I'm starting my 20B for the first time and am having a few problems. It has 800cc primaries, 1600cc secondaries using LS7 ignition coils. It's an E11v2 of course.

I've stabbed the CAS per Mazda spec, using Trigger Angle 65 and Tooth offset 11. Trigger system is Multitooth Rotary. I get good RPM signal at a steady 200-300rpm during cranking. I have Rotors 1, 2 and 3 to fire at 0, 120, and 240 respectively.

I copied the low rpm areas of the fuel and ignition maps from my E6X 2rotor which has the same injectors and similar ignition (LS1 coils instead of LS7, so firing edge is rising instead of falling). While cranking the 20B feels like it wants to start, but doesn't, and I get a very loud bang from the exhaust every 15 seconds or something. Problem is I can only do this a few times before my neighbors will lose their mind

What is this loud bang symptomatic of typically? Too much or too little fuel? I remember having the same problem with my 2rotor but eventually got it started, and don't remember how exactly.

I've attached my map, any advice appreciated before I tinker some more!

 

Have you verified ignition timing with a timing gun?
Loud bangs like that are indicative of ignition timing out-of-whack.


-Ted

 

Haven't checked it with a gun, but I relined up the pulley to -5* and restabbed the CAS at least twice. I don't have a helper this weekend so its tough to use a gun and crank the car!

I did make some extra progress - evidently these LS7 coils I'm using are falling edge (just like the LS1 coils) and *NOT* rising as I had them set. As soon as I switched them to falling it almost started right away. Still not there yet though. I wonder if I've damager the coils by using rising instead of falling?

 

you need a remote starter switch which you can buy from any auto parts store... then while your cranking the engine over you can turn the CAS little by little until it fires

 

Ok now I'm really confused. I loaded up my previous map which was set for rising ignition spark edge, and the car started right up. It was only running on 2 rotors though and pouring smoke out of the exhaust (heavily fuel filled smoke).

Should the car even start and run like that if the falling/rising edge is incorrect? How can I verify what these coils actually are?

 

OK, multiple problems solved. They *are* falling edge coils, what happened is that I forgot to power cycle the ECU after loading the new map so even though the ignition setup page showed Rising it was actually still Falling because I hadn't cycled it. That was confusing the **** out of me!

Next problems were that I forgot to adjust the coolant and air temp correction tables, so it was dumping in about 4x as much fuel as it should. Once I turned those off on the Main Setup page, it fired up instantly. Still only on 2 rotors though.

After checking compression I have 0 on the middle rotor Not sure how that could be as when the compression was checked 6 months ago when I bought the motor it was fine.

 

Your taking a big risk firing up a carbonized engine without cleaning it out. Carbon chunks can break the stock 3 piece seals very easily.


Also what's this falling and rising edge coil info? Please educate me as I'll be wiring my 20b next month.

 

how do you clean a carbonized motor without firing it up?

 

^ The best way is to open the engine, clean it, and use a gasket kit to put it back together. The cheaper other way is to place the engine on it's side (exhaust side up and removed) and pour in some kind of injector cleaner and let the rotors soak. Message the apex seals so they get some movement so the engine makes better compression. You can also take a long skinney screw driver and some pieces of scotch pads and scrub the rotor faces. Your just trying to scrape away all the loose carbon so it doesn't flake off. My D-series 20b engine had no compression when I got. I did the un-opened cleaning and got even pulses out the exhaust. I've since opened the engine to do it the right way.