Megasquirt / Megajolt timing tables

[burgandy81]

Hi All,

This thread will be my first in a series of MegaSuirt Spider topics. I will start with timing. Hopefully this will be of some use to others in the future.

For those of you who are not familiar with MS it is a DIY engine management system. Megajolt is related system that focuses on ignition only.

While I have managed to complete the build and get the car running I could use some help on the fine tuning. I hope to spend this summer tuning my long-term MS Spider project. I have receive fantastic help and support on the MS forums for all generic questions. Now it is time for very Fiat specific input. For that, I appeal to the FS.com brain trust.

A few details

Car = 1980 Fiat 2000 FI. 120,000 km and ran well for a few years of ownership.
-Stock internals.
-GM temperature sensors for water and air
-Innovative LC Wideband O2
-Lancia Delta intake manifold
-DSM 450cc injectors on custom fuel rail
-EDIS4 ignition with COP conversion
-stock FI exhaust manifold and exhaust (for now).

Megasquirt firmware = MS2 Extra v2.0.3
Software = TunerStudio


So here is my current timing table. The car starts OK and runs OK without load up to 4000 rpm, in my garage.

The map signal allows input up to 250 kpa which is in preparation for a turbo, the driving force behind the whole project.

This table has a "trough" from 800 - 1000 rpm. The trough was created to help stabilize idle and has been very successful in conjunction with a similar trough on my fuel map (which I will be looking for help in another post).

At 400 rpm the ignition is set at 2 degrees above idle. This is my low tech idle control. If the idle drifts below 800, the timing advances to increase engine speed.

As the ignition table is foundational to the engine running well I am looking for input and comments



This is the same map in 3D. In this view the idle stabilization trough is easier to see and the timing retard for boost is well represented with colors and contour.




Thanks for looking!

Jordan

[Daniel]

Hey Jordan

This is what I'm setting up on my engine hopefully soon thanks for the post.

[burgandy81]

Hi Daniel,

Looking forward to seeing a bit more about your project. Do you have

Have you done any research on ignition curves? Any comments on what I am using?

I am hoping to get some comments to help finalize this table. Once that is done (and i find some time) i will begin the rest of the tuning.

[unplugged]

Jordan,
I am in almost exactly the same spot you are. I have a Megasquirted '81 with the EDIS ignition. It has only been on the road a few weeks. The internals are not stock and I have much less power then I was expecting so I have started to play around with my timing tables. I do not have enough experience to comment directly on your table or even how much an impact timing can play a role in the issues that I am experiencing. I have been trying to research this myself and have not found much if anything useful online. On Miller's Mule's Blog he posted a 2D table for Megajolt. http://www.millersmule.com/blog/. His 2D map appears similar to what you have on the bottom end of your table. I have GC's book and there are several tables published in there including 8 tables generated by Fiat for the Delta 4WD turbo. The 8 tables range from 18 kPA - 180 KPa. I might try to map those into a spreadsheet as a place to start.

I have HC pistons, ported head, new cams, new larger injectors and I am only seeing 0-60 in 13+ seconds. AFR looks good so I believe it is getting enough fuel.

[Daniel]

Hey Jordan

I'm using the V3 not sure if that matters or if all the same software applies at this point I'm a noob at this
and learning by other user posts and forums so i wouldn't be of any help or at least till i get some data charts up.

My engine is a ways from being completed we shall see how it turns out.

Daniel

[burgandy81]

Unplugged,

It is my understanding that map based timing is VERY useful is ringing out those last bits of power. Thanks for the links. The idle control trough on the Millers Mule site is more extreme than I have. It makes sense; if the advanced timing helps, great! If not, it is going stall anyway. I wonder if that is a Fiat curve?

I have a couple of Millers Mule EDIS parts on my car and several more are on my wishlist. Fantastic goodies! I was hoping Jason may offer an opinion if he is around as he seems to be doing some interesting stuff with Megajolt.

My concern with using a Delta map is that the compression ratio was lower (7.5) and the cams were different on the Delta engines. This is where I run out of knowledge. Should i use the Delta map on the Fiat motor? Is the factory ignition curve best? What did the racing crowd use for advance in a stock 2L?

I am having issues with cold start and will post a MS cold start thread once I get the timing sorted and some basic tuning dialed in. Let me know if you have any other specific issues and maybe we can create a combined thread to solve a common issue or two.

Daniel,

Thanks for following up. Looking forward to seeing where you end up.

Cheers,

Jordan

[Daniel]

Hi Daniel,

Looking forward to seeing a bit more about your project. Do you have

Have you done any research on ignition curves? Any comments on what I am using?

I am hoping to get some comments to help finalize this table. Once that is done (and i find some time) i will begin
the rest of the tuning.

The one thing i can share with you, 36 Degrees is the normal maximum advance any normally aspirated engine
running pump gasoline. Your advance curve will depend on a number of factors, the cams that are
selected and compression will have the most impact on the timing needed for your best desired performance.
Fine tuning will be a case by case basis unless it's the same exact engine with the same setup that being said
this almost never happens. Your most likely going to need some experimental time and a lot of patience on a
new project like this. I like the ideal of keeping this post going with the people on here who have made this FI
system cross over. I promise to do some photos, maps and info once i get to this point ( hopefully soon) if it
helps someone out that will be great.

[timinator]

Hi Jordan, just a few quick thoughts. The idea of using a turbo based load map is not going to help you with an N.A. engine. You want as much resolution as you can get so don't have most of your map dedicated to loads you can't achieve. Make a new map when you get to the turbo as the ignition timing will be way different. Since you are limited to a 12x12 matrix don't devote so much of your rpm scale to idle. The program will interpolate for you in the low rpm region. Add more columns around max torque where things happen with more destructive results. At low engine loads(read as cruise) the engine can use more than 36 deg. of timing for best fuel economy. I find it helpful to set the bin at highest load and lowest rpm to zero so when you are rotating the matrix in 3-D there is an obvious point of reference.

[burgandy81]

Timinator,

Good post. All of the problems I have had with this project have been from me trying to get too far ahead of myself. A solid NA map is a good idea.

Will work on this and report back.

Anyone have a sample?

[burgandy81]

OK. Following some good advice I have begun creating a NA map for my spider project.

In my search for information I found a document that listed 8 graphs showing the ignition map for the Fiat Ritmo 130 TC. This is from an official looking Magneti Marelli document detailing the Digiplex system. Keep in mind this was a higher compression engine at 9.4:1. As I understand it, the Digiplex was an early mapped ignition unit that allows for much greater control of ignition events. These graphs show some very interesting variation in timing.

Below (i hope the image works, it is not showing up on the previews) is a MS map that includes all the points listed. The maps only showed variation up to 40 Kpa. Everything over 40 Kpa is the same. Note the very high advance of 44 in some places.

The low rpm bins are mine to stabilize idle as mentioned earlier posts. The Digiplex maps is 10 degrees from 0 to 1000 rpm in all vacuum ranges.









Anyone have any thoughts or comments? Specifically, what changes would you suggest for use in a stock 81 Spider?

I will keep looking.

[timinator]

Can you describe the term ignload % in units? Imperial would be easier for me, but metric is o.k.

[ORFORD2004]

The spark advance table is RPM related to Manifold Air Pressure (MAP) in my megasquirt.

[burgandy81]

True. 100% = 100 Kpa which is atmospheric.

[timinator]

Before you start filling out timing maps it would be helpful to select which boost gauge you plan on using. That way you can select your map units that correspond better with the units of your gauge IMO. If you have a gauge that reads in absolute pressure then you can continue as you are. The latest map you posted makes no sense to me. 44deg. at 100% load is just wrong. At very low engine load and lean mixtures 44deg. would be more correct. I believe that the vacuum advance on a fiat is approx. 9 deg. crank. It starts to advance at 5-6 inhg and is all in by 14. If your max timing is 35deg. then adding 9 would give you 44deg. They just put it on the wrong area of the map.

I like to start my timing maps on the conservative side so on a Fiat that would be more like 33deg. As Jason says just install a map that acts like a mechanical distributor and then go back and fine tune the areas where you can gain fuel mileage or better control of detonation. So something like 33deg. with 100% load@ 4000rpm down to 42deg. with 20% load @ 4000rpm.

[burgandy81]

Timinator,

I appreciate your following along on this thread and your input is very helpful.

It is likely I interpreted the maps incorrectly. Below are the original maps I was using to create my map. It doesn't help that my French is very poor and both documents are in French only. I assumed that the maps were all I needed.

Looking at these maps in light of your comments, I feel that I have this exactly backwards!! By reversing the readings it makes sense but I still cannot figure how to read this correctly.

These are the Lancia Trevia digiplex documents. This is a 2L engine developing 115Hp in 1982. Close to North American spec Spiders.










So after all that, i will follow sound advice and replicate the mechanical advance curve as below.

Timinator, I did not understand where to taper to 42. can you suggest an area of the map please?