MFI Questions

[Todd Simpson]

The 2.2T w/Zeniths is out of my car and the 2.2S is in! First start up is scheduled for tomorrow night. I've got most of the electric stuff figured out, and fuel pump and lines have been converted. Turns out 71's already have the return fuel line built in, overall the swap has been pretty simple.

Where does the wire at the top of the cold start solenoid go?

What are your recommendations for cold and hot starts? Hand throttle, pump the gas, hold the gas? I've had carbs and CIS, any details you can share on "life with MFI" would be appreciated.

Todd

[mgoldleaf]

I have completed 600 miles since the purchase of my 72 911 with MFI...so I am no expert. BUT, I the method that I have used (to great effect) is:

1. Depress gas pedal 3 times.

2. Turn ignition to on - leave for 2-3 seconds

3. Engage starter and slightly depress pedal.

4. When motor fires, let off throttle pedal.

5. Warm engine oil for 2-3 min.

6. Enjoy.

I will check out my Haynes manual to figure out where the wires go -- or will check my car this evening.

Good luck.

/marc

[Ron,K]

Marc,

Cold start valve is fed by the grey/white wire that comes from pin #7 on the forward 14 pin connector. This is assuming you have the factory control panel that was fitted to the MFI engines.

[Early_S_Man]

Todd,

Take a good look at the following diagram. The Cold-Start Relay operates the valve. The relay gets a ground from the ThermoTime Switch on the breather cover, which in turn gets +12 Volts from the Yellow Starter Solenoid lead, which passes through the 14-pin connectors from the front of the car! Do a search on 'ThermoTime Switch ... if you haven't heard of it before.

Did you get a Speed Switch (aka Speed Relay or Rpm Transducer) with your engine? Very important! Do a search on 'rpm transducer!'



[img][http://www.pelicanparts.com/911/911_Parts/Electrical/911_electrical_1971_legend-2.jpg/img]

[TWJ]

Just another opinion...

I have had my MFI car for three years and use the following start procedures. BTW, I believe these procedures are spelled out in the owners manual and thats where I got then (if I remember correctly).

Cold Start:

Put hand throttle up (on) all the way.
Depress gas peddle to the floor ONE time and release.
Turn the key on to hear gas pump then continue to start.
As it warms a little and idle stabilize & gains RPM release hand throttle.

Warm Start:

DO NOT touch gas peddle, just turn key and start.

After either procedure enjoy safely!

[304065]

I disabled the drippers for my cold start mechanism. Here's my procedure:

1. Shoot dimethyl ether starting fluid into air intake; (With apologies to Steve Wiener, who told me NOT to do this)

2. Crank motor for 10 seconds with throttle to floor- floods cylinders with fuel.

3. Lift off throttle, closing throttle plates, richening mixture, continue cranking for 10 seconds.

4. Repeat 2x until engine fires.

Idle will come up to about 500 rpm, not enough to get the alternator to excite, but I let it tick over for a few seconds, verifying oil pressure before giving it throttle. As soon as it reaches about 1500 rpm, the charge warning light goes out and the voltmeter flicks over to 14v. * * * procedure complete

With a properly functioning cold-start system, you shouldn't have any problems, however.

Don't forget to snap a cool Beck's and raise a toast to the MFIWDP!

[Early_S_Man]

Todd,

If you let the fuel pump run for 30 seconds or so before ANY start ... hot or cold, the hand throttle is all you need to touch to fire up the engine! Adjust idle speed with hand throttle after cold start to 1400-1500 rpm.

[jluetjen]

I donow Warren...

Up here in the colder climes, I tried to do that with my car prior to fixing the cold start solenoid. It didn't change anything. I still had to crank the engine for about 30-40 seconds before it would start weakly. Holding the throttle wide open for the first 10 seconds and then closing it slightly seemed to help, but not a lot. I'm lucky since I have '69, I was able to wire a switched 12 volts up to my cold start solenoid on the MFI pump which pegs the rack. When that is engaged, the engine will start almost immediately when cold. But the '70 and later MFI's don't have the cold start solenoid, so I guess they have to suffer with the cranking if the factory's cold start spraying system doesn't work.

[Swank911]

I have had my 2.4 MFI for 7 yrs, it was just removed last month.

But here is my starting procedure, it follows Early S Man's suggestion with a slight mod:

Turn key to hear fuel pump prime, wait until gurgeling stops,

Depress thottle slightly, turn key and feather throttle as needed.

Once engine is turning over, pull hand throttle to 1500 rpm to warm up engine.

This variation may be due to my engine tuning. As I have heard many others with similar starting procedures.

Other than the great trottle responce, MFI is adds another bonus of security. I do not know a person not familiar with MFI that could start my car.

Good luck

[True Brit]

I could be wrong....but I thought my manual offered the following instructions for cold starting:

DON'T touch the foot throttle.
Pull the hand throttle all the way up.
Crank the engine for a few turns.
Switch off.
Switch on again, and crank until the engine catches. Still NO foot throttle. It will start running rather slowly but then magically pick up to about 3000 rpm, at which point you can adjust the hand throttle to let you warm it up at about 2000rpm.

Whatever - everyone seems to have different ways of starting, don't they? I shall certainly try one or two of the above suggestions!

[Matt Smith]

Hmm. I'm not sure why you guys need to do all that cranking over.
My start up is similar to Swank's, but basically (including last night, which was coooold) I turn the key and she fires INSTANTLY. Almost like an EFI car.
It likes a bit of throttle to keep it alive, and I usually only need the hand throttle for 30 secs or so. It just keeps going.

MFI isn't, what most people will lead you to believe, rocket science. If it doesn't do what it should, FIX IT!

[Swank911]

I agree with Matt, if you are cranking the engine over for any period of time, something is out of adjustment.

Once warm, even after sitting for an hour or so, I can just turn the key and she'll turn right over

[tmctguer]

i'm with S man.........i pull up the hand throttle, turn the key to energize the fuel system for 10 - 15 seconds, then crank away. when i hear the engine fire and engage, i give the throttle an ever-so-slight blip, then monitor idle RPM's via the hand throttle to around 1400.

works like a champ.