Author Topic: Megasquirt and DASC - Need info.... (Read 11691 times)

JiXer · « **on:** December 12, 2007, 10:47:51 PM »

I will be doing a DASC (Downing Atlants Super Charger) on my e30 318iS and I want to use Megasquirt for Engine Management.

I was hoping to find a similar write up from someone who is boosting approx. 7 PSI and running megasquirt.

My main concerns are things like choice of air temp sensor, crank position sensor and pulse wheel, beginning fuela/spark maps, etc.

I figure there is a write up somewhere on here, but I wasn't having much luck finding one. I can also get on r3vlimited and e30tech if someone knows of something there.

Thanks in advance for the help.

J.
http://www.bigfishmotorsports.com

nickmpower · « **Reply #1 on:** December 12, 2007, 10:52:34 PM »

your best bet is to just read what grassroots motorsports did to theirs and copy it. Megasquirt isnt going to get you much above the hp they got if you even match it, and you have a much greater chance of blowing your motor because of tuning

tim_s · « **Reply #2 on:** December 13, 2007, 04:23:54 AM »

i don't agree, especially with the bit about blowing your motor. Megasquirt would be a very good solution, and standalone management is the way to do things properly. Clearly with the grassroots motorsports car they had a lot of trouble with mapping, and a full standalone would be a good solution, as long as you're prepared to put the work into it.
I'd say you're much more likely to blow your engine on the factory ECU, esp with factory timing on a blown engine, and with all the modifications it would require to the fuelling, cahnging the fuel pressure etc, than with a full standalone solution with wideband lambda feedback and AFR targetting based on it's output. The megasquirt will ensure that the engine is fuelled correctly, timed correctly and as a feedback system when coupled with a wideband lambda/knock sensor will ensure that you don't run lean and don't run any det etc., meaning your engine is much better safeguarded against blowing.

tim_s · « **Reply #3 on:** December 13, 2007, 04:27:39 AM »

Quote

My main concerns are things like choice of air temp sensor, crank position sensor and pulse wheel, beginning fuela/spark maps, etc.

You shouldn't be too worried about this. You can use the standard 60-2 wheel no problems, likewise with the temp sensors if you calibrate the megasquirt. For base maps, I can help you for a standard M42, although you'd be well advised to have a go from scratch yourself. Once you have the car idling correctly then you can make a good estimation of a workable map, then with some testing on load you can get pretty close, and use autotune/megalogviewer to help you hone the map further to help you understand how to get it perfect. I think the real heads up that you'll need will be getting the map perfect, which is much mroe difficult than getting a good map - acceleration enrichment, for instance, is tricky to get right.

haledj · « **Reply #4 on:** December 13, 2007, 05:35:19 PM »

I don't have any experience with the DASC, but plenty with megasquirt.

I would suggest just starting with fuel, and using the stock ecu for spark until you have a workable fuel map. (I am not sure if the ecu will do this, someone with more experience with the stock ecu might be able to tell us)

I am also a huge fan of MS2 vs MS1.

I haven't put too much though into MS on an m42 application, but I do know that all the required elements are there and useable.

Also, you NEED a wideband, and I would set that up before switching to MS, get it up and running on the car in the NA stock setup. I don't know of anyone using the JAW, but it sounds competent and cheap.

http://www.14point7.com/JAW/JAW.htm

Do you plan on running water/meth injection with MS?

I use MS2 v3 on our superflow dyno engines and MS1 v2.2 on our RX-7 race car.

tim_s · « **Reply #5 on:** December 14, 2007, 05:45:41 PM »

good link in that thread above, never seen the JAW wideband! thanks. I've not been 100% happy with my LC1, but it is nonetheless an invaluable tool. Why are you so much of a fan of MS2 over MS1? I run MS2 but I also think MS1 extra code is really strong, feature packed yet stable.

If you keep the AFM, there's no probs using Motronic for spark and MS for fuel.

haledj · « **Reply #6 on:** December 15, 2007, 11:31:24 AM »

I really like ms2 because of the accuracy. every aspect of it is that much better. MSnS for 2 is questionable, and I havent used it yet. but for testing engines on the dyno the precision is amazing, especially on forced induction applications.

tim_s · « **Reply #7 on:** December 18, 2007, 09:49:29 AM »

I don't think MS2 extra is questionable at all imo, although the betas have many more features than the release. It's interesting how much our opinions and experiences differ, the precision has made negligable difference in the cars I've tuned! I found MS1 extra to HR code gave a little difference however.

haledj · « **Reply #8 on:** December 19, 2007, 07:06:53 PM »

I think fuel tests on an engine dyno where you can measure every variable and alter them is a completely different situation than using it in a car. I can't go into detail on what I do, but we are making power on some pretty crazy fuels.

The only reason I said MS2 extra was questionable is that I haven't used it nor did I know anyone that has, but now i do.

JiXer · « **Reply #9 on:** December 08, 2008, 06:04:25 PM »

... since I started this post and I hope you guys are still out there as I am finally am getting around to doing this build.
Couple of updates on me and how this thing is going together:
I have now built and set up a few different engine management systems for a few cars including a Megasquirt for an M20 stroker. I did the whole thing from scratch and though it took a while, I did learn a lot. One of things I've learned is that I would pay money for a quality MS timing table to get my tuning going. Fuel tuning is a piece of cake if you know where you want your AFR, but the timing is still a mystery to me.

So if anyone has a boost timing table or more specifically, one running a DASC, I would be stoked. I know that would not be a turnkey thing for me, but a good starting point is key.

All that said, here is the set up I am going to run (I call it an M43

- M44 motor (head, pistons, rods - all stock)
- M42 Crank
- Compression Ratio should be around 9.3:1
- Boost Target = 12psi (stock 5.75" crank wheel & 3.4" pulley)
- M42 front cases, cam sensor, 60-2 crank sensor, throttle body & TPS
- M44 knock sensors
- Megasquirt (fuel & spark) running off of MAP with 42# Hi-Z injectors, full length headers, & 3" exhaust

Where, oh where do I begin with timing. I DO NOT feel comfortable with even trying to start the car off of one of the MS generated maps. No way.

I have started a series of posts below that outline the basics of setting up the file. Most of this is based on what I just did for an M20 motor, but it is all subject to review by others and I haven't (REPEAT - HAVE NOT) run a motor on this file yet, so please don't take any of this as a sure thing just yet.

J.

JiXer · « **Reply #10 on:** December 08, 2008, 06:37:20 PM »

Megatune 2.25 - Specifics:
Engine Constants:
Required Fuel: 7.2
- Displacement: 1900cc
- Cylinders: 4
- Injectors: 42 lb/hr
- AFR: 14.7 (gasoline - in my case 91 octane)

Injector Characteristics:
(Delphi 42# High Impedance)
- Opening Time: 1.2ms
- Battery V Correction: .2
- PwM Current Limit: 100%

- FIdle Threshold: 160�F

- Baro Corr.: off

Injector Control
- Control Algorithm: Speed Density
- Injections per Engine Cylce: 2
- Injector Staging: Alternating
- Cylinders: 4
- Injectors: 4
- MAP Type: 250kPa
- Engine Type: Even Fire

JiXer · « **Reply #11 on:** December 08, 2008, 06:41:59 PM »

Megatune 2.25 - Specifics:

Using Innovate LC-1
- Sensor Type: Wide Band
- EGO Switch Point: 2.352
- Ignition Events or msec per step: 31
- Controller Step Size: 1%
- Controller Authority: 10
- Active above CLT: 140�F
- Active above: 1,400 RPM
- EGO Corr. Step Counter: mSec

JiXer · « **Reply #12 on:** December 08, 2008, 06:50:55 PM »

Code Type
Distributor: off
Neon/420A Decoder: off
Wheel Decoder: Generic Wheel
EDIS: off
TFI Ignition: off
HEI Ignition: off

The following is subject to your hardware set up.....
Input/Output pins
Fidle Function: Idle Control
LED17: Spark A
LED18: Spark C
LED19: Spark B
Multiplex Ignition: Normal
X2 JS0: Fan Control
X4 JS2: Output 1
output3/Spark D: Spark D
pin10/ shift/Spark E: Shift Light
knock in / Spark F: Knock input

JiXer · « **Reply #13 on:** December 08, 2008, 07:15:12 PM »

Base Teeth: 60
Second Trigger Enable: This is where things get ify for me. The last motor I did was an M20 which does not have a crank sensor. Is this where you would enter it in to the equation?
2nd Trigger Active Edge:

?
2nd Trigger Missing Teeth:

?
Missing Teeth: -2

And thats where I get stuck. Does anyone have this figured out? I will verify it once I have the pulley system back on and TDC set, but I want to know what others have come up with.

JiXer · « **Reply #14 on:** December 08, 2008, 07:19:24 PM »

Clueless. Someone gave me the numbers for the M20, so I never even really read about it.

Author Topic: Megasquirt and DASC - Need info.... (Read 11691 times)

JiXer

Megasquirt and DASC - Need info....

nickmpower

Megasquirt and DASC - Need info....

tim_s

Megasquirt and DASC - Need info....

tim_s

Megasquirt and DASC - Need info....

haledj

Megasquirt and DASC - Need info....

tim_s

Megasquirt and DASC - Need info....

haledj

Megasquirt and DASC - Need info....

tim_s

Megasquirt and DASC - Need info....

haledj

Megasquirt and DASC - Need info....

JiXer

Its been quite a while.....

JiXer

Engine Constants

JiXer

Exhaust Gas Settings

JiXer

Codebas and Output Functions

JiXer

Wheel Decoder Settings

JiXer

Dwell Settings...