Hi there, first post--new to the club but long time reader. I'm currently about 2 week(ends) away from starting my 97 Eclipse with a custom Garrett T3 turbo, and powered by our friend, Mr. Megasquirt. I have done a lot of reading by your posts Mr.Slick and totally agree with you that Megasquirt is a breeze to assemble. However, I have a couple questions I was hoping you could help me with:

1: I found a diagram posted a while ago that will greatly help installing the MS, with wire colors, PIN numbers and so on. However, I noticed that you have the 2 batches of injectors labeled as (1 & 3) and (2 & 4). If the firing order is 1,3,4,2, wouldn't it make sense that you run the MS in alternating mode with the batches on 1 and 4, and then on 2 and 3? I am triggering the MS using the two supply lines to the coil packs using two diodes, so I can run the MS in 4 cylinder mode. Am I missing something here?

2. What is the max voltage the MAP can see? We're running a potentiometer (sp?) to bleed off extra voltage. Is it above 4.5 Volts that it'll throw a CEL?

3. How much would you charge to give me a VE table if I told you the injector size...etc, that would just start the car. Obviously, we'll have to tune it to our conditions once we get it running.

I think that's it for now. Thanks for your time, and your answers are most valued and appreciated.

Brian

if you look in your block, pistons 1,3 go up when 2,4 go down. hence having 2 patch firing. also map dosent like over 4.5, some are differentm, but that seems to be a good number to start with.

If you're running a MS, you don't need to worry about the stock MAP sensor anymore. You can run a real MAP sensor, like a 2.5 or a 3 BAR sensor, because this ECU won't tweak out when it notices boost.

You can't get rid of the stock MAP sensor because the stock ECU uses it for ignition timing calculations.

Grain- have you ever even looked at your rotating assembly? If you had you'd notice that it's pistons 1&4 and 2&3.

I recommend using a Synapse Engineering Missing Link (check valve device) for the MAP sensor instead of a voltage clamp. It prevents damage to the sensor and yields much more consistant results.

Grain aren't you running MS? How do you have your injectors connected in the banks? Are you running in a 4 or 2 cylinder mode?

I just had my oil pan off (for the return line), I never thought to look at the rotating assembly for cylinder synchronization.

Doug, where can I get this missing link? I'm assuming it's basically a pressure bleed as opposed to a voltage? How does it work?

Thanks for your help guys.

Hi,

Basically the reasoning behind squirting 1+3 and 2+4 together is that because of the firing order, youll have the fuel there pretty much int he order that it's needed, i.e. the same order that the cyclinders will fire in.

Next, you probably could get away with using diodes and running off the coil pack, but the better way is to run it in 4-Cylinder mode, running off the factory Tach signal. The way to do this is to perform the following mod's to the MS:

. Remove D5, D8, R10
. Remove jumper between XG1-XG2
. Fit wire between XG1 and right of D5 (non band)
. Fit wire between bottom of R10 and right of D9 (band)
. Fit 1k resistor in place D8 <1K>

Then you can use the stock Tach. output... ;)

And yes I could give you a MSQ file to use if I know your injector size and some more about your setup.

Oh, and yes you need to limit the MAP voltage so that the stock PCM will still be able to control the ignition. One way is to use the missing link as mentioned above.

Lee.

Excellent, thanks man :thumbsup

I'm still trying to get why you wouldn't want to just have injectors 1 fire, then 3 fire, then 4 fire then 2 fire (i know MS doesn't do sequential, but batch them so it does that)


In a quest for understanding,:scratch I wrote out the firing order, and then underneath it the injectors that would be firing (assuming the MS fires the injectors every time there is an ignition event).
From your explanation, are you saying that having 1+3 and 2+4 firing like, that gives some time for the fuel to vaporize once it hits the intake valve? Thus when the time comes, the valve opens, and better vaporized fuel goes in as opposed to just shooting it when the valve opens?
I know our ignition system is a batch system, is our stock fuel batch as well? Do you know if it runs 1+3 and 2+4 together?

I'm not doubting you however, you're the one with the running car!! I'm planning on hooking up the way you told me. Thanks for your time to help me understand.

Can I just PM you with my specs and get that table?

Thanks again

Brian

Hey guys,

I am the owner of the yard that Brian's (forcefed420a) project is being worked on in hehehe. Actually I am helping Brian complete this project as well.

I have a few questions/comments myself...

For the MAP clamp... is there an actual published PHYSICAL pressure that the MAP sensor can withstand? I know on most sensors the max physical pressure is MUCH higher than the actual max pressure that the sensor makes a voltage for.... We have a simple circuit for a map clamp that is adjustable so that we can dial the max voltage as close to the max without going over so that the ecm sees the signal as accurate as possible. I myself am a Turbododge guy and we've been tossing map clamps (zener diodes) on 2 bar map sensors (14 lbs of boost max) and cranking 30psi of boost through them for years before folks started making 3-bar calibrations with no ill effects.

Mr Slick,

With the injector hookup that you describe, do you run it in ping pong mode or all injectors firing? i assume ping pong....

Another question for you... Fuel system... did you use the schrader valve for the fuel return like everyone is doing lately? We didnt. We used a 55psi stock shelby charger fuel pressure regulator about a foot before the fuel rail based on the theory that the pressure in the rail and the rest of the line should be equal. we are running 52lb (at 55psi) chrysler injectors from the Mopar Super 60 package and we wanted a large enough fuel return so that the fuel pressure doesnt become too great at idle so that the car will idle smoothly. any comments/cautions on this... i figured that quite a few neon guys stick with the returnless system and the factory 2gnt has the regulator before the fuel rail that this would be ok.

Brian,

Mr Slick's method of making the modifications to the MS for the tach are really easy looking. you might want to do this so we arent hacking the harness for the coilpacks and jerryrigging crap. (though you know I like to jerryrig crap lol) think about it.

Thanks Guys

Brian

just wanted to comment

Originally posted by reliant_turbo
on 2 bar map sensors (14 lbs of boost max) Brian

a 2 bar map can read more than 14psi. 1 bar = 14.7psi

Originally posted by turbo8u
just wanted to comment

Originally posted by reliant_turbo on 2 bar map sensors (14 lbs of boost max) Brian

a 2 bar map can read more than 14psi. 1 bar = 14.7psi

turbo8u-
You're referring to gauge pressure, not absolute pressure.

1 bar of GAUGE pressure = 14.7 PSI
1 bar of ABSOLUTE pressure = 0 PSI

MAP = Manifold Absolute Pressure

Get it? Learn something new everyday! ;)

Originally posted by dougie2

Originally posted by turbo8u just wanted to comment

Originally posted by reliant_turbo on 2 bar map sensors (14 lbs of boost max) Brian

a 2 bar map can read more than 14psi. 1 bar = 14.7psi

turbo8u- You're referring to gauge pressure, not absolute pressure. 1 bar of GAUGE pressure = 14.7 PSI 1 bar of ABSOLUTE pressure = 0 PSI MAP = Manifold Absolute Pressure Get it? Learn something new everyday! ;)

Yeah, I was gonna say this but he beat me to it :) Dont worry, Im no fool :) You cant be a total idiot and build a K-car that spins the tires from a 55 mph roll in 3rd gear heheheh ;);)

Brian

Originally posted by reliant_turbo
For the MAP clamp... is there an actual published PHYSICAL pressure that the MAP sensor can withstand?

Not that I have seen, but i'm with you on this - thinking that 10-20psi of boost will break a 1bar map sensor is ridiculous. it's not like there's a diaphram in it to break, it's a solid state sensor. I don't use ANY sort of clamping device - either electrical or mechanical (Benefit of the 95 model year), and i have never lost a MAP sensor. My car has been turbocharged for nearly 4 years.

yeah we're just going to use the dennis doza radio shack special MAP clamp and be done with it. I dont really like the missing link style stuff cause its a mechanical fix on a sensor that is CRITICAL to the engine staying together. Plus lots of guys are always saying "missing link is goofing up and i had to clean it cause it was dirty" and i dont want to have to deal with that kind of crap. an electical clamp is much more reliable in my mind as long as its set correctly from the start. I didnt think that the 2gnt had a "special" MAP that the plastic casing explodes at 14 psi lol. :)

Brian

No physical damage will occur to the stock 2gnt MAP sensor from running it under boost.

You just need to limit the voltage that the stock pcm sees from it.
I limit the voltage to 4.6V with a simple circuit I built consisting of a resistor and a zenor diode. It's simple, it's reliable, and it works perfectly.

As far as the fuel injectors go...
The stock 2gnt fuel injection system is a sequential injetcion system, hat is it fires each injector at the time it'e needed... however if you know anything about sequential fuel injection, then you'll know that it can only work in sequential mode at idle and lower rpms, because there is only so much time available in which you can inject sequentially. Sonce a certain rpm/load point is reached on the stock pcm it has to revert to a batch injection system of sorts.

The whole batch vs sequential arguement is one that still rages, however on out engines, batch injection of the injectors works perfectly. If it didn't I wouldn't be able to idle on 780cc injectors now would I.. ;)

As far as the setup that I use ont he Megasquirt, I run the injectors in Alternating 2 Squirt mode, basically this means that for every 720 Degrees of rotation of the crank, you get 2 squirts, first on injectors 1+3 together, then 360 degrees of crank rotation later you get 2+4 squirting.

Hit me up with any more questions that you have.

Oh yeah, get rid of the returnless fuel setup, and run a return line from the valve on the end of the fuel rail.

It is a lot harder to run and tune a turo car without a return line... I have seen this in person.
If you have no return line then as boost increase, the diferential pressure between the fuel injectors and the intake air pressure decfreases, thus the effective size of your injectors decreases as boost goes up.
Run a return line, it's simple, it works and it's safe. Not to mention easy to tune.

Lee.

Thanks Mr Slick, Im sure the other Brian will express thanks as well.

We'll run it in 2 squirt alternating batch mode...

As far as his fuel system goes, we did install a new 3/8" line from the fuel pump to the engine bay, a boost referenced 1:1 55psi regulator (stock 87 chrysler turbo regulator) in the engine bay and used the existing 5/16" return line back to the tank. what we did a little different was the fact that the regulator is about a foot BEFORE the fuel rail and bleeds the pressure back to the tank in this manner. Theoretically it should maintain the same pressure throughout the entire line and fuel rail. The test port thats usually used for the return line seems a little small and could build pressure at idle as the fuel pump is cranking away in the back making the car run rich... then again, you are able to idle with 780cc injectors. Let us know any of your comments. thanks

Brian

Yes, thanks very much Mr.Slick, and everyone else. Much appreciated help.