c43 low pressure on HPFP
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C43 amg
c43 low pressure on HPFP
hello, i have a MB c43 2019 with m276. for three years i had a upgrade HPFP and upgrade LPFP and stage 2 tune ecu+tcu, i got an issue 5 months ago with LP on the HPFP and went to my tuner with my car to see what was the problem. common rail was very corroded, LPFP was broken and they told me that the HPFP is too, they change LPFP with a new one, i put back original HPFP of the car, cleaned common rail and injectors, after that i put stage one on ecu and i have same issue, LP on the HPFP, i even bought another genuine hpfp and tried and same issue. what is happening is that i start the car, everything works normally, you can drive it on 2000-3000 rpm and everything works good, but when the car try to build boost it lights on the engine sign and is running very jerky. i don't know what to do anymore because already 5 months since my car is not working....
Out Of Control!!
Joined: Apr 2019
Posts: 11,921
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From: Silicon Valley
W212 MY'14 M276-3.5NA @75kMi
LOW PRESSURE WHERE??
hello, i have a MB c43 2019 with m276. for three years i had a upgrade HPFP and upgrade LPFP and stage 2 tune ecu+tcu, i got an issue 5 months ago with LP on the HPFP and went to my tuner with my car to see what was the problem.
Common rail was very corroded, LPFP was broken and they told me that the HPFP is too, they change LPFP with a new one, i put back original HPFP of the car, cleaned common rail and injectors.
After that i put stage one on ecu and i have same issue, LP on the HPFP, i even bought another genuine hpfp and tried and same issue.
What is happening is that i start the car, everything works normally, you can drive it on 2000-3000 rpm and everything works good, but when the car try to build boost it lights on the engine sign and is running very jerky. i don't know what to do anymore because already 5 months since my car is not working....
Common rail was very corroded, LPFP was broken and they told me that the HPFP is too, they change LPFP with a new one, i put back original HPFP of the car, cleaned common rail and injectors.
After that i put stage one on ecu and i have same issue, LP on the HPFP, i even bought another genuine hpfp and tried and same issue.
What is happening is that i start the car, everything works normally, you can drive it on 2000-3000 rpm and everything works good, but when the car try to build boost it lights on the engine sign and is running very jerky. i don't know what to do anymore because already 5 months since my car is not working....
> You have a pecise test case:
engine bugs down above 3kRpm.
-1- Read your Lo/Hi fuel pressures to confirm all new pumps hold pressure & flow under load.
-2- Check the vacuum pump check-valve is pass/failed.
-3- Untune ECU back to stock for sole comparison
-4- How does your engine idle... sound clip??
-5- Is it time for bore-scope or a compression test ??
Last edited by CaliBenzDriver; Dec 2, 2025 at 10:56 AM.
