Ignition start on a cold engine

[david.avrahami@]

1987 Porsche carrera...recently when I turn the ignition key, the engine fires right away BUT it sounds like on a 5 cylinders FOR ABOUT 1-2 SECONDS and then reverts to normal. once driving and restarting, it starts normally and right away...
It is not a big issue...just wondering why???

[old man neri]

Something is probably slightly out of tune/not working right. Could be an older plug wire, could be a distributor, could be an injector, could be the base idle mixture not set right anymore could be....blah blah blah.

In essence, not only is it a 30 year old car but it is a 30 year old design as well.

If you want, post a vid. Maybe someone can be more precise with what the issue could be.

[dfhtrhjn]

^ +1 on the above. If those items haven't been serviced in a long time then that's probably it.

[Steve@Rennsport]

David,

How long has it been since the plugs, cap, rotor, and plug wires were replaced?

Ever had the injectors cleaned?

[kent olsen]

If you jump in and turn the key right away it may be you just need to wait a sec for the fuel pump to build equal press to all injectors. If not Steve's idea would be my next step.

[uwanna]

Originally Posted by kent olsen

If you jump in and turn the key right away it may be you just need to wait a sec for the fuel pump to build equal press to all injectors. If not Steve's idea would be my next step.

Makes no difference, the fuel pump does not run till the DME sees pulses
from the flywheel sensors.

[kent olsen]

Shows you what a weber guy knows.

Hi Steve

[david.avrahami@]

The wires, cap and rotor were replaced about 4 years ago...
recently The wire cap on one of the cylinders popped out and I tightened the wire cap connection to the spark plug...it is not popping anymore but may be the reason.
The injectors are part of Sal Carceller MAF kit that was installed June 2017 (amazing kit)
and my top end was overhauled last year, as well. Car never ran as well as it runs now...I will wait a few seconds, as suggested, to allow fuel pressure buildup and report.
Thanks

[Steve@Rennsport]

Originally Posted by kent olsen

Shows you what a weber guy knows.

Hi Steve

LOL,..Hi Kent!

[Steve@Rennsport]

Originally Posted by david.avrahami@

The wires, cap and rotor were replaced about 4 years ago...
recently The wire cap on one of the cylinders popped out and I tightened the wire cap connection to the spark plug...it is not popping anymore but may be the reason.
The injectors are part of Sal Carceller MAF kit that was installed June 2017 (amazing kit)
and my top end was overhauled last year, as well. Car never ran as well as it runs now...I will wait a few seconds, as suggested, to allow fuel pressure buildup and report.
Thanks

How many miles have you driven in the past 4 years?

I would consider replacing that plug connector.

Make sure the fuel pump check valve is working correctly.

[david.avrahami@]

I drove approx 20,000 miles...
Where is the fuel pump check valve in an 87 carrera?
can you replace one wire only from a set?
I did try to start the car after waiting for 2-3 seconds with the ignition key on...same result. but shutting it and re turning the key it was perfect...very strange....

[old man neri]

Originally Posted by david.avrahami@

I did try to start the car after waiting for 2-3 seconds with the ignition key on...same result. but shutting it and re turning the key it was perfect...very strange....

On a more modern car that will make a difference as it allows the fuel pump to prime. On yours it will make no difference as the fuel pump does not prime.

I wouldn't go too far trying to fix things that may not be broken. My 88 does sound a little rough for a second or two when starting from cold. Post a vid to see what we are talking about.

[david.avrahami@]

Thanks all for the responses...
I put TECHRON full system solution and guess what...issue was resolved!

[scarceller]

Guys for the record: David runs my custom MAF system and with this system if you turn key to RUN it primes the fuel pump for 3 seconds. You will actually hear the pump run for 3 seconds. I highly suggest that prior to STARTING you move the key to RUN and allow the pump to prime then proceed to START. The feature that primes the pump is unique to my MAF setup and is not the way the stock system works, stock system never primes pump prior to START.

If the car sat for a few weeks with E10 fuel in the tank and the tank was not full it's possible the ethanol separated from the fuel and gathered up some water moister and sat at the bottom of the tank. If this were to occur you would run lean at startup till that fuel at the bottom of tank was used up or till you agitated the fuel in that tank by driving.
So how long has the car sat? And more important was the tank low on fuel, below 1/2 tank? And do you use E10 fuel?

[uwanna]

Originally Posted by scarceller

Guys for the record: David runs my custom MAF system and with this system if you turn key to RUN it primes the fuel pump for 3 seconds. You will actually hear the pump run for 3 seconds. I highly suggest that prior to STARTING you move the key to RUN and allow the pump to prime then proceed to START. The feature that primes the pump is unique to my MAF setup and is not the way the stock system works, stock system never primes pump prior to START.

Sal,
I agree that the three second pre-prime is a great idea to include in your system, but for us folks that can't quite afford your complete system as of yet, there is a solution. Focus9 Technology offers a solid state DME relay that includes the three second pre-prime feature. I have used one for the last two years and it operates perfectly.
911 Solid-State Relay (Pump-Prime) — Focus 9 Technology, LLC

[scarceller]

So long as the relay you mention works well and has the added bonus feature for 3 second prime that's a nice option.

Also keep in mind that if the engine dies for any reason (especially in a car crash) the DME will always deactivate the relay. This is so the fuel pump shuts down in the event of a car crash. You need to be certain this solid state relay honors this behavior ALL the time. I'm sure it does but it's worth asking.

Originally Posted by uwanna

Sal,
I agree that the three second pre-prime is a great idea to include in your system, but for us folks that can't quite afford your complete system as of yet, there is a solution. Focus9 Technology offers a solid state DME relay that includes the three second pre-prime feature. I have used one for the last two years and it operates perfectly.
911 Solid-State Relay (Pump-Prime) — Focus 9 Technology, LLC

[david.avrahami@]

I re read my own thread because the issue originally posted is back...and only on a cold start. I did try using the suggested 3 seconds priming of the pump ...no luck...
I do have Sal's MAF kit and I also have the focus 9 DME relay...
Steve@rennsport did suggest to check the fuel pump check valve and so did my long time mechanic...but since my car is 32 years old and I do have a brand new fuel pump that has the check valve on it, I will replace the pump some times this winter.