Hi guys,
I'm setting up MS3 on my type 4 1971cc engine with stock injectors. I've got two question regarding some basic settings, hope some has experience with these.
- What value do I use for required fuel? I've got 17,9 now (based on 1971cc, 4 cyl, 185cc/min flow rate and afr 14,7)
- What PWM settings should I use? I've got it set to 1ms dead time, the standard correcte curve 1 and pwm current limiting off, but I'm not sure this is the correct setting.
Hope someone has these figured out already!
Injector Dead-time/PWM and req fuel on 1971cc type 4
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- Chip Birks
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Re: Injector Dead-time/PWM and req fuel on 1971cc type 4
Ms3x doesn't like low imp injectors. Unless of course you are just using the main board injector outputs.
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Re: Injector Dead-time/PWM and req fuel on 1971cc type 4
I'm using the main board injector drivers. I'm also using the stock resistor pack, doesn't make that high impedance injectors?
- Piledriver
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Re: Injector Dead-time/PWM and req fuel on 1971cc type 4
That's fine.MadMax78 wrote:I'm using the main board injector drivers. I'm also using the stock resistor pack, doesn't make that high impedance injectors?
Cannot comment if those #s are sane for stock injectors though.
A LOT of modern injectors will fit the stock manifolds just fine with a new fuel rail and modified hold downs.
(it's easier than that sounds)
Injectors have come a long way in the last 40 odd years.
Try to scale your re fuel so the peak value in your VE table ends up ~200, lowest value should be >50.
...that's not really a requirement for MS3 as most values are in .1 increments (and the max value is really like 16384, unless set to 255 as an option) but it help the resolution and makes wrapping your head around some things easier...if only to get help from folks used to seeing it set up that way.
Addendum to Newtons first law:
zero vehicles on jackstands, square gets a fresh 090 and 1911, cabby gets a blower.
EZ3.6 Vanagon after that.(mounted, needs everything finished) then Creamsicle.
zero vehicles on jackstands, square gets a fresh 090 and 1911, cabby gets a blower.
EZ3.6 Vanagon after that.(mounted, needs everything finished) then Creamsicle.
- MarioVelotta
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Re: Injector Dead-time/PWM and req fuel on 1971cc type 4
Can you expand on this a bit. Chip and I have talked about this a couple of times, and you have brought it up a couple times this week.Piledriver wrote: Try to scale your re fuel so the peak value in your VE table ends up ~200, lowest value should be >50.
...that's not really a requirement for MS3 as most values are in .1 increments (and the max value is really like 16384, unless set to 255 as an option) but it help the resolution and makes wrapping your head around some things easier...if only to get help from folks used to seeing it set up that way.
Example:
2.2L Turbo motor
Calculated Req_fuel 3.8ms
100lb injectors
Idle VE 75
Max load in boost VE 235
Idle PW ~ 1.75ms
What would you suggest?
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- Piledriver
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Re: Injector Dead-time/PWM and req fuel on 1971cc type 4
if it's recent MS3 firmware (and probably recent MS2-extra, not using it ATM) you could scale it up ~at will.
OTOH 75 min/235 max is reasonable in my mind, is he having issues setting idle AFR properly?
Is it in the injectors linear range at idle?
Sometimes a vacuum referenced reg is the only way to get large injectors working at idle.
(and I imagine sometimes it's not enough, particularly with a big cam/little vacuum at idle)
The scaling trick cannot fix hardware limitations, it just keeps you out of the issue of lacking sufficient resolution to make a small enough fuel change at idle to have good control--- doesn't really apply to MS3 unless your VE number is really low, as VE is in tenths. It makes a significant difference on MS2 and very probably MS1, and at worst hurts nothing on MS3.
On a 4 cylinder, if you have an MS3+MS3x the simplest sure hardware solution to "too large" injectors at idle is a second set of smaller injectors and use the staged fuel features.
You can even do it on a V8 with the primary injectors at idle, where the staged larger set run as batch off the mainboard drivers. (above a certain rpm and load, sequential doesn't really help unless you need per cylinder fuel tweaks)
If you aren't running sequential and lack even the MS3X you can do it strictly using the 2 mainboard drivers to run the primary/secondary injectors in batch.
OTOH 75 min/235 max is reasonable in my mind, is he having issues setting idle AFR properly?
Is it in the injectors linear range at idle?
Sometimes a vacuum referenced reg is the only way to get large injectors working at idle.
(and I imagine sometimes it's not enough, particularly with a big cam/little vacuum at idle)
The scaling trick cannot fix hardware limitations, it just keeps you out of the issue of lacking sufficient resolution to make a small enough fuel change at idle to have good control--- doesn't really apply to MS3 unless your VE number is really low, as VE is in tenths. It makes a significant difference on MS2 and very probably MS1, and at worst hurts nothing on MS3.
On a 4 cylinder, if you have an MS3+MS3x the simplest sure hardware solution to "too large" injectors at idle is a second set of smaller injectors and use the staged fuel features.
You can even do it on a V8 with the primary injectors at idle, where the staged larger set run as batch off the mainboard drivers. (above a certain rpm and load, sequential doesn't really help unless you need per cylinder fuel tweaks)
If you aren't running sequential and lack even the MS3X you can do it strictly using the 2 mainboard drivers to run the primary/secondary injectors in batch.
Addendum to Newtons first law:
zero vehicles on jackstands, square gets a fresh 090 and 1911, cabby gets a blower.
EZ3.6 Vanagon after that.(mounted, needs everything finished) then Creamsicle.
zero vehicles on jackstands, square gets a fresh 090 and 1911, cabby gets a blower.
EZ3.6 Vanagon after that.(mounted, needs everything finished) then Creamsicle.
- Chip Birks
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- Joined: Wed Mar 12, 2008 5:59 pm
Re: Injector Dead-time/PWM and req fuel on 1971cc type 4
My setup is is close to what Mario has described, VE table values are all on the low side though. Although, I know that the whole map needs retuning, bad. I did some major injector timing tweaking and now the car runs rich across the board. I just haven't been able to drive it since the 1st of November.
I had an issue with the car not starting without throttle pedal use, after doing some research I decided to drop my cranking pw way down from where it had been. I ended up with it down in the single digits on a recently fired, but still pretty cool engine. Fully warmed up it, it seemed like 1% r 2% was almost too much. In discussion with Mario, we tried messing with the req fuel and VE table values, hoping to get a little more resolution on the cranking table, unfortunately both numbers were already very low. 3.8 req fuel, and VE values in the 20's at idle. I ended up doubling the req fuel, and halving the tables, so now my idle numbers border on single digits. Luckily it is MS3/3X and fully sequential, so resolution is still theoretically in the low triple digits. But it didn't really gain me a whole lot of resolution on the cranking table. I did find that there is a setting for fools like me with huge injectors installed on little engines that allows it to fire the injectors in a more alternating pattern during cranking. This actually gained me the most resolution on the cranking table. The numbers are still way low, but it will actually fire and catch as soon as it syncs. There is definitely a learning curve to this stuff.
I had an issue with the car not starting without throttle pedal use, after doing some research I decided to drop my cranking pw way down from where it had been. I ended up with it down in the single digits on a recently fired, but still pretty cool engine. Fully warmed up it, it seemed like 1% r 2% was almost too much. In discussion with Mario, we tried messing with the req fuel and VE table values, hoping to get a little more resolution on the cranking table, unfortunately both numbers were already very low. 3.8 req fuel, and VE values in the 20's at idle. I ended up doubling the req fuel, and halving the tables, so now my idle numbers border on single digits. Luckily it is MS3/3X and fully sequential, so resolution is still theoretically in the low triple digits. But it didn't really gain me a whole lot of resolution on the cranking table. I did find that there is a setting for fools like me with huge injectors installed on little engines that allows it to fire the injectors in a more alternating pattern during cranking. This actually gained me the most resolution on the cranking table. The numbers are still way low, but it will actually fire and catch as soon as it syncs. There is definitely a learning curve to this stuff.
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Re: Injector Dead-time/PWM and req fuel on 1971cc type 4
Hello,
I used to run low impedance Vanagon injectors in my 1971 type4 from 81 Vanagon - but they were getting tired, and they produced some electrical noise. I decided to switch to later Vanagon injector (HighZ). Click on the link. These injectors are fine for naturally aspirated type4.
You could get 800-1206N (disk type) or BWD 57530P (disk type)... or plain BWD 57530 ... $25 /pop or so with discounts+tax. (AdvanceAuto,AutoZone,OReillys all carry these at discount).
They are direct plugin after you remove the resistor bank.
Injector-dead time is around 0.910 for HighZ, and around 0.71 for LowZ...
Voltage Correction is around 0.20.. These are the default values..
Req Fuel 16.7 (8.35ms)/2 squirts per cycle/simultaneous/untimed injection.
I used to run low impedance Vanagon injectors in my 1971 type4 from 81 Vanagon - but they were getting tired, and they produced some electrical noise. I decided to switch to later Vanagon injector (HighZ). Click on the link. These injectors are fine for naturally aspirated type4.
You could get 800-1206N (disk type) or BWD 57530P (disk type)... or plain BWD 57530 ... $25 /pop or so with discounts+tax. (AdvanceAuto,AutoZone,OReillys all carry these at discount).
They are direct plugin after you remove the resistor bank.
Injector-dead time is around 0.910 for HighZ, and around 0.71 for LowZ...
Voltage Correction is around 0.20.. These are the default values..
Req Fuel 16.7 (8.35ms)/2 squirts per cycle/simultaneous/untimed injection.
1981 Volkswagen Vanagon Westfalia - air-cooled Type4 1970cc CV (hydraulic lifters, 42x36 valves, stock cam, microSquirt FI)
1993 Ford F-250 XL LWB Extended Cab 7.3L IDI
1993 Ford F-250 XL LWB Extended Cab 7.3L IDI