SD - first test success
Feb 9, 2009, 03:55 PM
#151
Hey John,
ok I fiddled with the numbers and the car feels a lot better - I am not sure if its that worthwile using the WB02 as a reference point to how the car is running.
Interestingly I increased my 101kpa bottom row, and the car was visibly/felt to rich (wbo2 confirmed). So I decreased it and its ok. However now on 110kpa it STILL is too rich, Do I decrease more?
One thing, I have a lean idle, after the idle settles and the STFT also settles its about +10%.
Now I figured I could add %10 to the load for the appropriate kpa cell, but assuming the MAPVE table is correct wouldn't it be a better idea to add 10% to the idle cell for the RPMVE table?
ok I fiddled with the numbers and the car feels a lot better - I am not sure if its that worthwile using the WB02 as a reference point to how the car is running.
Interestingly I increased my 101kpa bottom row, and the car was visibly/felt to rich (wbo2 confirmed). So I decreased it and its ok. However now on 110kpa it STILL is too rich, Do I decrease more?
One thing, I have a lean idle, after the idle settles and the STFT also settles its about +10%.
Now I figured I could add %10 to the load for the appropriate kpa cell, but assuming the MAPVE table is correct wouldn't it be a better idea to add 10% to the idle cell for the RPMVE table?
Last edited by tephra; Feb 9, 2009 at 05:14 PM.
Feb 9, 2009, 05:18 PM
#152
Further to that I am still not sure about:
1) leaving the MAF connected, does the baro play a significant roll (or only at high boost/rpm's)?
2) cold running, ie does the ECU injector more fuel that normal - is that a problem for this setup? or will/should it just be like MAF-based?
3) accel enrichment - obviously this still exists do we need to disable?
1) leaving the MAF connected, does the baro play a significant roll (or only at high boost/rpm's)?
2) cold running, ie does the ECU injector more fuel that normal - is that a problem for this setup? or will/should it just be like MAF-based?
3) accel enrichment - obviously this still exists do we need to disable?
Feb 9, 2009, 06:19 PM
#153
The US OBD MAF test is at 0x23EA0. I could easily put a bt just after the start of the subroutine to skip over all the useless code down to the point where #1 -> r0. What I'm more interested in doing, if possible, is completely skipping the test. There are several OBD routines that contain only "#1 -> r0", and I was thinking of substituting the address of one of these in the place of the MAF OBD test. Just a thought.
Last edited by mrfred; Feb 9, 2009 at 06:27 PM.
Feb 10, 2009, 01:04 AM
#159
Evolved Member
Thread Starter
Hey John,
ok I fiddled with the numbers and the car feels a lot better - I am not sure if its that worthwile using the WB02 as a reference point to how the car is running.
One thing, I have a lean idle, after the idle settles and the STFT also settles its about +10%.
Now I figured I could add %10 to the load for the appropriate kpa cell, but assuming the MAPVE table is correct wouldn't it be a better idea to add 10% to the idle cell for the RPMVE table?
1) leaving the MAF connected, does the baro play a significant roll (or only at high boost/rpm's)?
2) cold running, ie does the ECU injector more fuel that normal - is that a problem for this setup? or will/should it just be like MAF-based?
3) accel enrichment - obviously this still exists do we need to disable?
ok I fiddled with the numbers and the car feels a lot better - I am not sure if its that worthwile using the WB02 as a reference point to how the car is running.
One thing, I have a lean idle, after the idle settles and the STFT also settles its about +10%.
Now I figured I could add %10 to the load for the appropriate kpa cell, but assuming the MAPVE table is correct wouldn't it be a better idea to add 10% to the idle cell for the RPMVE table?
1) leaving the MAF connected, does the baro play a significant roll (or only at high boost/rpm's)?
2) cold running, ie does the ECU injector more fuel that normal - is that a problem for this setup? or will/should it just be like MAF-based?
3) accel enrichment - obviously this still exists do we need to disable?
I like narrowband and STFT for low load adjustment. It seems to respond quicker.
To decide whether to bump up MAPVE or RPMVE you need to work out whether you are also lean at that MAP at say 2000 RPM. If you are, fix the MAPVE, if you're not, fix the RPMVE. Mine works best with a 10% drop in RPMVE for 500 and 1000 RPM.
I do think you're best getting intial VE figures from an old MAF log, plot MAP vs RPM vs load/MAP on an Evoscan maptrace. Later I'll put up an example (from your logs if poss), all then becomes clear when you use averages of many runs through these cells what the trend is.
Leaving the MAF connected, the way I have coded it, the baro will affect the load and fuel calcs. I think this is undesirable as we already have automatic compensation from the MAP for pressure and this looks after the vast majority of baro changes I reckon.
Cold running and accel enrichment are just as before.
We are replacing the MAF volume values before it gets all the usual compensations applied. We get all this still happening, and all is desirable except the baro comp.
Good thinking on the OBD checks mrfred.
Hehe, I'm in a guru sandwich in this thread
Feb 10, 2009, 01:14 AM
#160
^ i think your WELL OVERDUE for G-status yourself 
I found my GMMAP formula is slightly off - i've reworked it, but I don't think it will be enough to cover the lean idle.. will retest tomorrow!
Sorry I don't understand why accel enrichment doesn't need to be disabled?
I found my GMMAP formula is slightly off - i've reworked it, but I don't think it will be enough to cover the lean idle.. will retest tomorrow!
Sorry I don't understand why accel enrichment doesn't need to be disabled?
Feb 10, 2009, 01:21 AM
#161
Evolved Member
Thread Starter
Accel enrichment is still needed for speed density, sometimes moreso because the MAP sensor doesn't get an inlet manifold filling spike on acceleration transients like the MAF sensor does, which gives an advance burst of fuel for the forthcoming air about to hit the engine. I think the reason we get away without adding any enrichment (I had to do loads on the Subaru) is because our MAF sensor signal is quite smoothed and the acceleration enrichment is already set with this in mind.
http://www.sae.org/technical/papers/940759 there is a download somewhere for free of this (on "simcar" I think) but I can no longer find it if you want to read more. Prof Moskwa's paper and very kindly his personal advice, helped me with my design for the Subaru MAF emulator.
http://www.sae.org/technical/papers/940759 there is a download somewhere for free of this (on "simcar" I think) but I can no longer find it if you want to read more. Prof Moskwa's paper and very kindly his personal advice, helped me with my design for the Subaru MAF emulator.
Last edited by jcsbanks; Feb 10, 2009 at 01:26 AM.
Feb 10, 2009, 01:24 AM
#162
hrmm - ok. but MAP updates almost instantly with the new amount of air being ingested by the engine??
ps - my old scaling was x*100/82 and x*82/100
I have worked out that the raw ADC value needs this formula to convert into kPa:
((5.0*[GMMAPRAW]/255) + 0.01765)/0.0159100
So should I replace the scaling with this (and the opposite for the later)?
ps - my old scaling was x*100/82 and x*82/100
I have worked out that the raw ADC value needs this formula to convert into kPa:
((5.0*[GMMAPRAW]/255) + 0.01765)/0.0159100
So should I replace the scaling with this (and the opposite for the later)?
Feb 10, 2009, 02:10 AM
#163
Evolved Member
Thread Starter
Your old scaling was so close to the new one I wouldn't bother changing giving the error on these things - the offset is about 1 RAW, and the difference in gradient is about 1%. I don't want to ignore small errors, but this error is not the reason for any remaining driveability or AFR errors, it is the VE settings for MAP rather than the calibration. Plus your logs are all calibrated using your old scaling. As long as the same scaling is used in your logs and your Ecuflash tables it doesn't matter.
It may be fuel dynamics that causes the lean excursion on acceleration transients, but it sure happens. Without acceleration enrichment it would be undriveable and misfiring on transients. With a fast (<<4ms) MAF sensor you get the inlet manifold filling spike between the time the throttle moves until the MAP sensor value reaches a new equilibrium. During this time, MAF based fuelling on Subarus at least gives a large part of the acceleration enrichment required. In the Evo I think it is more filtered.
One other thing I've noticed is that my LTFTs haven't moved from zero on my latest patch (which only has the OBD baro error killed). I will continue to observe, but I would have expected them to by now, and they did on my first patch that had both the MUT and the OBD baro errors killed. It may be that I need to kill both.
It may be fuel dynamics that causes the lean excursion on acceleration transients, but it sure happens. Without acceleration enrichment it would be undriveable and misfiring on transients. With a fast (<<4ms) MAF sensor you get the inlet manifold filling spike between the time the throttle moves until the MAP sensor value reaches a new equilibrium. During this time, MAF based fuelling on Subarus at least gives a large part of the acceleration enrichment required. In the Evo I think it is more filtered.
One other thing I've noticed is that my LTFTs haven't moved from zero on my latest patch (which only has the OBD baro error killed). I will continue to observe, but I would have expected them to by now, and they did on my first patch that had both the MUT and the OBD baro errors killed. It may be that I need to kill both.
Last edited by jcsbanks; Feb 10, 2009 at 02:16 AM.
