Author Topic: accleration enrichment - again  (Read 10821 times)

Offline Seight-v8

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accleration enrichment - again
« on: June 30, 2013, 06:11:28 pm »
hi all,

Already had problems with my acceleration enrichment that were caused by a version of vemstune.

So back to the drawing board to tune my acceleration enrichment from the start, so I thought change all the settings to zero, so there's no enrichment at all then work up from there.....but for some reason the engine dies and wont re-start.....why I ask myself.....

for some reason the acceleration enrichment is having an effect on the running of the engine, even though vemstune shows nothing in the logs for acceleration enrichment.

my car now drives, runs & idles well, but can I bu**er get the acceleration enrichment right, and its making overtaking a nightmare on the road.

can anyone put some light and why this might be, running V1.2.13 with dual lambdas.

cheers scott
Engine:Rover V8 4600cc
Vems Firmware:V1.2.38, GPS, SDcard, LCD & Dual lambdas, Wasted spark, 36-1 trigger, Cam Sync & Bluetooth serial.

http://www.vems.hu/wiki/index.php?page=MembersPage%2FScottRichmond

Offline Seight-v8

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Re: accleration enrichment - again
« Reply #1 on: July 04, 2013, 08:42:31 pm »
wow well out my depth here.....this acceleration enrichment just does not make any sense to me....

Done a log tonight and pressed pedal as quick as I could so have a highest reading of 156 in dTPS/dt, but no acceleration enrichment, the lambda goes well lean and engine stumbles.

So I am thinking from the log that I need to get the enrichment to work, but when I change the settings nothing happens....and its lost me....I just cant make any difference.

current settings are
dtps   enrichment
5                12
35              15
80              30
175            45

really struggling here and just cant see the problem, its the last thing stopping my car from driving well and getting some miles on the clock.

http://www.vems.hu/files/Scott_Richmond/v3.3_n001401-A-2013.04.7-19.57_Upload.vemscfg



any help welcome.

scott
Engine:Rover V8 4600cc
Vems Firmware:V1.2.38, GPS, SDcard, LCD & Dual lambdas, Wasted spark, 36-1 trigger, Cam Sync & Bluetooth serial.

http://www.vems.hu/wiki/index.php?page=MembersPage%2FScottRichmond

Offline mattias

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Re: accleration enrichment - again
« Reply #2 on: July 04, 2013, 11:42:07 pm »
Acceleration RPM enrichment : You need the most enrichment at low rpm.
Use a baseline of 100% at the lowest rpm (1000).  Then taper off at higher rpm where you need none or very little.
Now you can tune the dTPS/dRPM table and let that be the primary way of tuning.
0.59 sec is pretty long to fade out, use 0.27 or even shorter.
I use 300% acc cold factor, and 100% added amount. That usually works out real well if you want it to handle cold climates.


A comment on other things :

Your VE table is a wonder of cliffs and rocks. Smooth that out.
A simple tip is to use at most  20,40,60,80 & 100 kPa to begin with. Tuning will go faster and the increased resolution is really wasted if you can't tune it.
Same for rpm, one for every 1000 rpm to begin with, maybe some extras around idle and low load, and insert points only when you are certain there is a change in VE that requires more data points.
You can do all this with the remap function if you open the tables in 2D window. A dumb limitation in the remap is that you can't increase the highest point, or decrease the lowest. Set them manually first.

I doubt your injector effective rampup is 1560 us, but with such small injectors it won't affect much since the pulsewidth is long at idle compared to a small turbo engine.
Unfortunately we don't have a setting for the cranking that affects injector firing, you're using simultaneously with divider 1 which means all injectors fire 8 times during the 4-stroke cycle. Luckily your injectors are small, but it usually means difficult tuning the cold and hot starts when the injector resolution goes down at such short pulsewidths when it is divided up that many times. Use divider 4 to get them to fire once on every revolution which is enough.

You should set all knock action settings to 0, not sure how it affects anything but the code is not working at the moment and I know there was an issue with this many firmwares ago.

Offline Seight-v8

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Re: accleration enrichment - again
« Reply #3 on: July 06, 2013, 04:46:23 pm »
so done some things today.

1. I've smoothed out my ve map up to 3500rpm, as I've not really gone over this limit yet for long, will see what happens tomorrow when I drive it.

2. tried changing the injector rampup, but car wont start with anything below 1200us....and really lumpy if change to it 200us like help says, not sure why this is.

3. changed acceleration enrichment like you said, and looks like the flat spot when pedal pushed in anger is gone, again will try tomorrow, looks ok otherwise, but a fine tune is needed.

I did notice from my log yesterday I have 74.5% duty cycle in my injectors at 51% throttle......thinking an injector upgrade is needed here?

Current injectors are standard 4.6v items, serviced/cleaned last year, 180-220cc (20lbs), maybe 240cc (24lbs) would be better in my engine.

cheers

scott
Engine:Rover V8 4600cc
Vems Firmware:V1.2.38, GPS, SDcard, LCD & Dual lambdas, Wasted spark, 36-1 trigger, Cam Sync & Bluetooth serial.

http://www.vems.hu/wiki/index.php?page=MembersPage%2FScottRichmond

Offline mattias

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Re: accleration enrichment - again
« Reply #4 on: July 08, 2013, 08:09:23 pm »
Injector rampup changed and no start? Must be a too low cranking VE%. If you use a high gear, and go WOT at 1000 rpm. The VE% in the table you get there is usually about the same value that you should use for cranking VE%.

You should look at MAP, not TPS. If you have atmospheric pressure in the intake, and low TPS %, that only means the engine is getting more than it needs already at that rpm.


Offline gunni

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Re: accleration enrichment - again
« Reply #5 on: July 10, 2013, 08:19:21 pm »
so done some things today.

1. I've smoothed out my ve map up to 3500rpm, as I've not really gone over this limit yet for long, will see what happens tomorrow when I drive it.

2. tried changing the injector rampup, but car wont start with anything below 1200us....and really lumpy if change to it 200us like help says, not sure why this is.

3. changed acceleration enrichment like you said, and looks like the flat spot when pedal pushed in anger is gone, again will try tomorrow, looks ok otherwise, but a fine tune is needed.

I did notice from my log yesterday I have 74.5% duty cycle in my injectors at 51% throttle......thinking an injector upgrade is needed here?

Current injectors are standard 4.6v items, serviced/cleaned last year, 180-220cc (20lbs), maybe 240cc (24lbs) would be better in my engine.

cheers

scott

2. You need to tune the rampup correctly to get the right value.

Quickest way is to live tune it with the engine at it´s lowest pulsewidth = idle speed.
Here are the steps.

1. Get the engine running lambda 1.0 while idling and turn off closed loop
2. Change the target lambda to 0.8 and make sure it´s in an area large enough to cover rpm changes and map changes when it´s running richer.
3. Now if and only if your lambda went to 0.8 the value is correct. If the lambda is leaner then 0.8 that means that the deadtime in effect is not long enough (i.e you asked for more fuel by % but didn´t get enough). if it´s richer then it´s to short.
4. Adjust the rampup value in the direction needed by 100us
5. Tune the VE table to maintain lambda 0.8
6. Set the target lambda to 1.0 , here if the value is right again you can see lambda 1.0 , if not then keep adjusting the value until you can request a large step change in lambda from the lambda table and you see that results in the lambda WITHOUT having to adjust the VE table.






Offline Seight-v8

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Re: accleration enrichment - again
« Reply #6 on: July 15, 2013, 08:06:03 am »
cheers everyone.

Been reading about new injectors for a while, and come to the answer that I really need to replace my 20 year old lucas pintle ones with something better, if I want the engine to be better......at the moment I have standard rover 4.6 ones 19lbs.

I've sourced some bosch gen III 24lbs injectors from the USA that will be a direct replacement, will need to increase fuel pressure from 36 to 43.5psi, but otherwise a good upgrade.

don't think there's much point in trying to tune my engine with the ones I have at the moment as they might be knackered.

will get report back once I've done the upgrade.

scott
Engine:Rover V8 4600cc
Vems Firmware:V1.2.38, GPS, SDcard, LCD & Dual lambdas, Wasted spark, 36-1 trigger, Cam Sync & Bluetooth serial.

http://www.vems.hu/wiki/index.php?page=MembersPage%2FScottRichmond