Morgan Making Smoke
Literally….
Things went well. Things went less than well…
Another visit up to Lynn’s house to get the Miata powered Morgan alive. The check list for today was much shorter than expected and we were able to get it running quickly.
Tasks for the day:
Wire in the hazard and turn signal switches (because Mazda used a clever switch with multiple contacts I needed to replicate with a few relays)
Relocate the MAF and IAT wiring (Morgan will run its air filter below the intake manifold)
Check all lights working
Start it up!
This was the great part of the day. Took a bit of cranking to get the first fire, but that’s expected on a “new” build. It takes a while for fuel to make its way through the system and injectors. After a bit of a rough idle it cleared up and was running pretty well.
Next came the disappointment. After the first start we had major belt squeal, a quick check and re-start an we were good. Clearly the belt was a bit dusty or dry, either way it self healed. Then we just monitored the engine for usual suspects; watching for hot spots, checking exhaust temperatures to ensure equal, listening for odd noises. We had none of the above, just watched as the header wrap burned in for its first time. After it started to warm up I noticed a few check engine codes, not too big of a deal. Then there was significant smoke from the exhaust. Shut down immediately.
Did you know that relays have a coil in them that can serve as a resistor in a pinch (pin 85 - 86)? Paralleled two of them for approximately 50 ohms.
• P0107 = Barometric Pressure Circuit Low Input
Condition PCM monitors voltage from EGR boost sensor when intake air temperature is more than 50øF (10øC) and EGR boost sensor solenoid is turned off (atmospheric pressure is applied to sensor). Code is set when input voltage from EGR boost sensor is less than .2 volts.
Need to find EGR sensor to get car to run properly.
• P0453 = Fuel Tank Pressure Sensor/Switch Too High
The fuel tank pressure sensor is what detects that the pressure in the system is too high. This is a measure of air pressure in the tank, not fuel pressure. Once it does, P0453 is thrown. The fuel tank pressure sensor is typically on the top of the gas tank, fuel pump, or fuel level sending unit.
Removed, need to find and fool...
• P0463 = Fuel Level Sensor Circuit → High Input
Your Miata will get the P0463 code when the signal coming from the fuel tank indicates that there is more fuel than is mathematically possible for the fuel tank to hold.
Confirmed gauge cluster working via external resistors of ~50 ohm
• P1141 = HO2S Bank 1 Sensor 2 Heater Circuit Low Input
Need to fool. Expected code.
Miata dash surrounded by lovely wood. The key here is we confirmed wiring for fuel gauge with the relays.
As you can clearly see above something isn’t right. We scoped the cylinders and found no issues, they actually looked great. Compression testing was additionally a good sign. #1 - 185psi / #2 - 195 psi / #3 - 200 psi / #4 - 200 psi
Tasks for next time:
• Horn wasn’t working, unknown reason
• EGR boost sensor <— Greg/Lynn to acquire
• Fuel Sender <— Greg/Lynn to acquire
• Burp Coolant
• Solve smoke
Currently our best guess is valve stem seals or guides. Hoping its just the seals, they are annoying enough to replace.
• Fool the rear O2 sensor (this is a pre-1975 car and thus required to not have 2000 smog items)
• Trick EGR sensor (same pre-1975)
• Wiper motor wiring
