 | Home > Technical (L405) > SDV8 strange HP fuel pump noise |
 
|
|
|
| Astanavits Member Since: 23 Sep 2024 Location: Paris Posts: 26  
|
unfortunately no but this video may help you
|
||||
4th Aug 2025 8:41pm |
|
| Astanavits Member Since: 23 Sep 2024 Location: Paris Posts: 26
|
Update: i changed 8x injector new bosch , engine harness new(melted ), engine ECU , Central junction box / BCM , new denso generator, noise still there
|
||||||||
|
10th Oct 2025 11:59pm |
|
| Astanavits Member Since: 23 Sep 2024 Location: Paris Posts: 26
|
So after lot of test i discover it’s electrical problem like interference or something if i unplug the earth strap behind de engine ECU the noise disapear if you plug the earth again the noise came back
|
||||||
|
11th Oct 2025 2:23pm |
|
| Astanavits Member Since: 23 Sep 2024 Location: Paris Posts: 26
|
Anyone with obd reader or sdd can share his data please look at this 0 to 6 second of the video is engine at idle when i press throttle pedal and keep the engine running at 700/750 rpm the car shaking badly like the engine run on 6 cylinder
|
||
|
11th Oct 2025 2:29pm |
|
| fisha Member Since: 25 Sep 2009 Location: Scotland Posts: 1557 
|
What values are you looking for ?
|
||
|
11th Oct 2025 4:50pm |
|
| fisha Member Since: 25 Sep 2009 Location: Scotland Posts: 1557
|
Then that is your issue. The fcv. The knocking is it doing its job of regulating the fuel. There are a couple of posts online including a Daimler tech bulletin which describes a knock sound which disappears when the fcv is disconnected , and that this normal operating noise and not cause damage. It sounds like the same should apply for the sdv8. V8 or else ... |
||
|
11th Oct 2025 5:04pm |
|
| Astanavits Member Since: 23 Sep 2024 Location: Paris Posts: 26
|
I would need to compare the following data about the throttle body mine are erratic
|
||||
|
11th Oct 2025 6:00pm |
|
| Astanavits Member Since: 23 Sep 2024 Location: Paris Posts: 26
|
You are right, I also found the Mercedes report where several customers complained about the noise and indicated not to change the injection pump for this reason. I also found a report produced by VW and Ford about the Bosch CP4 pump noise . Here is how the valve works depending on the engine temperature and other parameters. There are three operating modes: MPROP control, PCV control (bleed valve on high pressure fuel rail) and coupled pressure control (CPC). The MPROP is Bosch’s name for the fuel metering inlet valve, this controls how much fuel is delivered to the plunger chamber. During MPROP closed loop control, the PCV is over-closed and MPROP delivers the proper fueling to achieve desired pressure in the fuel rails. This method has been used since 2001 on the CP3 pump and is robust. When the accelerator is released the MPROP closes to decrease flow and the PCV opens momentarily to relieve excess rail pressure as the requested pressure is decreased. The next mode of operation is PCV control. Here the MPROP is fully open and delivering max fuel to the pump plunger and the PCV regulates the fuel rail pressure in closed loop control by closing only enough to reach the desired rail pressure. The downside to this mode is that the high volume of fuel that is pumped into the rail and then recirculated out thru the PCV consumes a lot of power inside the pump and also generates a higher amount of heat. OEMs generally use the PCV-only control method when fuel temps are cold, in order to heat up the fuel faster. This control strategy is also employed on the CP3 and CP1/CP1H pumps. With the EDC17 era was possible also a new mode called CPC (Coupled Pressure Control). This mode allows to prescribe a desired value for both the metering unit flow and also the rail pressure controlled via the PCV valve, leading both actuators to be under closed loop control via PID-governors (proportial, integral, and derivative components). The purpose of this is to allow the metering unit to operate in a more controllable flow rate but not pay the penalty of power consumption and heat rejection by full PCV mode. You can think of this mode as the PCV one but with lower flow rate thru the metering unit. Source: https://www.jeepgladiatorforum.com/forum/t...ing.65339/ |
||
|
11th Oct 2025 6:06pm |
|
|
|
| All times are GMT + 1 Hour |
< Previous Topic | Next Topic > |
Posting Rules
|
Site Copyright © 2006-2025 Futuranet Ltd & Martin Lewis
