NoPistons -Mazda Rx7 & Rx8 Rotary Forum

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-   2nd Generation Specific (https://www.nopistons.com/2nd-generation-specific-17/)
-   -   bad ECU? (https://www.nopistons.com/2nd-generation-specific-17/bad-ecu-72562/)

FC_BOY 06-14-2009 03:03 AM

so ya still working on this hot starting issue and now i am looking into the possibility of it being the ecu but how will i know if it is the ecu??? is there a way to test the ecu???

dsmhero 06-14-2009 11:02 AM

first thing to check is open up the ecu and see if there is anything that is burnt or melted.

RE_TurboFB 06-14-2009 02:12 PM

I have had my share of fried ECU's... The Ignition circut likes to fry on the FC3S ECU's.



Have you done a compresstion check on the engine while it was hot...??? I have had engines that had low compresstion that would start no problem when there cold, But no dice once it would warm up...

FC_BOY 06-14-2009 09:51 PM

well on a previous post someone said if it idles good then there should be no compression issues

RE_TurboFB 06-15-2009 06:05 PM

Well.. I had a 12A that started right up idled great, But once you shut it off It would not fire back up unless you waited about 20 min OR if you could get it rolling fast it would "push start". And it's problem is that it had low commpresstion.



On the first plug that goes to the ECU ther is a Green/Yellow wire. That is the signal wire to the leading coil pack.



On the theird plug that goes to the ECU there are four wires LightGreen, lightGreen/Red, light Green/Black, LightGreen/white. Thoes are the injector signal wires.



All those wire are negatives. So to test them take a test light. clip one end to a 12V+ power source, Then stick the probe into one of the wires when you turn the motor over you should see short faint blinks from the test light.. If not the ECU may be fried...



Good luck!!


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