| Hi all, My 1990 300ZX TT that starts easily when cold but when hot will crank and crank without starting. Sometimes it will start after cranking for 10+ seconds. Other times I will have to press the gas pedal about half way to get it started. When it's struggling to start it will fire a bit but just not enough to get running. If it is able to get running it runs pretty rough at 500-600 RPMs before coming up to idle at 800. If I disconnect the Coolant Temperature Sensor the car starts instantly but what's strange is that in Nissan Datascan, the coolant temperature value is correct so I don't think the sensor/wiring are defective. I also tested resistance per the FSM and it passed at the 3 test temperatures listed. I have completed the following repairs/tests:
1. The wires for two of the ECU ground pins were broken, repaired them but no change.
2. Compression test, 145-150 across all cylinders
3. Power balance test, all cylinders cause drop in RPM when disconnected
4. Fuel Pressure at ~39psi when cranking
5. Vacuum/Boost test, fixed several small leaks, had no effect
6. Replaced all injectors with new Nismo 615s
7. Replaced all 6 spark plugs with the proper NGK Twin Turbo specific plugs.
7. Tested CAS/Injectors/Sparkplugs/Coils by removing and spinning and listening for clicks of the injectors and seeing spark on the plugs.
8. Installed 120k timing kit and ensured engine is timed correctly.
9. Completed FSM "Impossible/Hard to Start When Hot" testing. Tried all the tests mentioned here. This is how I found the broken ECU ground wire that I fixed but still had no effect. It is the exact same issue that was described here but there was never a resolution posted:
[ http://twinturbo.net/net/viewmsg.aspx?forum=technical&msg_id=1140083&forum=technical&dtSearch=2 ] At this point I think it may be the ECU but I am totally stumped.
Anyone have any experience with an issue like this or any idea what might be going on? Thanks,
Matt
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15:21:46 01/02/23
