Our customer David reached out to us about tuning his super clean ’78 Datsun 280Z he had installed what was advertised as a plug and play Megasquirt ECU. He installed everything according to the provided instructions and the car would barely run, after becoming frustrated at the car’s inability to run, he reached out to us and had it towed in. Our head tuner Travis plugged into the ECU and identified a laundry list of issues. When we received the car, the ECU was reading RPM’s all over the place, bouncing between 0 and 6,000 RPM causing it to do acceleration enrichment, spark cut, advance, and retard timing multiple times a second, it was properly confused.
Travis quickly identified a different reluctor wheel in the distributor than the ECU was looking for. After establishing what reluctor wheel it was running, he was able to get it to hold idle and was running much better, he then adjusted it to recognize the correct injector size and it cleaned it up even more. At that time, he started looking at cylinder temperatures using a thermal camera and infrared thermometer. He identified that the front 2 cylinders were not producing near the heat that the back 4 were. Verified that all cylinders had spark and injectors were receiving proper signal to fire. He then pulled all spark plugs and ran a compression test. All cylinders produced good pressure, but the noticed spark plugs had incorrect diode length and did not protrude into the cylinders far enough for optimal combustion. He installed the correct spark plugs and also identified that the oil had been thinned out a lot from unburnt fuel making it into the crank case cause from the reluctor wheel/ECU miscommunications. After performing that the front cylinders had warmed up, but still were not performing as well as the back 4. At that time, we surmised that there was either a valve lash issue or the there were ring or internal issues with the engine. He got the vehicle to operating temp and pulled valve cover and found all valves were adjusted too tight. At that point the car was running quite well, so he wanted to change the oil and filter before doing pulls on the dyno. Once on the dyno under load, the front two cylinders started to perform as desired due to the adjustments made and correct oil viscosity. From there tuning was straight forward and the car makes great power. We can’t wait for some dry weather so that David can really lean into it and see how well his Z performs now.
