Ohhhh 🤣

 

Hmmm, I noticed no differences after the float charge, maybe my battery condition is both good and charged enough that the electronics were satisfied and running at full potential already.

 

Maybe it has to do with alt-lin unplugged and no more drain by driving, so battery is still in good shape and charged effectively. I am sure ctek is still good to have though.

 

> FLOAT but "no change"...
You report FLOAT does not yield improvement over ALT-LIN on your chassis : that is very good news for you!

You are not loosing basic performance from aged PreFuse dropping your main power.
Your car is not yet impacted by unstable voltage.

Another way to transcribe this is... "Oxidized Prefuse gradually chokes performance like a dirty fuel filter" by design.


> Back to "stock + float" ?
If your test drive shows not sensitive to voltage, then may be no benefit from ALT-LIN 14.15V either for you??

Repeat battery float test in stock ALT charge (ALT-LIN active back to stock)

What is not desirable through prefuse is high current heat.


I suspect stock voltage will show performance difference because the AGM SURFACE CHARGE above 12.6v is useful to help smooth ripples. Battery acts as a capacitor with low internal resistance.


> AUX or CAPS?
Is your AUX battery a small AGM in the trunk or is it the newer "voltage converter" module made of 4x Farad capacitors ??

These heavy caps may hide Prefuse issue by smoothing current riples.


> ROOT CAUSE: PREFUSE drop!
One thing is clear the root cause is OXIDIZED PREFUSE main path from ALT.

The floated battery is able to smooth out current ripples dropping voltage.

Practically the chassis main power from ALT gradually oxidize tinned connections to significantly drop voltage inside PreFuse.
After years this unstable power impact whole chassis performance.

Current ripples could be evidenced with a fancy scope... easiest way is with simple float test (or best with "bypass strap") helping or not.


> NEXT STEP...
Clean & protect prefuse oxidized connections to see if "bypass strap" still useful to provide self-float condition.
If No... strap will come off else strap will stay.


-A: input from ALT -B: to AUX in Trunk

A+B directly connected to prefuse distribution main bar through 350+250 Amp links.

Bypass strap delivers power to main bar with less drop than existing single oxidized 350A connections.



W212 prefuse OXIDIZED opportunities

 

Thanks forum member CaliBenzDriver. I will pay more attention to those.

 

When and if the engine ECM decided to play yoyo with alternator output aka voltage and amperage, there is nothing we can do.....if you are still LIN connected for the alternator

 

The stock variable voltage (12.6v to 14.9v) I don't think is beneficial for GDI and neither is yo-yo for CAN stability below 12.0V - Hence 14.15V is a step towards chassis stable power supply..

This afternoon I saw the thread where your have your prefuse all apart. You noted the main input 350A link has a U-shape link instead of a round eyelet.
I suspect this fuse connections gets oxidized passing yoyo high current.

I am studying the power distribution to trace high current paths and ripple noise sources.

There's a chance I may end up doubling up F-SAM to ECU + Coils + Injectors power supply lines to prevent dropping voltage that create riples

 

Well, you know how bad the ECO charging algo is.............. there is nothing we can do to dictate it.
Its ALGO main aim to not fully charged the battery to a 100% at all times ...............in preparation for some capacity... for charging the battery during certain de-acceleration is what we hate the most.

 

The stock ECU power supply is far from being as stable as needed for precise GDI timings.

> De-Tuning combinations:

1. Bosch variable Voltage (12.6/14.9)
2. Disfunctional Yo-Yo (12.0...11.0)
3. PreFuse drop in connections/links
4. Undersized Harness drops !!!
5. (Jittery cylinder contributions)

I'm positively satisfied by the improvements related to the Prefuse "strap bypass".
Chassis responding to cleaner voltage highlights it is sensitive to riples (~500mV): duh!

I'm curious to further discover what happens with cleaned up smaller RIPPLES.

Bean-counters assess DC current need a small gauge IGNORING the conductors need to be sized to supply the Max current of spikes. That is 30A peak transient vs. 5Amps DC.

Need for bigger gauge to pass current:
Some if us know that coils are inductive loads charged by current, not by voltage like capacitive loads.
Coils responded significantly to strap, that is a call for more fixing in that direction....


Prefuse built-in cleanup capacitor 👍
My schematic provider shows a cleanup Cap built inside my prefuse. This is outdated!! It is no longer in use despite being necessary.

The cap was supplying the current surge necessary to charge up magnetic coils.

All of this hair spliting is really practical.
By stabilizing engine timings I canceled the high heat (FAN:OFF).
The Bosch ECU does an excellent job when given a chance to deliver performance.
That is very much like perfect Tranny shifts when engine throttle is predictable.

These predictable "engine timings" are resting on the ignition + GDI injection + sealed cylinders.

Realize that drafty cyl. drawn the importance of precise ignition & injection. This is how lean misfires create laggy throttle + sloppy shifts + Fan:ON in winter.


bypass strap around the 350A link

> Float vs. Strap....
If floating the main battery delivers a transformed engine/tranny...
then it likely means the experimental prefuse "strap bypass" will provide the same longer lasting effect 24x7.

This is the most stable chassis response I have tested so far.
Minimal change with strap + float combination means strapping around "350A main fuse" is the keystone ie. nasty drop!


> HEAT vs. MPG savings
I bet all the power transformed in heat from frictions caused by marginal timings has a significant cost.

Everyone is supposed to get excited by Euro oil reduced friction for up to 1% savings, ignoring the heat losses.

> High engine HEAT is from:
+ unstable timings of sparks
+ unstable cyl. contributions
+ pistons heat accumulation
+ mapped lazy Tstat
+ (delayed smart fan)

These fixes have replaced lag with torque and low heat. This is how I know what is the better way.

if your powertrain runs fine then enjoy
else pay attention to experiment tips.

 

Use EPC/WIS, dont use 3rd party wiring . Many are wrong/garbage. Come on man.
I never seen inteference capacitor in my F32 wiring schematic nor its physical presence.
What is your VIN, let me find you the proper F32 wiring for your variant.




I am happy with my beefed up ground wire.
Cleaning the F32 fuses , during that teardown........... was a good thing.
Most pleasant is of course ALT LIN disconnected.


BTW
Your grey parallel baby wire is a fire risk, I am sure you know that.
Its like a second fuse, in wire form but its PCV jacket is close to suspension tower, which is metal, albeit painted.
Becareful with it. I do take positive power from Circuit 30g at F32 too for my extra AUX lights, thus I am very careful about it.

.

 

Yes, your caution is correct to never short-circuit positive DC power to chassis ground.

You think this strap is an overloaded fire risk, my experiment does not show that.

The bypass strap itself...
You know about electric current, flow of electrons right?


bypass strap connections
How much current flows through the strap shown above ?


internal path in parallel with strap
what's the resistance of this path?
(2x fuses + 4x connections) = ?

How much DC voltage is dropped ?
How much DC ripples voltage are present ?

Is the strap sized well with 12 or 10 AWG. ?

> Equivalent diagram...
Let's consider the path from Prefuse ALT input post.
Stock goes through 350A link to distribution bar
Strap goes through both 350A + 200A links to bar
The two fuses are now in parallel.
Its not a 50% split current because fuses have different resistance based on current rating.
This give a more direct connection to where battery voltage lands through SSR relay.

Exactly what I wanted to test as a float level supply.


min batt charge current

> Amp clamp & Scope...
I did not bother to throw my Amp meter clamp over these cables because the riples are not DC and not AC:60Hz = false measurements numbers.

This Amp measurement requires a calibrated load resistor and a scope but life is short before next Asia tour.

> Fasteners Upgrades...
I find the NUTS fasteners solution a bit substandard:

• Single nut
• zero washer
• no plastic insert stopper
• no Loctite
• no counter nut
• plenty of vibrations
• no redundant path

What is MB expecting with this setup??
Stainless steel nut conduction does not seems as good as brass conduction.

Currently we have oxidated tinned nuts.


Prefuse cap is as described: a much needed legacy gone missing.

Next steps to include:
Bypass harness between SAM to ECU splice.
Prefuse pimp: oxide + nuts

 

What I am saying is, the baby gray wire of yours is dangerous not because of the amperage load it will carry during engine operation or alternator powering up the
MAIN BUS BAR of the F32, but because of the fuse size between MR8 ( aternator - 350 amps fuse ) and IM1 ( to K114 relay Aux battery - 200 amps fuse ) at F32.
MR8 and IM1 is Circuit 30, always hot, always have power.
That is why I do not use it for my AUX lighs power source, I choose Circuit 30g IG1 which can sleep and of lower fuse rating of 150 amps. Still 150 amps is scarry when 4mm wire is what I use.


200 Amps alone will burn that baby gray wire if and when its jacket get wounded and short to ground.
But there is also 350 amps fuse of the alternator which is via Q-Diode and to B1 terminal which is battery positive. Double danger, twin power source.



.





.


.




.




F32 wiring diag attached.
Looking at your F32 external, your F32 is 100% identical to mine in terms of function and components, because surely you have B03 Start Stop option and
your pyrofuse is at the battery positive terminal.


Anyway resistance goes up with heat and load/amperage.
You cleaning your F32 like I did will be best move Cali.
Your baby grey wire add-on is just you being lazy and placebo effect is what made you feel positive here and there.

.

BTW.... if you still remember...
I have even beefed up my positive power supply to all my six COPs.
https://mbworld.org/forums/e-class-w...ml#post8830623

I gain 0.3 volts less voltage drop at peak load. Not the greatest , for the effort. But I do now have more copper conductor for the COP and long term it would be good to assist the aging MB original wires.


Anyhow, becareful of short circuit risk, that is all I can say.

============

To show you how I respect ( fear is a better word ) prevention of short circuit on my car ..........................

Below is my added protection for my F32, because I use battery maintainer a lot , I do not like my crocodile clip copper teeth to touch the painted body by accident. Item 1.
I also added extra insulation to MB cables end, more so where it is resting on painted surface. 3M electrical tape. Item 2 to 4.
Item 5 is fuse as close as possible to most upstream power source.


Many extra layer of 3M electrical tape where the wires are touching the painted surface.



===============


Tripple layer.
A = Heat shrink and B = 3M tape and C = TESA tape , where potential problem may arise
and D - plastic mesh for the wire itself.
Thanks to this discussion, I added simple clear vinyl hose Item 8 , to reduce any possibility of that heat shield steel screw from hurting any wires and/or my fingers.
Usually I use blue silicone hose as protection, for such protruding sharp surface, but in this case for shape of the screw thread ....clear vinyl hose is better.




==============


Since I am on a RHD car, the battery positive post is a dangerous orientation. I mean it can touch the car body, if say the clamp is loose or whatever Uncle Murphy wanna do.
The pyrofuse metal cage is not carrying current, I mean it is not +12V , a good thing.
I keep older Varta battery protection cap and use thick plastic protection sticker, you can see the hazzy color.






.

 

I totally agree my quick "bypass strap" is not a true fix. It is a troubleshooting intermediate step with significant results I enjoy.

Any useful contribution is highly regarded.



> Troubleshooting bias...
We don't always need overwhelming data. Many field data are irrelevant based on test setup.

I find trends more useful. We can abstract numbers by using limits to skip over unknowns.

I am biased to make progress forward:
Problem ---> Solutions!

A better fix could be to deoxidize the Prefuse tined fuse connections. This increasing tin oxidation is like a built-in drop provider of sort.

The total resistance value of the whole path:
1- ALT --> 2- Prefuse --> 3- F-SAM --> 4- LOADS:
coil/injector/ECU branches is what's significant.
The solution is not yet clear.
Candidates to drop resistance are:
new relay + higher fuse value + oxidized tin.

My LED headlights getting visually brighter with Batt-float/ Bypass-strap vs. stock dimmer lights is a quick result that show present drop condition - Try float/strap at night to see live results !!!
No need new extra headlights... improve stock setup or stick with stock to keep dim lights.
(High heat also derate Hella LED's).

> The big question...
-- WHY do you think a "small drop" in prefuse is so significant ??

At first this does not make any sense yet this is the reality of this stock setup. A premium grade issue.

My strap around ALT 350A fuse input should hardly make any difference, yet it does.

This "bypass strap" acts very much like a "float charged battery".
That's why for now I enjoy the results of this power strap.


> HOW DID I...
I got to this stage by considering the path between where the main battery lands and the chassis Main power input must have actively drop voltage.

So I researched what I could do about it...
I simplyfied things down to testing if I could improve stock setup with a dual input using 200A in parallel.

That troubleshooting TEST outcome proves powertrain is highly voltage sensitive.


> IMPORTANT MISSING ELEMENTS...
Normally a good engine setup SHOULD NOT respond to very small voltage differences.

Battery float or Bypass Strap should make NO difference.
Yet we evidenced the opposite. Is that Mercedes quality?!?


> How is that ??
The answer is what is happening downstream within the power distribution.
Surya already reworked his ignition coils that were dropping 1.5V: that is a huge drop !!!!
The coils were starved... that explains a lot.

SAM ignition circuit Relay is a prime suspect for rewarding service. Perhaps a relay but this is already bad since low mileage.


> What gives?
Got to find more answers by studying power distribution schematic downstream towards engine VIP circuits :

• Ignition
• Injectors
• ECU itself

Then more hands on to inject clean power with yet another live strap. Easiest way into circuit is to get in at the supply fuse.


> Monoxide!
I am not setup to run my engine inside enclosed garage to collect data.
So I skip steps to test results.


I am not aiming towards using capacitors I know would help because they can age rapidly, shortout... The test rig must be made more reliable, not less.

I do realize chassis is self-adapting to less that good conditions. It very much seems as if chassis was designed to respond to degraded electricals.
Chassis should be setup 100% as the opposite:
RESILIENT AGAINST MARGINAL CONDITIONS.
I bet this setup is not a fluke, right ?

 

Prefuse rework to include:

> Beef up MAIN input 350A fuse... towards 450/500Amps by: ANL; MIDI; MEGA brands.
This fuse acts as an INLINE RESISTOR subject to supply 100% of chassis power. It drops voltage by design.
By increasing fuse Amp we lower inline resistor.
FYI: this limit electrical protection...
OTHER OUTPUT fuses (ECU supply) may need to be up sized to lower drop (less harness protection).


> Clean up oxidized tinned contact surfaces. Polish without removing tin "protection" layer.


> Upgrade connection nuts to stainless serrated flange lock nuts (see pic below).
Stock basic nuts get loosened...ouch!!


> Protect surface oxide with electrical compound (not lubricating screws thread!)


> Torque fasteners to near stock values.


Target is low inline drop voltage (500mV) for stable engine performance ECU can adapt to.

"Bypass strap" may stay or not based on test-drive results


fasteners don't pass much power, surface to surface does that job


detailed circuit names of fused paths... what are low-drop VIPs ??

### TBD VOLTAGE QUESTION...

>> Open Question:
How can the ECU be so hyper sensitive to prefuse (1.5V drop?) and not to the 2.3V delta from Bosch opportunistic charge (12.6/14.9V) ?

It seems the ECU is given the ability to adapt to "stable" variables ie. slowly changing in minutes not over micro seconds.

#### INCENTIVE: HARD KICK ECU response:
Kick your own butt with a HARD pull throttle without any lag from 900Rpm & nimble precise.

 

Here you go…

My redundant ground strap between the chassis and the engine.

 

That's a perfectly good looking short return GND setup you have now.

This is better than mine that's longer... I did not think of taping the under side beam.

Plenty of peace without glitches on tap.

 

The smart Master Tasos is now designing automotive electronics.


Tasos does electronics 👍🏻

• Tasos first demo is a radiator bypass controller.
• Tasos second demo is a spark plug coil tester
• Tasos third system is a GDI injector test bench

This is brilliant because it takes a lot of time to get a concept architecture to work - All 3x systems are based on totally different designs.

My favorite is likely the coil tester. I guess Tasos is using this digital scope to sample the count from his signal inputs - Then he says an Arduino reads it and sends it onto tiny display. Less than $500 Hardware kits. $ 300 for the genius.
I bet China has a few tools that can do that already.
Notice how the wiring is undersized to pass peak coil current and Power Supply likely undersized too.


The smart coolant bypass is brilliant but is going to trigger ECU coolant temp faults.
Other issues with cooling components are valve reliability under extremely hot conditions.

What do all these systems have in common?
They are all related to engine heat control or heat soak damages.
Tasos understand controlling heat is positive thing and so do I. > DISABLING HEAT SOAKS...
The key to curbing engine heat under control (without tweaking Bosch firmware) is to :
1- not produce more heat (exact timings)
2- over what can be removed (effective spray)
Then you have a strong cool engine with nimble fuel injection at no extra cost.


> CLEAR RECIPE...
Exact timings are the combination of predictable crank rotation from sealed cyl. PLUS reliable voltage supply to let stock ECU learn precise spark + injector maps.
Our electric coils are highly sensitive to unstable glitchy stock power delivery.


> NEARLY SIMPLE...
Meaning what prevents lean misfired engines from running properly are jittery contributions fired approximatively by variable voltage powering glitchy circuits... Not a chance!


> BASIC A/F COMBO....
The stock setup forces: SPARK + FUEL + AIR CONTROLS out of the optimal window of Bosch ECU can handle well.

Much like tranny is forced into wild shifts when pushed out to its normal limits.

Results are High stress vibrations and hot energy losses with reduced driveability.

This is a Mercedes: it can run okay.


Working COMFORT tranny starts in D1... never 2nd gear unless upset

> RECOGNIZING MARKERS...
We could expect smart tools like Xentry to help us diagnose cars to run well. Unfortunately a lot of tech still forced to use the parts canon to make progress.

--- Recognize ENG. VIBRATIONS...
Are the markers of very uneven contributions. Crank speeds up slows down vastly through its rotation instead of nearly equal revs.
ECU control is unable to smooth cyl. runtime due to drafty rings on bores.
Gunning that setup wacks soft bearings (UOA!)


--- Recognize HOT SOAKING ENG...
Is the marker of poor timings and high friction.
Get heat circulated out and help time engine well.
Fuel rail hisses 10mn after shut down
Big fan runs non-stop simmer & winter!
LED fan spins non stop du to engine bay heat
(never mind decoy temp displays)


--- Recognize TRANNY SHIFTS...
the marker of goofy tranny is to only starts in D2 when forced by approximative throttle.

When powertrain is working with a good engine partner, tranny always starts in D1 then shifts D2 with engine RPM MATCH and shifts all the right gears selection around 2000.R... it drives well: what a concept!!

 

Good job, did you noticed any diff after the GND strap? i see you're with 276 TT

 

This secondary GND strap devides the return current in half for starter crank and Alternator powering chassis + batteries charge if primary strap is still remains ok.

 

Interesting, I might give a try too with the guy above how he did