speedpro decel

[rarebit]

how do i get the speedpro to pull out more fuel on deceleration? it seems the motor always goes mucho rich when i let my foot off. i cant figure out how to fix it. ive tried leaning out the low map cells. ive tried fattening up the cruise cells to trick the ecm into leaning it out when i pull my foot off...any ideas?

id also like to take a look at some other trucks ae settings. especially tps and map ae.

when i gas it from about 50mph it always seems to go way rich. gassing it from a stop holds the a/f just where i want it. just cant figure out how to stop it from going way rich from 50mph stomp. its like the speedpro needs a mph vs a/e % or an rpm vs a/e %. it seems the more rpms the motor has the less a/e it needs. the speedpro has tps vs ae % it doesnt seem to be useful for this problem.

when your going down a grade at 50mph and the throttle is closed and map is low and then proceed to stomp on it the rpms go up way faster then if they would if you did the same thing going up a grade. consequently, the wrong amount of ae fuel gets put in. ie.- too much going down hill. not enough going up hill. any thoughts?

thanks for any help and ideas anyone might have about this stuff.

 

[smeagol]

All you can do is lower the VE value at the low MAP values versus RPM in the VE table. This was a beef I had with FAST as well, as I saw the same thing.

I have managed to get the DE decent on most FAST cals.

 

[nightdiver]

Thats how i did it and it worked great :wink:

 

[rarebit]

hmmm...

hmmm...

i decided to do a little test. i set all the ve in lower two map rows to 0 to see if that would stop it from hitting 11:1 af ratio. it didnt work that well... the af still hits 11:1 sometimes 12....that leads me to believe that quite a bit of fuel is still left in the combustion chamber and headers when the throttle closes. maybe its a timing issue. would cranking up the timing on the lower cells help burn the fuel off? how do you know how much timing to put in on the lower cells?

 

[leroy]

I think less timing would help with decel, but may not help your a/f ratio.

Jim

 

[nightdiver]

Less timing will make the fuel burn inside the headers/downpipe =high exhaust temps and maybe flames from the exhaust pipes
Dont forget that when decellerating the info (gases) to the WBO2 goes really slow so you dont have accurate readings
If you want go to the buick forum and search for decellerating.I remember i read something about this

 

[nightdiver]

Forgot to say that i have 11:1 decell and i like it this way cause some fuel will make my pistons colder
my lower VE is 30 right there
Do some logging while decell at high speeds

 

[smeagol]

You definitely need to watch it & log it during the deceleration portion, to find out exactly which cells to change. Just changing the bottom two rows might not affect the condition.

You also may not work too much on the midrange portion during WOT tuning, so it may not be fully tuned, yet those values are used when you do a decel from a high boost/WOT run. Those values may need changing too.

 

[rarebit]

toolin around more with the lower cells

toolin around more with the lower cells

i noticed if the lower two rows are leaned out too much it tends to want to stall when climbing a steep grade and then hitting the brake. this is at parking lot speeds(<15mph). somewhere around 30-40 for the 2nd row seems to clear up the wanting to stall problem. the 1st row i cant quite figure out cause i cant get it into that region long enough (maybe if i drove down mount everst it would suck enough vac to tune it right) but the 1st row values do seem to effect the ve% when the engine is operating in the the 2nd row region. deceling from i high boost run is kinda hard to tune for as well. its tough to keep it in that cell region for long. its gonna take a while to get that right.

doing some more fiddling-
the midrange cruise cells(3rd row) i fattened up as to cause the wide band feedback to pull out fuel(i.e. correction is -5.5%,-10%,etc...) while cruising. now when the throttle closes it will kind of trick the speedpro into yanking out more fuel when it goes into the 2nd row cells which are already leaned out. reason being is that it takes a little bit of time for the feedback loop to stop leaning it out. so it gets extra leaned out right when you let off the throttle for only the amount of time it takes the wb feedback loop to compensate. i dont know if this is the right way to do it or not. it may adversly effect accelerating out of the midrange cells into the 4th row and up cells causing them to appear to be to rich. by the time the wb tries to compensate it could possibly be in the higher rows(5 and up) and incorrectly lean them out. not to mention it makes it harder to set the ae curves. i havent tested this but it sounds like this is what would happen. so where's the trade off?

btw- how do you tune the map ae and the tps ae? all i can determine is that the map ae will add gas a little after the tps ae. is the map ae even required? why not just jack up the ae decay rate and set the map ae all to 0. i can see if you had long runners the map ae would be quite useful cause it would take longer for the map to change. i thought maybe the map ae would be for a turbo cause it takes longer to spool but no. turns out the map ae is extremely fast compared to the pressure changes a turbo can make. so its probably only for tuning for different intake manifolds. i figure the more length(not volume) in the manifold the more map ae and less tps ae all else being equal.




i checked out the buick board. not a whole lot of info but i did find a little faq someone made-

http://pages.sprint.ca/norbz/files/beta65.html


here's a piece from that faq-

After Start VS CTS

This enrichment happens after crank mode is done AND "Cranking & Starting\After Start Revs VS CTS" is counted out. Also this enrichment only last for a short period of time. (amount of time varies, can be aprox. 5 – 20 seconds)

Check "AFT Corr. (%)" sensor reading for current enrichment % being applied.

Common Problems: Engine starts, but dies shortly after. If the engine is able to idle OK while the coolant is cold AND "AFT Corr %" is equal to 0%, this is what you need to change.


t

im having the exact problem about the engine dieing shortly after starting. i have tweaked the after start vs cts from hell and back and still the same problem. the aft corr % always reads 0 no matter what. anyone know what im doing wrong?

thanks for all the help everybody. maybe this stuff will help someone else.

 

[nightdiver]

Making the driveability right is difficult. I select "VE" from the dash and so i can see what does it takes exactly from each ve area.
Do you have it closed loop that low ? 600-700 rpm like i do ?
For ae vs everything i just copied from the experts (BG-Mckoy)and then modified to my needs-i needed more fuel at ae vs rate of change-i have a dash setted for the corrections also. We cant monitor AE cause its too fast.
I had the same stall problem .It came when i gave big nrs at the "start iac vs coolant" , then i moded the "after start vs coolant" & the" warm up vs coolant" and now it runs great
Now for the map AE remember that there are times that with a little tps more we get full boost ( in D & 3000 rpm with a 9/11) i bet this table adds fuel that time
For the idle near stall i setted the correction so that it doesnt get too lean from the wbo2
Since BG is helping us its easy to tune.Hey Brian what about on line tuning ?
A lot of things to do ,but i love it

 

[smeagol]

Since BG is helping us its easy to tune.Hey Brian what about on line tuning ?

FAST for windows supports this I believe.. it'd be fun to tinker with, but i'd be afraid of lag etc (not turbo, internet connection )


For VE/DE stuff, the good decel w/o stalling is the key. What I ended up doing was leaning out the 3rd line of the table usually, then add a bit of fuel at the 1st and 2nd. Now remember that there is interpolation between points on that table, and it is very fine actually. This means that if you are at 1600rpm and the VE value at 1200 is 20 and the VE vaule at 2000 is 40, the lookup value for the current 1600rpm value will be 30. It does this in each direction, I believe 16 points can be interpolated between 4 values in adjacent cells, if that makes sense. Anyways, the point is to remember that the table should be examined as a surface graph. If you have richer values on the bottom row, if you are sitting in the 2nd row of manifold pressure, you will still utilize the 1st row to an extent. Putting some fuel in that 1st row may keep it alive. I usually make a ramp at the bottom of the fuel map. For example, if you put 30 in cells in the 1st row, 20 in the 2nd row, and 10 in the 3rd row, it will not be a stepwise graph. Due to interpolation, it will act like a gently sloping ramp. So as you decel, the fuel leans out and RPM drops, if it has less fuel at the low map levels, it will die. If you put some fuel down there, it will bump the RPM up to keep the engine running.

As far as the startup issues, the crank fueling is basically only used during the initial cranking. If you crank and the engine fires for a few seconds, chances are your crank fueling isn't the issue. It may not be tuned optimally, but it probably isn't the issue. Watch what the actual AFR is doing. Is it bogging from fuel, or dying from lack of fuel? Startup IAC is crucial at this point as well. Closed loop shouldn't come into play in this situation, as there won't be any correction this soon after startup. Does 'footing' the throttle help or hurt the situation? Keep an eye on IAC counts, as well as TPS setting for idle. You want IAC to be 20-30 at idle, warmed up. TPS should be less than 15% for closed throttle idle. Startup IAC counts should be set pretty high. When you start the truck up, watch the AFR at startup, it should be rich, then it probably races the idle a bit (1200-1400). If it goes lean there, the motor may just die. Since you don't idle at 1200-1400 much, your fueling is probably not tuned really well there, so you may have to throw some fuel at it for that point. You may see the engine startup, have rich AFR, RPM rise up to 1200-1400, then go very lean, engine RPM drop sharply, and truck dies. Do whatever you can to add the fuel at that lean spot, then you can work from there, as you know what the problem is at that point then. Adding fuel via VE, possibly reducing IAC counts after startup (less air let into the motor has a richening effect), possibly richening the fuel after startup for that coolant temp... could be done several ways, the trick is finding the *best* way. Timing may even come into play.

 

[nightdiver]

Jesus,
i love this guy
in a few days ill get a laptop,currently i tune with a friends and i am half way to do a laptop mount from aluminium
Ill be back
Thanks

 

[rarebit]

yeah, i got the closed loop set down real low like you. you were right about setting the limits on the o2 so it doesnt lean it out too much at idle. seems like -5% in the lowest two rows really attenuates the stall tendancy. still kind of goes fat immediately when you take your foot off though.

the map ae im still not sure about. the ae doesnt even function under boost. this is if the ae threshold is set to the suggested 100kpa limit. the tps ae says cts/4ms and the map aes say cts/50ms. so for example if the throttle goes from 20-30 in .004 seconds the result would be 10. now if the 10 colum in the 2d tps ae graph has .99ms in it, this is what gets added to the injector pulse width. taking into account that map ae lags the tps ae, if a lot of tps ae is put in, at some point the tps ae is probably gonna start falling into and effecting the map ae setting. i dont know if this is good or bad. i would think ideally map ae would take over after tps ae falls off. actually im still baffled as to how to go about tuning all this ae stuff.

my iac is around 28 and the throttle is at 16%. these #'s are on the high side of what you suggest. i could turn the throttle screw out a few turns but wouldnt this raise the iac? i got the idle at 950. keeps the oil pressure up.

thanks for explaining the interpolation. makes sense now. i started logging the aft, cts, map, rpm, and a few other params. logging sure does help. i found that the aft wasnt kicking til about 10 seconds later. i also found that you can set the aft to kick in like 30 seconds later. i think thats really nuts. why would you want to do that? i shortened it up to about 4 seconds. one thing i noticed is that if you have 40% cts enrichment and 40% aft enrichment you get 80% total enrichment. thats a shitload of enrichment. i think the best way to tune these is to tune the aft when the truck is warm when no cts enrichment is being applied. then go back and tune the cts enrichment as to prevent over doing it with to much enrichment. i think probably only about 5-15% aft enrichment is needed and maybe 40-60% cts enrichment. with cts dropping off to 0 as the engine warms(120F+) and aft decaying out slowly as heat starts to spread through the heads and fuel start combusting better.

when i was messing around with the idle stuff i noticed something. the timing trim allows you to add up to 12 degrees correction for errors as small as 16rpm. that seems like an awful lot of correction. for a 16rpm error i cant see trying to correct it with any amount of timing. its just too small of an error. even for the highest (112rpm) maybe only about 2-3degrees. anymore would probably cause an overshoot problem.

 

[smeagol]

Ok, couple of things.

The air temp fuel scaling table is NOT used in speed density mode, as it is part of the speed density equation... it has to be, just how it is. The table is there for alpha-n mode.

EDIT - current versions DO use ATS now, older versions do NOT... how to find out? mess with the table. This really bothers me, because if a calibration that I tuned up in a truck w/o the ATS is passed on to a truck that has the firmware update to use the ATS, now the values have to be worked on. Hmmmm this is annoying....

Idle stuff - you said you had 16% TPS, 28 IAC and idle speed at 950. What cam are you running? I'd close the throttle and lower the idle RPM. Anyhoo, if you want to keep the high idle speed and throttle positioning, you should at least raise the minimum idle TPS setting in FAST. Probably set to 15% now, raise it above what your closed throttle TPS reading is.

The AE stuff is usually added in as *additional* pulses, not calculated pulsewidths then added to the synchronous bank to bank regular pulsewidth.

The idle timing adjustments shouldn't really be needed in any but the most radical buildups. In fact, it will probably hurt your cal IMO. The more stable you can keep the motor during idle, the better the idle will be (just my thoughts on it, after doing chips & aftermarket tuning for too many trucks). This is why I like a closed loop idle. Take out the timing changes at idle, eliminate the integrator/fuel trims, minimize IAC movement, and your idle should be pretty damn good.

 

[rarebit]

oops

oops

please substitute aft for ats in my last post in the 4th paragraph. i became confused on the 3 letter acronyms. ats is for air temperature enrichment and aft is for after start enrichment. hope this doesnt confuse anyone.

i happen to have the firmware that doesnt use the ats table. seems like air temperature is a fairly important part of the equation. even if it uses speed density to calculate air temp. i think something like every 11 degrees air temperture requires an extra 1% fuel. i wonder how i can get a firmware update?

im running the comp cam 215/220 with brodix heads. i like the idle high(950) to keep the oil pressure up and to keep the alternator spinning a little faster. otherwise id turn it down. i figure the lower i can keep the iac the more headroom its gonna have when it needs it so the throttle screw is in a little more then normal. i double checked the tps threshold and its right at 18. closed throttle is 16.

you said the ae pulswidths are not added to the final equation but just put in as additional pulses. i hope this doesnt mean ae pulses go right over the top of the normal pulses. in other words, a 4ms normal pulse and 1ms ae pulse are issued at the same time so you end up with still a 4ms pulse. or does a 4ms pulse occur then a short delay occur and finally a 1ms ae pulse?

 

[rarebit]

i just corrected the paragraph

 

[LuvBoost]

I just had the firmware upgrade done on mine. Call Craig @ FAST 810-225-2700. It cost me 40 bucks and the ATS works fine now.

 

[nightdiver]

during winter i was traveling with very low temps and i noticed 28-32* F in the intake !!!!!!! I guess thats where ats would be more usefull
Ive got an extra sensor and digital display inside the truck (in C*)
its an Elliwell module i think