Power Enrichment OBDI

[robertisaar]

D-TPS = current TPS - previous TPS.

(new-old)/old would make an odd value.... not sure what i would refer to it as, since it would account for both the delta and previous values.

[LZeppelin513]

(New - old )/ old would equal a percent increase from the previous value.

[robertisaar]

i wonder if that would be useful......

[LZeppelin513]

I would like to be able to track AE and DE in a1 like in nast1. I was wondering if u don't mind Robert, would u be able to tell me the values for AE and DE? I haven't really figured out how to use the txt file with all the code values yet.

[robertisaar]

you want the actual pulsewidth or the status bits for when they're active?

[LZeppelin513]

Just status, on or off.

The 4 digit transmit value so I can put it in the stream.

[robertisaar]

0042

bit 1 is AE flag
bit 4 is DE flag
bit 5 is PE flag
bit 6 is F100 re-entry flag
bit 7 is Async fuel is calculated, waiting to be injected

you may not see bit 7 often, since by the time the datastream comes around, it's usually already injected.

[LZeppelin513]

Cool thanks a lot.

[LZeppelin513]

If D-TPS updates every 12.5 ms and every sample is about 125 ms long, then ever sample has about ten D-TPS changes. That means to get an estimated D-TPS average for a sample you would need to divide the calculated D-TPS (new - old tps) by ten.

^ Is that correct?

[LZeppelin513]

I don't think that could be right though.

Being updated every 12.5 ms really throws me off.

12.5 ms is very tiny, it would heard to get D-TPS as high as 10% in 12.5 ms even if you slammed the pedal down.

Edit: for reference, the blink of an eye lasts about 300 ms. If you slam the throttle down (at a relatively consistent rate) in the blink of an eye you are only getting a D-TPS of a bit less than 5% every 12.5 ms.

If D-TPS is really updated every 12.5 ms something doesn't add up (I must be missing something critical for the D-TPS calculation). Either that or we need WAY more resolution from D-TPS 0-5% and really no need for anything above it.

[robertisaar]

somewhat.... you could also do some mode 2 or 3 (i forget which) commands and grab only a few values per packet and bump the log rate up to 30-70Hz(similar to how OBD2 datastreams function).... i've done that before to test some variables that i couldn't quite understand how they worked to watch how they interacted.

sample rates can vary a little bit. i average 10.67HZ with the A1 size datastream, but computer speed can change that significantly(mostly in the downward direction).

you could attempt to log D-TPS at high speed as well.

[robertisaar]

could also think of it in terms of duration to reach full pedal.... if it takes 1.96% D-TPS to enter AE in 12.5mS, then if you open the throttle at the rate of fully closed to fully open in 51 loops, AE will most definitely be active the entire time. 51 loops at 12.5mS is 637.5mS.

if 1.18 to remain in AE once entered with a 1.96 D-TPS entering, then 83 loops (1,037.5mS).

those are BFBD values and the calibration you started with may or may not be different.

[LZeppelin513]

I do not fully understand it yet, what is a loop.

I am trying to understand how the DTPS table is applied. How, for example would a DTPS of 50% ever be achieved in order to use that value in the table? I cant think of how more than even 10% DTPS could ever be reached, yet the table goes to 50.

[robertisaar]

the 68HC11 processor has interrupts, some of which are timer based. one of the timers expires and forces the processor to do a specific set of calculations on a 160Hz schedule. after that, every other interrupt(timer expiring), it does the 80Hz loop stuff, every other one of those, if a 40Hz loop exists, it does that as well. there is also a lot of stuff set to be done on a 10Hz schedule, but almost all of the important fuel/spark calculations are done on the 80Hz loop.

i'm not really certain how 50% could happen in 12.5mS either, but the capability to account for it does exist.

i may dig into it some more and run some test code on the bench to have something happen every time AE is checked for/called upon and have it increment a value. then just see how quickly the value counts up and compare it to a known timeframe to see the real frequency it's done at. last time i looked at the code, it looked like it was done on the 80Hz loop. fairly certain 10Hz would be far too slow to account for transitional(AE/DE) fuel and i don't think there is a 40Hz loop.

[LZeppelin513]

could also think of it in terms of duration to reach full pedal.... if it takes 1.96% D-TPS to enter AE in 12.5mS, then if you open the throttle at the rate of fully closed to fully open in 51 loops, AE will most definitely be active the entire time. 51 loops at 12.5mS is 637.5mS.

So a bit over a half sec to go from no pedal to full. That's somewhat fast, yet on average DTPS will be somewhere between the very first two data points on the graph. Even if you hit full pedal twice that fast (which is probably close to as fast as someone will be slamming the pedal down) it will still be looking up values before the third data pt on the graph.

That just seems crazy to me that there would be such poor resolution for usable DTPS values in the table and then have the majority of the graph be basically useless.