Bringing TBI and Multi Port Fuel Injection to a New Level.     EFI Conversions and Tuning! Seattle to Portland! E-mail Tuning Consultant!
Page 2 of 2 FirstFirst 12
Results 16 to 27 of 27

Thread: An Idiot Learns to Tune, Part 2

  1. #16
    Fuel Injected! spfautsch's Avatar
    Join Date
    Apr 2015
    Posts
    637
    Quote Originally Posted by kur4o View Post
    Than start increment by 1 and at $63 what a difference. I looked at the afr, map and feel for reference, if AFR goes lower the fuel is evaporated much better and the engine have excess fuel leading to richer mixture.
    I've had mine at $69 since last summer. Haven't spent any time with this since installing the 170F thermostat so it might be worth revisiting.

    Quote Originally Posted by kur4o View Post
    I also noticed that in closed loop only couple of cells are used most of time. I am sure this is not optimal and I am looking for some tweaks there.
    This is what I'm currently running:

    Code:
    RPM	MAP
    1200	42
    1650	56
    2100	68
    But this is with a M6. I decided to put the main RPM split at 1650 because there's really only two cruising gears for me - 5th and 6th. Below 55mph in 6th is pretty sketchy around 1500 rpm so I generally run in 5th under 60mph. With my cam this hits a wider range of cells with typical driving. An A4 would probably behave quite differently with these thresholds.

    Quote Originally Posted by kur4o View Post
    Now the wideband at closed loop goes from 14.6-15.1 all the time at stoich. At idle that changes to 15.4-16.
    Is that leaner range idling in gear, out, or both?

    I'm seeing a pretty consistent range from 0.97 to 1.06 λ in all closed loop operation. That's roughly 14.25:1 to 15.58:1 assuming 14.70 stoich. But that's unfiltered data - it's not using eehack's wideband functionality, just D27 adc conversion.

  2. #17
    Fuel Injected! Terminal_Crazy's Avatar
    Join Date
    Oct 2015
    Location
    Lancashire England
    Posts
    356
    Quote Originally Posted by kur4o View Post
    I just tested some tweaked cyl trims. Took the base from the last blm stable ones at idle and adjust the off idle based on them. The engine started to run much better.
    I think that if the trims are not optimal in the long run of engine running, some cylinders will get heated more some less and the total balance will be screwed. Also at off idle and take off conditions the engine will be heat soaked differently and it will also affect that and the engine will run like crap all the time even though only idle trims are off.

    After good warming I checked the blm at CL on idle and they were almost even. Than decided to give some play with EOIT target.
    Tried all kind of it from 40 to 70 in hex. |First I thought stock was $50. It turned out it was $60, Than start increment by 1 and at $63 what a difference. I looked at the afr, map and feel for reference, if AFR goes lower the fuel is evaporated much better and the engine have excess fuel leading to richer mixture.

    I got lucky from the first try to get the sweet spot on the first try.

    The fuel evaporation test with EOIT must be done at fully heat soaked engine and increment it by 1 and wait at least 30-60 seconds to feel the change.
    I guess the optimal settings is cam, temp, head, valve dependent, and the the time needed for best fuel evaporation must be found by feel and experiment.

    Than I give it a short drive.

    Now what a difference from small eoit move $60 to $63 and part dialing the cyl trims. The engine got quieter by a lot[I could hear the stereo again]. It felt some much better[from crap running to almost stock like running].
    The interesting part is that you can not see any significant change in the logs. It is all by feel. It started to shift much better also and the overall throttle response increased.

    And that is with guess dialed off idle trims. I still haven`t figure out reliable method to get this dialed unless there is a driver with and a tuner in car. Getting some steady conditions and monitor the blm closely for splits.

    The blms are great for
    dialing bank to bank difference[split blms are almost definitely from bad ind trims.]

    I also noticed that in closed loop only couple of cells are used most of time. I am sure this is not optimal and I am looking for some tweaks there.
    Anyone got any experience with it.

    Now the wideband at closed loop goes from 14.6-15.1 all the time at stoich. At idle that changes to 15.4-16.??. I guess this could be from low airflow or it could be from not optimal CL settings.
    Hi guys.
    Kur40: My test data the other year showed also 163 (#63) to be about the best for fuel atomisation.
    I went back to some stock values with the newpipes & TB but will try the #63 again.

    Some thoughts, I need to check previous data logs.
    Question: If I technically have bigger injectors than required the time for injection would be reduced? Ie double the injector size would need half the time to inject. Would this affect the atomisation?
    Also ( I'm still not 100%in my head which way the target is moving... #60 is 180 degrees , #63 is 163 degrees ) so the EOIT is actually earlier giving more time to evaporate. This would move the window for injection back slightly... IF the injectors we not big enough you might not have enough window spare.
    My 42'# had a Duty cylce of around 70%. At the track last week I actually managed to turn 7Kover the 6400 previously, so need to recheck what DC I was acheiving.

    I relogged recently using cylinder cut to measure changes in individual cyl trims.
    OTTOMH, 0% TPS was doable as the results were within the Wideband range. Results averaged & calced accordingly.
    >0% I think I ran about 2.5% TPS which is where my surge seems & logged again. On several cylinders the WIDEBANDS maxed out so the data was inconclusive other than some cylinders needed more fuel.
    After calculating and setting the trims ( I didn't like the size of difference between cylinders like up 7%) the car seemed to run pretty well, until the BLM's relearned and the surge came back. I've since cut the trims back.

    Scott: I see you mentioned BLM differences of upto 10 points, I've got down to around 6ish ie from -6 to +6 which seems pretty good.
    I'm currently idling about 124 128 but with 2 widebands running I notice 1 side reads lower than the other ie in EEHaack graph, 1 O2mV trace is slightly higher than the other (Voltage Offset maybe or Difference in O2 Output ??)

    I also note with the 2 WB, It's rich on the left down low but WOT up top they finish up the other way round, lean on the left ( upto 1.0 AFR )

    Kur4o: I'm interested how you calculate the individual trims.


    Mitch
    '95 Z28 M6 -Just the odd mod.
    '80 350 A3 C3 Corvette - recent addition.

  3. #18
    Fuel Injected! spfautsch's Avatar
    Join Date
    Apr 2015
    Posts
    637
    Quote Originally Posted by Terminal_Crazy View Post
    Also ( I'm still not 100%in my head which way the target is moving... #60 is 180 degrees , #63 is 163 degrees ) so the EOIT is actually earlier giving more time to evaporate.
    Correct, I think.

    $60 = 180 ATDC = 540 BTDC (before cylinder fires)

    $63 = 163 ATDC = 557 BTDC - more time for evaporation

    Quote Originally Posted by Terminal_Crazy View Post
    This would move the window for injection back slightly... IF the injectors we not big enough you might not have enough window spare.
    My 42'# had a Duty cylce of around 70%. At the track last week I actually managed to turn 7Kover the 6400 previously, so need to recheck what DC I was acheiving.
    I calculated it way back when were originally discussing this. I don't remember the exact number, and it changes with EOIT, but at injector duty cycles larger than roughly 40% you're going to be injecting fuel during the intake stroke. And at large duty cycles you'll be injecting fuel through the entire intake stroke. So evaporation time isn't going to make much difference at WOT / large throttle openings. For all intents and purposes, at large injector duty cycles it's one big fog of fuel.

    Quote Originally Posted by Terminal_Crazy View Post
    Scott: I see you mentioned BLM differences of upto 10 points, I've got down to around 6ish ie from -6 to +6 which seems pretty good.
    I'm talking about PEAK BLM SPLITS, not average which is what eehack's analyzer gives. My averaged splits are generally never more than 4 or 5, and the lean condition moves from right to left as the throttle opens.

    The point I was trying to make is that BLM splits change within the same BLM cell based on engine load, baro, humidity, air temp. This is most apparent in cells 0, 1 and 2, but also can be witnessed in 4, 5 and 6. In my opinion, achieving perfect balance by looking at BLMs is an impossible task. Even the factory tune with a completely unmodified engine showed similar behavior with largest average splits around 4-5 and peak splits as high as 8-10. Looking at the logs I uploaded with eehack may make it more self-explanatory.

  4. #19
    Fuel Injected!
    Join Date
    Mar 2013
    Posts
    980
    Bigger injectors spitting fuel fast will need more time to evaporate even though the end of the injection is at the same place the start of the injection will move and there will be less time for evaporation. Increasing fuel pressure will help with atomization alot.

    So the injector size must be included in the EOIT variables.

    Low res signal can be seen as ms for each 90* rotation. Multiplying it by 8 will give total time of 2 crank revolutions. Compare that by the injector opening time, and you will get the duty cycle of them. If you want to make sure the injectors are not spraying in the intake stroke, multiply the low res ms by 6 to exclude the intake stroke from the duration. Adding the eoit target to this you can still overlap events unless eoit matches the start of intake stroke.

    To get some initial cyl trims I used some variables like exhaust shape and length of individual tubes. Intake passage holes modified or stock uneven size.
    And make some chart of the passages and how the air is drawn for the firing order of the engine. Made some initial matrix but have no idea how close I am now with the initial guessing. I can`t find them anywhere.

    For some reason right side always needs less fuel. It could be because the stock exhaust merges near right side and the left side exhaust is longer that the right side making the more efficient. Higher length = better exhaust scavenging = higher vacuum in the cylinder and better filling with air.
    I also fine tune later for map and afr change with cyl cutting. You need to take into account and fuel robbing by other cylinders. Adding to one cyl can make others run richer.

    Last technique I used was to monitor blms at idle and making them 128 even on both sides. I am sure in the end you can dial it too so there is no split.
    7% difference shouldn`t bother you. You need to inject fuel matching the air that enters in the cylinder. I think the biggest split I have now is from 136 to 119.

    I closely monitor the behavior of the INT. On the right side it is really some subdued wave line. On the left side it is at zig-zag pattern, that matches the wideband fluctuations. This gives me some thoughts that left side is not in bank balanced. I will do some more experiments with adding and cutting inbank.

    I did the map test and the results are #1 the strongest, and 5 and 6 the weakest. I hope to use that data and see how it relates with the trims.

    The point I was trying to make is that BLM splits change within the same BLM cell based on engine load, baro, humidity, air temp. This is most apparent in cells 0, 1 and 2, but also can be witnessed in 4, 5 and 6. In my opinion, achieving perfect balance by looking at BLMs is an impossible task. Even the factory tune with a completely unmodified engine showed similar behavior with largest average splits around 4-5 and peak splits as high as 8-10. Looking at the logs I uploaded with eehack may make it more self-explanatory.
    I also noticed per cell splits, evens and opposite splits. That is the reason I want to reconfigure the cell arrangements. Some explanation how to modify for closer denser cells between 1000-1500 rpm where is most of the time the engine runs.

    I think that in cell splits can be due to different cyl trims needed at off idle, based on the airflow, map and rpm.

    I am sure there needs to be at least 3 different off idle trim ranges. That can be easily patched once I figure how to tune them and nightmare to add real time control on all of them.

    I am starting to think how to add a button in the eehack controller window that will save a screenshot with date, time stamp of it. Now some ideal settings can be lost really fast. I will be really glad if some of you guys can encode something like that.


    I got the leaner wideband in park, no load at the engine. With perfect blms at 128, I suspect the wideband not reading right at low airflow.

  5. #20
    Fuel Injected! spfautsch's Avatar
    Join Date
    Apr 2015
    Posts
    637
    Quote Originally Posted by kur4o View Post
    I also noticed per cell splits, evens and opposite splits. That is the reason I want to reconfigure the cell arrangements. Some explanation how to modify for closer denser cells between 1000-1500 rpm where is most of the time the engine runs.
    It seems fairly self-explanatory.

    BLM.jpg

    The rpm thresholds are in table 0x273f and the map thresholds are in table 0x2742.

    I think for giggles I'm going to try stacking my map thresholds a little closer together and see if anything changes.

    Quote Originally Posted by kur4o View Post
    I think that in cell splits can be due to different cyl trims needed at off idle, based on the airflow, map and rpm.

    I am sure there needs to be at least 3 different off idle trim ranges. That can be easily patched once I figure how to tune them and nightmare to add real time control on all of them.
    This is why I mentioned that adding load at idle / 0% TPS causes my BLMs to add fuel and become almost perfectly balanced. I'd hate to see you go to the trouble of patching in another individual trims table based off of TPS when it might work better to have different tables based on load or airflow. For example, without the load of A/C my idle is around 45kpa and 9g/s. With A/C it's more like 48kpa and 11.5g/s.

    Edit: However, I'm not optimistic more trimming will "fix" the issue. It seems like these imbalances are most prominent at very low manifold pressures. I'm beginning to wonder if there could be something to your theory that O2s are less accurate at low air velocity.

    Quote Originally Posted by kur4o View Post
    I am starting to think how to add a button in the eehack controller window that will save a screenshot with date, time stamp of it.
    There's probably a 3rd party utility you can install on windows that will do that for you without messing with coding it into eehack. On most linux distros the [printscr] key mapping is already configured to do this.

    I finally had a chance to check for spark leak last night and found absolutely nothing. I think I'm going to beef up my MAP vs RPM multiplier in the ignition controller and see if a little fatter spark makes any difference with what I initially thought was surge.

  6. #21
    Fuel Injected!
    Join Date
    Mar 2013
    Posts
    980
    I did some runs with fixed EOIT target and guess what the idle cyl trims are off again. A slight adjust of the off idle trim gave positive results and some of the nasty noise on high load low rpm take off is almost gone now.

    Now the car have much more crisp throttle, and a increase in power can be felt at very low rpm. Much more tamed and quieter also.

    I did change the curve of the eoit target during warm up. Now it leans much earlier and for longer. I guess the curve must be dialed pretty good for a good warm up.
    The main transition is around 50*C where you get some lean spark. I am thinking keeping the straight in cyl spray longer might be needed longer, since the head is colder and can`t evaporate fast enough the fuel.


    Right now I am having 650rpm at idle with 7.5agfs and map varies 42-47 for no reason, sometimes it is 42-43, sometimes 45-46.
    Now all surging is gone and the blms are almost perfectly balanced around with stock maf table.

    I think INt can give some very good tuning data about the ind trims.
    I need some completely stock engine log in good health to see how the blm and int act there.

    After close looking at some of the logs, the Int acts like that, goes down 1-2 points, wait for 02 feedback, if the mv are still high and not moving, goes down 1-2 more points and so on until the 02 are lean enough around 50-100mv than the action is reversed. With some timer it adds to blm if the response is too slow. Looking at code doesn`t give a clue how that pid system works, so guessing the basic algorithms of the control and than finding them in code can be better. Playing with the real time control can show what goes where in the inputs.

    I am not sure eehack can be draw realtime the int. Anyone tried the graph at realtime logging.

  7. #22
    Fuel Injected! spfautsch's Avatar
    Join Date
    Apr 2015
    Posts
    637
    Quote Originally Posted by kur4o View Post
    After close looking at some of the logs, the Int acts like that, goes down 1-2 points, wait for 02 feedback, if the mv are still high and not moving, goes down 1-2 more points and so on until the 02 are lean enough around 50-100mv than the action is reversed.
    As I understand it, the amount that's added to / subtracted from the integrator is derived primarily from the 0x270c Base O2 Proportional Step Size table. I've increased the higher airflow cells by 4 points over stock, and the result was more cross counts for the same amount of driving vs stock. Also less number of integrator changes per swing / cross cycle.

    Edit: It's worth nothing that the stock Y-body values for this table are 24, and the stock F-body are 32. Having 42lb injectors, I expected to have to reduce this value.

    The amount of time it waits is in the 0x26fb Base O2 Integrator Delay table. I ended up with the table below after graphing the integrator and finding example frames at different airflows, then adjusting the delay to match the amount of time between the integrator change and the moment the O2 starts to swing. If your Prop Step isn't big enough there may not be enough fuel being added and so the integrator will need to to be adjusted again before a cross happens.

    Code:
    AF    Stock    Mine
    00    0.40    0.53
    16    0.18    0.35
    32    0.13    0.25
    48    0.11    0.20
    64    0.10    0.15
    This is for equal mid-length headers.

    The threshold, whether going rich or lean is the 0x26f1 Fast O2 Rich/Lean Threshold table. I haven't touched this. My assumption is if after the integrator delay, if the O2 voltage has crossed this threshold the integrator is then moved in the opposite direction.

    The idea is to get the O2 voltages to oscillate around the 0x26f1 threshold without excess over or under-shoot. None of this is really new information. I'm sure there are a bunch of other things that can be tweaked such as the slow O2 filter coefficient and the integrator and proportional step gain tables.

    Ultimately my goal is to get to the best running tune possible in all weather conditions, and for whatever fuel blend being burned. Unfortunately instead of being out logging and testing, I'm sitting here letting the "grandkids" (two exhausted border collies) get their afternoon nap in.

  8. #23
    Fuel Injected!
    Join Date
    Mar 2013
    Posts
    980
    There is one more component in the CL control that is not logged for some reason. The CORRCL. It is changing too fast to log I guess. I only know that it makes immediate changes to the mixture for really fast corrections.

    Maybe after I gather some more thoughts about how the CL control will look again in the dissasembly to figure the missing pieces.

    For me CL settings off idle never give any troubles. It was at idle that was terrible but after copying all the vette parameters[ THANKS for making that discovery] now CL idle is great, especially after fixing the evap valve.

    I think that cyl trims can greatly affect INT behavior at low airflow. If tuned and balanced properly the INT is like subdued wave. Going up down slowly. Untuned it is like zig-zag pattern with some peaks. Also the oscillation between stoich on the wideband can give an idea how good the CL settings are.

    To get really good understanding you need perfectly tuned engine so it doesn`t mix or cover some of the output.

    I suggest you keep stock settings and very slowly work any changes from there. The best will be to make the wave resemble as close to stock engine wave as possible.

    Closed loop control at idle on lt1 is not perfect, that is the reason gm upgrade it on later pcms[ls1 code] with some special settings for idle.
    ON 96-97 code there is also some tables for swing voltages.

    So what will be the general consensus. At idle subdued wave, off idle some zig-zag pattern with wide or short peak?

    Really interested to see some stock logs to compare.

  9. #24
    Fuel Injected! spfautsch's Avatar
    Join Date
    Apr 2015
    Posts
    637
    Quote Originally Posted by kur4o View Post
    So what will be the general consensus. At idle subdued wave, off idle some zig-zag pattern with wide or short peak?
    I think (solely my personal opinion) for all ranges other than idle, a square wave without massive overshoot of the O2 voltage is preferable. There is some scientific theory behind my opinion, but for now let's call it "redneck premonition".

    Quote Originally Posted by kur4o View Post
    Really interested to see some stock logs to compare.
    The log I uploaded back on post # 14 is the best I have [link]. If I get time tomorrow I'll dig through and see if there are any others. But this was on an engine with 160,000 miles on it. So it would be good to have some other examples to look at.

  10. #25
    Fuel Injected! spfautsch's Avatar
    Join Date
    Apr 2015
    Posts
    637
    I played with my BLM thresholds this week and ended up here:

    Code:
    RPM    MAP
    1400    38
    1650    50
    1900    62
    I've only driven this on interstate (primarily in 6th gear @ 75mph) so it's a little soon to declare it "good". But I'm seeing a much wider range of cells being touched with typical driving. Normally my "boring" commute on interstate results in cells 2 and 6 seeing the majority of action. I'd be interested to see how these thresholds work in an A4 car.

    I'm hoping to make time to work on EOIT and individual cylinder trims this weekend. I'm out of ideas on fixing the surge / bucking I'm getting between 2-6% TPS and < 1400 rpm.

  11. #26
    Fuel Injected! spfautsch's Avatar
    Join Date
    Apr 2015
    Posts
    637
    After a couple hundred miles logged I'm liking the BLM thresholds / boundaries above. Results in a much wider number of cells being touched.

    Over the weekend I messed around with individual trims and EOIT. After quite a bit of fiddling I was unable to see or feel a difference between 0x63 and 0x69 so moved it to 0x63 as that seems to be the consensus.

    Individual trims seem to be a tough nut to crack. Based on header tube temps I found that #2 was quite a bit hotter at closed throttle than the other holes. So I started by adding to it (was 134, now 142). I noticed immediately the clutch is much less "grabby" when feathering and the idle is much more stable with the A/C on. I still haven't found a magic set of trims to eliminate what I was diagnosing as surge at cruise. I did however manage to move it to another load / speed range which helped me find an instance of it in a log and now think it's actually lean misfire caused by integrator overshoot (actually undershoot, if that's a word).

    Anyway, one thing I noticed is that adding fuel to #2 didn't seem to change the tube temp. So I conducted a little experiment in the parking lot just now. I'd been looking solely at max temp on my IR gun and wondered what the min/max/avg would look like if I left the engine running in closed loop so the AFR was oscillating and measured for roughly 10 seconds each. After looking at the data in a spreadsheet I find #2 has the smallest deviation - 2*C vs #8 with the highest at 35*C. I don't know if this means anything, but I'm going to experiment further with it this evening. My hope is that managing the temp deviation is the key to getting the trims just right.

  12. #27
    Fuel Injected! spfautsch's Avatar
    Join Date
    Apr 2015
    Posts
    637
    After numerous hours trying to improve on individual trims I'm throwing in the towel and going back to what I was running from two weeks ago.

    I'm not sure header temps can tell us anything. Repeated min/max testing showed no patterns that could be repeated, either in closed or open loop. Once the hood is opened everything seems to change and it takes 10 minutes or more before temperatures moderate. And then if you're like me the cooling fans switch to high, which causes further inconsistency.

    The only hang-ups I have with the current tune (assuming it runs the same as it did two weeks ago) are:

    1) low speed bucking at closed throttle or very low throttle opening, open or closed loop
    2) a missing / surging sensation at cruising speeds (closed loop) with low throttle openings - mostly prevalent with the a/c on

    After digging through logs from that last few days I think my second issue is being exacerbated by the IAC ramping down when the A/C clutch disengages, and that happens to coincide with instances where both integrators are swinging negative. The IAC closing causes a temporary rich condition, but the integrators continue to go negative trying to drive the O2s below the threshold, resulting in a severe lean condition that is felt as either a miss or detonation. Whatever it is, I think I can live with it as long as it otherwise runs excellent.

    I'm not sure I'll be able to do anything with the low speed bucking. I suspect it's either the closed-loop idle spark fighting the car's inertia, or the IAC similarly oscillating. Whatever the cause, it hates the idea of allowing me to get to work without spilling my effin coffee all over the console / myself. Not to mention the stress it must be putting on the driveline.

Similar Threads

  1. i'm an idiot
    By georgefatt in forum Introductions
    Replies: 4
    Last Post: 04-22-2019, 12:41 AM
  2. TBI injector part #ís
    By C2500 in forum GM EFI Systems
    Replies: 1
    Last Post: 02-14-2018, 04:24 PM
  3. Runs worse as it learns....
    By mikeames in forum GM EFI Systems
    Replies: 20
    Last Post: 06-19-2014, 05:59 AM
  4. Name this part - and it's function
    By User Nameless in forum Gear Heads
    Replies: 0
    Last Post: 04-04-2014, 10:55 PM
  5. new guy, the idiot who tried to practice
    By budweiser_man in forum Introductions
    Replies: 4
    Last Post: 09-12-2013, 07:37 PM

Bookmarks

Posting Permissions

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