02-06-2020, 02:39 PM | #1 |
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N47 Regeneration interval? 328d low fuel economy?
Anyone watching or logging their regenerations? I recently started and am regularly under 200 miles interval, requests at a soot mass usually just over 20g. Burns off 7-15g only, ending somewhere normally under 10g.
This behavior was logged multiple times on flat open highway. Twice I manually requested a second regeneration and both times burns down to about 3.5g. My overall economy for mixed driving (last 14k miles) is under 29 mpg. |
02-06-2020, 03:16 PM | #2 |
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The car definitely needs a good diag. It could be a lot of things, and mpg shouldn't be that low unless you're doing only city stop and go.
What car exactly?
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02-06-2020, 03:32 PM | #3 |
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My regen interval is typically right around 300mi on KermaTDI Stage 2. With JR Stage 2 it was more commonly 200-225mi.
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02-06-2020, 04:09 PM | #4 | |
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I've known about a bad O2 sensor with readings that instructed to replace the DPF and presented documentation to SA at 2 different dealerships since Oct. They are pointing finger at NA for not allowing them to look into the vehicle because there is no check light. At warranty end with my mileage log and fuel economy complaint, NA instructed a foreman to compare it against another wagon from the shop and instructed them to snapshot the instant mpg readings of both cars while on cruise control over a same short stretch (with a few clear disqualifiers to disregard the test entirely, spoiler alert they were both low). When this "comparison" resulted in comparable readings, my car was deemed normal and could look no further. At this visit, the foreman also ran a function test on my O2 sensor failing in my same manner, (I showed him the video of my test immediately prior to pulling in their lot). He proceeds to do a partial repair on my O2 sensor issue by cleaning and reinstalling the sensor without replacing the DPF per test plan results. now my O2 function tests fail >60% of attempts while circumventing that I possibly or likely have some damage to the DPF. My next step is to appeal to NA. I took video evidence on most testing to back up all my data points, but after what I have already endured it seems like going to be an uphill battle for them to facilitate a complete repair. Last edited by AlpineX; 02-06-2020 at 09:14 PM.. |
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02-06-2020, 04:35 PM | #5 |
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DPF performance is monitored by the particulate matter sensor and the differential pressure sensor way more than the Oxygen sensor. I don't trust that diagnosis of needing to replace the dpf at all.
It certainly wouldn't impact your mpg that badly if your dpf regens are within reason. Depending on driving conditions, they can be between 200-400miles and run for maybe 5-10 mins. It doesn't use that much fuel though. Failing NOx sensors can increase fuel consumption, as well as a bad MAF or other vehicle factors. Do you know what software version your engine ecu is on?
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02-06-2020, 06:52 PM | #6 | |
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While the DPF overall performance is more greatly monitored by the PMS and DPS, the quality of the regeneration definitely has ties to the O2 sensor. My fuel economy is up 1.8 mpg since the sensor was cleaned over 1200 miles ago. The sensor continues to fail the function test regularly so I'm somewhat confident it will make a reasonable difference when replaced. Not just for regeneration but overall A/F management. As for the condition of DPF that's hard to say. Certainly unsettling is getting a 100% return rate of 'replace filter' over 2 months including the morning of warranty end visit, having a tech perform the suggested measures omitting the DPF because couldnt bill BMWNA, and resulting in O2 testing that is >60% fail, and otherwise 'OK' (but barely passing) and no mention of DPF. I have software F020-19-11-520 updated at the first visit end of October and 5k ago. While this update cured my surging at idle during regeneration, it was only performed because of a total i-level update required by my gauges crashing. I have a healthy mix of city and open road driving, the previous owner definitely did not. Was likely a short slow commute and in cold climate. I suspect the car seldom fully regenerated its first 3 years. In an uninterrupted regeneration, shouldn't the DPF burn to 0g soot and is 20-25g a low threshold for soot estimate for a regeneration to trigger a request? I get DPS values that dont always correlate with the estimated soot mass, 6.96hpa@7.77g, 9.98hpa@16.21g, 3.98hpa@12.68g, 7.96hpa@22.54g, 6.96hpa@13.78g, 1.97hpa@14.33g, 2.97hpa@8.76g My regeneration intervals are (in miles, asterisks are manual request long burns): 195, 167, 151, 252,*, 176, *, 142, 124, *, 142, *, 141. |
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02-06-2020, 07:31 PM | #7 |
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Regeneration is mostly driven by preset maps, some O2, and the differential pressure sensor to call up 'on demand' regens.
They never go to 0g. I've had some go to 7g and be happy and end regen. I have a few screenshots I have been getting from ISTA here and there.. one is at 563km since regen (8 hr and 32 min of engine on) and I was at 11.89g. It would have gone a bit more. I self commanded a regen so I can dyno the car uninterrupted, and it took maybe 5 km and 5 mins and it was satisfied. The soot count will also go down when flooring it and heating up the dpf really well. But that might be tune dependent. I worked with this ecu (+all the tuning) and emissions system extensively and the knowledge that people and even dealers have is still minimal. I think the problem lies elsewhere.. quite possibly a bad O2 sensor, which cleaning will not help it any. There are some test plans in ISTA that can measure the performance of it. I wish you were closer as I'd get to the bottom of that quite quickly. I average about 37mpg of 50/50 mixed highway/city in my wagon. On trips I can average 40mpg as long as I keep it under 80.
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-2019 M2 Competition MT, Alpine White. Self-tuned 560hp -2016 Mini Cooper S, MT. Many plans. Others: -E36 328is. 2000 Z3 Roady. 2003 VW Jetta TDI Manual. Estoril Z3M Coupe. Last edited by Enabled; 02-06-2020 at 07:36 PM.. |
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02-07-2020, 06:47 PM | #8 |
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Have you had the EGR recall done? My milage was crap before I had it done. My car needed practically all the parts under recall.
After the recall things are back to normal |
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02-10-2020, 09:32 AM | #9 |
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AlpineX , we have gone quite a bit back and forth regarding the rough idle issues. As you know, my car's O2 sensors have passed, but iLevel update never really resolved the idle issue. Someone here mentioned EGR issue possibly causing problems, and folks that deleted EGR have reported improved economy, cooler running engine, and less regens. So I know our problems are not quite the same, but here is what I did and I would possibly recommend that you try. My EGR was replaced last week after it threw the sticking valve code. Since then, I have been watching my EGR with CarScanner app. It has consistently exceeded 20-99% error, being more open at all times than commended by the ECU. Hence, the car has been running rough at times, with MAF readings fluctuating, RPM fluctuating, and MAF error reaching 99% or above when this happened. So what I did was to simply unplug the EGR. I know, as I expected, it threw Drivetrain Malfunction and MIL came on. It suggested in message that reduced power was available. However, I must drive like a grandma, because the car idles smooth as a gasser, economy has improved, car runs at lower RPM for same speed, and feel very torquey and responsive. I will force BMW to fix whatever the issue is with EGR since I am under warranty, however as soon as warranty is up, this EGR mess is going away. And MAF shows much higher MAF readings (from 8 normally up to 14), which makes sense as EGR is blocked off. My recommendation is to try to unplug the EGR to see if that in any way solves your issue, it may be in some ways related given your MAF variability and poor economy. The plug is a b**** to unplug, since you have a double locking mechanism and I had the hardest time with the small white piece on the side due to clearance issue, but once it all unplugged, I don't want to plug it back. Just don't like CEL on my dash, brings bad memories from my older cars. Let me know if I can help in any way.
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02-10-2020, 10:00 PM | #10 | |||
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Thanks for your help and responses.
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