89 Mx5 shutting off whilst driving

hahaboy · Postby **hahaboy** » Thu Jun 04, 2015 10:01 pm

Hi guys, can you please help diagnose an engine/electrical issue i'm experiencing on an 89 mx5.

Car cranks and turns on fine from a cold start. I can even drive it. However, usually less than a 1km in to the trip, the car dies on me. It happens when i'm slowing down, but at other times too.

I can get it back up and running, but have to crank it multiple times (which is strange as it starts first time around at the start). It's not great when i'm in the middle of traffic. Once its up and running again, i don't tend to have any other problems.

Any help?

davekmoore · Postby **davekmoore** » Thu Jun 04, 2015 10:20 pm

Somewhat random symptoms but as a guess how about a partially blocked fuel filter?

Where are you?

Whose MX5 is it, as your info says you have a non MX5?

93_Clubman · Postby **93_Clubman** » Fri Jun 05, 2015 10:44 am

davekmoore wrote:Where are you? Whose MX5 is it

OP lives SE of Melb & it's his 1989 Eunos Roadster - it was the one with the list of RWC items earlier this year:
viewtopic.php?f=29&t=67744
Might be coilpacks or may be the fuel pump/fuel gauge assembly wiring connector at the inside top of the fuel tank deteriorating.

93_Clubman · Postby **93_Clubman** » Fri Jun 05, 2015 11:53 am

Also might be 'Fuel Inj' (aka 'EGI') relay in the engine bay main fuse box.

But the following MX5 diagnostic checklist might help:
https://docs.google.com/file/d/0B1P63nz ... edit?pli=1

Checklist is based on this initial development post:
http://forum.miata.net/vb/showthread.php?t=279746
In use:
http://forum.miata.net/vb/showthread.php?t=461932

hks_kansei · Postby **hks_kansei** » Fri Jun 05, 2015 12:37 pm

Check the diagnostic codes.

They're not perfect, and often say everything is ok (when it's not) but it might give you a starting point at least.

How is the car stopping? is it simply that when the clutch is in the idle drops far too low and it stalls?
Is it a distinct sudden stop (ie: if you clutch in at say 3000rpm does it just drop down to nothing like the key is off?)

If the car starts, but then stops after a few minutes, I would first of all check that a previous owner hasn't installed an immobiliser.
I'd also double check the idle speed (perhaps the bleed screw is too far in/out and the idle is too low to allow it to idle smoothly)

After those two easy jobs (also free), then I would be looking at the more expensive ones like fuel filters, coils, etc

hahaboy · Postby **hahaboy** » Sat Jun 06, 2015 3:38 pm

Thank you for the reply guys. Yup, it's my 89 mx5. Picked up recently.

Speed Racer it's exactly as you described..."simply that when the clutch is in the idle drops far too low and it stalls".

Will have a look at the two initial options and your posts 93_clubman. Where do i check for the bleed screw?

hks_kansei · Postby **hks_kansei** » Sat Jun 06, 2015 6:59 pm

That's the throttle body in the pic.

http://www.miata.net/garage/ignition.html#idle

93_Clubman · Postby **93_Clubman** » Sun Jun 07, 2015 1:46 pm

Manga's idle drop post might also help:
viewtopic.php?f=76&t=60434

And the clutch switch might also be worth checking:
search.php?keywords=clutch+switch+stall*&terms=all&author=&sc=1&sf=all&sk=t&sd=d&sr=posts&st=0&ch=300&t=0&submit=Search

hahaboy · Postby **hahaboy** » Tue Jun 09, 2015 10:35 pm

I like you guys. Thank you for the help.

Going to try checking the idle bleed screw based on this vid tomorrow.

https://www.youtube.com/watch?v=PVi2uaxAwnU

Looking into the other links as well. Seems like it might be worth cleaning the throttle body too?

hks_kansei · Postby **hks_kansei** » Tue Jun 09, 2015 10:38 pm

Do one thing at a time, it saves headaches when it comes to chasing issues.

As long as the throttle butterfly opens and shuts cleanly (ie: smooth) it's unlikely to be the throttle body.

Might be the idle bypass is caked in sh*t, but that doesnt seem to be a common issue (I've not heard of it being a problem on any MX5)

Geordie · Postby **Geordie** » Mon Jun 15, 2015 2:18 am

hahaboy wrote:Hi guys, can you please help diagnose an engine/electrical issue i'm experiencing on an 89 mx5.

Car cranks and turns on fine from a cold start. I can even drive it. However, usually less than a 1km in to the trip, the car dies on me. It happens when i'm slowing down, but at other times too.

I can get it back up and running, but have to crank it multiple times (which is strange as it starts first time around at the start). It's not great when i'm in the middle of traffic. Once its up and running again, i don't tend to have any other problems.

Any help?

I had a similar issues when the car got hot and it was the crank angle sensor. When it cools down it starts fine again. Worth checking