Thread: CNP/COP conversion for OEM ECU

Hello everyone. I just wanted to share the progress of what I have been working on for the past semester as a class project. This is a Sequential CNP/COP ( Coil near plug/ Coil on plug) conversion for the sr20de (fwd currently) using the OEM ECU. This setup is currently running on an unmodified 1999 p11 ECU. I am using GM LS2 coils that have ignitors built into them as well as a heat sink. The entire circuit is custom designed to be driven off of a ECU that uses one ignition driver. This means that it will work for any SR20 chassis. Forgive the potato video, i'm not very good at presentations. This is NOT a wasted spark setup. This IS sequential ignition!!

Did some more testing last night to determine the OEM Dwell timing. At around 1000rpm, dwell was steady at 3.6ms. Seems like all the info I have found shows that is too short for the ls2 coil. Once I get a daughter-board for a b14 ECU I have and retune the dwell table, I should be able to drive her around the neighborhood.

Ls2 maximum dwell time is 4ms at 14v... 3.6 should be just fine

Ok, see i never did compare to my operating voltage. I will need to check that. Voltage and dwell are inversely proportional, correct? So if its 4ms at 14v, then 13v you require a higher dwell?

kinda.. its only a maximum.. anymore and they get hot.. 12v is 4.5ms and usally at cranking its around 6ms but for such a short time... Stock SR20 coils if I go higher then 3.2 it starts to miss and sometimes I have to tuen them down to 2.5ms.. So its only a maximum.. LS2 coils will work really low and have a good spark.. I don't forsee any problems with what your doing.. I build lots of Megasqurit ECUs and we figure this stuff out as part of the process..

I know its a long shot, but does anyone have a b14 xdf file that has the dwell vs voltage and dwell vs rpm tables?

See the issue I am running into is this; if I were to leave the distributor hooked running the motor, and pulled number one wire from the cylinder an swapped it with #1 coil, it runs perfect. Free revs great, no issues. Now if I keep it in this configuration and swap out say #3, I start to get a little breakup on free rev. HOWEVER, if I do one coil at a time, each coil preforms perfectly in tandem with the other 3 cylinders being ran off the distributor. Now this leads me to believe something is going on with either the dwell or the most likely cause is grounding or connection. The coil in the distributor is still hooked up at the moment, just the signal wire pulled so the cap doesn't arc. I think that when I disconnect the coil, reground the GM coils and double check all the connection it should work out the problem.

As it stands, the car starts perfectly and will hold an idle without an issue. Bumping the throttle a bit causes some breaking up. I have re-timed the ignition too, but without a laptop its hard to tell if its really in timing mode.

So your trying to do wasted COP with only 1 coil driver?? If so you may need even less dwell actually as your over driving the coil to some extent. All are firing very rapidly.. Remember those coils are on a sequential V8 and fire way less often.. Just a thought

By the way I like the fact that you're at least trying to figure something new out most people on here just want to plug in and go. It's good to see someone trying to hack the system .free thinking is where its at

No this is a sequential ignition design. I just used #1 and #3 coils as example due to firing order, 1342. Hopefully this weekend I will have some time to hook an oscilloscope to the coil and see what is actually happening. Also have a few modifications planned.



Hey thanks man. I do appreciate it. I see you take that very position when posting on the forum and face book. I just hope the effort isnt wasted. Hopefully I can bring this to market at a reasonable price.