Megasquirt / Megajolt timing tables

[timinator]

Setting up timing and fuel maps are a hobby unto themselves. The timing map you have now will work fine for full throttle acceleration, since it works with a distributor, and therefore you can be reasonablely confident you won't blowup your engine. So for one region of your map you are more or less done. Every place else on your map is about driveability. The upper left hand corner of your map describes loads and rpms that the engine will never see. 100% load at 400 rpm is not important. Same can be said for for the extreme lower right corner. 0% load and 6000 rpm doesn't matter either. You still have to put something there though. Upper left I put "0". Lower right I put what ever max timing will be, say 42 deg. The next step is to go drive the car and data log what the engine is doing. High load should be at 12.5 afr, low load at 15 afr. Since you already have the stock fuel map it should be a straight forward process to adjust timing to gain this result. Then all the other areas of the map should blend into these points. Sounds easy right. Before the discussion starts, this is a basic map. Those people wanting to explore the fact that bin number 56 needs to be 16.175642 afr will need to wait until Jordan has a running car.

[ORFORD2004]

Send me your timing data and i will be able to translate. I'm French Canadian.

[FiatMac]

I have a couple of books on tuning engine management systems which may be of interest and thought that I would provide a description of what is contained in these books. There may be others out there that are better. I would be interested any other books on the subject that others have found. I know the Megasquirt site has a lot of information also.

The first book is “Performance Fuel Injection Systems” by Matt Cramer and Jerry Hoffmann ($16.29 from Amazon.com).


Jerry Hoffmann is the owner of DIY Autotune, a supplier of Megasquirt hardware and software (diyautotune.com). Matt works there. I have bought a few of my Megasquirt components from them as well as a wide band O2 sensor and controller. This is a more general book. Options for tuning OEM ECUs, Standalone aftermarket ECU’s and Piggyback systems (tunable system in parallel with the stock system), are discussed. The various components and options for a system are discussed including fuel pumps, fuel lines and rails, injectors, manifolds, throttle bodies, idle control valves, sensors and ignition systems. In the section on Standalone ECUs there is a fairly comprehensive list of the systems out there with a brief description of each one. The book finally gets into configuring and tuning your system at Chapter 12. For those who don’t have access to or money for tuning on a dyno, the authors devote about two pages to a methodology for street/drag strip tuning. The book then moves on to strategies/procedures for tuning a system on a LOAD BEARING DYNO (not to be confused with an inertia dyno). They highly recommend using dyno tuning as it is more accurate and safe. It is virtually impossible to get an OPTIMUM ignition map by street tuning. The case studies (a ’77 Nova 350 small block conversion to Megasquirt EFI, a Toyota MR2 converted to turbo with a Megasquirt system, and Lotus 7 replica using a Ford Zetec ITB engine controlled by Megasquirt) only talk about hardware and configuration with no details about the actual tuning.

The second book is “Designing and Tuning High-Performance Fuel Injection Systems”, by Greg Banish ($16.47 from Amazon.com).



This is the better book, in this engineer’s opinion. It deals mainly with Load Bearing Dyno tuning and does not present much information for a street tuner. It does, however, provide more detail than that presented in the book above. The author goes through a methodology for tuning on the Dyno. In the sections on tuning there are screen shots of the maps in the various steps of the tuning process. The fueling map is tuned first using a “safe” ignition map. Once the fuel map is pretty well dialed in the ignition map is tuned by adjusting the timing to obtain MBT (Maximum Brake Torque) at each map location of the ignition map with the exception of idle. Here the author discusses backing off from MBT and using ignition timing to improve idle performance as discussed in this thread. (increasing timing/torque with the ignition map when speed drops below desired idle and decreasing timing/torque when the speed jumps above desired idle speed). The Appendix contains a tuning example for a ’69 Corvette big block converted to fuel injection with a Megasquirt ECU.

Neither of these books is a definitive work (how could they be at 152 and 128 pages respectively). Being a mechanical engineer I would like to have seen more depth and detail. However, together they do provide some insight for developing a strategy for setting up and tuning your ECU.

[burgandy81]

Timinator,

So far, so good with the timing table. The best/worst aspect of Megasquirt is the incredible flexibility. In this case it means the AFR table is customizable as well as the ignition and fuel tables. Thanks again for being the voice of reason and suggesting a stock ignition curve.

Orford,

Thanks for the offer. I sent PM. Did you get it? I was unable to attach a file to the PM. If your offer is still valid pleas send me a PM and I will respond with the document.

I think I know where I went wrong. The documented maps are labeled 0 - 40 mmhg. I interpreted this to mean from the absolute as Timinator surmised in a earlier post. I now suspect that the document explains these are vacuum from atmospheric which would invert my table and make MUCH more sense.

Stan,

Outstanding post! Thanks for the information. Knowing which sources of information to trust is half the battle.

I have also purchased a couple of items from DIYAutotune and really like them. Matt is a very helpful presence on the message boards.

I will look for those books as a little more theory would help me immensely. Just enough to be dangerous, as they say

[burgandy81]

Hi All,

Happy new Year!

Well it has been a long time since I updated this post and I have made a little progress and would like some feedback from the team.

I ran all year with a timing table (as suggested by FS.com members) that mimicked a mechanical advance unit and all was well. My tune improved with each drive and it was a very enjoyable season.

Continuing on the search for a better timing table I stumbled across this thread on Turbo124;

http://www.turbo124.com/forum/viewtopic ... tor#p48844

Great information and spot on for my needs, as I understand it.

I used the excel sheet on that thread to produce a table for my spider (stock 80 FI). In my case I will not be running any boost (yet) and my redline will be 7000 RPM. Please see below for the table that was generated.



Note how closely this matches the curves described in the French Lancia documentation on the first page of this thread. This excel generated ignition map also clarifies my poor interpretation of the French documents. Very happy I did not run the table that I originally came up with!!

It will be a while before I am back on the road again and I am interested in any thoughts that members may have.

Kind regards,

Jordan

[Dombrockt]

I megasquirted my supercharged mustang several years ago, and agree with the other posters about the timing and A/F tables being a hobby unto themselves. Seems no one else ever has the exact same setup as another. I spent an entire summer data logging and adjusting values. Once you have it running on a decent ignition map, the autotune feature of the software is worth it's weight in gold. After spending days figuring out a map just to get the car started, I had weeks of getting the car to run well all over. If you really want to dial both the ignition and fuel in for maximum power, my suggestion is to get some dyno time in. It's nearly impossible to maintain a constant load, tune, and drive all at the same time. I tried doing it with 2 people, and that was still difficult on public roads. Much easier to throw it on a dyno, maintain a constant load, fiddle with the timing, then move on to the next group of cells. Easier to listen for detonation also. If you have been disappointed with your power, then ignition is the place to find it.

Also, the book from DIY autotune guys is a great reference.

[Holshot]

Great thread! I'm sure I'll be needing to reference this eventually when I get my project where I envision it.

[burgandy81]

Hi All,

Minor update.

I have been driving/tuning for the last couple of evenings and am thrilled with the new timing table. It is like a different car! Great acceleration all through the RPM band with a lovely responsiveness that I do not recall from last season.

The tuning program (Tuner Studio) for MS has a tune-as-you-drive feature that uses some kind of voodoo matching wide-band O2 readings with all of the other readings to adjust fueling as you drive. The new timing table has required more changes to fueling than I would have thought, which probably illustrates how little I know about this stuff.

So, for my car, this seems like a good timing table (read: nothing has blown up yet).

[racydave]

Here are a few things I found while tuning. I set the cranking speed and timing at 10 BTDC, but once the engine runs, it is closer to 17 BTDC. You may not need any further adjustments past 5,000 rpms. Narrower parameters allow for finer adjustments. My engine sounded like popcorn on decell, so I made some adjustments that corrected this. What value you use to represent the vacuum is confusing. I related to inches of mercury best, its what I have always used. I have a new lap top, I will see if I can figure a way to show my map to you. You really need some help so you can tune on the fly. Driving and adjusting just does not work.

[burgandy81]

Thanks Dave,

I am very interested to see your table.

The units on the X axis of my timing table are % Kpa where 100% = atmospheric.

101.325kPa = 1 bar = 1 atomsphere = 29.92" Hg (mercury) = 14.6965 psi

I tried to convert my table to in Hg but did not see an obvious way to do so.

[joelittel]

I'm currently setting up my idle and looking very much forward to driving the car. Is anyone willing to post their current tune, or tables, for me to look at? I know every engine is different, and there are always a few ways to get from A to B, but I'd love to have a look at your tables and compare notes.

[burgandy81]

Hi Joe,

Just saw this. Sure, happy to share although, as you say, it may not actually be helpful.

I will try to attach a tune for you in the next few days. I am running MS2extra.

Recently I have been getting back into MS and the YouTube content is great these days!!!

Do you have a thread going on the Msextra forum?

What are you running for RPM signal?

Cheers,

Jordan

[joelittel]

Hey Jordan, so far it's been a real treat and I'd love to connect with you and other FIAT owners on the topic.

I knew nothing about Tuner Studio or MS when I got my setup so it took me awhile to get comfortable with what i was doing/changing/altering etc. After lots of research and emails to Andy at Vick's I'm starting to feel pretty good about what I'm doing.

I've had a handful of unforseen setbacks slow my progress (ie. the wires running into my double relay did not match the colors on my wireing diagram AT ALL, I ruined an O2 sensor and had to order an adaptor, broke an ignition key, fixed some wiring issues "while I was in there," received and installed a faulty ignition switch, then fixed my original ignition switch and reinstalled it... and so on) which has all kept me from doing much tuning. However cold start and idle are dialed in better than they have ever been before so tonight I hope to get it out and drive it around, for the second time. Autotune truly is as amazing as everyone says it is. Once I got my issues sorted (new sensor with adapter, ignition switch that works etc) the car has run better every time I turn it on. I can't wait to get into some actual tuning while driving.

I'm using Vick's kit and so far I'm very happy with it. RPM signal is handled by a toothed wheel on an aluminum pulley. I'll write up a full product review on the VAS EFI soon. Other than taking me FOREVER to save up for I have no real complaints. Like all my mods it has taken some customization to install but I expected that with such a custom kit.

I'd still love to see other people's tunes and discuss their methods but I am now so happy with where mine is at that I don't think I'd change anything without serious consideration first. I'm most interested in the "Why" concerning our setups. MSextra.com is open to anyone with MegaSquirt so I'm trying to seek out FIAT owners first. Tuner Studio does a great job of explaining every button you could push, but it lacks in the general "Here's how you get started" category. Vick's instructions will get someone like me up and running, but once a unique to my car situation came up I felt lost searching MSextra.com to find a solution. A good example would be setting a smooth idle at 900 rpms. For me this wasn't super straight forward, like it is with the Bosch L-Jet. My issue was that if the RPMs started to dip below 750 the car would almost always die. It wasn't until I found this post that I was able to fix my problem.

All growing pains and no real issues. Like I said, very happy and getting happier all the time.

When I first started tuning the idle it seemed that every video I watched started with the host saying "If you blow up your car don't blame me." Because of this I was very reluctant to manually change anything in Tuner Studio. But now I understand a little more than before so progress is being made every day I'm able to work on the car. Andy is most likely sick of holding my hand, and hearing from me so often, but his help has been greatly appreciated.

I do have an issue with my tuner studio and ecu serials mismatching but Phil at MSextra.com has offered to look at the error log for me. The error seems to occur when I shut the car down and start it back up without shutting Tuner Studio down as well. So far, it's not a real issue, but does get my full attention when a big error message pops up on screen.

Once I'm a little further along I'll post my VE and Idle tables.

[ORFORD2004]

Idle tables?

[joelittel]

Maybe it's a timing table I was thinking of. I'm not near my laptop so i can't confirm at the moment.