I am hoping somebody has run into this problem And can provide some help.
2008 S 550 4matic. I have a problem that seems to be directly affected by ambient temperature. When the temperature is 50 or above ( possibly as low as 45) I get a pinging/pre-Ignition on any kind of acceleration. I only use the highest Octane gas which is usually 93 or 91 in my area. So obviously when it does this the engine pulls back timing I guess and the power gets very low and obviously I have the pinging/pre-ignition happening. As soon as it gets below 455 or 50 outside, the colder the better, no matter how warm the car is pinging or preignition does not happen no matter what I do. So, I'm trying to determine what the problem is. The scanner does detect engine knock but I don't know where to look as far as what sensor or whatever might be causing this when the outside temperature is at or above 50. So the car is been running wonderfully this winter but now spring is coming and were in the 50s so I'm getting the pinging back I'm trying to track down the reason for it.
Has anybody else experienced this? I am currently using a LAUNCH X431 CRP919 EBT Elite scanner.

 

how do you know you get "knock", never heard it on my 273 - not even got close - kevm14 has stated he hears it on his 4x4 - is it not something else of the drive train causing a different noise you both believe is Knock ?

the point you say with it happening at cold temps is also weird as it should much harder to get in the cold and damp, than on a hot dry day... - could it be you both confused, and its a lack of grip (with cold tyres and grubby roads) and the engine being reined in by the traction control - a quick test but it will get lively - the ESP button lets it of its reins a bit - or cluster fiddle into dyno mode with rule it out - but you'll leave some black lines out there and likely crash

its also why sport is problematic - the car gets off the line with far less drama and almost as quickly using Comfort... rather then the tyres trying to light up and the traction control needing to rein in the engine

 

I clearly hear the "knock" from the engine same sound as pre-ignition on acceleration. Verified with my scanner showing engine knock on the screen when I hear it. It is internal and ONLY happens when the outside temperature is at or above 50 deg. Cold temps outside the car runs strong with ZERO knock/pre-ignition. Something or some sensor is causing a problem when the outside temps are higher. Yesterday It got above 50 and on any acceleration I got the knock today, its in the 20's and ZERO knock no matter how hard I go on the gas. I am assuming some sensor is reading things wrong or is off when it get hotter out.

 

it would make some sense if you meant 50C but I suspect you mean 50F which is only 10C.....

 

if the world survives the lunacy of the psychotic halfwits in Europe, (who've spent the last three years trying to start ww3 to stop Donald taking back control of the US), if as a celebration he'll finally let you have the grown up number system the ROW uses ?

 

Yes, definitely Fahrenheit

 

there is a lot of weirdness built in the Merc ECU - there are settings to swap fuelling from lean, to base, and then stupidly rich, - why that is there is an enanthema to me - there is legal sensible fuelling that works most the time....

sure there will be the odd areas on certain days where certain weather and certain throttle conditions mean a smidgen more here and a smidge less there would create a better driving experience - but that's never covered by a blanket mess it all up too lean or too rich lash up...

later in life (allegedly on later models) Merc started to introduce fake errors related to information it shouldn't be getting from the Ambient temp sensor - tractors used it off offset fuelling (and thus emissions) as part of Dieselgate - and petrol ones used it to fake an EML fault if the car wasn't used for 3 weeks - all explained in large fines, jail sentences, TIPS documents and Software updates....

In the last year we have had some weird and wonderful posts

two owners claim magic fixes happen after entering Dyno mode - where ABS sensor faults allegedly repair themselves - I have suggested its more likely intermittent wire breaks on wheel speed sensors, and the dyno mode does a dirty reset of the ESP ant brain - few have responded

one owner stating the later model Red Battery warning light issue resets - if you hold the key in the crank position for 10 seconds (obviously it will start doing this - but it doesn't matter as the starter cuts out upon engine start regardless of what you're doing with the key)

for myself I have regrets about using Xentry to do some engine and TC adaption resets - all of which seem to have made things a magnitude worse - and even once you find in other sections of the tool weird and impossible to complete setup procedures for it to rebuild the base adaptions from, the car is never quite the same

to me it seems there is mischief built in to Merc software

I originally wondered if the game was only explained via factory tech training courses - where the special ones should follow undocumented procedures, the tool deliberately fails to nag you to undertake
but now I think its time related triggers to get the cars off the road and you can't fix - because at this age you are not able too
and backing this up more and more, elements of the tool are no longer accessible - where the tool appears to have reached end of life - BMWs ISTA-P does the same


.

 

I have been experiencing some weird and wonderful behaviours with my car re engine management...

the UK first infected decent petrol with ethanol crap E5 unleaded in the summer of 2019 - which is lovely at certain cars and bikes (basically any pre 2008 - 2011 vehicles) were never built to use this utter rubbish - not only do you lose power and drink more fuel, it doesn't burn correctly in engines built before they dreamt up the bank theft of adding this damaging trash in a further effort to steal money from the poor and destroy older classic cars. Role on a short while later and all standard fuels were mandated to have up to 10% of the ethanol rubbish, when the country moved to E10 unleaded in Sept 2021 - this added to all the issues and if its really got 10% ethanol in there you lose 6% of the energy density vs what you get burning real petrol....

vehicles that were built with this rubbish fuel in mind got a later engine map and other mods that partially optimise their ability to run of rubbish fuels to lessen the effect - but the 221 M273 engine wasn't built for it and so runs and performs less well if you use it.- of course Corporation's never ones to look a gift horse in the mouth reinvented E10 fuels to be far worse than only missing 6% of its energy density

in my experience all my vehicles are drinking as if its 20% of the energy that's been stolen - and most of the time out of principle, I'm trying to operate them with economy in mind, but I'm still losing the battle....

all of which gets me back to adaptions... as E5 was stealing money and the car wasn't running as well, in 2020 I started looking at causes, (after all mine's only had 65K miles and was running OK on pre E5 fuels)

Around the same time all my bike's began to get a lumpy idle and all started getting a drinking problem. On one BMW where the map is a total joke from the factory (and was then made worse with a manu map update it only received in 2018), I spent ages trying to remap with an add on device with limited success. And whilst fighting this I slowly gleaned more about how closed loop CAT systems behave. How older bikes don't care if the CAT sensors are disconnected - and indeed it can help, as this stops adaption incorrectly messing stuff up when hit with muddled data from ageing / faulty sensors - but then you lose out on other temp and altitude corrections - as it turns out (but no one explains this leaves you stuck with the last tweaked base tables (map)) - which is how the gadget compensates for the original gibberish (but its really only any good if you always use in similar ambient conditions....).

When a vehicle with CATs and O2 sensors on closed loop emission control operates, it manages two sets of live adaptions - these are built on the fly as you go down the road - short term it continually takes pre CAT O2 info and fiddles about trying to continuously optimise running conditions.... so tweaks its running on whichever of multiple tables (aka maps) the ECU decided best matches the conditions its in - Buried inside it has ones for a rainy day, or a high altitude day, a cold day, was that engine knock, or I'm having a temper tantrum day today etc. So its always tweaking fuelling and ignition just for fun. But if its continually deciding that tweak is above a certain threshold, it says I can't be bothered with all that effort, I'll write that tweak to the long term trim tables... So next drive the long term adaption tweaks becomes the new normal... and on it goes - often taking 250 miles from a reset before its "normal" is remotely close to normal and further optimising every drive for evermore - till something upsets it, or it gets wiped by some idiot

All that sounds great - until a sensor starts getting old and decrepit - and it slowly starts building a fake suboptimal modified normal - and slowly the cars performance and efficiency slides. But there's nothing you can normally do to resolve.... And if the gits move the goal post introducing stuff like duff fuel that doesn't work - maybe we are all just getting stitched up...

Buried in the lies and mischief Merc peddle is
Cold start Adaptions
Normal Adaptions
Cam timing Adaptions (should be desirable - getting cam timing back on track as the cam chain stretches)
Allegedly CPS Adaptions (crank position sensor adaptions - but I can't believe it has this - or even imagine how this load of lies can function - unless its more like lets mess up efficiency because I can see fiddly fingers have been getting at me !!!)
TC Adaptions (these should be desirable - compensating for wear - but seem to go mad if you try to reset)
Gearbox adaptions (these should be desirable - to compensate for wear)

On the back of the horrific fuel consumption E5 brought and remembering a 15 mile drive with a faulty coil pack - when I realised I had equipment to do it - a few years back I reset both cold and normal fuelling adaptions, and for about 1000 miles it seemed to help.... it drove and felt exactly the same (no sign of any difference whatsoever) - but since the reset I saw the highest 4.56 litre gallon mpg I'd ever had, going from 27 mpg to 31 mpg (note: that was over 8 years of driving the same car)

Then in came E10 and the fuel consumption overnight really fell off a cliff.... and my ave of 25 mpg trying to get good economy nose dived to less than 17 mpg.
I'd also had three other coil packs take an early bath - so wondered about resetting adaptions again - but I had started to find on one bike (BMW again) it appears that resetting adaptions just makes the thing become hyper critical to sensor info and seems to misbehave more after trying to make it run better...

In the end I figured I'd see if a remap on the 221 would help - after all if done well it could bring in better compensation for E10 rubbish fuels and should optimise running a smidge... So 12 months ago - I went to one of the best places that so happens to be round the corner, and he had done a few (even ran one himself for a while) and believed it was well worth the effort... and he'd personally pull my map and get his cronies to optimise my cars OEM map - so I had the best of both worlds... Then on the way out the door after I said I had Xentry, he said well it would be well worth clearing adaptions and it rebuilding a great set up - so I did - Fuel consumption did improve about 2 mpg and it was far livelier around the 2k rpm band, with a smidgen more top end - allegedly going from 387 to 420 bhp

Then I noticed on the remap running super unleaded seemed to be much flatter on performance and really shocking on mpg - I couldn't get my head around why - unless they'd built a map really optimising what E10 can do and any high octane was now burning sub optimally (slower burn as it does) - previously I'd never noticed any change on the between fuels on the OEM map. Just the reassurance the vandalism of ethanol is lower when running on E5 super unleaded

But soon after, fuel consumption took another drive.... and has been spiralling ongoing to very little.... And I'm seeing this on my bikes too - its like the fuel available today is utter junk - I have given up on Esso and Shell it doesn't even smell like petrol any more - only BP super unleaded which is between the 91 and 94 Octane USA use still smells exotic and all my bike's run far better on it...

but the car doesn't seem to notice if I use it and just empties the tank before I get home - Every time I look there is nothing wrong with how its running and nothing ever showing up in diagnostics - then the other day the two year Oil change nag popped up and usually the stuff I take out at circa 11k miles looks almost like new - but it turns out I've only done 4k miles since the last change, so I expected it to be clean as - only to find it was black as hell like it had been in there 30K miles - so the hideous fuel consumption is real and its been contaminating the engine oil badly

So now I'm very confused... what changed and why's it seemingly getting worse each drive...

I decided what’s to lose I'm going to fiddle with the madness inside the ECU and have a play - but when I connected it up - (aside from the usual coil stick fail day to day fiasco you always get on any German trash - which I've always fixed asap) for the first time I got a real engine fault listed - Throttle body stuck or stiff - I'm like really ! - it starts and drives OK, adaptive cruise is normal, there's no EML and only last week I'd recalibrated the throttle damper (after updating Rear SAM) and it sailed through that calibration - Making it all the more strange, it cleared the throttle body error ? Leaving me wondering are you just lying to me ! So I carried on and swapped the silly fuel setting to Lean, from Base - drove home 5 miles, it felt and drove identically - but instantly showed 9 mpg better (jumping to 25 mpg) the highest I've seen for more than 19 months - So it was looking promising - until the next drive and magically it dives to the worst fuel consumption I'd ever seen, at 14.9 mpg (remembering a Std gallon is 21% bigger than the strange baby gallon used in the USA).

After that peculiarity, I decide to wipe adaptions again to see if it will lock in the change - where upon on connection of diagnostics it showing both TWC sensors have high voltage - odd as I'd been looking to see they were working in Xentry 2 days earlier and the then were trending happily up and down controlling just like they are meant to - So OK maybe they are part of the issue - but this feels more like some sickness built inside Xentry and the ECU playing silly buggers - So I said nope they're just fine upon which the car went TRUE !!!! but stated your throttle BODY is DEAD - to which I went nope its just fine you lying little ****er and it said Nope its not...

So pulled off connectors to the throttle body which were clean and dry - reconnected - but now its making its usual ticking noises - and completed the calibration process and magically isn't unhappy any more !!!! - Mooched about remaking connections around the fuel rail and ECU for nothing - then reset adaptions on all bar the cam sensors and gearbox - rechecked for issues and it was lying all is OK...

Went to check videos of how to get in Dyno mode (aka road test mode) which as I eluded too a few posts above now seems to be some secret behave yourself comand - kicking the car in the nuts.... Drove with no parking sensors, stiff power steering, no cruise and got it to read 30 mpg - which it hasn't done for at least 4 years - did 12 gentle miles, but by the time caught in traffic and got home it dropped to 24mpg (a bit lower than I'd have liked) - where upon connected it up to find NO Faults at all !!!

SO what going on - no actual idea - but starting to think maybe I have a leaky injector - which oddly is something I'm about to try on the BM bike - got to love ethanol !!!!!!!!!!!!!!!!!!!!!


NOTE for both you and kevm14 there is a setting for the ECU to adapt for Bad Fuel - I wonder if you guys don't have this set to ACTIVE

the ECU is full of crap like
Advanced diagnosis of ambient temperature ACTIVE
Variable fuel pump NOT FITTED
Purge control PARAMETER [2.4]
RON [ROZ] correction ACTIVE
SBC NOT FITTED
Shift ban (DE only) NOT ACTIVE
Low fuel grade ACTIVE
Fuel Sulphur content (DE only) LOW
Air injection diagnosis EUROPE / USA ( As of model year 2006 )
Starter Generator operating strategy NOT FITTED
Air injection diagnosis ACTIVE
Sound Design NOT ACTIVE
Fuel tank leak test NOT ACTIVE
Control unit 'Fuel pump' NOT FITTED
Heat management ACTIVE
Delay time correction ACTIVE

 

Meant to say 45 deg Fahrenheit not 455. Also, any day it goes below 45 I do not get the pinging/preignition so I don't believe it is something that happened over time otherwise it would continually happen regardless of the temperature outside.

 

check my post just tweaked it - added another bit of madness which is what actually got me typing it all.....

Advanced diagnosis of ambient temperature ACTIVE

 

Botus... A good read you assembled. You Brits got the urine we are stuck with in the USA MUCH later then we got to suffer through here in the States. The big give-away to corn farmers in the name of ‘clean air’ is and always has been pure bulls..t. Especially with modern engine management. As soon as we got that ish EVERY CAR ON THE ROAD immediately got whatever manner of ick that had been previously collecting (harmlessly) at the bottom of the gas tank delivered right through any and all filters to plug up every low speed fuel port and fuel mixture correction solenoid in carburetors. Injectors plugged up. Fuel lines that were perfectly happy with gasoline crumbled and failed to leaks. Fuel pumps ground themselves to bits, delivering even more crud to injectors. I believe this to have been the undoing of many K-Jet injectors, fuel distributors ect. Yes; that era. Predictably fuel economy dropped 20-25%. Power dropped for naturally aspirated cars. Turbo cars made it up with boost with lower fuel economy.

OP does your engine sound as one cylinder pinging or all of them? If one; look to an injector laying down. Do all of them as they are the same age.

 

.... anyone remember mid last year, the chap fighting a fuel pump with excessive rail pressure and it kept burning out pumps - and we kept saying he's using the wrong part number....

seems earlier cars had one idea then they modified later facelift cars that get a different pump.... but his car had been modified with connectors and some pipework from a later car


I found this setting on my early 2007 model year Engine ECU....

Variable fuel pump NOT FITTED

 

I prefer supply and return lines with a fuel pressure regulator on the fuel rail to vary pressure.

They call it progress. I see $30.00 saved by not fitting a return line with a more expensive to replace pump that is a bigger PITA to diagnose intermittent issues.

 

turns out that same bike ( I'm grumbling about above) has a pump control module... its slows the pump round town and revs it up for high speed (allegedly to save wear and tear), when I pointed out surely that means a naff injector spray pattern and the grotty running it has round town. Some guy who's been through 4 pumps in the 120k miles he's done, modified his bike with a permanently installed fuel pressure gauge, and says, No, the pressure regulator reins in the pressure regardless...

so at low speed, low voltage the pump runs providing 3.5 bar rail pressure and at higher speeds the pump gets full voltage and winds it up to around 8 bar, till most bleeds off in the tank, and whats left at the fuel rail, is governed by the fuel pressure regulator in the injector circuit keeping the pressure constant - so if you watch his, the fuel pressure in the rail doesn't vary under any conditions - with the earlier model getting 3.5 bar, and a facelift twin cam getting 4.0 bar using a later pump

all of which makes me think the controller is pointless, but adds in an extra point of failure for good measure (AKA additional profiteering)...


.

 

here goes the next better than Merc trash parts replacement programme

my car is drinking like hell, and now I'm seeing a TWC overheating message - and applying something new I learnt - it wasn't until recently I became aware overheating CATs is usually a sign of an injector leak or serious ecu issue with dramatic over fuelling causing the CAT to get over excited and burn out

Add that idea in with a tickover that has a very slight miss on the left bank (nothing in diagnostics and not even the lambda trace looking off) and mainly coz the engine oil at 4k miles was black as hell. I've decided without bothering to look at the car yet, aliexpress is going to get me 8 new fuel injectors....

Coz it seems the Merc ones are the biggest load of trash known to man - we've had many here play with them and I can buy (can you believe) 8 x 2720780249 for almost nothing delivered costing way less than Merc will sell one of their designed to die bits of crap

I can't be bothered to fight off the rail with nothing to try and its seems many say the stock ones are utter junk - and this place has sold 700 of them so some garages must be swapping lots !!!!!!!!!!!!!!
https://www.aliexpress.com/item/1005007735772740.html

Somewhere I was reading since the junk fitted in our cars, the spray pattern had been refined by a massive factor on later designs... not sure if these days it means everything transitioned across, or these just won't have 18 years of Mercs designed to die disintegration going on inside

Ooh, and I learnt why we all need wideband CAT sensors, but can't have them....

AFR (air fuel ratio) for real petrol is 14.7 :1, but 10% Ethanol infected death fuel needs 14.2 :1, but our cars have no way to control this need.... hence they lose power, run rough, and hate life

Ethanol death fuel wasn't about - and or the manus didn't care less, until in comes Euro 6 emission standards. As most junk made before 2011 use std O2 sensors - they have no way to sort the fuelling if you run death fuel. But wideband sensors with a very different engine ECU do lots more play time (my neighbour just shared a wideband sensor can force the sensor to drive in a certain direction allowing them to gain more info about what’s going on...) so the whole ECU is different and has a better brain and these sniff out the actual AFR, not just spare O2 and thus can control what the car needs every 100 milliseconds rather than NEVER which is what our engines do when your running on death fuel

a bit of a write up here... https://www.boostedtech.com/how-a-wi...-sensor-works/
.

 

I grew up in DeKalb IL in the 1980's, home of the famous DeKalb Ag and flying corn cob logo. And lived in Iowa most of my adult life in corn country. We knew even back in the 1980's that gasahol as it was called then was a questionable proposition, at best. I can't believe corn based ethanol has gone on so long with still 90+% of gasoline in the US containing corn. What a waste of precious farmland.

 

that’s the idea - we can cause more death and misery if we can get a global food shortage... as car drivers we are all unknowingly playing in to the hands of the wrong side

Zimbabwe was known as the bread basket of Africa till the UK decided to make it fail when mugabe decided he wanted to leave the evil brigade and go tit alone. Its brilliant, taken me 30 years to understand that game - and just in case they managed to turn to a corner and make a go of it, they invented the mess in the Ukraine, that was the new bread basket of the world.

In the "west" we are just lied to morons watching the destruction of our lives and the planet as evil rich plan our end. Yet still we magically believe the marketing, our declining safety, prosperity, and freedoms are gone (and are never coming back) ! At least your guy is trying a new approach for you...
If I was Putin, I'd tell Donald they are too stupid and far too sick, and I'm ending their lies and chaos - and just remove Western Europe from the map - the world will be a much healthier place and I won't have to watch them make the world suffer for another 5 years before they do what they are going to anyway

 

And, misguided 'help'. I'm just finishing a book about Haiti called Aid State. During one of their many crisis years ago, a US multi national donated many tons of rice, and apparently did so for a while. Rice farming was a staple in Haiti. The domestic farmers got put out of business by the aid, and then the multi national lost interest and moved on. Then, famine. Same with Tom's shoes in Africa. A truck pulls up to a village, donates a couple years worth of shoes, and puts the local cobbler out of business. Then the Tom's truck doesn't return. But we feel good because we've helped.

 

Ahhhh the “Do something disease.”

‘Something’ mostly having been poorly conceived, with zero regard to the ripple effects.

Yet those ‘helped’ reap the reward of ending up dependent on others who are off to the next shiny thing to ultimately wreck.

 

told a mate about the fact I saw a Lean, Std, or Rich mixture bit on the car ECU and he said if it shows that adjustment it MUST have wideband sensors already !!

intriguingly, bikes that run behind in the emission world, only started to get wideband stuff in BMW land for 2017 and I can see that too - my 2019 MY one also has a tweak for the fuelling - so either Merc were way ahead of their time or something strange is happening...

and the to good to be true bargain came crashing down, when the gits renegade on the price and having stated 8 PCS and show two photos of a box of 8 Injectors in the advert, they now want that price each - so I'm not getting them....