Hey guys, so for the past month and a half i’ve been having an issue with my car where the car drives normal but if i floor it, I start losing power and the car’s fuel pressure starts to drop for a few split seconds which causes misfiring which then ecu reads and puts the car into limp mode, but sometimes it doesn’t and the car continues to misfire and shake intensely, but with a quick restart to the engine everything returns to nornal, even if its really quick like just turn off and turn on the engine while coasting in neutral and everything returns to normal till I floor it again and the same cycle happens, now that i’ve explained what happens… let me tell you what i’ve done so far to try and fix this problem, so I took my car to my local amg specialized workshop and had the car diagnosed and they claimed it to be the LPFP finally giving up after 12 years since the car left the factory… so i said fine and had them replace it with a new OEM LPFP which was not cheap at all… so i take the car out for a spin and everything seems to be back to normal, till I get on the highway and decide to test the car there where the problem happens again… now at that point i notice that the issue starts when the car is under load and at higher speeds, it rarely ever happens on 2nd gear but always at 3rd gear or higher… anyways i return to the workshop and explain to them the issue is still there, the mechanic then tells me to keep the car there for a few days till they can really figure out why its still happening… so about 3 days later they call me and tell me that they’ve checked the fuel rails and injectors and found them to be in good condition and working properly but when they were checking the HPFP’s in the engine bay they noticed that the passenger side HPFP was not working at all which they then proceeded to replace it with a OEM bosch HPFP which then they told me to come pick up the car and test drive it, which i then did and still had the issue occur like stated above, now the thing is… before replacing the HPFP, when i would turn the ignition on which primes the fuel system, it would start at 1500psi and then slowly drop down and would not hold the 1500… and after they replaced it, it would hold 1500psi and stay in that range or increase a little which would indicate that there was an issue with the HPFP before, anyways so back to where we were… I test drove the car and still the same issue persisted so i take the car back to the workshop and then they say it could be a faulty fuel pressure sensor which is misreading the fuel pressure when its at full throttle and causing the ecu to get confused at discrepancies in the data it’s receiving, so i change the fuel sensor and still have the same issues… so now im just really tired of trying to fix this problem and honestly just losing motivation to even continue pursuing to fix this issue because i’ve spent so much money on parts and labor and still haven’t resolved the problem… (note: spark plugs were changed and are brand new) so if anyone might have any idea as to what could be causing this and what the solution is… I’d really appreciate any suggestions and help, thank you all honestly cause it’s been really stressful and saddening not being able to enjoy my car fully… thank you.

 

Have you checked this out?

https://mbworld.org/forums/w212-amg/...fixes-diy.html


A few questions:

- have you lodged this? What's the boost, and timing data?
- fuel trims?
- is this tuned or modified - if so what are the details of the tune or mods (ex: intake)
- what codes are stored as permanent
- how many miles on the car
- when were the coils last changed - this is your #1 thing to consider
- is there oil in your wiring harness? Is there oil at the ECU plugs?
- have you replaced or inspected all CPS and solenoids?
- which cylinders are misfiring? Always same bank?
- how's your fuel - new gas station?
- o2 sensors?
- what are your IAT's?
- how are the turbos and wire harnesses to the turbos?

post this in the w212 amg forum - way more traffic

check out this thread from the sticky referenced above:

https://mbworld.org/forums/w212-amg/...30-45-mph.html