1972 Porsche 911T 2.4 MFI

[BasherBell]

I hope you all have your thinking caps on.
I have a persistent problem and am a little unsure how to proceed.
CMA may be the only solution, having read every post and CMA a couple of times I may be ready to try it......., but I would welcome background to what may be happening here before I Check Measure and Destroy

My cold start switch on top of the fuel filter is disconnected.
But Car starts fine with a little between the seats throttle.
However pops and farts big time and struggles to pull under any load initially. Idle ranges slightly and
If I run the car for twenty minutes - 30 minutes it eventually turns into a super sports machine, but getting there embarrasses me, frightens small children and dogs , and is lethal to old people as I pass.

Plugs just removed and replaced with NGK BPR7ES very sooty but not wet after 30 mins run

Cold start Thermostat stripped , cleaned and re assembled, doesn't appear to be the problem .

Is this popping and farting lean running or rich running? I'm just afraid that the sooty plugs are too rich a mixture and I'm diluting my oil and damaging the engine, even though it performs well when warm (180) . Or is the car warming up a telltale sign that I have more serious issues and the engine heat expansion is hiding worn pistons etc etc etc. obviously this 20-30 mins warm up affects something in a major way.


I am tempted to find a local UK mfi expert to book it in for a health checkTech 9 over in Liverpool have been recommended, I am in Yorkshire , but reluctant if it's something simple. There may be someone out there who this exact situation has happened to and can illuminate.
I feel far more comfortable with Porsche 912 engines. These 911 beasts are way too complicated The devils work.......
Cheers
Dave

[gptom]

Why is your cold start switch disconnected?

Normal starting procedure for MFI is to pull the hand throttle all the way up (press on the gas pedal to help the lever, then let go of the gas pedal) Crank & let it fire. As the idle increases, lower the hand throttle & drive slowly

Tom

[BSNMOE]

It may be that too rich until the thermostat leans it out.
When the car is cold remove and disconnect the hose at the thermostat. Get a good and hot hair dryer and put it right up to the thermostat and blow hot air into it so it leans out. now drive the car.
Make sure this hose is connected at both ends and your heater box flex tubes are connected as this blows the hot air up to the thermostat.

[tobluforu]

You really need to go through cma. Make sure car is in good tune then have at it. If the rods, idle screws, etc. are off then you will be chasing your tail until these are spot on, or close to it.