12-04-2019, 11:04 AM | #1 |
Private First Class
52
Rep 175
Posts |
Air Fuel Ratio disparity between banks
This is my first post on the forum. Lots of useful info here. I'll post pics of my ride soon. Its a 2013 F10 M5 Comp Pack. In the meantime, I'd appreciate some feedback from those in the know about an AFR issue that I've recently detected.
The issue is that when going WOT (and to a lesser extent, when idling and at part-throttle) there is disparity in the bank 1 and bank 2 AFRs. I can't upload the data log, but the disparate data on a WOT 3rd gear run is illustrated below: 5,000 rpm: 14.4 on Bank 1 14.7 on Bank 2 5,500 rpm: 13.2 on Bank 1 13.5 on Bank 2 6,000 rpm: 12.3 on Bank 1 12.6 on Bank 2 6.500 rpm: 11.9 on Bank 1 12.2 on Bank 2 This is measured on a DashDAQ unit via the OBD. I understand that the refresh rate may be a little slow but there is clearly a pattern - Bank 2 is leaner than Bank 1 and I am guessing that the extent of the disparity is indicative of an underlying issue. I plan to switch the O2 sensors and test. Apart from catless down pipes, the car is stock. The bank 1 injectors were replaced about 2,000 kms back. I had not logged AFRs before then and therefore do not know whether the disparity was an issue prior to their replacement. I'd appreciate input from anyone who thinks he may know the possible cause/s/ |
12-05-2019, 05:58 PM | #2 |
F10 1/4 WR: 9.9s / 142.5mph 1/2 WR: 175.5mph
1087
Rep 1,968
Posts |
This level of difference is minor. Keep in mind that this is a cross-bank system so two cylinders from the driver-side mixes with two cylinders from the pass-side (and vice versa).
The system is closed loop and will always try to hit the target lambda. Check where STFT's are. If they are pegged you have different issues. |
Appreciate
0
|
12-06-2019, 03:59 AM | #3 | |
Private First Class
52
Rep 175
Posts |
Quote:
|
|
Appreciate
0
|
12-06-2019, 06:28 AM | #4 |
Captain
251
Rep 606
Posts
Drives: 2000 M5, 2001 M5, 2013 M5 6MT
Join Date: Jul 2018
Location: Buffalo
|
How many miles on the "primary" or otherwise known as "precat" O2 sensors? It could be as simple as one of them not working as well as the other. Best to replace in pairs and to not exceed 50k on them. I replaced my originals at 60k and there was a noticeable improvement in driveability which means they actually needed to be replaced sooner than 60k. My car is completely stock, no tune.
|
Appreciate
0
|
12-06-2019, 06:56 AM | #5 | |
Private First Class
52
Rep 175
Posts |
Quote:
|
|
Appreciate
0
|
12-09-2019, 09:03 AM | #6 |
Private First Class
52
Rep 175
Posts |
I've logged fuel trims (long term and short term) while cruising (part-throttle). I don't know how to upload the data logs but they show this:
The extremes reached on STFTs on both banks range from about -7 to +7. They are not pegged. The LTFTs are usually about 8 apart. The bank 2 LTFTs range from about -6 to +2 while the bank 1 LTFTs range from about 0 to +8 I have an extremely basic understanding of fuel trims but what confuses me is that I would expect the bank 1 LTFTs to be in the negative and the bank 2 LTFTs in the positive because the bank 1 AFR is richer than the bank 2 AFR. However, the opposite is true. The bank 1 LTFTs are consistently in the positive and the bank 2 trims are, for the most part, in the negative. Can anyone make any sense of this? Apologies if this makes no sense and if someone can explain how one uploads a zdl data log, I'll try and do that |
Appreciate
0
|
01-04-2020, 10:36 PM | #7 |
Private First Class
52
Rep 175
Posts |
Sorted by removing the cat foolers. Seems the down stream O2 sensors will tell the ECU to add fuel if it thinks that the cat is blocked. Also established that running catless downpipes without cat foolers does not trigger a CEL - so no cat foolers required on this car - something I did not know
|
Appreciate
0
|
01-05-2020, 03:36 AM | #9 |
Private First Class
52
Rep 175
Posts |
If you mean running catless dps without a tune and without cat foolers will trigger a CEL, that would seem to be incorrect. Been driving it like that for a month without issue. I removed the cat foolers on the advice of a friend who has been running catless dps without a tune on his M5 for about 6 months - without any CEL being triggered
|
Appreciate
0
|
01-05-2020, 08:53 AM | #10 | |
Major
711
Rep 1,107
Posts |
Quote:
__________________
'13 Black Sapphire Metallic - BPM Stage 1 Tune - RPI Exhaust - KW HAS Kit - 12mm spacers all around- Carbon Fiber front lip - High Kick Trunk Spoiler - Rear Roof Spoiler - IND Kidney and Fender Grills - 20% Tint all around 50% Front Windshield - PPF
|
|
Appreciate
0
|
01-05-2020, 09:02 AM | #11 |
Private First Class
52
Rep 175
Posts |
Bought it secondhand. When buying, BMW checked for a tune - a precondition to transferring the motorplan - and concluded that it was stock. I’m boosting about 19/20 psi - which I think is stock boost. My mate’s car is also stock. Is it possibly a widespread misconception, I wonder. Most people who do downpipes, do a tune simultaneously I assume. So they would not know from personal experience
|
Appreciate
0
|
01-05-2020, 09:11 AM | #12 | |
Major
711
Rep 1,107
Posts |
Quote:
__________________
'13 Black Sapphire Metallic - BPM Stage 1 Tune - RPI Exhaust - KW HAS Kit - 12mm spacers all around- Carbon Fiber front lip - High Kick Trunk Spoiler - Rear Roof Spoiler - IND Kidney and Fender Grills - 20% Tint all around 50% Front Windshield - PPF
|
|
Appreciate
0
|
01-05-2020, 11:03 AM | #14 | |
Major
711
Rep 1,107
Posts |
Quote:
Unless I'm wrong, which I could very well be, I'm pretty sure that's how it works.
__________________
'13 Black Sapphire Metallic - BPM Stage 1 Tune - RPI Exhaust - KW HAS Kit - 12mm spacers all around- Carbon Fiber front lip - High Kick Trunk Spoiler - Rear Roof Spoiler - IND Kidney and Fender Grills - 20% Tint all around 50% Front Windshield - PPF
|
|
Appreciate
0
|
01-05-2020, 01:30 PM | #15 | |
Private First Class
52
Rep 175
Posts |
Quote:
|
|
Appreciate
0
|
01-05-2020, 05:09 PM | #16 |
Captain
161
Rep 687
Posts |
I know several people that had check engine lights
Its possible due to ambient temps and altitudes that its not 100% the case in all circumstances As a general rule it would appear And personally i wouldnt run catless downpipes unless car had a tune to suit |
Appreciate
0
|
01-05-2020, 09:06 PM | #17 | |
Private First Class
52
Rep 175
Posts |
Quote:
Would you opt for a tune with catless dps simply to extract the full performance benefits or for some other reason? If the latter, for what other reason? I will get a tune done - just weighing the options but I ask as I will expedite my decision if driving with catless dps without a complimentary tune is potentially harmful to the motor. This is not what you’re suggesting, is it? |
|
Appreciate
0
|
01-06-2020, 05:23 AM | #18 |
Captain
251
Rep 606
Posts
Drives: 2000 M5, 2001 M5, 2013 M5 6MT
Join Date: Jul 2018
Location: Buffalo
|
Strange that you're not getting a CEL, but could be as simple as South African emissions standards compared to where most of us are from. As a separate market, it's possible the DME's are programmed differently.
As for tune/no tune with DP's: the car should adjust to the extra flow/less restriction without having a tune. There shouldn't be any concern over harm. Extracting maximum power from the modification is the main reason to tune with DP's. |
Appreciate
0
|
01-06-2020, 10:47 AM | #19 | |
Private First Class
52
Rep 175
Posts |
Quote:
|
|
Appreciate
0
|
Post Reply |
Bookmarks |
|
|