Miata dies, does not start until like 20 minutes later, no fuel/spark
#1
Miata dies, does not start until like 20 minutes later, no fuel/spark
I've been having a weird issue where after driving for a while the car either dies, or when I stop it and start it up a few minutes later, it doesn't start. It's usually remedied by waiting like 10-30 minutes then it starts up like normal. During the times it doesn't start, I've done a few tests, keep in mind there is no spark or fuel when cranking. This is what I've found so far, the CAS (NA 94) connector reads 0-12-5-5 volts, I can fire both coil packs through Tunerstudio's test mode, the fuel pump primes when turning the key to run position, and any log taken during the time its down shows basically nothing (attached). Grounds are clean and read low resistance. I have had recently some sync loss codes relating to the CAS/4G63 where the tach would drop to zero for a split second then shoot back up to normal, car misfires during the tach drop too, feels like hitting a limiter for a sec. When it dies, it isn't subtle, one moment it's running then the next moment it's completely dead, no misfiring or stumbles as it dies. Is this a CAS issue? Coil packs?
I've already gotten ahead of myself and have torn into the CAS and will be replacing the hall sensors inside of it. Perhaps I should've been a little more patient...
Logs and tune posted, running on a diy MS3X using Brain's guide.
I've already gotten ahead of myself and have torn into the CAS and will be replacing the hall sensors inside of it. Perhaps I should've been a little more patient...
Logs and tune posted, running on a diy MS3X using Brain's guide.
#2
I have had similar issues with a Mazda 323 which is very closely related to Mazda Miata, and of a similar age.
There are a couple of relays that supply power to the ignition system and the injectors. The contacts burn, and after about twenty to thirty years and do not always make such good contact.
Sometimes the engine runs, sometimes a momentary stumble, sometimes it stops and will not start. But comes good by itself after a time.
There are a couple of relays that supply power to the ignition system and the injectors. The contacts burn, and after about twenty to thirty years and do not always make such good contact.
Sometimes the engine runs, sometimes a momentary stumble, sometimes it stops and will not start. But comes good by itself after a time.
#3
I have had similar issues with a Mazda 323 which is very closely related to Mazda Miata, and of a similar age.
There are a couple of relays that supply power to the ignition system and the injectors. The contacts burn, and after about twenty to thirty years and do not always make such good contact.
Sometimes the engine runs, sometimes a momentary stumble, sometimes it stops and will not start. But comes good by itself after a time.
There are a couple of relays that supply power to the ignition system and the injectors. The contacts burn, and after about twenty to thirty years and do not always make such good contact.
Sometimes the engine runs, sometimes a momentary stumble, sometimes it stops and will not start. But comes good by itself after a time.
#7
Elite Member
iTrader: (37)
Join Date: Apr 2010
Location: Very NorCal
Posts: 10,448
Total Cats: 1,900
There are a couple of relays that supply power to the ignition system and the injectors. The contacts burn, and after about twenty to thirty years and do not always make such good contact.
Sometimes the engine runs, sometimes a momentary stumble, sometimes it stops and will not start. But comes good by itself after a time.
Sometimes the engine runs, sometimes a momentary stumble, sometimes it stops and will not start. But comes good by itself after a time.
Lack of fueling points strongly at under dash fuel pump relay, especially if there is an aftermarket fuel pump involved. The "Main" relay is a good suspect as well. Time to bust out the DMM and start doing some diagnostics
#8
There are three positions of the ignition switch (apart from off), accessory, ignition, and cranking.
You can have all your accessories work, and the engine will crank. But no ignition power means no fuel pump and no spark and nothing to the injectors.
I have had this problem myself, and when you pull the ignition switch apart, you will be appalled how crude it is, and shocked by the cost of a new one.
The copper tracks, burn, pit, and wear out. If the car is driven every day for twenty plus years, hardly surprising really.
#9
Elite Member
iTrader: (37)
Join Date: Apr 2010
Location: Very NorCal
Posts: 10,448
Total Cats: 1,900
Cheggit: https://www.miataturbo.net/general-m...failure-91002/
Main relay and as @Warpspeed said, ign switch are where I'd look first
Main relay and as @Warpspeed said, ign switch are where I'd look first
#10
Cheggit: https://www.miataturbo.net/general-m...failure-91002/
Main relay and as @Warpspeed said, ign switch are where I'd look first
Main relay and as @Warpspeed said, ign switch are where I'd look first
I'll be cleaning/checking out my ign switch tomorrow. I did clean it about a year ago though, maybe I messed it up or something.
#12
Elite Member
iTrader: (37)
Join Date: Apr 2010
Location: Very NorCal
Posts: 10,448
Total Cats: 1,900
Locate your fuel pump relay, can you reach it from the driver seat? When you go for a drive, reach under the dash and give it a pinch, see how hot it gets. I'm betting its going to be scorching. Mine gets uncomfortably hot with a DW200 in the tank. I carry a spare.
What I've done in the past with "thermal" troubleshooting is to take a can of computer duster (dust off, etc) and flip it upside down and then spray the suspect overheating component and see if that magically fixes it. The instructions specifically tell you not to do this, and for good reason. Some of that **** is flammable, and it leaves that concentrated "bitterant" on whatever surface you spray it on, and its sure to cause condensation as well. Get it anywhere near your mouth or eyes and you'll be sorry. BUT! Its a quick and dirty way to cool down a suspected overheating component for troubleshooting when you are in a pinch. I wouldn't make a habit of doing this.
Car dies, car won't start, find super hot electrical component, cool with duster stuff, see if car starts. If still doesn't start, move to next suspect component. Etc. I'm sure you get the idea.
If main relay fails I wouldn't expect the pump relay to trigger and prime the pump, but then failing fuel pump relay would cause the same symptom
I believe the ECU power is fed off the main relay, so if main relay fails I wouldn't expect you to be able to connect to the ECU. I think. I'm sure someone else in here knows better than me.
All kinds of stuff run off that relay, but I'm not sure which specific things because I don't have a wiring diagram for your car I know my NA will crank with the ECU sitting in my garage, but it sure as heck won't start.
I find most electrical systems to be voodoo without a wiring diagram
What I've done in the past with "thermal" troubleshooting is to take a can of computer duster (dust off, etc) and flip it upside down and then spray the suspect overheating component and see if that magically fixes it. The instructions specifically tell you not to do this, and for good reason. Some of that **** is flammable, and it leaves that concentrated "bitterant" on whatever surface you spray it on, and its sure to cause condensation as well. Get it anywhere near your mouth or eyes and you'll be sorry. BUT! Its a quick and dirty way to cool down a suspected overheating component for troubleshooting when you are in a pinch. I wouldn't make a habit of doing this.
Car dies, car won't start, find super hot electrical component, cool with duster stuff, see if car starts. If still doesn't start, move to next suspect component. Etc. I'm sure you get the idea.
All kinds of stuff run off that relay, but I'm not sure which specific things because I don't have a wiring diagram for your car I know my NA will crank with the ECU sitting in my garage, but it sure as heck won't start.
I find most electrical systems to be voodoo without a wiring diagram
#13
Locate your fuel pump relay, can you reach it from the driver seat? When you go for a drive, reach under the dash and give it a pinch, see how hot it gets. I'm betting its going to be scorching. Mine gets uncomfortably hot with a DW200 in the tank. I carry a spare.
What I've done in the past with "thermal" troubleshooting is to take a can of computer duster (dust off, etc) and flip it upside down and then spray the suspect overheating component and see if that magically fixes it. The instructions specifically tell you not to do this, and for good reason. Some of that **** is flammable, and it leaves that concentrated "bitterant" on whatever surface you spray it on, and its sure to cause condensation as well. Get it anywhere near your mouth or eyes and you'll be sorry. BUT! Its a quick and dirty way to cool down a suspected overheating component for troubleshooting when you are in a pinch. I wouldn't make a habit of doing this.
Car dies, car won't start, find super hot electrical component, cool with duster stuff, see if car starts. If still doesn't start, move to next suspect component. Etc. I'm sure you get the idea.
What I've done in the past with "thermal" troubleshooting is to take a can of computer duster (dust off, etc) and flip it upside down and then spray the suspect overheating component and see if that magically fixes it. The instructions specifically tell you not to do this, and for good reason. Some of that **** is flammable, and it leaves that concentrated "bitterant" on whatever surface you spray it on, and its sure to cause condensation as well. Get it anywhere near your mouth or eyes and you'll be sorry. BUT! Its a quick and dirty way to cool down a suspected overheating component for troubleshooting when you are in a pinch. I wouldn't make a habit of doing this.
Car dies, car won't start, find super hot electrical component, cool with duster stuff, see if car starts. If still doesn't start, move to next suspect component. Etc. I'm sure you get the idea.
#14
Elite Member
iTrader: (37)
Join Date: Apr 2010
Location: Very NorCal
Posts: 10,448
Total Cats: 1,900
You can buy new OE Denso relays for the main or fuel pump for $30-40, or harvest one from the junkyard and keep it as a spare. Another option would be to wire the fuel pump through a basic relay directly to the battery in the trunk. You are still using the OE relay to flip the second relay, but at least you can buy a basic, easily replaceable 40/60/80 amp relay (and a spare) upgrade the pump power wiring AND you take the load off the factory wiring. There are details here on the forum on how to wire it up safely
Good luck with the troubleshooting, let us know how it turns out!
#15
Oh yeah, that stuff is gross AND it sticks around forever. I got some on my glass top desk and I was picking it up for weeks. Eventually had to clear everything off the desk and just "detail clean" it :P
You can buy new OE Denso relays for the main or fuel pump for $30-40, or harvest one from the junkyard and keep it as a spare. Another option would be to wire the fuel pump through a basic relay directly to the battery in the trunk. You are still using the OE relay to flip the second relay, but at least you can buy a basic, easily replaceable 40/60/80 amp relay (and a spare) upgrade the pump power wiring AND you take the load off the factory wiring. There are details here on the forum on how to wire it up safely
Good luck with the troubleshooting, let us know how it turns out!
You can buy new OE Denso relays for the main or fuel pump for $30-40, or harvest one from the junkyard and keep it as a spare. Another option would be to wire the fuel pump through a basic relay directly to the battery in the trunk. You are still using the OE relay to flip the second relay, but at least you can buy a basic, easily replaceable 40/60/80 amp relay (and a spare) upgrade the pump power wiring AND you take the load off the factory wiring. There are details here on the forum on how to wire it up safely
Good luck with the troubleshooting, let us know how it turns out!
I will post an update if things seem fixed or break again. If all ends up well I'll probably post a write-up on rebuilding the CAS. I can hardly find any info out there on it. If the rebuild I did works and is safe to do, I'm glad I only had to spend like $5 on new sensors So far its got like 40 miles on it, all is well. We'll find out soon...
#18
Welp! Looks look I spoke too soon. Car cutout on the freeway for a second then caught back up. I then brought it back into my garage for diagnosing stuff and it just quit while idling. Same issue, no fuel (so it seems) or spark, fuel pump primes. I tested the main relay. Put it on a copper plate and sprayed brake clean on it to cool it off, no fix. I did touch the fuel pump relay under the car and man does that thing get hot. I couldn't figure out how to get the thing off in time before the car was able to start up again. I'll go figure out how to take that damn thing off... Also I did clean the ignition switch the other day, looked fine to me.
Logs are attached. They are shortened version of the full ones, but I think they convey the issue well enough. Sync loss.msl is a log that captured some sort of sync loss. No reason, the car also did not buck or do anything, just a CEL then it went away.
EDIT: Added tune
Logs are attached. They are shortened version of the full ones, but I think they convey the issue well enough. Sync loss.msl is a log that captured some sort of sync loss. No reason, the car also did not buck or do anything, just a CEL then it went away.
EDIT: Added tune
#19
Doing some poking around, found these two things.
PO left a rats nest for the ignition switch wiring. It might be fine, but I'll be redoing the wiring.
Coil pack is missing a screw and is jiggling around in the carrier. Not sure if it's ok, but I'll be fixing these two issues and seeing what happens next.
I'll start thinking about re wiring the fuel pump with a separate relay for the dw200 as well.
PO left a rats nest for the ignition switch wiring. It might be fine, but I'll be redoing the wiring.
Coil pack is missing a screw and is jiggling around in the carrier. Not sure if it's ok, but I'll be fixing these two issues and seeing what happens next.
I'll start thinking about re wiring the fuel pump with a separate relay for the dw200 as well.