2.4T MFI issues

[Jef911]

Hello everyone,

My name is Jeffrey and i live in belgium.
I have some troubles with my 2.4 mfi car .
Full story : The car never ran well and i knew from the beginning the mfi system was not set up properly . But it ran ... Now I'm planning on putting EFI on the engine but before i do that i would like to try and set up the mfi properly .
I'v noticed before that when my throttle valves are at their stops the pump arm was not at its stop , now i know why ... After setting all the throttle linkages , throttle valve stops as should , repairing the rpm transducer ( broken transistor and several soldering has broken) the car starts , runs but will not idle .
Then i tried to figure out if it was to lean or to rich . When i put my pump a little bit open with the throttle valves closed , it idles . so to lean .
I tried to turn the idle screw on the pump ( through the fan) clockwise , but doesn't have any effect . I also noticed I didn't feel the "clicks" everybody is talking about . ( something broken in the pump ?)

Now is my question , is there a basic setting for this idle screw on the pump ?

Thx

[tobluforu]

Have you looked at CMA, if not then you need to start there. It has everything you need to get started. The idle adjustment really doesn't do much at all, but when you place the tool over that bolt, you push in, then turn it. You will feel the notches. The clicks you are referring about is in regards to the main adjustment screw located behind the Allen screw on top/front of the pump. Place skinny screwdriver in hole, turn until you feel screwdriver grab into slot, then turn and it will somewhat click into place as you turn left or right.
Not sure what pump arm you are talking about, but if its the one that connects to the rack and also connects to the pump, this has to be 114mm.
CMA will be your friend, spend a good 1,000 hours reading that and off you go.

[Jef911]

Yes I used CMA , everything is set up as described .
If i push in the bolt i can feel it take grip in the idle screw but no notches ...
Yes indeed , I'm talking about the pump arm thats connected to the rack . it's perfect 114mm.
thx for thinking with me

[tobluforu]

If the car is in perfect tune, plugs, cap, rotor, points, and timing, then the pump is next.
Are all the hoses connected correctly which warms the thermostat up, one on top, one under car on left side.
Now, is the pump timed correctly?
Have you adjusted and synched the stacks?
Have you adjusted the pump using the main adjustment screw, if so have at it. If you think its lean, go two clicks counter clock, write that down, then go from there. Leave idle screw alone, pretty useless.

[Jef911]

Jep , hoses are all connected , thermostat has been cleaned and is working . Pump is set correctly , stacks synched .
Havent touched the main adjustment screw yet . I will try that . thx !

[Sway Bar]

Idle adjustment through the fan is adjusted after the main rack is done. May even involve jumping between the 2 for the real final adjustment (so much easier with an AFR guage). As for not feeling the 'clicks' the screw may have been backed out too far. It's a hex head screw that is between some flat spring metals (don't have a pic off hand) and if you back it out too far it no longer clicks on the springs.

Hard to describe...but regardless , if you follow the CMA you find most of the adjustments are via the main rack.

Can be fun but tedious.

[Jef911]

Ok thx , Will try this weekend ... wish me luck

I have an innovate motorsport lm-2 .

[dicklague]

I went through all this with my 2.7 1973 911.

I studied all the posts here on MFI.

My suggestions.

1. Make sure everything is up to CMA specs.
2. Permanently install an AFR instrument. I used the Daytona-Sensors WEGO IV [available from Pelican] which has 2 hours of data that you can download and an instrument panel digital readout. If you don't have this you don't know where you are.
3. Upgrading the CDI away from the dated Bosch unit made a big difference.
4. I removed the cold start stack and installed an adjustment screw. do a search on this.

My MFI is great now......worth the work and helps the resale so much.

[RSTarga]

Not having a warmup stack in Belgium is a whole lot different than not having one in Southern California.
I understand that using an AFR while setting up is neat, but from my experience, once set up properly, MFI is very reliable and doesn't need constant adjustment.
I spent years having mine fiddled with and it never ran correctly. I then found a tech who knew what he was doing and since it has gone years between adjustments.

[dicklague]

Originally Posted by RSTarga

Not having a warmup stack in Belgium is a whole lot different than not having one in Southern California.
I understand that using an AFR while setting up is neat, but from my experience, once set up properly, MFI is very reliable and doesn't need constant adjustment.
I spent years having mine fiddled with and it never ran correctly. I then found a tech who knew what he was doing and since it has gone years between adjustments.

"Not having a warmup stack in Belgium is a whole lot different than not having one in Southern California. " NOT REALLY. I live in an area where it can be very cold in the AM at our altitude. I did not want to go into too much detail, but now that you have objected to removing the warm up regulator and objected to a permanently installed AFR I will bore you with the details .

For cold starting I have a push button on the dash that actuates the fuel solenoid and inject fuel into the stacks. This works just like and old fashioned choke. You don't need the warm up regulator and its mechanical inaccuracies. Using the solenoid works well and was designed that way by Porsche for starting. I had more problems with the warm up regulator keeping the engine too rich for too long. And my AFR instrument tells me that.

After much research I learned that the warmup system regulated by a 6mm screw with a lever gives you fuel mixture adjustment from idle to mid-range.

On a hot track day, I can richen my MFI with a half turn to keep it in range and cool the engine a bit.

I did consult some experts and learned all I could about MFI and set it up very well and It NEVER needs adjustment. I leave the AFR instrument in the car so I can know where I am at all times........and with the new adjustment I have added I can fine tune it to meet conditions very easily.