and spark, then fuel delivery is probably the issue. The 65 cars were an anomaly, with coil packs and modules going bad. On everything else, if you've taken care of plugs and don't have pressure leaks, it's more likely the pumps. I haven't heard of any ECU issues on these.
maw
P.S. Unfortunately, these pumps look like they are in the tank. Brilliant.
Last edited by maw1124; Jan 25, 2019 at 08:57 AM. Reason: P.S.
