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Could it actually be your rails? Faulty injectors?
No clue,
Wouldnt they pop a error code or smth? i mean the local mercedes shop cant find any problems at all with the car. they did all their tests and nothing seems to be off for them.
Ordered a LPFP to replace and well see what happens nothing points towards it. but its the last thing i can think off not working properly
I think you are onto something with LPFP starving the HPFP, namely the control module, the pressure sensor and the noise that 3-Phase pump creates.
The ECU, tranny and LPFP are on the same CAN-E for direct control. The high-speed CAN wiring to rear passenger seat being long and noisy is a trouble factor.
Voltage deep during acceleration may be blamed as well.
I think you are onto something with LPFP starving the HPFP, namely the control module, the pressure sensor and the noise that 3-Phase pump creates.
The ECU, tranny and LPFP are on the same CAN-E for direct control. The high-speed CAN wiring to rear passenger seat being long and noisy is a trouble factor.
Voltage deep during acceleration may be blamed as well.
Yeah i have no idea…
Replaced the LPFP with a new one yesterday. No change at all.
So hard to find something when there’s no error codes and the systems the Mercedes workshops use flags the car as there is nothing wrong at all
I replaced the battery like 6 months ago because it had poor performance.
Replaced the LPFP with a new one yesterday. No change at all.
So hard to find something when there’s no error codes and the systems the Mercedes workshops use flags the car as there is nothing wrong at all
I replaced the battery like 6 months ago because it had poor performance.
It's interesting you mentioned swapping battery for poor performance - Actually check your battery voltage display to see how badly your ECU is causing voltage drop duringaccelerations.
I think there's a relationship between 3-PH LPFP and voltage crashing. When ECU commands pump increase the Alternator takes a dump temporarily.
> FREE fix under 5min:
The quick workaround is to disconnect the Alternator LIN connector. This will give you a smooth regulated voltage and well charged battery to boost loads.
Confirm if this fixes your pressure control.
Last edited by CaliBenzDriver; 07-02-2022 at 02:42 PM.
Geesh that's a tough one. Can you post your logs and draggy times?
I dont have acess to the tuners log but i could prob get it if its needed but here is the dragy time i did after i replaced the LPFP and a screenshot he sent me
It's interesting you mentioned swapping battery for poor performance - Actually check your battery voltage display to see how badly your ECU is causing voltage drop duringaccelerations.
I think there's a relationship between 3-PH LPFP and voltage crashing. When ECU commands pump increase the Alternator takes a dump temporarily.
> FREE fix under 5min:
The quick workaround is to disconnect the Alternator LIN connector. This will give you a smooth regulated voltage and well charged battery to boost loads.
Confirm if this fixes your pressure control.
Did this 60-130 ish pull just now. to check it out and its dropping V the faster it goes but im not sure if its supposed to be that way or not im clueless about stuff like this.
If you think i should try to disconnect the alternator lin connector ill try it asap
Did this 60-130 ish pull just now. to check it out and its dropping V the faster it goes but im not sure if its supposed to be that way or not im clueless about stuff like this.
If you think i should try to disconnect the alternator lin connector ill try it asap
> Recap #1..6:
-- We see how alternator goes offline and leaves 100% of the 80Amp load on the battery alone.-- Car Voltage keeps dropping as the battery gets deeply more drained.
-- This is both ridiculous and dangerous, not a feature! The center piece in this chaos is courtesy of LPFP disturbing coms.
> Quick Fix:
-- Now unplug ALT LIN connector (optionally let your battery charge current get down to near +5Amps)
-- Smart alternator has internal voltage regulation and load, temp compensations.
-- Accelerate all you want to your heart's contempt with a new video, please!!
> Cherry on your cake:
At the end of today, do a battery disconnect to reboot both SAM's that like to soft-crash under low voltage. Car will run much better when all CAN networks are undisturbed by SAM's gone wild.
+++ [Further more] +++
-- The voltage display at battery posts reads near 12.3V. Now imagine 80Amps current going through prefuse relay, links and harness to the car rear probably drops an extra 2Volts.
-- The inline resistance (impedance) of Battery + Relay + Harness is much greater than having the straight alternator online. Battery normally supplies nothing else than starter connected straight through.
-- Normally the ALT path feeds current directly to consumers, not through Prefuse main SSR relay... drop voltage!
-- This uncontrolled deep discharge also happens in conditions when the car tries to generate "12.6V"... instead this soft-crashes the SAM'S and go into deep drain below 12.2V... be curious for yourself.
-- During accelerations, ECU/SAM power Mgt try to back off high charge voltage (from 14.4V to 13.7 or 12.6v) in order to minimize battery current but LPFP noise crashes the R-SAM voltage tracking, causing the ALT to go 100% offline out of control... ouch!
-- This issue is getting old enough that MB/Bosch who designed that control should flag an DTC Error anytime the voltage control gets lost. Selling new batteries is not a professional fix.
Last edited by CaliBenzDriver; 07-03-2022 at 11:07 AM.
Reason: 1000Watts chaos 😳
Is there any down side to disconnecting the ALT LIN connector?
NONE, pure bliss!
Having the alternator supplying the car directly instead of ghosting will give you intended performance and save you bundles in uneeded services.
> Say goodbye to... :
moody engine performance
crashed F-SAM draining battery
limp modes on low voltages
prematurely wasted battery
starters wasted on high currents
PreFuse toasted with 1,000W (1KW!)
🤪
> Take a look with IC Display:
-- Once the battery is done absorbing a charge current it will be transparent with near zero load.
-- Alternator voltage is internally regulated between 14.4V and 13.7V.
Last edited by CaliBenzDriver; 07-03-2022 at 02:27 PM.
Then why did MB put it there in the first place? What is its intended purpose?
> Put what... in where?
Regarding the busted external regulation, it is designed to allow the ECU to do couple new tricks:
1- Manage "opportunistic charging" during slow downs.
2- Sensing the batt internal temperature to expedite the charge with higher current after cold starts.
3- Bump voltage back-up when R-SAM signals high consumers demand.
> Furthermore :
In *NO* instance the AGM system battery should be discharged with ALT offline. That is a defect, not a feature.
I believe the car Voltage going off the rail is linked to LPFP doing the same...
This design originates from Bosch. Most manufacturers like Ford, Toyota, Honda make it work well, MB turned this into a service opportunity.
Last edited by CaliBenzDriver; 07-04-2022 at 03:35 PM.
Now that we have seen above how the ALT Control crashes during accelerations - Wait, there's more!
> ALT offline during cruising:
The external voltage regulation allows for a tailored voltage in mutiple stages. This old concept is over 50Yr old, typically the voltage gets lowered once the battery is all charged up.
[14.9V >14.4V > 13.7V > [b]12.6V!!]
We cycle through multiple stages to charge the battery then finally maintain top charge like float-chargers do.
On impacted cars, the 12.6V stage causes the ALT to get offline with similar results as above.
Extremely low voltage and high currents: 11.7V, 90Amps.
To reproduce this particular condition:
charge your battery and go for a non-stop 90mn highway drive during daytime. Keep consumers turned Off (no headlights, no A/C, no defrost...) - Observe your voltage management as battery charge is complete.
The LP pump control must be disrupted as well while controls are soft-crashed.
✌️
Last edited by CaliBenzDriver; 07-04-2022 at 09:38 PM.
Have you witnessed this bug deep draining your AGM? If yes you will spot the difference and your car will benefit.
> ALT LIN vs. LPFP:
While disconnecting ALT LIN clearly does work around the deep drain low voltage bug, you want to see if this also significantly helps the LPFP Controller regulate good fuel pressure. Look or graph live data.
> Chicken or the Egg:
I don't know if the low voltage crashes the pump controller
-Or if the pump crashes the ECU voltage control of ALT.
Last edited by CaliBenzDriver; 07-05-2022 at 06:11 PM.
I unplugged the LIN & and did the battery off reset.
The V and AMPs are now stable at 14V & 10-20 amps at all time never goes -
BUT the car still does not run as it should. Doing 60-120 at 8s 8.2 and its should do low 6s
So you can tell WOT performance is still short 2 seconds.
Earlier we found out the buggy voltage regulation was crashing during WOT. We applied a workaround but fancy LP controller still not cooperating.
Let's get the obvious out of the way: still no scan code, right? The fact LP controller can be nuts without code says it is disrupted crazy.
You need to diagnose your 2-stage fuel supply. (3000Psi HP likely ok because well controled directly) - That sends you to LPFP fuel control that is known for falling flat down under demand. Confirm if indeed that is still your problem: Low-Pressure pump is starving High-Pressure pump
Can you quickly graph the low pressure sensor data with any scanner?
You've changed the 3-PH pump... Next I don't think a new controller will bring joy.
(Homework: Do charge your battery well with a CTEK... you want to read about 5Amps trending towards 0.5A - NOT 10 to 20A high! Considering ALT as a charger is not to your advantage) -
Last edited by CaliBenzDriver; 07-06-2022 at 08:29 PM.
Does your car ever go to the limp mode , when you have to reset it ? I started having problems after I did my St2 tune , and tuner would see significant fuel deficiency. I would say check your tune but sounds like you reverted back , did you have CPC ?
battery is still a good lead, let us know what u find out
what's funny is many chassis seem to suffer from this amazing fuel pressure issue that gets dwarfed by other engine problems. When you know what you're looking at you begin to see a sort of partner emerge.
artic silver heat compound to improve heat profile
There is nothing more fancy than a 3-Phase variable speed pump controlled by approximating Sinewaves from DC voltage. It would be an extremely nice design if Continental didn't go out of it way to seed troubles.
Manufacturing cost difference is not involved, it's near term repairs that are targeted.
Problem Solving :
The long story short today is these 3-PH LP controllers are used for many very different applications from 4 to 8cyl. They are factory coded to match specific demand map by software. We know how Germans love their endless version tracking of parts...
Practically you may want to get the latest superspeed P/N hardware and get it installed by your trusted MB indi.
My guts tell me the original hardware electronic board lacks adequate noise filtration (1900uF only).
Hopefully there is an upgraded controller module available by now.
aproximated sinewave x 3-Phases.... NOISE GALORE!
Or Plan B is to troubleshoot the electric noise issue with a scope on running engine.
I hate throughing parts blindly at genuine problems. It's best to find the smoking gun: "LP falling down on WOT". Even that is not good enough to pin the exact fix!
more data to analyze... gets more knowledge !
Last edited by CaliBenzDriver; 07-10-2022 at 01:59 AM.
06-28-2022, 01:49 AM
