pdexta

iTrader: (17)

My car is currently not running, occasionally I can get it to crank up and it dies a few seconds later. I'm also hearing the sound of a relay clicking while the motor is turning over (either cranking or running). I had this problem about 6 months ago and it seemed to randomly heal itself. Occasionally the car will crank and idle fine but the second you touch the gas the motor dies again. I tried to take a video of the clicking, which is coming directly behind the dash on the driver's side. If anyone has an idea of what it could possibly be I'd love to hear theories.

Car is a '99 with Brain MS. I've swapped alternators, batteries, and checked grounds but the problem seems consistent. I've spent several hours laying upside down under the dash and can't determine exactly where it's coming from. Any ideas?

fooger03

iTrader: (2)

Doesn't sound like a ground wire problem, sounds like a hot wire problem. Check your connections at the ECU.

pdexta

iTrader: (17)

I unplugged the ecu, everything looked as expected, reconnected it made sure the harnesses were all tight. Still having the same issue. I'd wondered if it was a short somewhere but I don't have a clue where to start isolating anything at this point. Thanks for the input though.

Preluding

iTrader: (10)

Is your fuel pump kicking on and staying on, my guess would no?
If you jump the fuel pump in the diagnostic port to stay running, will it start and run then??


Had this problem once in a prelude...main relay problem. I could be way out in left field here though.

pdexta

iTrader: (17)

I jumped the fuel pump and it ran. When I pulled it out the clicking resumed and the motor died. I'm not entirely confident that I know what this means, but you have no idea how happy I am, thank you so much. I'm assuming that means the fuel pump relay is bad?

hellaUNflush

iTrader: (1)

Replace fuel pump relay is what I have gathered from this, I am not sure off the top of my head but, if there is another identical relay in the fuse block to the fuel pump relay, swap and see what happens?

Preluding

iTrader: (10)

I believe there is a thorough troubleshooting guide in the owners manual linked in the stickies of the site for this. If not you could check for continuity in the wires coming from that relay with the same manual. If you have another relay handy it wouldn't hurt to switch it out though to save some time. Best of luck!

Braineack

iTrader: (62)

sounds like the firing order is out of whack.

Preluding

iTrader: (10)

knows best

pdexta

iTrader: (17)

Would there be a good way to get it back in whack? I've been searching all day, apparently I'm in well over my head and it's kinda cold riding my bike to work, even in FL.

Preluding

iTrader: (10)

Download(do not open) Service Manual:
https://www.miataturbo.net/useful-saved-posts-8/1999-2001-service-manual-48634/

Go to 01-01A-152 under troubleshooting
DO the "fuel pump control inspection"

Find faulty part/wiring
Profit....

Go find my thread in AEM about my car not starting and make fun of me... understand the Brain

Braineack

iTrader: (62)

what sorta changes have you made between now and then?

pdexta

iTrader: (17)

Unfortunately I’ve got a lot going on that is going to complicate things. FWIW, I was having the exact same problem intermittently about 8 months ago which seemed to just eventually go away. Recently, I swapped the bottom end with a built ’95 motor. In the process I broke the crank sensor and sensor wheel and replaced both. Upon putting the car back together the car cranked but didn’t seem to be running well, the tach read at half speed (if I was at 1500rpms it would read 750) and the clutch was soft and car wouldn’t go into gear. I then found that my slave cylinder had started leaking and replaced it, clutch is now firm. Now the car won’t start and has the clicking relay. I then jumped the fuel pump in the diagnostics box and it started, still at half speed on the tach which I checked on the MS gauge and it shows that it’s alternating between 0 and the correct speed. A day later I cleaned and tightened grounds and it won’t start at all now even with the fuel pump jumpered.

Personally I feel like the tach issue is something completely unrelated, which is why I didn’t mention it before. The clicking relay was not present after swapping the bottom end, but only after replacing the leaking slave cylinder. I also replaced the battery and tried starting the car with the alternator disconnected as when I previously had this problem I felt it was a charging related issue, neither have changed anything. With the way the COPS are wired there is no way I’ve gotten them somehow on the wrong cylinder but that’s certainly not to say I haven’t screwed something else up spark related.

Reverant

iTrader: (10)

The sound of the fuel pump relay clicking is because the MS is losing sync. Check your crank/cam sensors, wheel and wiring.

Braineack

iTrader: (62)

clicking relay is probably the boost solenoid? but it could be fuel pump relay if you're not syncing good during cranking.

on your MS you get your RPMs to the MS from the crank/cam signals, and then outputs that to your dash, if you don't sync those singals you will get intermittent spark and the fuel pump will trigger on and off.


can you post your MSQ and a log of you trying to crank?

pdexta

iTrader: (17)

I will post a log as soon as I get home from work. Thank you so much for the help!

pdexta

iTrader: (17)

Here's the log of the of the car cranking. It actually cranked up and ran for a few seconds before it died, didn't crank the second time. One the log you can briefly see it jumping between ~1400 and 0 rpms when the motor is running.

Braineack

iTrader: (62)

look at your loss sync count...

then look at the loss sync reason code...always 31.

and 31 = Miata 99-00 - 2 cams not seen

pdexta

iTrader: (17)

Thank you for the explanation. As far as I can tell it looks like it could be caused by virtually anything? The list I found:

Loose sensor
Loose cabling
Sensor wires running close to spark plug wires or coils
Slop in timing belt
VR sensor wired backwards
Fouled plugs causing misfire
Non-resistor plugs
Excessively rich mixture causing misfire
Excessively lean mixture causing misfire

Braineack

iTrader: (62)

I have a feeling it because you were fooling with your crank and cam sensors and they are not outputting a good clean signal. Or the way the rpms are syncing on and off suggests that you might be only getting one signal.


In TS, click the diagnostics tab. Then start a composite log and crank. It will update with a few spikey lines. Can you post the screen shot?