DT - How are the banks firing and what happens at 100%DC

havneren · Post by **havneren** » Sun May 07, 2006 12:49 pm

HI.

IÂ´m running MSnS-E in my old four cilinder rabbit. I have now bild in an ekstra set of injectors and are now converting to DualTabel. The two set of injectors are 4*304 and 4*580.

In the efford to reduce pulsing in the fuelrail, IÂ´m seeking some info on how DT triggers to two injector banks -

Does MS running in DT mode trigger the two banks simultaneously?

If it does, IÂ´m thinking about letting the first injectorbank run at 100%DC so the pusling is redused to the second injectorbank. This will only work if MS doesÂ´ent insist on closing and opening the injectors even at 100%DC

Does MS insist on opening and closing the injectors at 100%DC?

IÂ´m aware of other possible problems when running at 100%DC, but right now iÂ´m just considering my possibilities.

Greatings Christian Jensen, Denmark.

renns · Post by **renns** » Sun May 07, 2006 1:09 pm

Christian,

As I recall the dual table code fires both banks simultaneously, if the squirt settings are the same for each bank. You have a couple options other than dual table that might be of interest.

1.) Staged injection. With this mode, primaries fire until a specific threshold is reached (rpm, map, tps, or combo). Then both banks fire at a reduced duty cycle. The code supports different prim/secondary injector sizes as well. This does not address your concern of fuel rail pressure fluctuations though.

2.) Kurt Staging. This mode would work great for you, if a.) your engine will run equally well on either set of injectors, and b.) you switch to identically sized injectors in each set. This works in alternating mode, which is what you are requesting.

Both of these options avoid the need to tune via two separate VE tables.

As I understand it, if the injector is still open from the last squirt when the new request comes along, it simply never closes. This is what you desired, but I'm not aware of anyone running one set hard on (100%) as you describe. I suppose it should be possible as you are then tuning with the second bank only, but I'd suggest taking a look at one of the other two options listed above first.

Roger.

havneren · Post by **havneren** » Mon May 08, 2006 12:20 am

Hi...

Thanks for your reply! You nailed the isue right away...

IÂ´ll already looked at the "staged" option but I thought I would try DT first as I have heard about small problemes when staged injectores are going from only primary firing to the staged mode - Engine misfiring.

I guess the Kurt Staging really isÂ´ent an option besause of the different size injectors -

The problem with 100%DC is that GammaE canÂ´t make the PW go any higher wtih more fuel as an result. GammeE would stille be effective at the secundary bank but the enrichment would then be to small.
IÂ´m planing to run the engine quite rich so I acturly dont think the enrichment would be any problem as a few 0.1 in AFR dont matter much at full throttle - But still - Its just not quite right.

The alternating mode in Kurt Staging would be the better solution...

I guess a nother possible solution would be to let the secundary injectors fire 3 tims per engine cycle or even 5 times - A number that doesÂ´ent divide by the primary injectors firing times... Hummm -

Greatings Christian

jsmcortina · Post by **jsmcortina** » Mon May 08, 2006 4:05 am

You have to use a divisible number because of the way it is used internally. So 3,5 are not possible for a 4 cylinder engine.

Many people are successfully using the staging and the recent 029 codes have hysteresis built in so you don't get oscillation (on/off/on/off) if you drive around the transition.

I think staging is your best bet.

Trying to run the injectors >=100% is likely to be confusing as the injected fuel will not correspond with the reported pulse width.

James

havneren · Post by **havneren** » Mon May 08, 2006 4:36 am

jsmcortina wrote:You have to use a divisible number because of the way it is used internally. So 3,5 are not possible for a 4 cylinder engine.

Many people are successfully using the staging and the recent 029 codes have hysteresis built in so you don't get oscillation (on/off/on/off) if you drive around the transition.

I think staging is your best bet.

Trying to run the injectors >=100% is likely to be confusing as the injected fuel will not correspond with the reported pulse width.

James

It doesÂ´ent surprise me that you cant use 3 and 5

Aha! A hysteresis built in - Do I get this right - The opening and closing of the two incejtor banks are overlapping each other in the 029 code? A small time delay on the secondary bank perhaps?

Perhaps I should try staged first -

>=100% - Yes, I know... Dont like the idear either!

Regards Christian

renns · Post by **renns** » Mon May 08, 2006 4:52 am

jsmcortina wrote:Many people are successfully using the staging and the recent 029 codes have hysteresis built in so you don't get oscillation (on/off/on/off) if you drive around the transition.

Just to clarify, hysteresis has been included in the staging code since its inception in MSnEdis a few years back. What Ken added was a second staging condition option, and a 'gentle' transition feature in the recent release.

Roger.

havneren · Post by **havneren** » Mon May 08, 2006 6:40 am

renns wrote:
jsmcortina wrote:Many people are successfully using the staging and the recent 029 codes have hysteresis built in so you don't get oscillation (on/off/on/off) if you drive around the transition.
Just to clarify, hysteresis has been included in the staging code since its inception in MSnEdis a few years back. What Ken added was a second staging condition option, and a 'gentle' transition feature in the recent release.

Roger.

So you dont notis it shifting over to staged mode while running?

But if the banks are firing simultanisly - I still got the isue about the pulses in the fulerail.

Regards Christian

havneren · Post by **havneren** » Tue May 23, 2006 2:07 pm

So... I tried staged injection, but I canÂ´t get it to work. When the staged mode comes on, IÂ´m on my way througt the windscreen.

I chose to let the MAP controle the mode. At 130kpa the staged mode comes on and at 120kpa it go off. I did the scaling factor like this >

(304ml / (304ml + 580ml)) * 512 = 176

I did at log on it. The primary injectors is firing at 7ms as the staged mode sets in.

Now IÂ´m goind to try a bit of math to figure out what the new PW should be >

7ms - 1ms (Injector opening time) = 6ms

6ms * (304ml / (304ml * 580ml)) = 2,06ms

2,06ms + 1ms (injector opening time) = 3,06ms.

So... The 3,06ms is my new calculated opening time for the two banks in the staged mode.
Acording to the log the PW goes instantly from 7ms to 1,6ms and AFR goes from 13,5 to >18 instantly... And IÂ´m making stars in my windscreen.

What is going on? What an I doing wrong?

Greatings Christian

renns · Post by **renns** » Tue May 23, 2006 6:17 pm

Christian,

Do you have a part of a datalog, and also an msq you could attach? That would be very helpful. Recent releases of msnsextra include a 'gentle' transition that slowly brings the secondaries on-line, while at the same time reducing pulse width on the primaries. It's possible you've either got some of the settings incorrect, or you may have found a bug in that code version. Many people have used this feature with success, so let's take a further look at your settings and see what the problem is.

Roger.

havneren · Post by **havneren** » Tue May 23, 2006 9:35 pm

Hi Roger.

I have the log but I dont have the MSQ file. I didÂ´ent save it as I didÂ´ent got it to work.

I could try the whole thing again and do a new log and this save the MSQ file.

I know its not for much use with out the MSQ file, but I attached the log.

Greatings Christian