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Post by chippie on Nov 8, 2023 20:46:02 GMT 1
It’s a shame you didn’t log MAP readings too…..
I’d expect the two to correlate….unless there’s a leak….
Just driving around town and a commanded boost pressure of 240kpa ( that’s 2.4bar!) seems a tad high….for not a great engine load….but without seeing a full set of figures it’s difficult to judge …
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Post by valhalla on Nov 8, 2023 22:21:18 GMT 1
Yes, the commanded boost-pressure signals above are quite plausible - knock 100kPa off the figures, and you have (approximately) the gauge-pressure setpoints (i.e. what you would measure with a pressure-gauge connected to the inlet manifold) of 0.00kPa to around 140kPa (or 1.4BAR). In "turbocharger world" you need to use absolute pressures to be able to control pressure-ratios across compressor/turbine wheels, so that is why the data is presented that way.
140kPa gauge-pressure is quite an ambitious target pressure to achieve with any turbocharger, but I'm reckoning that Toyota must have had their reasons ! When you get up to these sorts of pressures, you really are "dancing with the Devil" on things like compressor-wheel stall, etc. etc. and that can rapidly lead to compressor failure. (Pressure-ratio here would be 2.4, which is right at the top of most compressor "maps" for this sort of application)
You need to bear in-mind that these figures are commanded pressures (only) and not what you would see all the time. There are a few good reasons for setting the command-pressure a bit high, but you need to be very clever as a controls-Engineer to get the benefits of this - and not really c*** things up......
In the ideal world, your MAP sensor pressure will follow this commanded pressure quite closely for engine speeds above 1600rpm, and for engine loads above 1/2 torque. How close MAP follows this commanded pressure is a measure of whether there is much wrong on the engine.
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Post by chippie on Nov 8, 2023 22:36:13 GMT 1
Just to back up what I said earlier about the high boost pressure…..
My VW Passat 2.0 l diesel has a max reading of 2.6bar (260kpa…) when running a good load….( the engine produces somewhere in the region of 180-190 bhp or 140kW )
So, if you go caravanning Thursday, try and log cbp and map and see how different they are…if you have a leak, depending on severity, you may even hear a whistle…
Does the car perform despite the symptoms?
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Post by arossco on Nov 9, 2023 13:13:52 GMT 1
It appears that with my OBD2 scanner ( Ancel BD300 with its own dedicated app ) it is only possible to graph one data item at a time. This is disappointing, as I can't log MAP pressure against turbo boost pressure.
The only thing I can think of is to either log one value on the way out today, and the other on my return next Tuesday, or stop half way at at the motorway services to change over.
I downloaded a couple of alternative apps to use on my iPhone, but it seems that my ODB2 scanner needs to be ELM compatible, and it won't connect.
The engine in my Toyota Verso ( 1WW ) is actually a BMW A47NC16A adapted by Toyota, so maybe the turbo characteristics are different from Toyota's ?
I would not be aware that there was a problem apart from the codes, apart from a slight drop in power - no smoke, poor idling and starting etc.
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Post by chippie on Nov 9, 2023 13:35:28 GMT 1
How about some snap readings at varying engine loads and speeds?
Least then we can see what commanded and actual pressures are..
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Post by arossco on Nov 9, 2023 19:54:27 GMT 1
Well, this is interesting. I reset the codes yesterday morning, and after driving for a couple of hours, both P00BD and P0471 came back as pending codes, but not current, as has been happening since the beginning of September.
Today after 55 miles mostly on the M8, the pending codes have gone ! The engine was working pretty hard, effectively flat out going up some of the long slopes with the caravan at 60 mph. I put in a bottle of STP Ultra 5 in 1 a few days ago, but wasn’t really expecting much.
I won’t be doing much driving, mostly urban, before next Tuesday when we come back. I will let you know if the codes return. I’m not too confident that all is miraculously better just yet !
Apologies, I don’t have any data after the journey. I set my iPad to log the commanded turbo boost for the journey and put it on the back seat so it wouldn’t distract me, but when we arrived the iPad had gone to sleep and had lost the graph. . On the way back my wife is going to log the live data from the iPad, which I will post here. I’ll also look into getting a better reader and/or app which will graph more than one data item.
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Post by arossco on Jan 25, 2024 18:39:35 GMT 1
Here is an update - sorry about the late reply.
It turned out to be a partially blocked turbo hose, and a small leak in the air intake. I had it serviced by Toyota Helensburgh, who diagnosed these, and unblocked the hose and fixed the leak. I can highly recommend them. The car is running really well now, and picks up far better from about 1200 rpm. In fact, it has more power than at any time since I bought it in July 2022 with only 29K on the clock. It now has 41K.
Anyway, all is well now. I can only imagine, as the car was so low mileage, the previous owner maybe put in cheaper diesel fuel and didn't do long journeys, which helps clog everything up. I have always used BP Ultimate, or Shell V-Power is also equally good. I will make sure I do the "at least 20 minutes at 2000rpm" drive every so often to help clear out the DPF. This will be fairly easy to do on my caravan trips.
I really think it is poor that these engines clog up with normal driving, and it is not a service item to clean the intake/DPF. It's almost back to the days of decoking petrol engines every 30K.
Thanks very much for all your help, chippie and Valhalla !
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Post by Noberator on Jan 26, 2024 0:36:02 GMT 1
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