Laker

Hello,
Does anyone else have to start the car twice when the engine is cold?
Outside temps are mild. I didn't touch the gas pedal.
Not sure if this is normal and part of the 964's "character" as Motronic tries to find it's groove.. Has anyone had this issue and resolved it? No Motronic fault codes are present.
Thanks in advance....

91 C4 Cab, 5-speed.

Babalouie

Mine does that too. Unless I twist the key for an extra-long time, it will burst into life briefly , then stall. No problem while hot tho.

I've replaced distributor caps and rotors and the DME relay, with no change in behaviour. Next thing to try are plugs and wires.

kboustani

mine always crank on first start.

Laker

So Babalouie and I have the same issue. (totally fine for me when warmed up, well actually totally fine after the first attempt) I too have replaced DME relay, caps and rotors in the course of general maintenance (not because of this). kboustani, glad to hear it doesn't have to be this way.

Babalouie

Hey Laker, I wonder if this might make a difference.

When you click the key to on and the warning lights all light up, let the fuel pump buzz away for about 10 secs before you crank the engine. If that makes a difference, maybe we got a partially blocked fuel filter, and the system is slow to prime from cold or something (or maybe the fuel pump is sick).

Laker

I will try that when I get home later this week. Good place to start, thanks
My engine fuel filter is new; the one in the tank, I assume is original.

kboustani

good point.once i turn the key on i also wait about 10 second to crank up.maybe this is the diffrence.i do that so the fuel pump have a chance to work.not sure my thinking is right,but it works.

Tim_78

My car does the same thing. After the second try it starts. I was going to replace the sparkplugs and cables. Does anyone have a DIY for it?

Babalouie

Ok, just went down to the carpark to give it a try The car was last driven at 9am (it's 2pm now) so the engine should be reasonably cold.

Turned the ignition on, the christmas tree lit up, and waited 10 secs. Then fired it up and it didn't immediately stall...I'll give it another try tomorrow morning.

But if this works, then I think we got a fuel pressure issue (but not necessarily a problem with the fuel pump tho)

Laker

I love this place.
Thanks guys...

(Babalouie, would have tried it myself if not on a biz trip)

sml

same problem for me.
i thought it was the fuel pump or fuel pressure regulator thing.
mechanic suggested gummed-up fuel injectors.
put in a bottle of injector cleaning fluid stuff.
C4 so you also need to do an adaptation with the hammer.
noticeable improvement.

summary:
1. bottle of injector cleaning stuff in fuel tank
2. system adaptation with hammer (do not waste time trying disconnecting battery technique - it does work with a C4).

Babalouie

Thanks, I'll buy a bottle of injector cleaner and report back

mcharus

My car had the same trouble, I dont drive it much so I put it on a battery tender, now with a fully maintained batt it starts right up first time.
i also wait 10 seconds just until I get my seatbelt on and start it up.
Watched the video again, same thing, check the battery, cheap enough fix if the battery needs attention.
Car sounds nice by the way.

Babalouie

Very interesting search results for injector cleaner. A robust discussion here: https://rennlist.com/forums/964-foru...re-gum-up.html

And I think this is the PCNA Tech Bulletin that mentions the use of Techron: http://members.rennlist.com/jandreas...10-TECHRON.pdf

And then in this thread Steve W says he's a fan of Techron (and that's good enough for me): https://rennlist.com/forums/964-foru...additives.html

Laker

Battery is 2 years old and always on a Porsche tender/trickle charger.

Car has primary and cat bypasses, hence the sound. Will check out Techron. Thx all!