What's your engine "cold start" routine?
 

Anyone that's been around these cars knows they have individual quirks...a personality. That may be one of the things that's endearing about a 911. I thought it would be interesting to find out what your "cold start" routine is, and see if there was some consistency in like cars or if all are different. Please include the year of your car and if it is stock or modified. I thought it was funny that the PO's of both of my 911's gave specific startup instructions.

I'll kick it off with my experiences.

1970 911 E 2.2 with Webers -
pump the pedal three times
foot off pedal
engage starter
feather in gas as engine catches

1979 911 SC stock -
Stay off pedal during process
engage starter
engine starts, runs 5 seconds and dies
engage starter
engine starts, coughs a couple times
fast idles up to 2K rpm
settles back in to smooth idle at 1K

Your SC should not do that.

My '78:
Tranny out of gear
Hit key
Motor starts and runs at 1500-1800rpm for a few minutes, then settles down.
Sometimes throttle may need to be applied lightly until rpm rises to 1500-1800 due to warm weather conditions.

'73T w/Webers & Headers:
Tranny out of gear
Pump throttle lightly as quickly as possible while turning over starter.
Keep doing this after car starts until idle is maintained by lever between seats.
The sound of that motor was soooooooooooo cool! Like an Indy car. It would rev quicker than you could pump the gas.

For the SC, do either of you turn the key to pressurize the fuel and wait, then turn the key to start?

John

I agree, your CIS car shouldn't start like that.

My 79 SC at -15 F

Engage starter. It will fire up after a second or two, idlez smoothly at about 1800 rpm. watch oil pressure come up, put on seatbelt, drive conservatively till the temps come up.

You've got a problem with your SC that you've just been living with. I hope you have a pop-off valve in your airbox!

My SC has had the little fuel cutoff switch unplugged because it is not working,. so when I turn the key on, the fuel pump starts running.
I usually turn the key and wait for about 2 seconds before cranking it.
When the car is cold, it acts almost identical to yours Expat. stumbles and dies... turn it off, try again... fires up reves, then drops and stumbles... then catches itself and revs again up to about 2500 rpm and stays there for a few minutes... then in steps... it drops back down to normal idle.

I know it's not right, but I've been living with it. :(

Maybe someday I'll sort it out.

Jdub

I do that, but I don't think it's necessary :)

My DME 3.2 idles at app. 1200 rpm when cold and quickly settles to app. 1000 rpm. When warm it's just under 900 rpm.

My car had similar cold-starting issues until I adjusted the timing. Now, no matter how cold it gets, it fires right up, idles about 1800 for a couple of minutes and then settles down to 900 RPM.

Mark my 76S does almost the same starts then almost dies then goes to about 2000 then settels down to 900

Hit the key starts, 1800-2000 rpm for a couple minutes and then down to about 900.

Mikkel:

My car is pretty well-behaved, but it is headed in the direction of Lee's I am sure. Over time (and this is a daily driver so it gets started cold every morning) I am finding that I am getting the "dip" when starting. So the process is start, jumps to 1600rpm, dips low, struggles for a second or two, then idles up around 1600rpm for ~2 minutes, then back to 1000rpm (cold now, around 30degrees).

I think it is only a matter of time before it gets to the heart-stopping state where it must be restarted. So I have tried turning the key, waiting a bit, then turning the key to Start mode. Seemed to work just fine this AM, but mixed results.

If we can figure this out we will have helped a lot of folks I am sure.

John

Anyone with early MFI cars chime in?

I'll start.

1. Depress clutch pedal.
2. Engage hand throttle to top.
3. Crank for about 10 seconds until it is turning over fast enough to catch.
4. Usually idles at 1200-2000 working out its bugs for about 10 seconds, and then pops up to 2500-3000 once it smooths out.
5. Reduce hand throttle to 1200 until it warms up.

'86 3.2L Carrera

1) Tranny out of gear, clutch out
2) Crank the key - starts immediately
3) Idles at 1000 for about 2 seconds, surges to about 1300 for about 2 seconds then settles around 900+
4) Take off, stay under 4400 RPMs for at least 5 - 10 minutes
5) Try to avoid hitting the rev limiter the rest of the drive

JrDavid68

stock '77 2.7 CIS
-netural
-clutch out, don't want to load eng. thrust bearing without oil psi.
-routine start
-eyeball CHT first, then oil temp...adjust driving to ga. readings

On an SC, if your fuel pump comes on when you turn the ignition to ON, then your airflow detect switch is disconnected. Besides bypassing a safety feature of the car, you are also applying power to both the WUR and the aux air regulator before you are starting the car. If you wait too long, then you may be missing the enrichened cold start mixture that the WUR provides. I also think that the extra couple of seconds that the engine cranks before firing helps to get the oil flowing.

It is kind of cool to have the engine fire up that fast though.

Dont quote me on this, but I learned it from an excellent mechanic who learned this after years of trying to start MFI cars:

before step 3. (above) turn ignition on. Wait 5 seconds for electric fuel pump fill up system.. then on to step 3. (cranking)

This should prevent a lot of cranking.. It always worked for me, my baby would start within 2-seconds.

Now I have webbers : - ( my MPG has been cut by a third, and I am back to the old pump - 1/4 throttle - turn key routine.. And drive it as soon as you can, slowly, this will warm you up the fastest.

Very good point Mr. Krauss.

My old mechanic (before I hired myself) unplugged it because it was malfunctioning.
When I rebuilt my motor, I plugged it back in and tried to start it.
No go... so I unplugged it and just reverted back to the old way of having the pump running in the on position.
I know it is also a safety device...

Any ideas of how to fix the switch???

Now I'm curious. Where is this airflow detect switch and what does it look like? Pics would be helpful. It sounds like mine may be disconnected as well.
Mark

78 SC :

Get in
Turn key ...foot not on gas pedal
Motor starts immediately.
Idles @1800 RPM for a minute or two depending on outside air temperature
Then settles down to 900-1000 rpm idle

wckrause:
My SC's fuel pump does indeed run when I turn the ignition key
although the PO's said nothing about disconnecting the airflow detect switch. What would be the benefit of doing so?

72 mfi. Put in neutral, pull hand throttle up 2 inches, turn key to on position, listen to fuel pump and all those bubles being pushed out, start car which takes about 2 seconds of cranking. Leave hand throttle at about a half inch until car is warm.

wow...very elaborate rituals
i just turn my key and back out of my parking spot...baby it till the temp needle is out of the thick white block at the bottom then off we go!!!

I think some people disconnect the switch just so the fuel pressure comes up a little quicker and the engine starts a little sooner. One of my previous mechanics told me it would help my cold start problem (it didn't, it just backfired sooner).

Leland -- with your switch connected, can you raise the sensor plate and get the fuel pump to come on? Maybe the resting position of your sensor plate isn't correct.

The switch is located directly behind the airbox. It can be hard to find if you don't know what you're looking for. I think one of Leland's engine pics showed the location pretty well. I like those pictures of the front side of the motor. It's kind of like looking at the dark side of the moon. You'll also need to find the disconnected cable end. It is a similar connector as the one on the WUR and the aux air regulator.

On my 74:
- parking brake on
- neutral, no foot on gas
- hand throttle up
- turn key wait about 1 second
- turn to on, car starts right up
- adjust hand throttle to 2000 rpm
- warm up for 3 or 4 minutes
- hand throttle off, drive off to the club

I was taught way back when that letting a car sit for a while with the fuel pump madly pumping away, without cranking it over, was not a good thing. The reason being that it would pit your points. Not true? Or is it that the 5 second wait we are talking about here is not enough time to do anything to the points?

Long and short of the story is that I only let the fuel pump bleat away for a while when the car has been sitting for more than a couple of weeks (winter) and the gas is clearly gone out of the lines.

Anyone know the answer, either anecodally or technically?

You mfi guys are forgetting the most important thing. Close the door before starting any of these to keep the smoke out of the cabin.;) :) :p

Tom

SC owners:

The CIS system should hold pressure when the car is off. You should not hear the fuel pump run when you hit the first key detent.

If you DO hear the pump run it could mean the check valve for the fuel accumulator is leaking. That would bleed off pressure when the car is at rest.

My start up procedure is the same as Jamul74. The p.o. told me the engine was a recent rebuild and thus far she fires right up.

For my '69E with MFI; my experience it similar (with a twist).

1) Pull up hand-throttle as far as it will go.

2) Crank the car (about 10-15 seconds) until it starts. Sometimes it take 2 tries.

3) As soon as the car fires, (usually slowly) back off on the hand throttle a little (which helps it pick-up because it is starting lean) and then keep the rev's between 1000-2000 RPM. I hate to hear a cold engine rev'ing higher then that.

The twist?
The cold start enrichment device on the MFI was "modified" by the PO. He removed the part of the system that dumped fuel in the back of the air box. Then he had the fog light switch on the dash wired into a relay that was supposed send 12V to the enrichment solenoid on the MFI. It worked great and the engine would kick-off within a couple of seconds every time --- until it was hot. Then it would just never start at all until it cooled down. After much thinking and checking I finally figured out the problem: The switch leaked voltage which meant that the cold start solenoid was ALWAYS kicking in. When I removed the wire from the solenoid: the car would hot-start immediately. So I permenantly removed the wire which is the current state of the car. I'm going to rewire what the PO did and this time ensure that there is no voltage leakage.

Nothing so dramatic with my SC.

Turn key, car starts, put seatbelt on, take off.

Drive easy until warmed up.

Racemor, that is FUNNY. I ALWAYS remember to close the door first or you get serious eye burn from the first puff of exhaust. Porsches are not good for the planet, but they sure are fun.

Rarly, and other SC owners

Whether or not the fuel pump comes on has nothing to do with risidual fuel pressure. If the wiring is per factory, the pump will be on only when the Ignition is in the START position, or the engine is running. (unless the alarm, or rev limiter is grounding the fuel pump relay).

Warren describes this circuit very well in this thread

http://www.pelicanparts.com/cgi-bin/vb/showthread.php?s=&threadid=59329



The spec for holding residual pressure is only for about 30 minutes. This is just to prevent vapor lock, and has no bearing on cold start.

Expatriot98,

The starting procedure for my 79SC is identical to yours. I have noticed that my fuel injectors are relatively loose in their sockets and can be rotated back and forth by hand with little resistance. I am wondering if this causes a lean condition upon start up, hence the stall? I plan to replace the o-ring seals in the near future and hope this will cure this two crank start action.


Chuck

Bill - are you certain that '78SCs are wired in that manner?

The fuel pump on my car does sound at the first detent when it has been sitting for better than a week. It has always done this. If driven more frequently the pump will not sound.

I noticed all of this AFTER replacing the leaking check valve when I first got the car together. It sounded every time I went to start the car.

Perhaps it is just the SOUND of the fuel pump that is different.

I'm certain the pump is wired that way. I've seen it in all of the wiring diagrams that I have on SC's, and I've had to trouble shoot that part of my wiring until I found the disconnected air flow sensor.

I didn't know I could do that Bill!

I'll try it tomorrow!
Plug it back in and lift the sensor plate and see if the pump runs... humph... never thought of that. :)

I know exactly where the switch is... and you're right... if you don't it would be a bear to find.

So, if I do this and still get nothing... how do I trouble shoot it?

My ritual is DRAMATIC!

Open the door for my lady. Close it for her.

Open my door, close it, key in, immediate turn to Start, buzzing sound starts, and then she and I argue as to "who pushes the red 'aux' start button."

Car fires up right away, all the time!

The longest time of the day is between 5:30 a.m. (this is the 'cold' point) and 180 deg. I JUST COULD NOT WAIT for the full warmup so I can push the car to its limit!!!!

PUSH THE CAR TO ITS LIMT!......of course, might as well enjoy every penny I spend on syn oil (3K interval).

HAR! HAR! HAR!

I'm not sure. I have an exploded parts diagram in my Haynes manual that shows the connector. It looks like the contacts of the switch are the sensor plate arm, and the small leaf spring it is suppose to rest on when the engine is off. The leaf spring is insulated from ground by two plastic insulators. When the sensor plate arm is at rest, it grounds the leaf spring, and when it raises up, it's open.

I guess you could check that when the sensor plate arm is up, nothing is grounding the leaf spring.

I'll scan the diagram and post it as soon as I can.

The points in a 911 with electronic ignition act as a "trigger" only and dont have that much juice in them.. that is what I have been told. Besides, new points are cheaper than starters..
Why dont you guys with MFI (who seem to be spending a long time cranking) try my technique - ignition on for five seconds - then starter. Good luck.

Here's the pic,

#18 is the connector. It is bolted to #21 (insulator), and is elecrically connecte to #24 leaf spring. The sensor plate arm #40 rests on the leaf spring, and serves as the electrical path to ground.http://www.pelicanparts.com/ultimate...mixcontrol.jpg