Page 18 of 20 FirstFirst ... 8 16 17 18 19 20 LastLast
Results 256 to 270 of 292

Thread: 2004 R1150RT Wideband O2 Sensors

  1. #256
    Registered User roger 04 rt's Avatar
    Join Date
    Oct 2011
    Location
    Massachusetts
    Posts
    1,290
    Before posting the Mixture Adaptation results tomorrow, i want to discuss a Bosch chart, below, which shows another reason why Mixture Adaptation was designed as an integral part of the Motronic and BMSK fueling/spark ECUs.

    As has been described, the alpha-n ECU design relies on throttle angle as an indirect measurement of air mass. And looking at the clip from Wikipedia below, you can see that Bosch's adaptive technology significantly predates Motronic and BMSK. The only real surprise is that BMW keeps this information so well hidden.

    On the chart below, which is specific to the Motronic alpha-n ECU but not specific to Oilheads, you can see graphically adaptations importance:

    --At low RPMs and small throttle angles a 3% change in throttle angle requires a 34% change in the amount of fuel injected to maintain a constant AFR. That means that a small TPS sensor error, or small change in air flow through the throttle body could result in a significant mixture error, leading to the conclusion that precise Mixture Adaptation is a necessity for accurate fueling at light loads.

    RB

    From Bosch Motronic documentation:


    Mono-Jetronic (1988?1995)--from Wikipedia
    Digital fuel injection. This system features one centrally positioned fuel injection nozzle. In the US, this kind of single-point injection was marketed as 'throttle body injection' (TBI, by GM), or 'central fuel injection' (CFI, by Ford).
    Mono-Jetronic is different from all other known single-point systems, in that it only relies on a throttle position sensor for judging the engine load. There are no sensors for air flow, or intake manifold vacuum. Mono-Jetronic always had adaptive closed-loop lambda control, and due to the simple engine load sensing, it is heavily dependent on the lambda sensor for correct functioning.
    The ECU uses an Intel 8051 microcontroller, usually with 16 kB of program memory and usually no advanced diagnostics.

  2. #257
    Registered User R100RTurbo's Avatar
    Join Date
    Jun 2013
    Location
    Abbotsford, BC Canada
    Posts
    86

    Alpha N

    I have avoided working with Alpha-N, seems to ignore so much of what is taking place on an engine. With "Speed Density" actual conditions are being utilized plus for a turbo'ed condition it is much superior, as loading and boost can be all over the map so to speak, even with a throttle setting that is constant. Some squirters have adopted the blended "Alpha-N/ S.D." tables which can help with engines having poor "map" characteristics but are boosted. Our boxer engines having two cylinders might qualify for that concern but I have found stability even at ultra low idle states such that I have no concerns.
    Each item you provide here seems to help paint a picture of what the Motronic is striving to do, and how under certain conditions the unwanted oscillation might take place.
    Really appreciate your informative approach.
    Lorne

  3. #258
    Jammess jammess's Avatar
    Join Date
    Aug 2005
    Location
    Florence, OR.
    Posts
    639
    [QUOTE=roger 04 rt;916028]

    --At low RPMs and small throttle angles a 3% change in throttle angle requires a 34% change in the amount of fuel injected to maintain a constant AFR. That means that a small TPS sensor error, or small change in air flow through the throttle body could result in a significant mixture error, leading to the conclusion that precise Mixture Adaptation is a necessity for accurate fueling at light loads.

    RB

    Hello Roger,
    I think the above quote from your last post pretty well sums up the reason why many of these oilheads exhibit the annoying tendency to surge at slow speeds and why the narrow band O2 sensor with its characteristic slow response time does not much to alleviate the problem. This also leads me to think that the LC-1 controller with the fast response wideband O2 sensor is the best option for use with these machines.
    Jammess

  4. #259
    Registered User
    Join Date
    Sep 2008
    Location
    Wilmington, NC
    Posts
    2,123
    Widebands are fine but cost and complexity are generally going to put this approach out of the range of the average owner who probably can't handle the work let alone understand all of the technical issues. For those who can- well, why not if it interests you?

    I had my first wideband as a monitor on a track car so long ago I forget when, exactly. It allowed me to keep an eye on what the very limited aftermarket ECU of that era (simple 8X8 map, no closed loop) was delivering to a motor that would grenade immediately if it got too lean. So its real purpose was to allow watching the "richness" to ensure enough for combustion cooling at the outer edge without it getting so rich it reduced power excessively- and to keep EGTs from literally melting the wastegate of that boosted motor. (It would go over 1750 degrees almost instantly even a bit on the lean side of EGT control- actually in the high 13s AFR- but that was also where it made max power)

    As is pointed out by Roger the real issue especially for oilheads may be the INDIRECT measurement of a critical material, air (oxygen), by a TPS rather than by a direct air measurement device.
    Its predictable that indirect measures are likely to have the largest per cent errors at low and fluctuating flows.

    One obvious way to cover such imprecision- much as I did (above) for several years- is to provide some extra fuel to avoid the lean side issues, whatever they happen to be.

    For myself, I don't want to repeat the work that went with track vehicles or my modified street cages on a bike. Plug and play OTOH is pretty appealing.

  5. #260
    On the Road MIKEFIGIELSKI's Avatar
    Join Date
    Sep 2005
    Location
    Northern, NJ
    Posts
    45
    Quote Originally Posted by sibud View Post
    Roger,

    On the BB website, it says it will NOT fit any R 1100 bike except the R1100S.

    Is that correct? I thought it would fit the R 1100 RT.

    Please clarify.

    Thanks
    Sibud, you are reading the description of the R1150 unit on our website. We also list an R1100/K1100 unit which will work for your R1100RT here: http://www.beemerboneyard.com/bmwafxied1100u.html .
    It is a splice in harness for now as the stock connectors are hard to find and very expensive. It is a simple splice into the O2 sensor wire lead, NOT the main wire harness. We provide 2 Posi-Lock connectors and 1 Posi-Tap connector. It is a very easy install even though it is not a true plug and play at this point. Well worth the effort as it will transform your RT. Thanks,
    Mike

  6. #261
    Registered User roger 04 rt's Avatar
    Join Date
    Oct 2011
    Location
    Massachusetts
    Posts
    1,290
    Quote Originally Posted by R100RTurbo View Post
    I have avoided working with Alpha-N, seems to ignore so much of what is taking place on an engine. With "Speed Density" actual conditions are being utilized plus for a turbo'ed condition it is much superior, as loading and boost can be all over the map so to speak, even with a throttle setting that is constant. Some squirters have adopted the blended "Alpha-N/ S.D." tables which can help with engines having poor "map" characteristics but are boosted. Our boxer engines having two cylinders might qualify for that concern but I have found stability even at ultra low idle states such that I have no concerns.
    Each item you provide here seems to help paint a picture of what the Motronic is striving to do, and how under certain conditions the unwanted oscillation might take place.
    Really appreciate your informative approach.
    Lorne
    From what I've read, using speed-densitiy (manifold absolute pressure) on a single cylinder engine (we have two on the same crank from a fueling perspective) doesn't result in a reliable signal from the MAP whose signal can bounce all over the place at low RPMs. Are you saying that's not the case from your experience?

    Quote Originally Posted by jammess View Post
    Quote Originally Posted by roger 04 rt View Post

    --At low RPMs and small throttle angles a 3% change in throttle angle requires a 34% change in the amount of fuel injected to maintain a constant AFR. That means that a small TPS sensor error, or small change in air flow through the throttle body could result in a significant mixture error, leading to the conclusion that precise Mixture Adaptation is a necessity for accurate fueling at light loads.

    RB
    Hello Roger,
    I think the above quote from your last post pretty well sums up the reason why many of these oilheads exhibit the annoying tendency to surge at slow speeds and why the narrow band O2 sensor with its characteristic slow response time does not much to alleviate the problem. This also leads me to think that the LC-1 controller with the fast response wideband O2 sensor is the best option for use with these machines.
    Hi Jim, I hear you and see your point. Bosch says the Motronic concentrates a large number of the LCF cells and Fuel Map in the lower RPM, lower TPS area--as usual we don't know exactly what that means but the chart is giving their rationale for that decision.

    Even though the stock O2 sensor is slow, and it takes a bit of time to compute the LCFs initially, once computed they are available to the fueling calculation without any delay, same it true of the Mixture Adaptations.

    WallyG and I each have a small amount of LC-1 data taken at light throttle during a "surge" event. It is not at all conclusive that the Motronic is modulating the fuel causing surging. The data is not conclusive that it's AFR variation causing surging. The best way for me to test that is to program the AFR on my bike to 16:1 to 17:1 and see whether I get consistent surging, and then see what the LC-1 reports. It's hard to get surging when you want to measure it.

  7. #262
    Registered User R100RTurbo's Avatar
    Join Date
    Jun 2013
    Location
    Abbotsford, BC Canada
    Posts
    86

    Beg to Differ

    Quote Originally Posted by racer7 View Post
    Widebands are fine but cost and complexity are generally going to put this approach out of the range of the average owner who probably can't handle the work let alone understand all of the technical issues. For those who can- well, why not if it interests you?

    I had my first wideband as a monitor on a track car so long ago I forget when, exactly. It allowed me to keep an eye on what the very limited aftermarket ECU of that era (simple 8X8 map, no closed loop) was delivering to a motor that would grenade immediately if it got too lean. So its real purpose was to allow watching the "richness" to ensure enough for combustion cooling at the outer edge without it getting so rich it reduced power excessively- and to keep EGTs from literally melting the wastegate of that boosted motor. (It would go over 1750 degrees almost instantly even a bit on the lean side of EGT control- actually in the high 13s AFR- but that was also where it made max power)

    As is pointed out by Roger the real issue especially for oilheads may be the INDIRECT measurement of a critical material, air (oxygen), by a TPS rather than by a direct air measurement device.
    Its predictable that indirect measures are likely to have the largest per cent errors at low and fluctuating flows.

    One obvious way to cover such imprecision- much as I did (above) for several years- is to provide some extra fuel to avoid the lean side issues, whatever they happen to be.

    For myself, I don't want to repeat the work that went with track vehicles or my modified street cages on a bike. Plug and play OTOH is pretty appealing.
    In case any confusion has developed: my reference and comments have tended to reflect a theme of utilization of a different strategy to ultimately go way beyond the solving of the surging issue(s) that are at the heart of this post - with a self programed device that at this point (not being commissioned "yet" on an oilhead) is not plug'n play by any means but in my opinion totally attainable. So yes, that process is not going to be embraced by many or any here. Once someone tries and tunes a Microsquirt onto an oilhead, there is going to be a means towards gaining a "plug'n play" device and that will be a remarkable paradigm shift indeed.

    The strategy Roger has been substantiating with significant test data and reference material, is ultra simple and of a plug'n play standpoint. I'd venture to say an easy install for most, on a weekend and then focus on riding.

    Wide band systems and costs have improved dramatically over the years and there are lots of choices now. Inovate's LC1 did let me down with reduced sensor reading characteristics after a few years in service, but LC2 seems rather more robust and has wider tolerance for being out of range and not crashing. I like a system called "14.7" which is the simplest and cheapest (unfortunately unable to work with the system that Roger is working with).
    Last edited by R100RTurbo; 01-07-2014 at 06:12 PM.

  8. #263
    Registered User R100RTurbo's Avatar
    Join Date
    Jun 2013
    Location
    Abbotsford, BC Canada
    Posts
    86

    Intake pulsation and MAP

    [QUOTE=roger 04 rt;916239]From what I've read, using speed-densitiy (manifold absolute pressure) on a single cylinder engine (we have two on the same crank from a fueling perspective) doesn't result in a reliable signal from the MAP whose signal can bounce all over the place at low RPMs. Are you saying that's not the case from your experience?
    QUOTE]

    Hi there Roger. Yes, I've been able to utilize "Speed/ Density" fueling tuning strategy with success, on the two lung potentially challenging boxer engine. Variation in MAP readings can lead to instability and oscillation for the ecu to digest, but with MS there are a host of lags that can be adjusted to suit particular needs, plus a few "Cheats" that I have taken advantage of. One such is a small CO2 cartridge set up with about a 0.040" orifice to act as a buffer chamber on the signal that I source from small sensor lines off each inlet runner. That allows a calming of an otherwise rippled reading, but without notable delay. Throttle response remains instantaneous but the MAP sensor signal is calm/ straight line.

  9. #264
    Registered User roger 04 rt's Avatar
    Join Date
    Oct 2011
    Location
    Massachusetts
    Posts
    1,290
    I'll now run through a full sequence of slides that show Mixture Adaptation. These are slides of Open Loop AFR, before and after an adaptation period. It is quite remarkable really and should inform everyone as to what types of fueling modifications actually make permanent changes.

    The approach I'm going to take with these is that a picture is worth a thousand words. Questions are welcome.

    Here is the original slide I posted showing Open Loop AFR for two scenarios: a fuel pressure increase, and a fuel pressure plus IAT Shift device increase:


    Here are the before adaptation and after adaptation results for Open Loop fueling with mixture richening caused by a fuel pressure increase. You can see that AFR was 13.0:1 after resetting the Motronic, but after a mixture adaptation period, the Open Loop and Closed Loop AFR were essentially the same: 13.8:1. To the right of the chart is a smaller one that shows the distribution of AFRs. The center is right around 13.8:1.


    Next Post will be before and after Open Loop AFRs for the fuel pressure and IAT shift device scenario.

  10. #265
    Registered User roger 04 rt's Avatar
    Join Date
    Oct 2011
    Location
    Massachusetts
    Posts
    1,290
    Below are the charts for Mixture Adaptation for the combination of the 53 psi fuel boost couple with a -20C IAT shift (using a BoosterPlug). In the first chart you can see that the reset, Open Loop AFR for the combined products were 12.1:1, that is a whopping 21% richer than stock (14.7:1). My LC-1 sets a Closed Loop AFR target of 13.8:1 and in this chart I've run Closed Loop for 15 minutes and then remeasured the Open Loop AFR. In that short time, the Open Loop AFR's mixture has been "adapted" to 13.3:1. That's not all the way to 13.8 yet but in 15 minutes adaptation has moved the Open Loop AFR by 10%.



    Next I put the bike back into Closed Loop by flipping the switch on my LC-1 and rode another 15 minutes in Closed Loop at 13.8:1. Pulled over, flipped the switch to Open and measure the Open Loop AFR. I hope you're not surprised at this point that the Open Loop AFR is showing 13.7:1, nearly at the final target of 13.8.

    I also hope it is clear at this point that the Motronic, has essentially fully altered the Open Loop mixture from 12.1:1 to 13.7:1 by Mixture Adaptation, and has "learned and removed" the fueling "errors" caused by the fuel pressure increase and the IAT shift device which dropped the air temperature 20 degrees centigrade. In other words, neither the FP change nor the BP had any effect on long term fueling and that it is the O2 sensor (and any shifts of it, in my case to 13.8:1) that set the Motronic's fueling.


  11. #266
    Registered User roger 04 rt's Avatar
    Join Date
    Oct 2011
    Location
    Massachusetts
    Posts
    1,290
    R1100, R1150 and R1200 Alpha-N Fueling and the Dyno: Post #1

    I've put together a series of fairly detailed charts on BMW Fuel Maps, Bosch Motronic Air Charge, GS-911 Engine Loading Data, and Intertial Dyno Testing. This information will only be useful to a few who read the thread but I've decided to include it because it has been hard to come by.

    In particular I'd like to review the inertial dyno results from an unmodified R1200GS that was sent to me, during which they ran the GS-911 also, and got some interesting insight into what goes on in the BMSK during a dyno test. My conclusion, which I'll show in a few posts from now, is that the inertial dyno isn't a great tool, but let's park that issue for a moment.

    I'm going to draw on several sources:

    --Bosch Motronic Documentation for Alpha-N (RPM/TPS based fueling)
    --R1100GS Fuel Table Data taken by John1100GS
    --R1150 GS-911 Realtime Motronic MA 2.4 Values
    --R1200 GS-911 Realtime BMSK Values
    --R1200GS Dyno Data

    My hope is that those riders working to improve the performance of their motorcycles will be able to review the charts in this post and a few that follow it, and use the previous Mixture Adaptation & Self Learning Cabability (post #358) from earlier in this thread, to get a good idea of what might or might not be effective improvements for their own motorcycles.

    The Bosch Motronic Air Charge chart, below is the ratio of actual air charge to theoretical maximum air charge. Although the chart is typical for a Motronic Alpha-N ECU, it is a good representation for the R1100, R1150 and R1200, and is consistent with the fuel table values read from the R1100GS chip. The amount of Air Charge in the cylinder is directly proportional to the Engine Load data we captured with the GS-911 during the dyno run (coming later). Notice that the maximum air charge is at mid-RPMs and is only about 85% of the possible charge. BMW developed this type of data for every motorcycle engine it produces as part of building the Fuel tables. Anyone claiming to have a replacement chip or reflash should have measured this data for themselves (I've yet to see anyone who's done this), which is time-consuming and costly.

    As an example, to get a 60% Air Charge (Engine Load) at 2000 RPM you open the throttle 14 degrees, whereas to get a 60% charge at 5000 RPM you need the throttle open 35 degrees, twice as much. (I'll come back to this later since the WOT dyno run produced only a 60% load at WOT, not nearly the 80%+ load the engine is capable of.)

    Air Charge Chart


    The bottom chart below shows binary fueling values, read from an R11000GS Motronic Chip by John1100GS (ADVrider). (Although the R1150 and R1200 data will be different by degree, it will be similar in shape.) The surface map chart was produced by entering the data from the fuel table, into an Excel spreadsheet. The fuel table values look correct to me, compared to Bosch documentation for Motronic Alpha-N fuel maps. However, I believe the axis in the table that's labeled Load is for a vehicle with a MAP sensor so I've modified the labeling axis for the Surface Map below with my estimates of TPS position for those Loads using the above Air Charge chart. This data looks consistent also with a stock Bosch Motronic Air Charge diagram.

    One of the most striking things in this data is that 2/3 of the data points are below 4700 RPM. Later I'll show that most of these values are within the area of Closed Loop operation, so if you were to install a new chip (or Re-flash the R1200), you wouldn't get different fueling since Mixture Adaptation and the Lambda Control Factors would bring you back to lambda=1 (14.7:1) unless you shift the O2 Sensor. Later I'm going to post a chart showing how little of the fuel table is exercised in a typical Dyno "pull" on an Inertial Dyno like the Dynojet 250i.
    RB

    Fuel Surface Map


    Fuel Table Values

  12. #267
    Registered User roger 04 rt's Avatar
    Join Date
    Oct 2011
    Location
    Massachusetts
    Posts
    1,290
    R1100, R1150 and R1200 Alpha-N Fueling and the Dyno: Post #2

    Earlier in the thread, Roland (Oldpathfinder) mentioned that he took his R1200GS to a Dynojet 250i to see what it did in stock condition and we've started to dissect the information from that run. Luckily for all of us, Roland and Terry also logged data during all their dyno runs with a GS-911 and therefore we have actual engine data from that time, in addition to the large set of R1150 data that we also have.

    I want to point out as I did in the last post that to get a full suite of information I've used R1100GS, R1150RT, and R1200GS data. Even though the data sets come from different bikes, the similarities for this type of analysis are far greater than the differences.

    Before looking at the Dyno data, take a look at a "scatter plot" of a spirited 25 mile, local & highway trip on my R1150RT (lambda=1) and then after an R1200GSA (lambda=0.94). Every diamond on the chart is an RPM/Throttle Position data point as recorded by a GS-911. Although the throttle range of the R1150 is 0 degrees to about 80 degrees, and the RPM range is 1100 to 7250,

    --2/3 of the data falls into the 0 - 20 degrees throttle,
    --and 2500 to 5000 RPM range (2500-4200 on the GSA after adding LC-1s).

    That's where a lot of our riding is done and ideally our Dyno tests would measure the points in this range. Unfortunately, that isn't what the Dynojet 250i inertial dyno measures.



    EDIT: Added chart for R1200, 45 minute local-highway ride



    Below is the table of data that was read from the R1100GS by John1100GS (advrider), entered into an Excel spreadsheet (used to create the surface map in Part 1). I've added highlighting to show the area from the chart above and other areas where there's GS-911 data showing the Motronic is in Closed Loop. (Although the table isn't from an R1200GS, that model has a similar Closed Loop range of operation, perhaps larger.)

    Also of note in the table is the area above 2000 RPM but below 5 degrees throttle that is NOT Closed Loop, which is a leaner area (based on LC-1 measurements) related to deceleration. This is an area prone to surging--light throttle mid RPMs.

    The table has also been highlighted to show those cells that were measured during the initial R1200GS Dyno test. Of the 288 cells in the fuel matrix, the GS-911 data shows that only 9 of the fuel cells were used by the Dyno run. Only nine! This is the norm for all inertial Dyno runs.

    In the next post, I'll show the Dyno information and then take a detailed look into what it measures.


  13. #268
    Registered User R100RTurbo's Avatar
    Join Date
    Jun 2013
    Location
    Abbotsford, BC Canada
    Posts
    86

    The Plot Thickens

    Hey Roger, some nice info here. I'm going to copy it/ save in case I end up integrating a MicroSquirt onto an oilhead.
    Lorne

  14. #269
    Registered User roger 04 rt's Avatar
    Join Date
    Oct 2011
    Location
    Massachusetts
    Posts
    1,290
    Thanks Lorne! Here's some more ...

    R1100, R1150 and R1200 Alpha-N Fueling and the Dyno: Post #3

    It's fortunate to have several dyno runs taken on a 2009 R1200GS. What follows is one of the runs made before adding an AF-XIED. After you get familiar with the chart, have a look at several charts which follow, in this post and the next, which use GS-911 data taken at the same time the bike was on the Dyno.

    The dynamometer used for this test, a Dynoject 250i, is run by a good quality operation, with a helpful and communicative operator, the shop and equipment are well maintained. It is not my objective to call their competency (which seems high) into question. Rather, I'd like to show some improvements that can be made.

    The Dynojet 250i is an inertial dyno, which means that the loading of the motorcycle is created by accelerating a weighted roller driven by the rear wheel. If the rear wheel isn't accelerating the engine experiences no load, and the load doesn't change with speed. Under normal riding conditions the engine is always working to overcome the air resistance which rises significantly with speed. I believe the shop has the ability to add a brake-load to the initial conditions but it wasn't done for these runs. The testing was all done in 4th gear, a common setup. Here is one of the measured runs.



    Peak Measured Horsepower is 95 HP
    Peak Measured Torque is 74 ft-lbs

    When you first look at it, it seems that there is a wealth of information on horsepower, torque and AFR (air/fuel ratio). What we found though is that there is a lot going on inside the BMSK engine control unit, that needs to be understood, to make sense of the results, and the GS-911 data shows that only a small fraction of a bike's performance is tested. Thanks again to Terry and Roland for the data.

    There are several conditions, not apparent in these results that were only evident from the GS-911 data. I'll list them here, and then in the next few posts look at them in detail. Then lastly I'll show the acceleration results from 4 runs without an AF-XIED and then four more with one attached on setting 8 (~13.8:1 AFR).

    Conditions Measured with GS-911
    1. Dynamometer Inertial-Load was only 50% on-road load.
    2. Rear Wheel acceleration was twice as fast as on-road acceleration
    3. Engine Load (measured by the BMSK) was ~0% at start of Dyno run. On-road engine load is 30% for same conditions.
    4. Engine Load was ~60% maximum on the dyno. On-road engine load during a 4th gear WOT acceleration is ~70%.
    5. AFR at the start of the dyno run was leaner than 16:1 resulting in a very lean initial acceleration. Due to the lean start, results on the inertial dyno don't reach operating AFR for about 2 seconds which is about 3500 RPM. This is a common inertial dyno starting condition. On-road AFR is 14.7:1 or 13.8:1 at the start of acceleration, depending on AF-XIED setting.
    6. Of the 256+ Fuel Table cells in the BMSK, only 9 were stimulated by the dyno test run. None of the cells were in the usual riding area. (See chart in earlier post.) The same limited area of operation is true for the spark table.

    The next post will show the BMSK data collected by the GS-911 for one of the dyno runs.
    RB

  15. #270
    Registered User roger 04 rt's Avatar
    Join Date
    Oct 2011
    Location
    Massachusetts
    Posts
    1,290
    R1100, R1150 and R1200 Alpha-N Fueling and the Dyno: Post #4

    Here's a chart showing measured lambda sensor voltage on the right O2 sensor (the left and right sensors were nearly identical) preceding and during two successive dyno tests. In each case you can see the RPMs coasting down to about 1700 rpm just before the throttle is being cranked fully open.

    During the coastdown phase, the BMSK sees the deceleration and goes into its Overrun Fuel Cutoff mode. When it does the injectors are shut off, the mixture goes lean and the intake tract dries out. This shows clearly in the very low lambda sensor voltages preceding WOT.

    Once the throttle is opened you can see that it takes about 2 seconds for the lambda sensor to reach 800 mV, which signals a rich mixture. This delay is caused by the time it takes for the intact tract film to be re-wetted. As a result, the acceleration at the rear wheel is slower than it should be and as a result of that the dyno under-estimates torque and HP between 2000 and 3500 rpm, an area of critical importance to us.

    A way to avoid this problem would be to have the dyno set to a 15 lb-ft torque load at the engine or a load that resulted in a 30% Engine Load as reported by the GS-911. Then the dyno operator would stabilize at 1700 rpm, wait until the BMSK reported Closed Loop, then fully open the throttle. That static load would result in normal fueling just prior to WOT, and produce a higher indicated torque and HP between 1700 and 3500 RPM.

    The next post will examine Engine Load (BMSK data) on the dyno vs the road.


Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •