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Posting in this forum because this is where a majority of the action seems to be!
I noticed something a little odd yesterday but didn't pay a lot of mind to it - the car was running great, lots of power at command - only one hiccup yesterday as I was pulling out of my space at office. Seemed like the idle dipped for a brief second and then picked back up a couple hundred RPM and corrected. Drove home, top-down, and all was good. I paid no mind because all of my fuel injected cars have done this at one time or another.
This morning I pulled her out of the garage and let her idle (probably a little too long) while I was wiping away pollen inside and out. When I left, she was 160 degrees oil temp and 198 water temp. I then drove up to the pharmacy a couple miles away - no issues though I wasn't running her hard at all. Then from the pharmacy to work (about a ten mile hike up). All was good until I went to merge with traffic on the interstate. Someone one was riding my *** so I was like, okay, let's put on a little bit of a show and merge and go.
Denied!
I gave her the beans and she misfired like she had a couple of dead cylinders. That wasn't good at all.
I limped up the interstate a couple of exits and got off early. I was able to cruise fine but anything with boost being made was not happening. I finished the rest of my journey off the interstate and made it to the office. In my parking space, free rev'ing sounds great. No issues at all. No odd noises. I restarted the car and then put her in gear and held the brake to simulate some load and it seems to drop in and out, but I couldn't tell if that was just a characteristic of the MCT or if it was the engine again attempting to misfire. There's no CEL and for all intents and purposes she seems fine unless you want more than about a quarter pedal.
I do know that a HPFP was replaced at some point but I need to look that up for specifics.
Seemed to start after getting gas last week - Thursday. WAWA, 93.
Any pointers are much appreciated. I have Xentry as well as Bluedriver.
Posting in this forum because this is where a majority of the action seems to be!
I noticed something a little odd yesterday but didn't pay a lot of mind to it - the car was running great, lots of power at command - only one hiccup yesterday as I was pulling out of my space at office. Seemed like the idle dipped for a brief second and then picked back up a couple hundred RPM and corrected. Drove home, top-down, and all was good. I paid no mind because all of my fuel injected cars have done this at one time or another.
This morning I pulled her out of the garage and let her idle (probably a little too long) while I was wiping away pollen inside and out. When I left, she was 160 degrees oil temp and 198 water temp. I then drove up to the pharmacy a couple miles away - no issues though I wasn't running her hard at all. Then from the pharmacy to work (about a ten mile hike up). All was good until I went to merge with traffic on the interstate. Someone one was riding my *** so I was like, okay, let's put on a little bit of a show and merge and go.
Denied!
I gave her the beans and she misfired like she had a couple of dead cylinders. That wasn't good at all.
I limped up the interstate a couple of exits and got off early. I was able to cruise fine but anything with boost being made was not happening. I finished the rest of my journey off the interstate and made it to the office. In my parking space, free rev'ing sounds great. No issues at all. No odd noises. I restarted the car and then put her in gear and held the brake to simulate some load and it seems to drop in and out, but I couldn't tell if that was just a characteristic of the MCT or if it was the engine again attempting to misfire. There's no CEL and for all intents and purposes she seems fine unless you want more than about a quarter pedal.
I do know that a HPFP was replaced at some point but I need to look that up for specifics.
Seemed to start after getting gas last week - Thursday. WAWA, 93.
Any pointers are much appreciated. I have Xentry as well as Bluedriver.
No CEL is the best part... it must be on the fence. So not the coils/plugs.
You did well by not hammering her with a condition that ment "not today!".
-- Can you read your LTFT, fuel pressures (tank feed+ HPFP1+2). We'll be looking for lean conditions.
-- Then a full chassis scan for CAN-C misc disruptions.
Lean misfire suck all around because engine needs to be even/neutral to get rich strong accelerations the ECU won't sanction with lean trim penalties.
agreed that I would expect a CEL, but for giggles:
Coils - when did you replace them
plugs - when did you replace them
bad fuel - new gas station lately? If you still have a relatively full tank, add about three gallons of E85 to the tank and see if this resolves the issue.
the coils are weak on this car - tons about this on the sticky
I know plugs were done a while back before I bought the car though I'm not exactly sure of when. Same with a HPFP but I'm not sure of which one. I tried to look through some CarFax (etc) reports that I had but they're expired (of course they are and the PDFs sent are garbage - not buying again). I replaced one coil (number 5) because I seemed to have had one that went bad - P0305 and P0355. But that caused rough idle and immediate CEL. Interestingly, the next day the problem was gone, but I replaced the coil anyway. I wanted to do the entire set but no one had any in stock locally - the one ended up fixing it so I left it alone.
I'll need to get plugged into the ECU tomorrow. Lots to look at though.
I really do think there's a chance of bad fuel. We have had a lot of rain over the last few weeks - WAWA really isn't the best either - but in the particular area I stopped in I do not see a lot of people looking to use 93 octane especially at $5/gallon - $80 to fill up my tank.
I have had multiple coils and multiple cars failed that did not throw a cel. At least not after I restarted the car the error code was not resident after restarting it
Just got home. I didn’t push the car at all… nice having the ability to get up to highway speeds without having to go much about 1800 rpm!
At a couple of stoplights it shuddered a time or two. Same as what I described above.
In the driveway running with the BlueDriver hooked up, the only engine code set was for the oil pump solenoid. Nothing else. There were other canbus codes for some circuitry things that popped up from when I disconnected the battery to pull the airbag to replace the steering wheel bezel. But that is all.
Looking at mode six data, it recorded five current drive cycle misfire counts on cylinder 6 (7 weight average in the last ten drive cycles). The last time I looked (January) cylinder 6 was quiet - nothing recorded.
Other live data… fuel rail pressure 1430 psi (though BD showed 12k psi at 2200 RPM - can’t be possible, can it?), catalyst temps at 850 cel. O2 working properly.
Thinking a bad coil? Guess I can swap and see what happens.
Will need to hook up SDS for a more thorough view but the above does point to a coil acting up.
The misfire was really strong though. Like it was running in total hammered dog***** mode. Thought for sure it would generate a CEL.
Thinking a bad coil? Guess I can swap and see what happens.
Every time I try to swap a coil...I tear the boot. I did get a bad batch of OEM coils during KungFlu days (from the Stealership). I am down to four (new) ones that are waiting for more failures between the E63's and 550...fun times. At least it is the easiest repair we could ask for with a misfire....
2015 SL400 (M276 Turbo), 2014 C350 Sport (M276 NA), 2004 SL500 (M113), 2004 Audi TT225 (BEA)
If it is coils and you have no codes, then something truly is messed up.
@TomZVB if you are going to get BlueDriver, get a LAUNCH scanner. BlueDriver is OK for reading and clearing codes, but not much more. (Yes, I have one, too.)
I have the whole SDS Xentry deal that I got from another member on MBWorld. Just couldn’t drag it out tonight. I’ll plug it in at lunchtime to see what’s up.
Coils couldn’t hurt. I think the raw mode 6 data supports it. Definitely seeing a misfire where there wasn’t. I think I just got out of it versus running it enough to pop a code.
The only fault (F) that pops up is for the oil control solenoid. Running through actuations that I can test at idle all produce normal/expected results. Fuel pressure was good. I could cycle all injectors and got expected results. Only other faults are stored from the steering, seat, turn signals, and distronic radar (again, from disabling power).
Anything else that I should be looking at in Xentry while in the garage? Next would be to have Xentry monitor while driving to see if it picks up anything. May require some visual inspections to see what's up, too: replace the coils as part of 90k mile maintenance, and pull plugs (and maybe replace based on condition - plugs were done at 70k miles).
Any other thoughts?
Also, @JettaRed - that thing I mentioned about the Xentry compression test being disabled is specific to AMG vehicles (I imagine it will work if you add a generic SL550 - maybe?). Test procedure states to conduct a manual compression/leak (leakdown) test and report results.
Your 20kMi plugs are ok but the boot and coils are known weak @PeterUbers and got cooked by heatsoaks. Not point here in scratching head: we must have predictable even spark.
Somehow I think there's more to that story because you reported working on cyl#5 did not satisfy the ECU.
Some ppl have reported that ALL coils not just one must be replaced at once! I buy that
This tells me these engines are very touchy about timing to create weak contributions.
You see... when the cylinder contributing before No5 introduces timing jitter, the ECU has a real hard time calculating when to best fire next cylinder.
Lookup your firing order and poke proceeding cylinder by moving coil with the cyl firing last... #8?
Some wise guys upgrade the undersized coil wiring. The multiple sparks need sky high current spikes. The wiring conductors need to be sized to pass the spikes not the average!
Misfire can also be the telltale sign of a weak cylinder contribution as in low compression. Do a Xentry "relative compression" test with a full battery.
Without knowing idle FUEL Trims and Pressures, I can only guess they are less than expected.
The one thing I can guarantee is your engine is running unevenly and that must be smoothed out at each and every possible levels.
There's a dozen causes that must ALL be A-Ok for predictible timings. When satisfied the ECU will hand out strong mixtures... torque+power.
How old are your chain tensioners?
+++ in other words:
We can't keep doing the same thing and expect different results - Not us!
Performance is tied to perfect combustion of all contributors - I can only imagine what early engines that can disable cylinders. Hello extremely crapy timings with big discrepancies.
BTW.. GUESS WHAT ARE VIBRATIONS ? Uneven cylinders contribution!
How to win in engine efficiency:
Its all the same topic to improve to regularity.
The limitations of the ECU firmware depend on it.
The firing is done in a loop, not individually yet. When there's randomness introduced in the loop, you miss the boat on all tailing cylinders in that loop. The unlucky cylinders without cool fuel and no oil...
Last edited by CaliBenzDriver; 04-24-2024 at 04:46 PM.
Reason: not only a single cause.... mixed combo
Your 20kMi plugs are ok but the boot and coils are known weak @PeterUbers and can get cooked by heatsoaks. Not point in scratching head ... got have evenly predictable spark.
Somehow I think there's more to that story because you reported working on cyl#5 did not satisfy the ECU. Some ppl have reported that ALL coils not just one must be replaced at once. This tells me these engines are very touchy about timing to create weak contributions.
You see... when the cylinder contributing before No5 introduces timing jitter, the ECU has a real hard time calculating when to best fire next cylinder.
Lookup firing order and poke proceeding cylinder by moving coil with a cyl firing later, #8?
Some wise ppl upgrade the undersized coil wiring. The multiple sparks need sky high current spikes. The wiring need to be sized to pass the spikes not the average!
Misfire can also be the telltale sign of a weak cylinder contribution as in low compression. Do a Xentry "relative compression" test with a full battery.
Without knowing idle FUEL Trims and Pressures we can't guess what they are.
The one thing I can guarantee is your engine is running unevenly and that must be smoothed out at each and every possible levels.
There's a dozen causes that must ALL be A-Ok for predictible timings. When satisfied the ECU will hand out strong mixtures... torque+power.
How old are your chain tensioners?
Yes, I replaced the coil pack on cylinder 5 because it showed major misfires - in that case the car was restarted after stopping at a store - bad idle and misfiring. It showed similar misfire events like yesterday's. I would have replaced all the coil packs at once but I couldn't source what I needed over the Xmas holiday, and since it seemed to be happy after replacing, I'm pretty sure it was the culprit.
Looking at the misfire data across all eight cylinders, only cylinder 6 showed significant issues. An occasional single misfire I would think is to be expected across weighted averages on an engine with some wear. In this case, cylinder 6 showed (during yesterday's drive home) qty 5 misfires on the way home and qty 7 from a weighted average of the last ten drive cycles. To me that points to the coil pack.
Good questions on chain tensioners. I believe they were done with the timing cover work. The chain is the new style heavy-link so it has been updated. I have no rattles or noises of any kind.
If you can give me specific tests to run in Xentry, I'll get them done and provide output.
Yes, I replaced the coil pack on cylinder 5 because it showed major misfires - in that case the car was restarted after stopping at a store - bad idle and misfiring. It showed similar misfire events like yesterday's. I would have replaced all the coil packs at once but I couldn't source what I needed over the Xmas holiday, and since it seemed to be happy after replacing, I'm pretty sure it was the culprit.
Looking at the misfire data across all eight cylinders, only cylinder 6 showed significant issues. An occasional single misfire I would think is to be expected across weighted averages on an engine with some wear. In this case, cylinder 6 showed (during yesterday's drive home) qty 5 misfires on the way home and qty 7 from a weighted average of the last ten drive cycles. To me that points to the coil pack.
Good questions on chain tensioners. I believe they were done with the timing cover work. The chain is the new style heavy-link so it has been updated. I have no rattles or noises of any kind.
If you can give me specific tests to run in Xentry, I'll get them done and provide output.
Replace all new coils + boots to be exactly equal. Your new-used No5 will then be retired as a spare.
If you want to pull plugs , we can regap them a tap lower and have a look at colors in relation to idle LTFT data. I know I would.
After that we can bank on the ignition and don't think twice.
Misfiring is not synonymous with bad spark!
Find out by swapping all your exhausted coils. Performance may marginally improve and remain as good as LTFT say it is.
The only winning ticket is to give ECU what it needs:
air/gas + spark + timings
Last edited by CaliBenzDriver; 04-24-2024 at 05:43 PM.
2015 SL400 (M276 Turbo), 2014 C350 Sport (M276 NA), 2004 SL500 (M113), 2004 Audi TT225 (BEA)
Originally Posted by TomZVB
Also, @JettaRed - that thing I mentioned about the Xentry compression test being disabled is specific to AMG vehicles (I imagine it will work if you add a generic SL550 - maybe?). Test procedure states to conduct a manual compression/leak (leakdown) test and report results.
I think the process is to do the manual compression and leak down test IF the relative compression test fails, at least for the non-AMG engines.
So looking at some things in Xentry, looks like I had a couple points of interest.
The left-bank downstream O2 sensor generated some out of spec numbers (dipping into the low .1xx and then spiking vs holding steady when compare ed to the right bank).
And manifold pressure was down slightly (307 hPa vs 311 hPa min).
Not sure if pics would be helpful. All other tests conducted seemed to go fine. Cam and crank sensors in spec, etc.
Maybe a beginning to fail map sensor and wonky O2? I read where someone had a similar misfire issue that ended up being the O2 sensor… but I’d think the problem would be all over that bank.
No driving tests tonight. Too much other stuff going on.
Took her out a couple of minutes ago… seemed like she was okay but I felt a little rpm dip when pulling away from a stop sign.
Ran her in the neighborhood a little and power seemed to be good! I wasn’t flooring it but I ran probably half peddle to 3k and she felt strong and pretty normal.
Took her out to the main road and got on her some… not even close to what I did in the neighborhood and it decided to misfire. This time I held it a little and sure enough, the flashing cel started going, and then went solid.
Limped back to the house and shut her down. Started her up and all clear. Checked codes and had a stored P0306 misfire code but without the coil malfunction definition that I saw with the cylinder 5 misfire in December. Remedies listed were of course replace the plug and coil pack. That will be my next step - coil packs.
I did log the fuel trims with BlueDriver. I’ll need to see what they look like. I’ll report back later - my son is wondering where dinner is!
04-23-2024, 02:32 PM
