Hesitation on Start-Up

[wwpants]

Hello All, thought I'd share an issue I'm having with my 2000 NB8A in the hope there may be someone out there on the Interwebs who has had the same problem

Info on the car:
Daily driver, well looked after.
109,000KM
Had 100K service and 110K service done Feb & Oct respectively this year.

This has been happening since before the 100K service in Feb this year:
When starting the car 'dead cold' first thing each day it always fires but, after it has initially begun it literally 'stumbles' to life for 1/2 a second then cold idles fine.

After I drive it, either short trip or longer, it then re-starts perfectly. No stumble, hesitation whatsoever.
If I have a very long day at work, say 12~13 hours, it will then stumble into life again as the car is obviously, 'dead cold'.

So, warmed up starts are good. Dead cold are not. (I'll try to record a cold start on my i-device and upload to ubertube so we can hear it). As I said, the car always starts but, I fear the day is coming when it will not

Any ideas?
I've checked here for idling issues, cleaning EGR valves etc..just not sure what this problem is/

As always, thanks in advance for my fellow MX5 owners ideas.
Cheers

[and1]

My SE does the same thing. From dead cold sometimes it stumbles and stalls. If I kick the clutch in the revs jump up to normal cold idle rpm and it doesn't happen anymore, until the next dead cold start. Does your car feel hesitant during the first couple of minutes of driving as well?

[93_Clubman]

Might be the coolant temp sensor at the back of the head, which provides the ECU with coolant temp signal. Another possible is the EGI or Fuel Injection relay located in the engine bay fuse box.

[bruce]

Could it be the battery? Only a guess...

[Regie]

Could it be the battery? Only a guess...

+1 sounds like the battery is on its way out

[wwpants]

Thanks for the replies folks. I really appreciate how great this forum is I'll look into those suggestions.

RE: Battery. When I had the 100K service done the guys had the car overnight so they experienced the cold start hesitation. They suggested (and helped me buy) a new battery in Feb this year. So, I don't think that is it.

To answer the SE owners comment: Yes, it does feel a little hesitant to rev when cold, but I figured that was just normal?? I'm starting to guess what might happen every time I start the car now

To make matters more worrying, tonight I left work (car started fine). did about 5km's then stopped to buy some things. When I re-started it took about double the normal time to crank into life!! So now, my car is contradicting the original post I made here.

Oh well, if it stops permanently at least I can pinch another car from work while I get it fixed.....ALLMAZ here in Melbourne may be getting a tow in soon

Thanks again. Time for a

If anyone else has ideas, please feel free to chip in. Oh, now I'm wondering if I should test the coil packs???

[Black_Penguin]

Fuel pump or ignition leads may another thing to check, I've had to replace both on my 1999 NB8A earlier this year.
Had some similar symptoms as to what you're having.

[ralt]

Hi.
Try the fuel pump test when cold. Turn on the ignition for 10 seconds turn it off and try and start. If it starts immediately it is a sign your fuel pump is dying. If you still have trouble starting you have eliminated the fuel pump as a problem.

[bruce]

Are you battery terminals clean and tight?

[wwpants]

Thanks for all the advice everyone. Checking a few things today being Sunday with some time!

[Insurgence]

from my exp (nb8a), warm start issues = coil packs.
i've had fuel pump die but that was immediate.
i had similar stumbling issues you describe from dead cold (mostly in winter) and it was the ignition leads.
mine were literally falling apart.

good luck!