78 SC not wanting to start

Hebrewhomeboy · 09-06-2008, 10:05 AM

Hi all. I have a 78 SC in great shape with low miles, and lately when I start it in the morning, it turns over just fine but doesn't actually start for a few seconds. It used to start virtually the instant I turned the key. I'm still pretty new to Porsches, so I'm not sure what may be causing this. Maybe something with the fuel system?

snbush67 · snbush67's Garage

Armon,

Welcome to the Forum. The problem more than likely is fuel/air related, if your car was tuned to use 92 octane and you are running 87 it could result in the hard starting issue you refer to. Saying that, your car was originally manufactured to run on 87 Octane.

Shane

Hebrewhomeboy · 09-06-2008, 01:26 PM

Hmm, that brings up a good point. I had used 92 octane (chevron) until just recently when I learned my car was made to run on 87. Now that I think of it, the harder starting started just shortly after I started using 87 octane. Time to switch back to the good stuff, I didn't like using 87 anyways! Thanks for the quick reply, I'll fill up with 92 today.

Formerly Steve Wilkinson · 09-06-2008, 01:50 PM

Why would you waste money on 92 octane, which your engine doesn't in any way need, just so it starts in one second rather than five? I'm sure if you ran it on ether it'd start in a nanosecond, but so what?

It's your money, of course, but 92 octane is doing nothing for you in terms of power or mpg.

tonythetarga · 09-06-2008, 03:06 PM

Try some Techron with your next tank of whatever grade you use.

snbush67 · snbush67's Garage

Quote:

Originally Posted by Formerly Steve Wilkinson

Why would you waste money on 92 octane, which your engine doesn't in any way need, just so it starts in one second rather than five? I'm sure if you ran it on ether it'd start in a nanosecond, but so what?

It's your money, of course, but 92 octane is doing nothing for you in terms of power or mpg.

Armon,

Just to caveat on what Steve wrote above....

You should run it on 87 octane, just to explain my original post; some people run 92 because they think it is better for their engine and performance or to clean their injectors and spark plugs....higher octane fuel does none of that.

Higher Octane will eliminate knocking or pinging, you should use the minimum pump octane fuel that will run in your engine without knocking. You're wasting your money on higher octane fuels if there aren't needed to control knock.

Part of the misconception is that, on our cars the recommended fuel is 91 RON which is not the octane recommendation. 91 RON is 87 Octane at the pump.

Great Fuel Reference:
http://www.faqs.org/faqs/autos/gasoline-faq/

Hebrewhomeboy · 09-07-2008, 01:17 AM

I use Chevron most of the time. I'm spending a few more cents than buying gas on base, but the military gas is Tesoro, not Chevron, and I don't mind spending a few cents if it's better on my car.

And formerly Steve, it's mostly just for peace of mind. My car used to start instantly, now it takes a few seconds. That in itself makes me worry a tad. This upcoming weekend I'll be giving it a tuneup though, so we'll see if that fixes things. I'm not looking forwards to changing some of those spark plugs though, doesn't seem too roomy in there.