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Official LH2.4 EZK Wasted Spark Conversion - Installation Instructions

My best wasn't good enough - immediately after posting I find someone in this thread with a similar issue. D'oh......

A couple pages back mylesofsmyles had this issue and it turned out to be a faulty j702t unit. Considering this was an $20 ebay purchase from a miata with 237k miles, this is looking like a real possibility. If the j702t isn't putting out a strong enough signal to trigger the tach, would connecting it to the stock coil like I did have amplified the signal and caused the tach to read? I'm gonna break out the multimeter and start browsing ebay again in the meantime.
 
Update: put in a second, better condition Miata module and the tach works without having made any other changes. So if everything but your tach works and you're using an na Miata module, odds are yours is faulty.
 
I just installed my WS board on my ecu. I have still need to complete the wiring. The person that was doing the soldering showed me that a couple of the resistors were blown out. He said he can replace them but would need to know what they are. When the car is running we are going to add in a high end protectant to all the solder points.
 

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the two burned resistors pictured are two 44.2 ohm 1% 1/4 watt (yellow yellow red gold brown) in parallel. used as an open collector current limiters to light the check engine light. i doubt the value is super critical
 
Somebody has mucked with your MIL / CEL dashboard light. The only reason that those resistors, and the equivalent resistors in your ECU, would be toasted is if someone tied the CEL wire to +12v to keep it off. (Or at least they tied it to +12v long enough to blow out the resistors.) I'd be worried that other parts of your EZK/ECU might be damaged too.

When you turn on the switch, but don't yet start it, does the MIL/CEL light turn on?
 
Hmm, seems like it is OK. The CEL is shared by ECU and EZK so that either box can turn it on. With the broken/burnt EZK resistors, either the ECU is turning it on before starting (which is normal, proper operation), or the CEL has been cross wired to something else (like the alternator wire). Or maybe the EZK resistors are still OK but ugly looking.

I leave it as-is since a CEL from the EZK is pretty worthless, or you could replace the 2 resistors. Any value around 50ohms +/- 10 ohms should be fine.

(The blink codes from the diag box should still work since that's a different circuit.)

[For esmth: it looks like the resistors are driven by a 16-pin custom labeled Bosch / TI B57881 chip. An older LH2.2 012 EZK has a ULN2003 driver chip, which may be the same as the custom. The ULN2003 can sink 500mA or 600mA for brief periods. 500mA through 22.1ohms gives 11volts / 5.5watts.]
 
bobxyz said:
[For esmth: it looks like the resistors are driven by a 16-pin custom labeled Bosch / TI B57881 chip. An older LH2.2 012 EZK has a ULN2003 driver chip, which may be the same as the custom. The ULN2003 can sink 500mA or 600mA for brief periods. 500mA through 22.1ohms gives 11volts / 5.5watts.]
Click to expand...
ooh yes i have an ezk116 somewhere that has it actually labelled uln2003 also. i noticed just now three of its outputs of it are in parallel which i thought was interesting. maybe they wanted some overhead for a bright ass check engine light :lol:
 
For the spark plug wires that attach to the Bosch 2x2, which ones would you guys recommend. I read that the 240 ones don't work. Also does anyone sell the mounting plate that goes on top of the valve cover or are they mostly custom?
 
i mounted my bosch 2x2 coil to the upper firewall lip and used a cheapo 7/9 wire set. you need the later style ends for the coil side, the older 240 style dizzy cap wire ends will not work.
 
ok, cool. I will try and find a set of wires. My brother might have a sheet of aluminum I could make a mounting plate for the top of the valve cover. I 3D printed a test plate but need a little fine tuning before I send it out to be cut.
 
I mounted my 2x2 coil where the standard 240 distributor would be located and needed to make my own set of wires. I couldn't find a lead on the correct size of the ends that plug into the head mount cap so I fashioned a set of wires using 240 wires and 740/940 cap plugs.
 
Here is the mounting plate I made from the test piece I designed and 3D printed. Its a little crude, need to get my spacers but have all the hardware figured out and now onto wiring.
 

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So I have it installed, but it is not starting. It attempts to fire but it then makes a weird sound. Any thoughts?

Here is a small video of what is happening. I have the switch 12+ going to the blue wire from the old coil could that be the issue.

 
I am about to order parts for the wasted spark conversion of my 1998 940 Turbo and I have a few questions about ignition modules. I was planning on buying a Bosch 0 227 100 203 but they seem to be sold out.
Can I use the 2-channel Bosch 0 227 100 200 instead?
The shop also has Hüco but the part number is not displayed, would any 2 or 3-channel work?

The modules are sold without the cooling plate that the 940 OEM module has. Can I run the new ignition module with a cooling plate?
 
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