|
|
|
|
|
|
BMW Garage | BMW Meets | Register | Today's Posts | Search |
|
BMW 3-Series (E90 E92) Forum
>
Cobb drag results
|
|
04-27-2011, 01:20 AM | #23 | |
Lieutenant Colonel
66
Rep 1,708
Posts |
Quote:
Good run Clap. where were you and what were the temps? Last edited by Joshboody; 04-27-2011 at 02:02 AM.. Reason: spelling |
|
Appreciate
0
|
04-27-2011, 01:48 AM | #24 | |
Major
57
Rep 1,175
Posts |
Quote:
|
|
Appreciate
0
|
04-27-2011, 02:23 PM | #27 | |
Captain
86
Rep 949
Posts |
Quote:
The AP rewrites the fueling table. The factory DME could target 13.8 and Cobb maps change that value in the dme to 12.2 (example). No swaying of the voltage to the widebands so they read accurate through the canbus logging. If you could take the BT tool and log AFR during a pull with the procede doing its thing you would see AFR's that are way out of wack because they are not legit - they are biased based on how much Shiv is pulling on them to appear lean so that more fuel is added by the DME. |
|
Appreciate
0
|
04-27-2011, 02:31 PM | #28 | |
Lieutenant Colonel
66
Rep 1,708
Posts |
Quote:
|
|
Appreciate
0
|
04-27-2011, 02:34 PM | #29 | |
Major General
136
Rep 5,040
Posts |
Quote:
|
|
Appreciate
0
|
04-27-2011, 02:39 PM | #30 | |
Brigadier General
105
Rep 3,460
Posts |
Quote:
The track is 33 feet above sealevel, but due to the warm conditions DA ended up being 1500+ feet above sea level. |
|
Appreciate
0
|
04-27-2011, 02:40 PM | #31 |
Captain
86
Rep 949
Posts |
Yes - to display this as a loggable parameter there is a bit of calculation to remove the voltage bias he implements. if you output the voltage translated into "AFR" it would just show innaccurately lean values because of the bias. that calculation impressed me a good bit. just not sure how accurate it is but I never tune a car without an aftermarket wideband so I have an AEM and an LM1 lol
Last edited by Jake@MOTIV; 04-27-2011 at 02:47 PM.. |
Appreciate
0
|
04-27-2011, 02:53 PM | #32 | |
Banned
287
Rep 5,876
Posts |
Quote:
1) I understand that procede is applying bias to richen up AFRs which makes the ECU think its following its AFR stock targets while the actual fuel injected is richer to meet the curves set in the procede. 2) I also understand that in order to get the mapping set properly Shiv had to use an external wideband. 3) I also understand that he's based his AFR calculations based on his calibrated Innovate LC-1. 4) I know that the ECU has load tables and that AFR targets are based on those. Now, my question is when COBB logs the AFR where are they getting the numbers from? I understand this would be lambda off of the front stock o2 widebands. They can also see voltage but at the level COBB is operating at they're just setting the targets in the tables. How're they getting the AFR curve logged? If they're just reading the AFR targets that would be incorrect and I'm sure that's not the case. To get it the AFR data points out of their device the only way I see is that they're taking "lambda" values off the stock widebands and doing a lambda to AFR conversion. ECU has no idea about "AFR", it sees lambda. BT tool doesn't log AFR, it logs short and long term fuel trims called additive and multiplicative adaptation lambda. So, again please |
|
Appreciate
0
|
04-27-2011, 02:57 PM | #33 | |
Lieutenant Colonel
66
Rep 1,708
Posts |
Quote:
|
|
Appreciate
0
|
04-27-2011, 02:57 PM | #34 |
3474
Rep 79,211
Posts
Drives: C6 Z06, 09 335i, 10 335xi
Join Date: Dec 2008
Location: www.TopGearSolutions.com
|
^ they are getting the numbers from the o2 sensors, dzenno.
If the PRocede were to read the o2 sensor it would read a FALSE lean. This is because the PROCEDE tells the DME its running lean so it actually adds fuel. Then that scaling is extrapolated to come up with the AFR you see in the logs. (they are calculations). The cobb reads the actual o2 sensors cause its not calculated its ACTUAL AFR. Cobb is able to achieve this cause they remapped the air fuel curves accordingly. So it targets ~`12 AFR and therefore your reading on the o2 sensor is actual. |
Appreciate
0
|
04-27-2011, 02:59 PM | #35 | |
Banned
287
Rep 5,876
Posts |
Quote:
EDIT: Also, procede doesn't have to tamper with the o2 sensor voltage as there are other values they could tap into and alter to richen up AFRs. How many of you heard of showing higher EGT temps from the cats than they really are? I found out about this only recently and basically if the ECU sees that the "cat converters" (even though some may not even run them) are getting overheated (EGTs) that the ECU will on its own inject more fuel to assist in cooling them...so what exactly "biasing" means in the procede world, it could be a few things |
|
Appreciate
0
|
04-27-2011, 03:00 PM | #36 | |
3474
Rep 79,211
Posts
Drives: C6 Z06, 09 335i, 10 335xi
Join Date: Dec 2008
Location: www.TopGearSolutions.com
|
Quote:
Edit I never tried logging with BT tool cause it would be a false reading. Good points being made I think I understand your question. Not sure if I know the answer. |
|
Appreciate
0
|
04-27-2011, 03:04 PM | #37 |
Banned
287
Rep 5,876
Posts |
well that's what I'm trying to get to the bottom of, what reading? there's no reading for AFR that the ECU sees other "calculating" it from lambda as seen by the stock front widebands...I'd like to think that the BT tool shows all the engine parameters from all the sensors available and currently there's no straight lambda value(s) you could convert there are short/long term trims but that doesn't give you lambda and therefore can't be used to calculate AFR
|
Appreciate
0
|
04-27-2011, 03:08 PM | #38 | |
3474
Rep 79,211
Posts
Drives: C6 Z06, 09 335i, 10 335xi
Join Date: Dec 2008
Location: www.TopGearSolutions.com
|
Quote:
We read right from the stock o2 sensors via the stand alone. It spit out 11.7 AFR and thats what we were running. It also read out short term and long term trims separately via percentage. If only we could go back to the simpler days. |
|
Appreciate
0
|
04-27-2011, 03:11 PM | #39 | |
Banned
287
Rep 5,876
Posts |
Quote:
Sooooo, what are they, how do they do it? How does COBBs tool arrive at AFRs logged when all their plugin tool has access to is CANBus data |
|
Appreciate
0
|
04-27-2011, 03:12 PM | #40 | |
Joint Chiefs of Staff
5044
Rep 116,174
Posts |
Quote:
Mike |
|
Appreciate
0
|
04-27-2011, 03:15 PM | #41 |
3474
Rep 79,211
Posts
Drives: C6 Z06, 09 335i, 10 335xi
Join Date: Dec 2008
Location: www.TopGearSolutions.com
|
|
Appreciate
0
|
04-27-2011, 03:15 PM | #42 |
Captain
86
Rep 949
Posts |
The o2 sensors on this vehicle do infact read out. You are correct in that it is lambda but those calculations to make it AFR are accurate as the lambda to AFR calculation is an actual formula. Both the JB and Procede tunes sway the voltage of the widebands to control fueling. I think I have heard Shiv mention he does a few other things as well but the main way they control fueling is swaying the widebands (ex of others - fuel psi etc). Those same voltages of the widebands being pulled on are where you can get Lambda and AFR.
If you take an MSD Dashawk on a bone stock 335 and plug it in - you will be missing a bunch of PID's to observe / log - but AFR is visible so the information is there. Hope that helps. Not sure if you were trying to be argumentative or not - I am simply trying to help clear what you were asking up. Internet sometimes makes it hard to see the "tone". From what I see your a standup guy so I will just automatically infer you are being genuine. |
Appreciate
0
|
04-27-2011, 03:16 PM | #43 |
Banned
287
Rep 5,876
Posts |
|
Appreciate
0
|
04-27-2011, 03:16 PM | #44 |
52
Rep 428
Posts |
For those who don't know (not dzenno), AFR/14.7 = Lambda (for gasoline)
The bigger issue here, as i see it, is that the DME calculates lambda/afr differently (and through different types of sensors) than aftermarket widebands kits. So they will likely provide different readings (even if no wideband bias is applied). Which is more accurate is subject for debate. |
Appreciate
0
|
Bookmarks |
|
|