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Old 03-17-2013, 11:56 PM   #1
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Default Timing map tunning and various other questions.

Hello ppl,

This is my first post in this forum but I have been gathering information from it for about a year or so. First let me introduce my car and basic engine mods:

* 1996 (1.8L) with 70K miles
* Toyota COPS using iridium plugs gapped at 0.035"
* 50/50 water methanol Injection Injection starts at 120kPa
* 550cc injectors
* FM turbo kit with GT2560R
* FM standard intercooler
* Max MAP 190kPa
* Coolant reroute
* FM crossflow radiator with the stock fans (will replace those fans soon)
* MSPNP2 engine management.
* 91 octane Texan gas

This is what my AFR table looks like:



And I have verified my VE table tune to be good with a wideband and megasquirt log files.

Because I had no decent turbo spark table after installing my megasquirt I came to the forum looking for something to base mine off of. I came accross Brain's replies to the following post:

https://www.miataturbo.net/megasquir...-tables-58872/

Reply #12 shows two base tables made by FM. In my first attempt at a timing table I used the '01 table version for some reason. I heavily modified it and ended up with a crazy table that I assume was giving me knock. I honestly try to pay attention to my engine noises and I cant discern knocking, or "marbles rattling in a can" kind of noises. With the crazy table I came up with I must have had the noises. Anyways this is what I came up with:



I used this table and the car MOVES.... and fast I must say.... Since I am a total tunning noob I continued to read posts because I was super insecure about the safety of this table. Well long story short I was not able to find anyone running the timing numbers I was.

Then, I came across another post by Brain in miata.net. For reference the link follows: Any one want to share their ignition map ? - MX-5 Miata Forum

I noticed he was running 93 and using a table with much lower numbers than me so I based my second attempt at a timing table on Brain's table 3 on reply #3 of that post. Because that table is a 16x16 and MS2 only has a 12x12 spark table I wrote a program to translate the larger table to a 12x12 format. This is what my program came up with:



Notice the MAP column is a little different because I am not boosting as much as him. I must say that the software I wrote is in a very preliminary state and it might have bugs. The tables look almost identical (I am open to arguments).

The problem is that once I burned this table into my controller it made me really flaccid. It felt like a great deal of power was gone. I am not saying that Brain's table was bad or anything but this happening raised some questions. One was: is it possible to get more power if you went beyond MBT?
If not then that means that I am not reaching MBT with Brain's table. Sure, I understand every engine is different but I should have been relatively near.

So to gain some of my lost power at WOT I increased the timing by 5 degrees in the region of boost where I start injecting methanol (120kPa+). The resulting table is this:



Power came back, not sure if it came back entirely but it felt pretty good. I would need a dyno to know for sure. Even though I added +5 timing throughout the boost range the numbers are nowhere near of what I had in my first attempt (about 7 degrees less actually ). I have an electronic detcan and no knock is detected. I guess I must have a wax filter in my ears or something. Is know something that I should be able to hear loud and clear when it happens? Hell, if I run my engine at 7kRPM and rattle a can with 10 marbels inside I would be able to hear the can over the engine noise any time. So loud.

Any comments?
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Timing map tunning and various other questions.-afr.png   Timing map tunning and various other questions.-ohhhmy.png   Timing map tunning and various other questions.-brains.png   Timing map tunning and various other questions.-brainwithmeth.png  
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Old 05-18-2013, 05:39 PM   #2
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That high value spark table is the highest I have ever seen. And Brain's seems a bit low. Bumping this because it is interesting.
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Old 05-22-2013, 04:08 PM   #3
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Quote:
Originally Posted by sixshooter View Post
That high value spark table is the highest I have ever seen. And Brain's seems a bit low. Bumping this because it is interesting.
Sorry I did not get back to you sooner but I have been out of town.

Yes, I do agree it is higher than anything I have ever seen as well. I confirmed I was not getting knock because later I greatly advanced the timing from 0-3000RPM (50 Degrees). I revved the engine in this range while parked in my garage and surely enough I heard knocking sounds from the engine not present with the table.

I double checked my megasquirt timing base calibration to be at 10 degrees with fixed timing so that is alright.

Maybe water/methanol is preventing knock under boost? As soon as I get home I will post my latest timing table. This latest one I am very satisfied with as I am not able to hear knock even when ambient temperatures are at 35C.
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Old 05-22-2013, 05:15 PM   #4
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Comments:

1. Check base timing -- make sure it's right (I think you already did that).

2. If your compression is low, you'll get away with more timing. Have you done a compression check lately?

3. You gain nothing beyond MBT. If you're gaining, you haven't hit MBT yet.

4. Butt dyno is extremely unreliable. Timing changes can change engine sound which is easily interpreted as more "ooomph." You either need to quantify your changes on a real dyno, or log data and use Virtual Dyno.

5. You can advance quite a bit with WI. It's similar to the octane effect of race fuel. But you had darn well better have some sort of failsafe mechanism to save your engine if the WI develops a problem.
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Old 05-23-2013, 12:58 PM   #5
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I agree 100%.

1. Check base timing -- make sure it's right (I think you already did that).

Yes, I already did.

2. If your compression is low, you'll get away with more timing. Have you done a compression check lately?

I did a compression test a few months ago but I did it the wrong way (cold engine). On the cold engine I was getting 130psi even on all cylinders. Very small variation across cylinders (I think +-4psi IIRC). I will repeat later with a fully warmed up engine. This engine has been a very healthy one, no much oil use and ran great with stock ECU.

3. You gain nothing beyond MBT. If you're gaining, you haven't hit MBT yet.

Yes, it is what I thought because torque is given by cylinder pressure and if max cylinder pressure is already achieved there is nothing one can do to increase torque.

4. Butt dyno is extremely unreliable. Timing changes can change engine sound which is easily interpreted as more "ooomph." You either need to quantify your changes on a real dyno, or log data and use Virtual Dyno.

I understand that the sound effects greatly alter the perception of a car's performance but I am relying on my cellphone's accelerometer. I get higher acceleration numbers when the timing is increased dramatically (from brain's tables to my latest). I think the accelerometer is OK for rather large changes but it has limited use for fine tunning IMO. A real dyno is the answer.

5. You can advance quite a bit with WI. It's similar to the octane effect of race fuel. But you had darn well better have some sort of failsafe mechanism to save your engine if the WI develops a problem.

Yes, I am afraid of running out of juice or getting a clog or other sort of malfunction.

Here is my latest map:


It is essentially brain's map bumped up. I discarded the last one in post #1 because the power came in too abruptly once boost started to come in. This is a much more gradual and well behaved table.
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Old 05-23-2013, 02:58 PM   #6
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Quote:
Originally Posted by s4w2099 View Post
Yes, it is what I thought because torque is given by cylinder pressure and if max cylinder pressure is already achieved there is nothing one can do to increase torque.
Just a nit, but we're after a combination of achieving high cylinder pressure + achieving high cylinder pressure at a crankshaft angle that generates torque.

Perfect example of the importance of crankshaft angle would be the pre-ignition situation. With pre-ignition, you could create high cylinder pressure at TDC (doing nothing torque wise but stressing the heck out of things) or even before TDC (creating torque in the wrong direction!).

Quote:
Originally Posted by s4w2099 View Post
A real dyno is the answer.
If you haven't tried it, Virtual Dyno is surprisingly good. There's a thread on it.
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Old 05-25-2013, 05:46 PM   #7
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Thanks for letting me know about virtual dyno. I was planning on writing a similar piece of software myself. OK, so I went out and took some logs with 3 different settings.

First: +0 Degrees of advance (the exact same table I last posted)
Second:-5 Degrees of advance (the last table posted with -5 degrees all over)
Third: +5 Degrees of advance (the last table posted bumped up by 5 degrees all over)

Here are the results (same runs just different smoothing to verify data is OK):




Do not pay attention to the absolute power numbers generated, I believe they are VERY wrong. Only mind the relative numbers which is whats needed for tuning.

Notice how much power I lost with -5 degrees! at +5 I am still gaining power (and no knock).

So this tells me that there must be something wrong with my base timing as I am not knocking and still gaining power. I will triple check it again. I have toyota COPs so to check timing I have to make an extension for the COP using my old spark plug wires to cylinder #1. then I measure timing like I normally would.

One thing that just occurred to me is that I have a belt squeak when I first start the car, I use gates belts and are properly tensioned. I wonder if the damper is broken and the timing marks have moved around.....

No clue, I will check it out.
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Timing map tunning and various other questions.-dynosmoothing1.jpg   Timing map tunning and various other questions.-dynosmoothing3.jpg   Timing map tunning and various other questions.-dynosmoothing6.jpg  
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Old 05-25-2013, 05:49 PM   #8
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Ahhh... I forgot to mention. Notice how I seem to have lost some power in the low end at +5 degrees timing. I wonder if it is because the timing is far too advanced in that area creating torque in the wrong direction as hornetball pointed out or just an artifact.
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Old 05-26-2013, 02:02 PM   #9
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Not so much torque in the wrong direction so much as the pressure peak is not in the optimum spot at low RPM. What this means is that you retard your timing a bit at low RPM while leaving it advanced at high RPM (i.e., advancing/retarding the ENTIRE table is kind of a rough-cut initial operation).

To check your timing marks, insert a dipstick into cylinder number 1 so you can detect true TDC. Then look at the marks on the cam gears compared to the mark on the pulley. There have been instances where pulleys go bad.

Most find that the inductive pickup of a timing light is sensitive enough to work off of the current flow in the COPS primary wiring. You might give it a try next time before rigging up the extension.

You're not the only one finding that you benefit from more advance than expected. Thread:

https://www.miataturbo.net/megasquir...advance-69662/

I love VD's consistency. Pretty nice tuning tool IMHO.
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Old 05-30-2013, 08:09 PM   #10
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Yes, I did drop the dip stick onto cylynder #1 to locate TDC and the pulley marks were perfectly alined. I also reset the base timing just in case. There was really no change so I am just going to conclude that my engine really likes timing, just like some others expecienced in the thread you reffered me to.

I will continue to use VD for tunning and not pay much attention to the absolute numbers given (I honestly dont think I am only making 150HP at 12psi boost). Relative numbers are great consistency wise, this allows me to tune the general shape of the curve and maximize HP in every region.

My car has a front and rear lip spoilers so the predefined constants might not be suitable. I do not know the exact weight of the car either. Many things could be wrong.

A compression test is something I will most likely do this weekend. This time it will be done on a fully warmed up engine.

Thanks!
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