NSX shut off after cold start, then would not restart

[MikeNSX92]

Hey all, my new-to-me 92 NSX has been running perfectly in my first month of ownership. Went to head out today and it fired right up but then stalled. Restarted fine, I pulled into the driveway and let it idle in neutral since it's only about 50 degrees. I climbed out and it stalled again. It then would crank, but then shut right off when I let go of the key...like I turned the key off. I was thinking maybe battery or alternator issue. The gauge cluster looked a little dim when this happened.

Then I wiggled/moved the key around a little, got bright dash lights and it fired right up and stayed idling just fine. So now I am thinking something in the ignition switch might be the culprit. Are these a known failure point? 31 years and 153K miles. Spins the starter hard so I don't think it's the battery.

-- Mike

 

[ofdlt10]

common problem.
$75 dollar part and 15-20 minutes to replace.
i always keep a spare one since they're so cheap. use the same key, just replace the switch.

 

[MikeNSX92]

common problem.
$75 dollar part and 15-20 minutes to replace.
i always keep a spare one since they're so cheap. use the same key, just replace the switch.

Thanks, I found a few older articles on the forum and those sounded exactly like my symptom. Part ordered! Thank you!

 

[Old Guy]

If you have trolled those older posts, you may be aware that you can pull the white plastic cover off the switch and clean up the contacts which may restore service until your new switch arrives. Install the new switch and keep the cleaned up one as a spare.

While you are at it, if you don't know whether the main EFI relay has ever been replaced you should order a new one and install it. Keep the old one as a spare. It would be low probability for a 1992 to still be running on its original relay; but, not impossible. If the relay is original it may leave you dead in the water at some inconvenient time. A bit awkward to repalce because it is located on the back firewall behind the interior panels; but, not technically difficult to do.

 

[docjohn]

If you have trolled those older posts, you may be aware that you can pull the white plastic cover off the switch and clean up the contacts which may restore service until your new switch arrives. Install the new switch and keep the cleaned up one as a spare.

While you are at it, if you don't know whether the main EFI relay has ever been replaced you should order a new one and install it. Keep the old one as a spare. It would be low probability for a 1992 to still be running on its original relay; but, not impossible. If the relay is original it may leave you dead in the water at some inconvenient time. A bit awkward to repalce because it is located on the back firewall behind the interior panels; but, not technically difficult to do.

Have you seen any correlation in the incidence of radio failure and MR failure, both being of similar technology?

 

[Old Guy]

Have you seen any correlation in the incidence of radio failure and MR failure, both being of similar technology?

I have a statistically insignificant data set from which to draw conclusions. However, like just about everything else on the planet that is man-made there will be a time based correlation, although the correlation is probably weak. That said, I am of the opinion that the failure mechanisms are different so I do not expect a direct correlation between the two failures.

Based upon my main relay failure, the mechanism looked like solder migration leading to solder crack / voids around the solder connections on the circuit board for the actual relays. That might be a case of a solder connection operating near its current density / thermal limit with failure induced by the vibration that the relay is exposed to because it is mounted on the back firewall. Based upon my experience and what I have seen in other posts all main EFI relays appear repairable with a simple re flowing of the solder joints. I speculate that failure is pretty much based upon actual operating time rather than age.

For the Bose amplifiers, the CCU and what @Heineken has reported on the head units the failures are actual component failures. Typically the electrolytic capacitors and some other component failures as reported by Heineken. The actual failed components (capacitors) are non repairable; but, replaceable. Capacitor failures are most commonly due to failure of the capacitor seal and leakage of the internal electrolyte which then causes associated board damage. It is a fairly well documented failure mechanism in the industry and a lot of capacitor manufacturers publish mean time to fail data versus capacitor temperature. Cars that live in cool climates may have an exceedingly low capacitor failure rate. Cars that get parked outside in the sun in Phoenix during the summer may have depressingly short capacitor life spans. Note that time to fail for capacitors is not based upon operating time. Store an unconnected electrolytic capacitor on the shelf at 50C and it will have a shorter life than the same capacitor stored at 20C. So, your capacitors are aging out whether or not you drive the car. Capacitors do warm up when they are in service so this probably accelerates the aging slightly. The electrolytic leakage problem can largely be avoided by the use of solid dielectric capacitors; however, these are significantly more expensive than wet electrolytic capacitors used in the NSX electronics and typically larger so they may create packaging problems.

Pre pandemic the average life of cars in the US was 11.8 years. Wet electrolytic capacitors were probably a reasonable choice for a car consistent with the expected life span. The problem with the NSX is that based on all the original cars produced, I expect that the average lifespan has blown way past 11.8 years. The NSX generally doesn't get scrapped unless it runs into something solid over flips over at higher speed. So the NSX gets to enjoy geriatric issues that are non existent for most cars because they have already been recylced into metal ingots.

 

[MikeNSX92]

If you have trolled those older posts, you may be aware that you can pull the white plastic cover off the switch and clean up the contacts which may restore service until your new switch arrives. Install the new switch and keep the cleaned up one as a spare.

While you are at it, if you don't know whether the main EFI relay has ever been replaced you should order a new one and install it. Keep the old one as a spare. It would be low probability for a 1992 to still be running on its original relay; but, not impossible. If the relay is original it may leave you dead in the water at some inconvenient time. A bit awkward to repalce because it is located on the back firewall behind the interior panels; but, not technically difficult to do.

I haven't replaced it, but see in the shop manual where it is located. I'll check with the PO and see if he ever replaced it, or if I am living on borrowed time.