COPs and Megasquirt
 

I already have my 30919-02239 toyota coils, I almost finished my COP harness (18GA wire) I went through all threads with COP in title and I still have some doubts about the COP setup with Megasquirt pnp on '94 1,8l, I wan't to check everything twice before I istall COPs ...so here are my questions:

Wiring :
I got my wiring according to Braineack's thread for '94 http://www.boostedmiata.com/FAQ/cops..._Schematic.jpg
but I found also this 1,6 wiring scheme which caused my doubts http://img186.imageshack.us/img186/7...hematicrq9.jpg
1) 10,000uf capacitor - some of You use it, some don't - do I need it?
2) 1kΩ resistor on a 1,6 cop scheme with *use 1kΩ for Megasquirt only - is it apliccable also for 1,8?

Megatune settings:
3) Dwell: I've found different setting... should I stick to DIY settings from MSpnp base map (5.5 cranking, 4.5 running) or start with 12v = 2.5ms, cranking = 3.5ms or other?
4) better spark means more complete burn - should I do any changes especially to cranking PW before I start the car on COPs?

Spark plug gaps:
5) I'm running stock gapped bkr6Es, should I regap them or just start with stock gap and then regap for a better burning?

Please note that I'm doing COPs because I fried my ignitor, so I don't have a possibility to check the ignition with stock coils if COPs wont start...

Wiring:

1. Use it.
2. Only required if you are running a standalone ECU on a 1.6L

Megatune:

1. the correct dwell for the Toyota cops is 2.5ms. cranking can be higher, 3.5-4.5ms range.
2. I don't remember making changes to my cranking values, but your VE fuel table will change.

Spark Plug:

1. Stock gap should work (11mm | .40")

As I'm sure you know our batteries are in the trunk so the electrons have to move a great distance before they reach the cops. The cap acts like a little battery for your ignition system, providing a surge of power whenever a plug fires.

For the love of god set your dwell correctly (3.5 crank 2.5 normal). It will run fine with an increased dwell for a while, but after a while the coil in the COP will burn through and you will be left with one or more dead cops. I was driving from Indiana to Austin, Tx a couple weeks ago and I had a COP die on the South side of Dallas (because I didn't have the dwell set correctly, like a dumbass). I can't tell you how much it sucks to limp 100+ miles on 3 cylinders.

Thanks guys, that's clear now


I suppose that just AFRs will be a bit leaner on COPs? or will the VE table change because of changed dwell?

BKR6E are something like 0.035, BKR6E-11 are gapped to 11mm/0.040 - correct me if I'm wrong...

This is a common misconception, but in reality, the battery actually becomes a load and not a source once the car has started. Nominal battery voltage is around 12v, whereas the alternator is set to produce a voltage in the low to mid 14s. As a result, the alternator becomes the primary supplier of power to the system, and the net current flow through the battery becomes negative (meaning it is consuming power to charge itself, rather than supplying power.)


I can't see why VE or AFR would change noticeably unless you were having serious ignition problems previously.


Specified gap for a 1.6 engine is 1.0 - 1.1mm, or 0.039 - 0.043". Prior to the COP conversion, I was gapped down to about 0.025", and now I'm running at 0.045" with no problems.

Here's a good source of info on NGK Plugs: http://ngk.com/

Stock gap on a BKRxE is 0.8mm (0.032"), whereas the BKRxE-11 is 1.1mm (0.044"). Trivia: the -11 suffix in NGK plug numbers is the gap in tenths of a mm.

thanks Joe, spark plugs unveiled:)

As to VE tables I thought that AFRs could be a bit leaner because of better fuel burning, but that's not me who said that VE table will change....

[QUOTE=Joe Perez;405078]This is a common misconception, but in reality, the battery actually becomes a load and not a source once the car has started. Nominal battery voltage is around 12v, whereas the alternator is set to produce a voltage in the low to mid 14s. As a result, the alternator becomes the primary supplier of power to the system, and the net current flow through the battery becomes negative (meaning it is consuming power to charge itself, rather than supplying power.)

You win.

The capacitor still provides a reservoir of energy for the cops though. I haven't scoped my 12V line with the car on but with an alternator or other rotary generation device, there is also going to be some amount of noise on the line. The capacitor helps to smooth out this noise such that the cops get nice clean power.

While we are learning about cops and MS...

How do you set/check the base timing? My timing light no longer has a plug wire to pick up the spark from.

put the inductive pickup over the wires off the connector...it'll work.

doh...
http://tbn0.google.com/images?q=tbn:...asy-button.jpg

Oh, absolutely the alternator is noisy as hell. There are even devices (such as aftermarket cruise control systems) which can determine engine RPM by noting the frequency of the noise in the power supply to the device.

I suppose it could be said that the capacitor's job is to a degree to filter this noise, though in reality large capacitors have too much internal inductance to be hugely effective at high frequencies.

More than anything, the capacitor is there to prevent voltage sags on the line. The coil primaries draw a fairly large amount of current at turn-on, and the supply wire going to the coils is not terribly large. These large current draws cause drop across the line, reducing the voltage available to the coil. and thus slowing the process of the building up the EM field inside. (Trivia: this is why the MS has a setting to increase dwell as an inverse of supply voltage.) By putting a big storage cap on the line, we let it charge up when the requirement on the line is minimal (coils not conducting) and then discharge into the line when the coil primaries are drawing large currents, to help keep the voltage up where it should be.

You dont need the capacitor, just make sure your MS is modded using the latest DIY-Auto-Tune configuration.

Are you referring to the 0.1 uF cap which is commonly placed across pin 11 of the CPU, or the 10,000 uF cap which is placed across the +12 supply of the CAP harness?

The latter is there to correct a deficiency in the factory wiring, to compensate for voltage sags in the supply. This is not absolutely necessary, but will improve ignition performance.

I haven't heard of any alterations to the officially sanctioned input circuit design that would obviate the need for the former. Your thoughts?

I'd definitely leave the cap on the coil power supply wire. This has been very common in OEM wiring harnesses since before I was born. Seriously, my '66 Dart has a cap on the coil power supply wire. Factory service manual implies it's for radio noise suppression.

Joe,

I'd assume he's reffering to not running the 10,000 uF cap on the coils with the updated values on the ignition output pull up resistors. (1k ohm to 330ohm)

--Alex

Yeah, thats the one.

Useless.

Oh really?

Last I looked it wasnt factory on the miata, my civic, or my dads lexus(which has the toyota cops I run).

As for your Dart, yea, nuff said, im surprised it still runs especially with the factory wiring.

The two are separate issues.

The 10,000 uf cap on the supply addresses a deficiency in the +12 supply available to charge the coil primaries.

The smaller resistor values in the MS driver circuit addresses a deficiency in the trigger to the igniters.

If you don't believe me, I'll try to rig up a DC current probe for my scope and give a practical demonstration. When (and if) I'm ever back home for more than a day or two...

Joe is 100% correct, Sam you should listen to him. My BS in EE agrees with him.

and my practical experience disagrees with the both of you.

I'm afraid I'd need to see scope traces to accept that there is no improvement in the coil primary current profile with vs. without a large capacitor across the supply, regardless of what the trigger pullups are.