jtsimaras

I have similar issue but only if it is colder out say below 5 degrees Celsius. I haven't performed any cleaning of parts near throttle body etc---could be the problem.

XxMerlinxX

Could be a leaky fuel injector that's dripping fuel while the engine is off. To test, pull the fuel rail with the injectors still attached, turn the key to on so that the pump primes, then see if any of the injectors leak. You can put tissue under them to make it easier to spot.

zeroptzero

Thanks I'll give that a shot as my car is going away for the season in a week or so , so it will be a good time to test it.

SpitfireS

What battery voltage do you see after those few days - before starting?
Is there a difference between no key and key in & ready to start?
What voltage do you see during starting? (not easy to measure with (cheap) digital multimeters as they are slow)
What voltage do you see with the engine running?

Do you have power where you store the car?
You could use a trickle charger on the battery and see if that makes a difference.

zeroptzero

I tried starting the car today, after it has sat for about one week's time. I did a quick start up just turning the key and holding the start button, and I even held in the clutch this time to reduce load. The car sputtered and I had to fire it up on the second attempt. Voltage was 12.2 volts prior to starting, I couldn't measure much during the start-up. It started like a champ for the rest of the day as I drove around to many places. I energized the fuel pump and let it sit for a few minutes to test for a leaky injector later in the day, and the car re-started perfectly fine, so I don't think it is a leaky injector or it would have sputtered after that test TTBOMK. I probably started the car about 10 times today and it fired up perfectly each time except for the first start of the day (after 7 days of being down).

chris_barry

I've had this on certain brands of fuel ( shell). I found using BP or Caltex's highest octane ( 98 in australia) started much better.

I also use Elf 102 octane race fuel and this starts and runs very well.

Its a race car, I practice on pump fuel, then switchover to Elf for qualifying/racing. Its worth around 400rpm top speed on our fastest race circuit.

XxMerlinxX

I'm not sure that your test is one that would actually diagnose a leaky injector as it doesn't give enough time for the test to take effect. The next night that you drive it and are about to park it for the evening, pull the fuel pump fuse and let the engine stall out. That way there won't be any pressure in the lines/rail, meaning a leaky injector wouldn't have any fuel to leak overnight. If it still starts hard in the morning once you put the fuse back in, you'll know it wasn't a leaky injector and can troubleshoot something else.

zeroptzero

I do use Shell V-power exclusively on the S2000.

zeroptzero

I'm not sure that your test is one that would actually diagnose a leaky injector as it doesn't give enough time for the test to take effect. The next night that you drive it and are about to park it for the evening, pull the fuel pump fuse and let the engine stall out. That way there won't be any pressure in the lines/rail, meaning a leaky injector wouldn't have any fuel to leak overnight. If it still starts hard in the morning once you put the fuse back in, you'll know it wasn't a leaky injector and can troubleshoot something else.
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Oh yeah that makes sense , I forgot about the leakage from the prior shutdown, that could do it was well. Thanks for the tip I will try that out next and then I might pull the fuel rail too. Thanks

SpitfireS

When it does start (cold) do you get the 2-2.5k rpm start-up rev spike?
And the air pump? As normal?