# 93 S13 ECM code 21 Ignition Signal Primary



## Sum Ting Wong (Feb 18, 2006)

Im having a hell of a time solving the issues related to this code (ECM code 21) and could really use some help. I am a mechanic and know alot about this car and its swaps but this shit has had me stumped for a week now. Car runs but very poorly, pouring out black smoke, very rough idle. In higher rpms doesnt do so bad but has an odd feel to it like its def. missing power. At an idle it looks like its gonna break my motor mounts and sputters like almost a constant backfire sound. This all started after a lite front end collision with the back of my ex g/fs car. Ive changed MAF, Ignition Module, Injectors(Used), cap, rotor, plugs     . To be honest im really trying to avoid having to check ECU pins, its such annoying pain in the ass. Please any ideas anyone might have would be greatly appreciated.


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## rogoman (Dec 16, 2004)

ECM code 21 points to the ignition components. Since you had a front end collision, the following components may be damaged:
1 - ignition coil and harness connector
2 - power transistor and harness connector
3 - resistor/condenser and harness connector


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## Sum Ting Wong (Feb 18, 2006)

*Thanks for your help..*

What are you referring to as the power transistor, the small module attatched to same bracket as the coil?? Ive always known that to be called an Ignition Module, at least thats what WorldPac(my parts peeps) calls it. And what are you referring to as the Resistor/condensor? I think we just have different names for things. My Car is a 5 spd, i didnt mention that before. Im pretty sure the resistor is only used on automatics. Ive already replaced igniton module, ignition coil, plugs, cap , rotor, maf, and even injectors and fuel pressure regultaor to be sure these werent causing any issues.
:cheers:


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