megasquirt and msd ignition box combined work great
for anyone wanting to control an ls1 i think this is an option worth looking at. the msd box with harness was $250 on ebay. the ms with harness is $390 at diyautotune. for a total of $640 you can completely control and tune the motor.
the msd box is completely plug and play. it plugs into the stock coil packs, map, crank and cam sensors. then it has a ground and power wire and also a couple of inputs to trigger nitrous timing retard or the 2step. the timing maps are pre programed or completely programable and you can use a 1,2 or 3 bar map.
there is a tach output on the msd that hooks up to the mega tach input. land a few wires to some sensors and to the injectors and vroom. fires right up. the mega has some nice features like running low z injectors, fan control, real nice nitrous control, many other features.
the mega still needs a couple of output circuits wired into it. not sure why they haven't made that standard yet. it is about $2 worth of parts and 20 minutes of work.
got a prety good idea from the boards and from other projects what a safe level is and just didn't go over that.
it is a dream tuning the fueling with the squirt. easy on the fly tuning. ability to run low z injectors, also added ability to run other stuff like fans and nitrous(wet or dry). if you do it this way you will still need a programer for the stock computer to do timing, shift points and other stuff like turn off codes.
i have never tuned anything like the 2 bar map set up that hp tuners has. might be a good way to go but you would still need an impedance converter to run the low z injectors.
With the squirt hooked up to the truck, say you changed the PE table or any other fueling table in HPTuners, does the computer not even see those changes? What I'm asking is, how does the ecm neglect any fueling calculations that are in your existing tune?
Will I still use the scanning tool in HPTuners to scan things like STFT and LTFT?
Hope these aren't stupid questions, just trying to learn.
Last edited by Blown06; Dec 4, 2007 at 11:58 PM. Reason: more questions
to tune the fueling with the squirt you fill out a ve table. it is very easy to do. the tuning is real time. you click and it changes. there is a map. either 8x8 or 12x12 cells that has rpm on one side, manifold presure on the other. as you drive thru the rpms there is a "ball" that moves around on that chart to show you what part of it the computer is using to do your fueling. you goto that part of the chart and click it up or down to add or pull fuel. just that easy.
you can also log it and then adjust after the run. i like to get it close with real time tuning. let someone else drive it and rev it thru the rpms and diferent loads as i click away. once it is close then i make full runs and adjust afterwards.
there are lots of neat functions you can mess with. the wot stuff is easy. idle is easy. the transitions during normal driving takes a little time to get just right. warm up enrichment needs to be done when it is cold and actualy warming up.
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it is night and day easier to tune with the squirt. sometimes it is a little hard to get it to fire up but if you can borrow a tune from someone it helps. once it is running you look at the a/f gauge and adjust by clicking on the ve map.
then just sitting there you rev it up a little and adjust. then rev it higher and adjust, then higher... till you have it tuned from idle to ~6000rpm with no load.
then you put it in gear with your foot on the brake(and nothing in front of the truck) and do the same thing again but you can only go so high in the rpm range before it starts to push. it all happens really fast. you save the tune every now and then just in case you mess up so you dont have to start all over.
then hop on the street with a driver. get it into 2nd and have them give it a steady lite throttle and go up thru the rpms. follow the ball and tune it as it goes thru the ve map. if it gets too lean have them let off and add several clicks and try it again. you can get an idea of where things are going and get some clicking done between runs, err on the rich side and work the map down. have them do the same lite throttle run till you have the a/f ratio where you want it. then do the same thing but with a little more throttle, then more....
from the time we got my truck fired and idleing to wot 10+psi runs was less than an hour. messing with the acell enrichment and some other little things to get it to drive like stock took longer. like a couple more hours to get it just right.
btw, what is the latest on your truck and the fairmont?
http://www.v8rx7forum.com/v8-rx-7-bu...tml#post411417
It is a bit tougher, you have to add a few more compnents and I also had to add some noise filtering capacitors to get everything running clean. All of that is documented.

Also, lets get some pics!
Last edited by Area 51 Racing; Dec 13, 2007 at 12:48 PM.
btw, If I were to run a fuel cell set up with a big external pump and bypass starting with a static fuel pressure of around 70 psi w/reg on a 1:1 for boost, how much power could I support with the 60lb. injectors?



