doktor
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« on: June 08, 2022, 04:14:00 AM »
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Sorry to hijack your thread, didn't want to create a new one... I'm running a stock 150hp AUM engine and getting an underboost problem. Attached is a graphical log of specified boost, actual boost and regulator valve duty. As you can see the specified boost is not reached by far but however the ECU is regulating the N75. I'm getting error 17608 - Boost Pressure Control Valve (N249): Mechanical Malfunction, but I think this is not related to the underboost problem, could be a faulty blow-off valve(?). I have logged VAG groups 110 115 118 if anyone needs more info. Log more groups? Other params were coolant temp 92°C, air temp in 35°C, engine load fluctuating near 100%. Any idea? The rubber vacuum lines and hoses look fine to me. Did not go past 4500rpm because of traffic but the problem is still clearly visible. Sorry if this is a dumb question  -Jan |
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fknbrkn
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mk4 1.8T AUM
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« Reply #1 on: June 08, 2022, 07:42:02 AM »
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Sorry to hijack your thread, didn't want to create a new one... I'm running a stock 150hp AUM engine and getting an underboost problem. Attached is a graphical log of specified boost, actual boost and regulator valve duty. As you can see the specified boost is not reached by far but however the ECU is regulating the N75. I'm getting error 17608 - Boost Pressure Control Valve (N249): Mechanical Malfunction, but I think this is not related to the underboost problem, could be a faulty blow-off valve(?). I have logged VAG groups 110 115 118 if anyone needs more info. Log more groups? Other params were coolant temp 92°C, air temp in 35°C, engine load fluctuating near 100%. Any idea? The rubber vacuum lines and hoses look fine to me. Did not go past 4500rpm because of traffic but the problem is still clearly visible. Sorry if this is a dumb question -Jan Replace faulty DV. End of story |
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doktor
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« Reply #3 on: June 09, 2022, 02:04:05 AM »
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Ok, sorry for that, the thread title was exactly my problem so I thought creating a new one would be redundant. But the discussion was much more specific. I will replace the DV that's a sure thing, checked yesterday its indeed faulty - stuck in a closed position. Thought that would not decrease the boost pressure, but maybe its a protection mechanism of the ECU? Will not post any more dumb questions unless I get everything else fixed |
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doktor
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« Reply #4 on: June 11, 2022, 03:56:51 AM »
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Replaced the DV and there are no error codes. However the log looks still exactly the same as above, the actual boost is consistently around 0.2 bar lower than the specified one, the n75 is reguating to that low value. Any idea where to go from here?
As for the forum rules, is the problem with my logs? I'm using vag-com to do them, I'm used to it from my previous diesel car. I plotted them in Excel for better clarity. Should I go about using something else or provide more info? Thanks for your patience, I'm new here and surely will learn more. Right now I'm considering remapping my AUM with AUQ maps, I now have a general idea how to do it but will do more reading before I actually attemt anything, want to be sure. Also with this boost regulation problem there is no point in remapping before it is fixed.
Thanks
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doktor
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« Reply #5 on: June 12, 2022, 02:36:59 AM »
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Well it looks like something around the n75 is shot. Unplugged it electrically and exactly the same low boost is reached, which I now realize is the wastegate opening pressure. The valve itself looks ok, resistance within limits, blocks the intake port when not energized, clicks with voltage and opens intake port, but obviously it does not do its job. Much closer to success now. Sorry for bothering with my noob questions, if you feel like you can delete this thread, but maybe it can serve for other noobs with similar problem?
Edit: Checked with a small light bulb (1 watt) that the n75 is getting voltage on acceleration. The piping around it looks all good, so I guess a replacement valve is due.
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« Last Edit: June 12, 2022, 03:41:12 AM by doktor »
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nyet
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« Reply #6 on: June 12, 2022, 06:20:04 PM »
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doktor
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« Reply #7 on: June 13, 2022, 06:01:52 AM »
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I see that the ME7logger is the preferred logging sw here so I will try to use that the next time. Its my fault for not reading the rules thoroughly, but to be honest, I did not see that recommendation for the first time. I did search for rules before using the search function but didn't find anything, just then I realized the search function is somewhat "dodgy"? It often produces very few results if any. I think this is a very good community, I really do not intend to cause any arguments, I think I will learn the standards here quickly.  |
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justinvw2646
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« Reply #8 on: June 13, 2022, 06:26:55 PM »
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When you use the search function always go to the forum home page first. In my experience that helps to land more results.
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nyet
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« Reply #9 on: June 13, 2022, 10:28:38 PM »
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I did search for rules before using the search function but didn't find anything
They're literally stickies (bold, always first) on every forum. No search needed. |
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doktor
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« Reply #10 on: June 15, 2022, 11:24:33 AM »
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Replaced N75 and it works. I feel really stupid now. Most of the time the simplest solutions are wrong, but surprises do happen... |
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nyet
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« Reply #11 on: June 15, 2022, 12:22:12 PM »
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Replaced N75 and it works. I feel really stupid now. Most of the time the simplest solutions are wrong, but surprises do happen... Thank you for following up! it is very helpful for others when they see what solved a problem. |
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