Question to the self-mapper among us: Knock detection?

[MartinS]

I'm curious who mapped the car himself?

Can anyone tell here from experience how he mapped his megasquirt setup or other aftermarket.

Who did you startet, any good literature? The problem is not understanding basics like A/F Ratio, Ignition timing. It's more how to approach and start mapping.

Who did you detect knock? Knock amp, headphones, redtop knock sensor wired in?

Any further infos, experience would be nice if you can share!

[NoHachi]

Start map: Fuel -> based on engine simulation software. A good estimate of the final torque curve (comparable engines) is a good start too. Add 25% everywhere and calculate how much fuel you need for the torque. Use that to estimate dutycycle.

Iginition..Start with the 4AGE base map. smooth out any bumps and take out 5 degrees of timing.

First pass: drive car with data logger untill all cells in fuelmap have corresponding A/F ratio values. Adjust fuel to target A/F-ratio's. (Megatune software is supposed to have a autotune mode for this).

Second pass. Plug in headphones/ knock amp, etc (best not to use auto-detection during tuning). Start advancing ignition untill engine makes no more power or starts to knock. Very difficult to get right without a decent load dyno.

After that the finetuning starts.. not much use doing that without a dyno either. However, car should be perfectly driveable.

[Uzelac]

Which ECU?

[NoHachi]

Does it matter ?

[Uzelac]

Misunderstanding, question was for MartinS

[MartinS]

Doesn't matter. But was bit focused on the DIY PNP Megasquirt.

Actually I'm not convinced about the ECU or about the ECUs on the market. Wiring isn't a problem, acutally. I've done wiring from scratch and i've got experience with electrical shit. BUT the big thing is, if you compare to the 200SX comunity you can ditch the original ecu with a nistune board, and still have the abilities you have with the original ecu, like check engine light, and a lot of fail safe things! Fact is car manufacturers invest millions in reliability and with nistune or ECUTEK you can retune a factory ecu, wheras a standalone doesn't incorporate these things as they are made for "race purpose only".

What can you recommend?

[NoHachi]

The ecu really isn't that important, getting the mapping right is. Even the cheapest and oldest megasquirt will run a 4a-ge just fine.
If you are concerned about keeping stock reliability, you really shouldn't be touching the engine in the first place.

[Speedline]

TechTom has available modifications for the AE86 ECU but are difficult to get hold of. And not really self mappable.

[off topic]
I agree with that using the stock ECU is the best way to go if available. But check engine light and oem's investing millions is BS. Yes, these ECU's are certified and tested. But oem's buy these things in the millions based on a draft of what they need to comply with emission legislation. And be flexible enough to support mapping for different types of engines.

And last but not least to incorporate lots of features to force the consumer to the dealer who then can extort money for diagnosing all sorts of problems who shouldn't even arrise in the first place.

For example, Nedcar produced Volvo's 440 with a Renault drivetrain with Renault supplied Siemens ECU's. The diagnose protocol is exactly the same as in every Renault with this Siemens Fenix ECU. But they changed the protocol as that it can only be accessed by a Volvo dealer diagnosing system...


Oem's don't invest millions in relability. They force suppliers to deliver stuff which is reliable for the lowest cost. If every manufacturer used the same suppliers and products as Mercedes used for their W123 and W124 they wouldn't sell a shitload of new cars. Because everybody would drive 'm for lets say 20 or 30 years...

These days I consider Toyota to be the best in some respects. But they use cheap labor in for example Thailand (Laem Chabang) to produce parts and cars in Toyota (subsidiary) owned factories. Toyota just has some really clever (Eu, Jap and US educated) people in their workforce who cover up all the shit and have set quality (for a price, especially parts...) as a Toyota brand value.

[on topic]

For knock detection I prefer headphones. Every engine has its own unique detonation sound. An advanced knock sensor is the best option if the ECU can use it properly. May late generation ECU write their own ignition maps to within part of a degree crankshaft rotation to the detonation limit. You can't beat this kind of mapping.

In the future I would like to see aftermarket ECU/ tuning guys delivery the same kind of stuff to the aftermarket. Would make lots of people's 'tuning' lives a lot easier.