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535d power loss after 3rpm

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Hi guys, my 535d, dpf delete cat delete, egr delete and stage 2 map, dyno bhp is 347 and 720nm torque. Recently I noticed power loss from the big turbo after about 3.5k to 4k rpm it's gone way slower than before, the power dropped back to about stock level about 270bhp, I scanned the car I keep getting the fault code for boost pressure sensor, 41AA and 41AB, I have replaced the map sensor with the oem bmw map sensor but the code doesn't ago, i have chcked wiring for damage and cleaned the connector with contact cleaner, I have also cleaned inlet temp sensor on the metal pipe, the code comes back after clearing it off and I can't regain the power I lost, before there was a burst a boost after 3krpm but now it's just a smooth acceleration from the small turbo to the big one and after about 4k rpm the engine is screaming and pulling but not how it was before, it lost alot of boost, I have done some research, other people had the same code and no matter what they changed they couldn't get rid of the code and their symptoms were worst than mines. If any one got to the bottom of it please shed some light on this, I dont want to keep changing parts based on assumption  I have read on some forums people changed almost everything including vac pipes, actuator, map sensor, boost converters, inlet manifold etc

Edited by JU54HED

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Start with cheapest things like a vacuum hoses. They might look ok visually , but when you inspect them, they are brittle.  Start with vacuum hoses. I had the same problem after a remap(like you had) a piece of vacuum hose coming from the pressure converter and going to the actuator, after I changed that, everything was fine after that.

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Very, very likely to be a failed vacuum hose. A leak means the turbos, bypass valve and wastegate cannot be controlled correctly. That shows up as a boost pressure fault, too much or too little.

 

Take off the acoustic cover and check all the vacuum hoses especially around the exhaust manifold.

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Hi guys thanks alot for your quick and helpful response, I have literally done that today, replaced all the vaccum hodes of all the actuators (was a pig) and also changed the diverter valve (not the pressure converters with 2 pipes comming out vertically) I've the replaced the small one with one pipe going horizontally and one going vertically, car feels slightly better but the code comes back after about 10 or 20 minutes of driving or re starting the car. The code is either 41AA or 41AB or both at the same time, saying Boost pressure sensor. Another thing I'm not sure about is when I plugged in the new vaccum hose to the actuators I was sucking the vacuum out to see if the actuators move, looking at turbos from the side of the car, the very big actustor on the upper left vertical rod moves freely and when I let go of vacuum it drops freely as well, but the actuator on the middle, horizontal rod, when I apply vacuum on it with my mouth the rod doesn't seem to move unless I push it with my hand then let go of the vacuum then it drops, but it does hold vaccum. On the very right actuator near the intake boost pipe and near the lower radiator hose, it moved back and forth with vaccum just like the first one. I'm not if the middle one is supposed to be like that or it's faulty because someone told me one of them actuators kick in at very high boost once the big one reaches the peak boost. I am baffled why the boost sensor code doesn't go, when I physically disconnect the boost sensor wire and re scan the car it instantly comes back along with another code saying boost sensor signal and the other code 41aa boost sensor. When I plug it back in and clear it off they'll go off but when i re start the car or something the 41AA or 41AB both saying boost sensor returns. I dont know if anyone ever got to the bottom of the code, I dont see any wiring damage of the boost sensor or anything.

 

Thanks for your help guys 

imageproxy (1).jpeg

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Other people had the same code and no one could get rid of the code and they have changed almost everythin. I was monitoring the boost pressure and maf data, why is my actual boost pressure data is higher than the set point boost pressure. This is at idle, set point boost pressure is 1008hpa and actual boost pressure is 1037hpa

Screenshot_20180502-172138_Carly f BMW.jpg

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I think I had the same error ( boost pressure too high and boost pressure too low, can't  remember the error codes.) I changed the sensor on top of the inlet manifold, but I got it from the dealership.  All fine now.  Where are you based?

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I'm based in east London, Dagenham, I did the same  first i put a sensor on from euro car parts aftermarket it didn't solve it, so I went to the dealer and got the OEM one from bmw and put it on, cleaned the connector, replaced the rubber grommet, sprayed cleaner in that boost sensor hole to clean the sitting area, cleaned the connector, now I'm losing hope, no matter what I can't get rid of the code 

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I will check the history of my codes later on. Might be the same ones. Is there any other errors besides the boost pressure error?  In ista  there is a option to check for a bad boost pressure converters. Not too sure about the carly... London. .. if you would live somewhere in Northern  Ireland I might be able to help you out more.

Edited by Biotoxic

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Thanks for that mate, no no other code just the boost pressure sensor code 41AA and 41AB, I used Delphi autocom as well and it's the same code, I do have ista software but got no clue how to use it, never touched it since the download, dont even know if it works, I have inpa, is there anything on INPA i could do.

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A hand vacuum pump is really helpful on the 535d. Test all the actuators. Check they all move properly and return. Check the different areas

hold a vacuum.

 

The pressure converters can be a nightmare too.

 

Over the years I've had all of these:

Failed vacuum hose

Broken vacuum T

Faulty pressure converter

Leaky brake booster meaning poor vacuum through the whole system

Blocked hole in the vacuum distribution T's (this happened twice)

Stiff wastegate, freed by exercising by hand

 

Given what you've done so far I'd check that the tiny 0.8mm holes in the vacuum manifold are clear. I'd also swap the pressure converters around and see if anything changes.

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Thanks again for your reply, Im thinking of biting the bullet and replacing the two pressure converters, they're about 155 for both on euro car parts, and one of my waste gate is stiff when I suck vacuum with my mouth the rod doesn't move unless I push it with my hand, it's the middle waste gate circled red in the picture I've uploaded earlier of a 535d twinturbo diagram. I haven't chnaged vacuum hoses behind the inlet manifold there's another pressure diverter there, I haven't checked the break booster either, I guess I'll check them as well, is there any way I can do complete vacuum system check? The thing is I dont know which line should hold vaccum or which line should allow vacuum flow freely. If you still got your car could you check if your middle actuator the red circled one moves freely with vacuum or just pushing it in with your hand or if moves on engine start or when you rev, also if u got diagnostic software, could you check what your actual boost pressure is and what your boost pressure setpoint is, whether the actual boost pressure is higher than the setpoint

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I was driving today constant acceleration most of time especially after start up it's alright it pulls decent (still not as good as before) then some times after about 50 onward on 3rd and above the engine is screaming pulling but not enough boost its just scresmimg and pulling it slowly and gear changes takes long as well and the code 41aa or 41ab comes back when I clear it. I turn the ignition on scan the car and code is there I'd clear it off turn the ignition off after a minute or two turn the ignition on and scan the car and code is back, so if the code was for vacuum how does the ecu know there's a vacuum leak fault before I even turn the engine on? Alright if I turned the engine and it ran for few minutes and vacuum was leaking then it might pick it up as the code but without engine on the code comes back instantly.

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So you're saying you can delete the code but it comes back before you start the engine...that can't be the vacuum system. The vacuum system only builds a vacuum with the engine running (and it takes 5s at idle to create a full vacuum ready for anything).

 

I think you need to get ISTA-D or DIS on this and really read the detail of what it finds.

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If you can with what you've got have a look at the live data for ambient pressure and manifold pressure with the engine off. They should be pretty close, there will be some difference though, perhaps +/-20mbar.

 

Because of the fault being detected without starting the engine the diagnostics must be assessing the value from the MAP sensor and determining it invalid. If you've changed the MAP sensor and that is reading correctly then something else must be giving duff values for some reason.

 

There is an ambient pressure sensor built into the DDE but that has its own fault codes. Perhaps that is giving a duff value though. Could be clogged up somehow, I'm not sure exactly where it gets its pressure from.

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I've monitored atmospheric pressure (which should be ambient pressure) the pressure seems to be alright it's slightly less than actual boost pressure with ignition off 

Screenshot_20180503-134716_Carly f BMW.jpg

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This is the read from Delphi software, sorry quality ain't great, the atmospheric pressure and actual boost pressure value doesn't seem to be off by a huge margin

20180503_135814.jpg

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I got my mate to check his boost pressure value on his 530d remapped, he's one reads about 100 without engine on and over 6 to 700 with engine on, my one reads about 200 without engine on and about 600 with engine on but even I disconnected the MAP sensor wire the reading is still 200 and that specific parameter is not available on my Delphi software. I have used multi meter to check for voltage at the connector of the map sensor, there is constant voltage and variable voltage from signal wire I just could check the variable voltage from the signal wire cuz there's no way to back probe the connectors without cutting out the plastic connector housing. I'm guessing the electrical side of it alright but I'm baffled I'm running out of ideas

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Last night I was thrashing it, high speed, all of a sudden I lost complete boost and I scanned the car it had a different code about boost pressure value low or something and no boost at all, then I cleared off the code while driving and that's it car was driving normal again

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OK the 200 bar reading looks like a quirk with Carly, because 200 bar is 2900 psi that's a lot of boost, it should be no more than 2 bar, ever.

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Yeah I think Carly is bullshitting, even after disconnecting connector of the sensor it still gave 201bar. And my mates 530d was getting those silly numbers as well. What do you think, should I spend 200 quid more and few hours, change all the pressure converters and remaining vac hose behind the manifold, if that doesn't solve it ill give up, ill also get a vac pump test in the next few days get my mate to give me hand to remove the manifold then get over it it's destroying my sleep this bug eating me inside out lol 

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I wouldn't change the pressure converters yet. What if the problem is that the swirl flap hose has fallen off. Changing the pressure converters won't fix it and would be a waste of time and money.

 

If your error code comes up before you start the engine then it has to be electrical. For some reason the DDE is convinced the pressure sensor is faulty but oddly the live values look absolutely fine. I think I remember someone once had something similar and it was some trapped/chaffed wires.

 

You are definitely sure the code is cleared, then comes back without starting the engine?

 

 

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Not all the time but after clearing off the code and shutting down the engine and turning the ignition on and scan it and BOOM!  (like Russian hacker on youtube) the code is there. I spoke a bmw specialist who sorted me out in the past when other mechanics couldn't, I told him the symptoms and told him some figures  he's saying the turbo is over boosting, he said the guy that mapped it he put too much boost on the turbo as a result the sensor detects over boost and cuts down power and hence the fault is intermittent, I've told him after that, the actual boost pressure around 40hpa higher than the set point boost pressure then he said there you go the turbo is over boosting, that's why the oem sensor is detecting too much boost and throwing the code as intermittent, ill be taking it on dyno soon to see how much bhp I lost and how much bhp it goes down to especially the time when it's screaming up the rev with little boost. What he said does kind of make sense he said he'll talk one of his guy that does them things to adjust the boost and things but that means hell put down the overall bhp. When I speak my remapper he tells me change all the vac hoses and pressure converters, he saying the pressure converters or vac hose are bad that's why boost loss 

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