Scamby Posted June 6, 2020 Report Share Posted June 6, 2020 Greetings, I have a problem that I have been chasing for a while and I can not figure out what is going on. Mazda 323 GTX BPT Turbo 1.8 G4+ PNP. When the car is stone cold and runs until normal operating temp everything runs fine. After a while like 30-35 minutes running the car pushing different loads (boosting and cruising) more or less the car starts to misfire even at light load. I changed everything ignition related (coil, cap and rotor, module, new leads, spark plugs). Besides a new set of DW 450cc high impedance injectors the engine is completely stock. Compression is good 170psi all 4 cylinders so the engine is healthy. Now I noticed something. When I shut down the car for a while for 10 to 15 minutes and look at the ECU temp is around 100 degrees Fahrenheit . When I start the car again and drive it the misfire is gone. But when the ECU reaches about 115 degrees the misfires start under boost. When it reaches 120 to 125 degrees the misfires get worse even at light load. Again I shut down the car (engine still hot) to bring down the ECU temp to 100 degrees, start it over and the misfire is gone. So I am getting suspicious that the ECU drivers for the injectors and ignition are having problems (overheating maybe) and because of that the misfires. The ECU is in the stock location. Please advice. Regards. Quote Link to comment Share on other sites More sharing options...
remski2 Posted June 6, 2020 Report Share Posted June 6, 2020 Plz post the map and a log. Quote Link to comment Share on other sites More sharing options...
Adamw Posted June 7, 2020 Report Share Posted June 7, 2020 No, the ecu should be perfectly happy at that temp. Generally we like to keep them below 70C (~160F). Quote Link to comment Share on other sites More sharing options...
Scamby Posted June 8, 2020 Author Report Share Posted June 8, 2020 Greetings, I ask the same question on the Facebook and other link forums and they told me that it could be a ground issue to the ECU. I will post a log and map when I have a chance. Regards. Quote Link to comment Share on other sites More sharing options...
Scamby Posted June 13, 2020 Author Report Share Posted June 13, 2020 Greetings, I am removing all the factory wiring loom to make sure I don't have any issues with especially for the grounds. The factory ECU use 4 grounds. The link looks like use only one. Map attached. Please advise. Regards. Mazda GTX Base Map V1.pclr Quote Link to comment Share on other sites More sharing options...
Ducie54 Posted June 13, 2020 Report Share Posted June 13, 2020 Try preheating the ecu with a hair dryer for a hot ecu test on a cold motor. Quote Link to comment Share on other sites More sharing options...
Adamw Posted June 13, 2020 Report Share Posted June 13, 2020 8 hours ago, Scamby said: Map attached. Please advise. What is the question? Quote Link to comment Share on other sites More sharing options...
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