Martin's928

Anyone have ignition timing maps (load vs RPM) for S4 engine for Megasquirt or Electromotive type engine management systems?

I have Electromotive setup on my '88 and have a VERY conservative ignition map. I want to get a little more aggressive but don't want to damage engine. Anyone who could post their maps to give me an idea what works would really help.

Thanks in advance

Martin's928

Anyone?

John Speake

It would be most unlikely anyone's maps would run well for you. The main problem is knowing what units your load axis represent; whether it is linear or otherwise etc.

928 map load axis is related to the MAF output volts. What load sensor are you using ? Probably MAP I assume.

Do you have effective knock detection system also present as part of the new Automotive FI computer ? That is essential to remap and achieve maximum performance with safety.

Mongo

Talk to Carl Faussett at 928 Motorsports. He has used TEC GT on a 928 before and may be able to help you.

Rob Edwards

This is one of the built-in burdens of going to an aftermarket ECU- you kind of have to invest the time and effort to be able to DIY, or go with one that has a built-in base of support where the community can walk you through the process.

I wouldn't ever want to work towards the safety limit of a particular map unless it was one I generated, and I'd be real hesitant to hand over an aggressive map without a whole lot of disclaimering about the wisdom of its use.

Carl Fausett

John Speake is right, Martin.

You cannot (should not) just trust that a map for someone else's install is right for yours. There are far too many variables - especially when after-market goodies are considered.

Your Electromotive TecGT is easy to adjust, but it is best if take it to a dyno operator so it can be strapped down, put under load, and tested safely. Then the ignition and fuel can be brought in a bit at a time to establish the best safe tune for your car.

As to your other questions, as soon a Myles comes in I can have him email you those answers.

Martin's928

Thanks everyone. Sage advise.

mskar

Martin, if you what you have is basically stock, I'd love to get a .bin file. I'm trying to figure out whether my Motronic editor can find all of the fuel and timing maps in a 928 ROM. I posted a thread on this last week if you are interested in seeing what I'm talking about:

https://rennlist.com/forums/928-foru...or-v2-2-a.html

entropy_engineering

When I tune a motor, N.A. or forced induction, I get it to...well run first lol, then cruise, followed by idle, followed by progressively harder throttle pulls, then sort driveability (like transitions, acceleration enrichment, etc.). To answer your question better, I start with a basic and conservative timing map and tune the fuel where I want, then follow with more timing until whatever limits are reached. If you can't tune the advance based on gear or amount of time into a long pull then I would tune it in high gear as much as possible because the heat accumulation will be more prone for knock. My favorite tuning tool is taking a wide band (Bosch) knock sensor and putting a long cord on it with a headphone jack at the other end and plugging it directly in to a laptop computer. You can listen with headphones and hear an ASTOUNDING amount of noise, including knock, before most computers can. I wouldn't be surprised if it needs a couple degrees timing pulled back when the intake tuning valve switches. VTEC Honda's need a tiny bit pulled back temporarily at changeover because the sudden (but small lol) jump in BMEP can cause a little knock. I think I have an old excel spreadsheet that estimates ignition advance from quite a few factors if you want to try it...I'm not sure if I've ever used it so...good luck.

Martin's928

Thanks entropy. I have done all you say and have the car driving as well or better than stock. In fact, I've been so happy with it, I've procrastinated doing more for a couple of years (and thwarted by electrical problem). I was hoping to see a few more aggressive ignition advance tables to get an idea what happened when the intake runner opened and see if there are any other trends. Was planning a few sessions to begin mapping where I used the knock sensors to make sure I didn't cause damage then book a dyno session or two and get things dialled in.

I like the idea of using a set of headphones you suggest. Can you give a more detailed description? I'd like to try this.

Carl Fausett

Yes! Me too!

entropy_engineering

This may seem comical, but it's literally as simple as it sounds. Either tap in to one of the oem knock sensors (might be easier), or take a spare one and mount it to a water jacket on the block (valley etc). I took a spare injector harness plug I think that fit the knock sensor and put on a long cable with a mono headphone jack on the other end. That plugs in to the external microphone jack on a laptop computer. You can enable the mic and simply listen to what's happening or actually analyze the sound with something like Gold Wave audio analysis software. You can here...EVERYTHING...injectors, forged pistons rock (especially cold), valvetrain noise. You can almost here a motor low on coolant cavitate in the water pump. Accessory bearings going bad...you name it. If you have an ear for detonation, like at all, then this is like holding your ear to the block while running and knock has a very particular noise. I suggest, especially on a forced induction motor, giving the motor too much advance intentionally at low load to induce mild knocking and get used to the sound. I suggest good quality headphones. For the price nothing can really beat the classic, but still made, Sony MDR-7506. They're the exact same thing as MDR-V6. Does that make sense? I'll post whatever you need if it helps.

entropy_engineering

Oh btw, advancing to the point of detonation isn't always accurate on race gas. I recently saw an LS motor lose a couple tenths in the quarter from more advance. It was running Big Stuff 3.

Mongo

Just out of curiosity, Tec GT come with an auto tune function? I suppose you can use that to build your map first, then take the car to a dyno for further tuning. Then again, I take it you already did this hence the 'conservative' map.

Carl Fausett

Yes it does. Its quite good. You input the initial parameters for the motor and it generates a fuel and ignition table that is pretty damn good. Allows the engine to start, run and drives well. many have gone no further.

At the dyno, we have been able to get maybe 5-7% more than the auto-tune gave us.