MkIndy7
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| posted on 27/5/09 at 06:30 PM |
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Mixing TB inlet and Injector designs
Basically I'm having problems setting up the Megasquirt, either my grasp of how its tuned and all the settings, the signals recieved back from
the sencors, or something physical wrong with the design.
There just seems to be no "progression" between part throttle and accelerating, there is so little difference its making it really hard to
tune.
Basically we've got a Pinto injection manifold in, and using the Pinto injectors and then the manifold is chopped and some 2002 R1 ITB's
on there practially "direct to head" as there prefectly inline and pretty close.
Could there be a problem with the fuel mixture as the injectors and spray pattern etc is designed to be after a large plenum with a butterfly on the
far end?
Should be be using the Bike injectors as they spray more of a mist in the inlet, and more how they were designed to work.
I've also attatched our last log and *.msq if anybody would be good enough to have a look and give your opinions.
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MkIndy7
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| posted on 27/5/09 at 06:31 PM |
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Doh.. and the log
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brianthemagical
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| posted on 27/5/09 at 06:51 PM |
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I can't seem to download the msq, keeps opening a new window. Not sure if it's just me, if it is can you email it to me please. Thanks
Are you using Speed density per chance? Where is the map take off?.
By the look of the logs the likley problem is the fuel table, the load bins needing some re spacing
[Edited on 27/5/09 by brianthemagical]
[Edited on 27/5/09 by brianthemagical]
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MkIndy7
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| posted on 27/5/09 at 07:25 PM |
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Hi Brian,
Yes were using speed density.
The MAP signal comes off each individual TB in a 1" long hose and then the cylinders are tee'd from No1 to No2, and then seperately No3 to
No 4 and then the combined outputs back to the Megasquirt.
The Fuel table is spaced to try and get the most resoloution in the areas of the map where we need it, the usable MAP is from about 80-95 with a idle
of 60.
I've tried attatching the MSQ again, no idea why it didn't the first time or if it will this.. I can't find your email either
lol.
Thanks
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brianthemagical
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| posted on 27/5/09 at 07:32 PM |
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When you say there's no difference between part and wot, difference in what? MAP/load?
Any chance of a photo of the set up, it sounds like the map is the problem, which is due to not having a massive restrictive inlet system, i'm
guessing either no filter, or a filter staight on the bodies.
The only way you'll get the beat out of such a set up is Alpha -N. there just isn't enough resolution avalible.
As for the injectors, bike injectors are worlds better, but unless they fit inplace of the origionals, there's little point. The standard set up
will work fine due to the nature of the fuels travel in the inlet.
I've pm'd my email address.
Hope that's of some help.
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MkIndy7
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| posted on 27/5/09 at 07:43 PM |
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Theres no progression in the MAP signal really it just seems to fly upto atmospheric and there's very little difference imbetween.
You have to really back off the throttle to get it loan off and its almost engin breaking, and then when you go back on it bogs down and takes a
moment to pull because its gone so lean.
There just seems to be no progression between the two, weather thats physical because the manifold etc are so free flowing, and as you've
suggested no filter (atm we do have 4 individual K&N's but they araen't fitted) or because we can't capture it
electronically.
We tried tuneing using the TPS last year and that was a hopeless resoloution, Watching the throttle guage you never really drive it over 25% really
unless completely gunning it and it was harder to tell if the engine was loaded or not then.
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brianthemagical
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| posted on 27/5/09 at 07:57 PM |
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Had a mooch at your msq, it looks fairly ok for the most part.
The problem is the use of speed density. The combination of having very little depression at closed throttle, and actual atmosphere at wot, coupled
with the natural fluctuations due to the engines intake cycle. my oppinion is that it's a waste of time. i tried Speed density at one pint on my
car when i changed to itb's, it wasn't good to drive. when i changed that engine to alpha -n it was much better, and a couple of very good
tuners have agreed.
Alpha n should be much better. i should be. Have you got an msq you were using? The only thing i can thing of is the load bins weren't too good,
they should start at 0, then go up in progressivly bigger numbers, then have about 85% then 100% as the last 2.
The msq on my car has 25% half up the fuel table. so there should be be more than enough resolution, mine is fine for town driving, and a number of
cars have been the same.
[Edited on 27/5/09 by brianthemagical]
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MkIndy7
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| posted on 27/5/09 at 08:09 PM |
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The TPS tuneing was on an old laptop so would probably start from Scratch if thats definately the way to go.
Since last year we've added restrictors onto the throttle butterflies to try and make them open more progressive, like these:
Vauxhall C20XE TB
Hopeing it would help with the MAP signal but it should also help make the TPS signal more progressive I suppose.
I think we've probably made it too much of a "race" setup at massive expence to the Fuel economy and to drivability in trying to
make it economical.
I'm actually considering taking off the ITB's and putting a large plenum straight onto the stubby manifold with a Vx TB on the end (as
shown above) there good for more than enough HP and progress very nicely.
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brianthemagical
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| posted on 27/5/09 at 08:22 PM |
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TBH, the first thing i'd do is try with alpha n again, it'll only take a few hours. While the inlet may be very unresticitve and
'racy', it is still possible to tune it to give a nice engine, assuming the cams and head are std. The only problem that can arise with
aplpha n is the throttle pedal resolution. due to the lack of progressiveness in the itbs, and the short travel on the throttle linkage, car pedals
can result in driving hell. I should have mentioned it earlier, sorry, but if you havn't already, try improving the pedal ratio to give a couple
of inches pedal travel.
Fitting a plenum will have little effect, it'll still have lowish resolution on the map, but you'll lose most of the advantages of itbs.
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matt_claydon
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| posted on 27/5/09 at 08:32 PM |
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I spent months getting a driveable setup on my Pinto with ITBs using speed density, then I changed to Alpha-N (and then hybrid alpha-n) and had it
running far nicer and more progressively within just a few hours. A-N or Hybrid A-N are the only ways to go with ITBs.
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martyn_16v
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| posted on 27/5/09 at 09:06 PM |
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In a nutshell, it's the throttles.
Throttles designed for pootling about in sit very close to perpendicular to the throttle wall at idle. This means the first few degrees of throttle
movement only open a small crack around the edge of the butterfly. The butterflies on bike throttles tend to sit at quite a high angle at idle,
meaning the first few degrees of butterfly rotation quickly open up a large area for air to pass through, and are much less progressive. I have no
idea why they're made like this though, the manufacturers then go to the trouble of fitting ecu controlled secondary throttles to stop you doing
accidental wheelies all the time.
A picture would probably paint a thousand words...
Do what Matt said, use A-N 
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mark chandler
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| posted on 27/5/09 at 10:50 PM |
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I believe its your KPA mapping, just had a quick Excel, you can see where the TB's signal exists, so you need to group the settings in the high
areas, you do not need one at 25, a few between 50 and sixty, one at 75 then group the rest from 80 - 95.
Megasquirt will reconsile the inbetweens and carries the final values forward.
Same applies for RPM, buch around where you are driving, 1000 - 3000 RPM, then just 4000, 5000 and 6000 no point in going to max revs as this again
will carry across.
My Fireblade engine was the same, a little throttle is a big jump in KPA.
Regards Mark
 
Rescued attachment map.JPG
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MkIndy7
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| posted on 28/5/09 at 07:32 AM |
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Martyn_16v, I understand what you mean with the high throttle angle as its been mentioned before altho if its such a problem people ought to stop
singing the praises of bike Tb's so much lol.
That was why we had the idea of fitting the restrictors to the butterflies to try make the throttles take longer to open.
I've tried to change the MAP values and RPM to zero in on where things need to rapidly alter and get more tuneability there but am still
struggeling as it changes so fast, i've attatched a Screen Cap of the exact VE table.
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clairetoo
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| posted on 28/5/09 at 08:22 AM |
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As others have allready said - alphaN is a lot easier to set up , and I understand it to be the only way to do individual throttle bodies .
I have mine on alphaN , and had similar issues - I put it down to the chokes being too big for the engine , but one thing that made a huge difference
to drivabilty was switching from normal acceleration enrichment to RPM based enrichment (advised to do that by Mtech)
Its cuz I is blond , innit
Claire xx
Will weld for food......
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cd.thomson
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| posted on 28/5/09 at 01:56 PM |
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I'm a MS n00b so im not going to say anything on the topic, but thought you might find these interesting if youve not seen them already
http://www.extraefi.co.uk/software/MAP_TPS.pdf
http://www.extraefi.co.uk/MSLVV_tuning.htm
Craig
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flak monkey
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| posted on 28/5/09 at 02:41 PM |
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I have the same problem on my pinto and its the just off idle problem associated with the tiny movements needed which arent enough to trigger a change
in the TPS ADC.
I will have to wait and see how they GSXR 750 bodies react on the duratec, but I am expecting similar issues.
What I may try is hybrid alpha-n, but I dont know if this will sove the problem either.
David
Sera
http://www.motosera.com
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martyn_16v
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| posted on 28/5/09 at 02:58 PM |
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quote:
Originally posted by MkIndy7
people ought to stop singing the praises of bike Tb's so much lol.
But they're cheap, look bling and sound goooooooood 
They are workable, just a bit fiddly. I have actually managed to get a car reasonably driveable with bike tb's on speed-density, but it was a
tintop and so had a bit more inertia behind it to smooth out the response of the vehicle somewhat. Progressive throttle quadrants help a lot, but
there's no avoiding the fact that you'll basically end up with half of the rows on your VE table occupying a range of about 10kPa
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