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Join Date: Sep 2005
Location: So. Cal.
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How smooth does your MFI engine run?
How smooth does your MFI engine run.
My engine pulls strong etc. It has maybe 10,000 miles on a professional rebuild, never fails to start, never dies, but at idle it will miss every couple of seconds. It has optical ignition and is timed properly etc, but as this is the only 911 and only MFI car I've ever had, I don't know what normal is. Or maybe I do and this is it - which is what I suspect. Am I expecting too much that it never miss - what with it being 42 years old and is mechanically injected to boot??? A very nebulous/non-scientific question I know - but I'm curious for your seat-of-the-pants experience. Thanks
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David 1972 911T/S MFI Survivor |
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Banned but not out, yet..
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Owned a MFI for 12 years and it always ran like a clock. Never missed, surged or otherwise misbehaved. What is happening is not normal. Don't have the experience to diagnose though. Good luck finding a solution and enjoying a well running. MFI car
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An air cooled refrigerator. ‘Mein Teil’ |
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Mfi
Hi Daepp.
My 73 T, MFI Is very smooth, powerful, fun to drive. No missing or popping. During the restoration, I had the MFI pump rebuilt to E spec by Gus @ Pacific Injection. I had Matt Blast in Boston rebuild my T throttle bodies to E spec. I found a set of E stacks here on Pelican. It's been rock solid. 1973 911 T MFI Coupe, Aubergine Steve ![]() |
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Mine runs butter smooth. Sounds like faulty fuel injector. Did you check or replace yours?
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Are you running a stock Bosch CDI box?
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RGruppe #79 '73 Carrera RS spec 2.7 MFI 00 Saab 95 Aero wagon stick 01 Saab 95 Aero wagon auto 03 Boxster 90 Chevy PU Prerunner....1990 |
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What everyone says above, mine will idle <400 RPM and you can just about hear every cylinder fire, 42 years old and never been touched. Amazing.
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1972 911T Coupe with a '73E MFI engine and 'S' pistons 10 year resto mostly completed, in original Albert Blue. ***If only I didn't know now what I didn't know then*** |
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If your butterflies are org. then it's going to pop/fart once in a while. Also, if you have a franken motor where one has different cams, cylinders, etc then it's tough to get just right.
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72 911 Although it is done at the moment, it will never be finished. Last edited by tobluforu; 06-16-2014 at 11:36 AM.. |
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What is a "fraken motor" never heard that term!
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RGruppe #79 '73 Carrera RS spec 2.7 MFI 00 Saab 95 Aero wagon stick 01 Saab 95 Aero wagon auto 03 Boxster 90 Chevy PU Prerunner....1990 |
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Location: Snohomish, WA
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'franken' motor, as in Frankenstein.
This Franken Motor starts like a street car, purrs like a kitten at idle, and screams like a demon when it come on cam. ![]() "lightning illuminated the object and discovered its shape plainly to me; its gigantic stature, and the deformity of its aspect, more hideous than belongs to humanity, instantly informed me that it was the wretch, the filthy demon to whom I had given life." |
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that 'splains it.........I just did not know what "Fraken" might be.
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RGruppe #79 '73 Carrera RS spec 2.7 MFI 00 Saab 95 Aero wagon stick 01 Saab 95 Aero wagon auto 03 Boxster 90 Chevy PU Prerunner....1990 |
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IS THIS A "Fraken" motor?
this might be a Fraken motor.
It has an overhead fanshaft!! ![]()
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RGruppe #79 '73 Carrera RS spec 2.7 MFI 00 Saab 95 Aero wagon stick 01 Saab 95 Aero wagon auto 03 Boxster 90 Chevy PU Prerunner....1990 |
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My car is not like the ones above, but if you take solex cams, rs pistons, T stacks and heads, E pump, mate it to a 75 tranny with an exhaust you built yourself, you my friend have what is termed a franken-motor.
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72 911 Although it is done at the moment, it will never be finished. Last edited by tobluforu; 06-16-2014 at 11:36 AM.. |
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Maybe you're referring to "Franken" as in Frankenstein rather than "fraken? Autocorrect isn't going to help with this one.
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72 911T 2.4 MFI 2017 Escape SE 2.0 turbo 2020 Honda Civic Touring Sport 1.6 turbo 10' Madone 5.2/17' Lynskey ProCross |
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Whooops, you are correct my friend, corrections have been made, reading glasses used.
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72 911 Although it is done at the moment, it will never be finished. Last edited by tobluforu; 06-16-2014 at 11:38 AM.. |
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Quote:
My old aubergine 73E w/ 2.7 RS-spec engine was smooth at idle, as well. My throttle bodies, stack and linkage were all rebuild to S/RS specs by Matt Blast. I ran a Pertronix ignitor with an MSD box. My dizzy was new, too.
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Thanks for the input.
The car has the numbers matching case, original T MFI and original TB's - not rebuilt. Pump has never been into. It case DC60 cams, JE 9.0 pistons and used S cylinders. It was professionally put together by Supertec. And AFAIK the injectors are original and "unrestored" or simply removed and re installed. It has always run strong, rich, and misses every once in a while, but not all the time like a bad wire/plug. It has plenty of power. Henry offered to rebuild the entire MFI but I was running out of $$. Since the optical ignition was installed it has been so trouble free that I have just lived with it, but it has always had this "miss". When it's happening, it might miss once every 15 seconds. Perhaps it IS an injector - can they be serviced? And what tells them to open?
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David 1972 911T/S MFI Survivor |
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Quote:
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72 911 Although it is done at the moment, it will never be finished. |
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Quote:
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Gordon ___________________________________ '71 911 Coupe 3,0L outlawed #56 PCA Redwood Region, GGR, NASA, Speed SF Trackrash's Garage :: My Garage |
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On decel in say second gear I'll get an occasional pop that I always believed was from worn TB's, but this is a miss at idle - like at a stop light. They are not rhythmic - just every so often, 3 or 4 times a minute.
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David 1972 911T/S MFI Survivor |
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How old are your plug wires? Mine did this just tad, decreased timing and this fixed it.
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72 911 Although it is done at the moment, it will never be finished. |
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