W212 boost issue

[Dangambino]

Hi I have a e220d that when I start in the morning surges and rocks back and forth at traffic lights
I’ve had a boost sensor replaced after it went into limp mode on the motorway but the problem still persists and I feel it’s something to do with the air intake

 

[Dangambino]

Diagnostic comes back with a boost pressure sensor a few times and then the part that regulates the fuel when you accelerate I believe

 

[mersum1es]

Hunting idle is often fuel pressure problem. Fuel quntity valve is very common culprit, rarely fuel pressure relief valve. Can you see rail pressure reading live data? Boost pressure fault may be caused by rapid change of fuel pressure which demand of boost pressure cannot follow. But if rail pressure is relatively stable (of course it may alter a bit when rpms hunt), it is boost related. But again you should check everything in boost side, actuator, boost pipe splits, cooler confdition, egr...

 

[Dangambino]

Hunting idle is often fuel pressure problem. Fuel quntity valve is very common culprit, rarely fuel pressure relief valve. Can you see rail pressure reading live data? Boost pressure fault may be caused by rapid change of fuel pressure which demand of boost pressure cannot follow. But if rail pressure is relatively stable (of course it may alter a bit when rpms hunt), it is boost related. But again you should check everything in boost side, actuator, boost pipe splits, cooler confdition, egr...

Did a smoke test and nothing from that either but I think I need to investigate the things that you mention here perhaps
Appreciate it man

 

[Dangambino]

Hunting idle is often fuel pressure problem. Fuel quntity valve is very common culprit, rarely fuel pressure relief valve. Can you see rail pressure reading live data? Boost pressure fault may be caused by rapid change of fuel pressure which demand of boost pressure cannot follow. But if rail pressure is relatively stable (of course it may alter a bit when rpms hunt), it is boost related. But again you should check everything in boost side, actuator, boost pipe splits, cooler confdition, egr...

Is it is the fuel quantity valve do you happen to know what I’d be looking at paying for it to get fixed at an independent at all mate

 

[mersum1es]

You can go parts darts if you want, new FQV is 100-200... easy to change in older 4-mug models but can't recall how OM651 is intalled.

But I would check rail pressure live data first, if problem, then measure injector tank line leaks. Of course my SDS has dedicated test for FQV so I would see results immediately.

 

[Dangambino]

You can go parts darts if you want, new FQV is 100-200... easy to change in older 4-mug models but can't recall how OM651 is intalled.

But I would check rail pressure live data first, if problem, then measure injector tank line leaks. Of course my SDS has dedicated test for FQV so I would see results immediately.

LOL appreciate that but can you be a little more clear please man I have limited understanding