Head scratcher////

[s-man]

My patience is dwindling with my 73 "s" with MFI...Have been experincing anoying mid range/part load, barely open, barely closed throttle running near or around 3000 rpm. Wot is without a doubt awesome!!! Idleis ok..

I would like to disclaim first that all of my check measure adjust is all done to a tee, dist mech. and vac. advance check aok.

Plugs, wires, coil, cap, rotor etc all new...

I am able to get the car running pretty close and one time got it near perfect only when I put a new set of points in, then within 45 miles or so, it goes downhill, points gapped and de greased before install.

I have checked all possible grounds, tach dico'd for a test session, tried a permatune, to no avail points still go off.

Thermostatt working as spec...

I even tried a crane optical trigger, but after a week of trying to get it right, I never was happy with it, the tach didn't work right, so I did away with it and put the breakers back in...

I am at my whitts end. Any suggestions would be appreciated....The neighbour is getting po'd lately, running the car at 3,000-5,000 rpm at 11pm isn't so kosher.....

"s" a pitty to drive anything else!!!!

[Superman]

I believe I had heard that those cars sometimes have 'part throttle' running issues. Tyson (BRAINIAC) once told me he found that the space cams on MFI systems get worn, eventually, and don't work right.

Me, I don't know. I'm a CIS guy who dreams of Webers.

------------------
'83 SC

[Early_S_Man]

Do you have the '72-'73 spec book, and have you checked the entire advance curve per page 48 for compliance though the entire rpm range? Your difficulty with points STRONGLY SUGGESTS DISTRIBUTOR PROBLEMS, NOT MFI TROUBLE!!!

Please refer to the recent thread for a thorough discussion of your distributor:
http://www.pelicanparts.com/ultimate/Forum3/HTML/009677.html


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Warren Hall
1973 911S Targa

[GIBSON]

I agree, the distributor seems suspect. I installed the Crane sensor a few years back in a 73S, it was too difficult to adjust. It did work,however. I'm now using a Pertronix
optical sensor, much easier to install, very little to adjust. However, if the distributor is not functioning, no points replacement will help. I like taking them apart to really see what is happening. You can clean things up and get the advance functioning much better.
The other thing that helps me is to remove the throttle bodies, clean the butterflies and set the stops and rods so they are dead on. You can do it in the car but it's much easier with them out. Partial throttle problems can be the pump but you should first rule out the distributor and t-bodies in my opinion.

Bruce Herrmann
73911S

[s-man]

I would like to accept my award for dunce of the year!!!! I'm not going to give away any clues, let's just say that I had my shoe on the wrong foot.

Car running stable at 3,000, nice and smooth right through the power band....

Can't beleive how stupid I was!!!

This is my sixth porsche, 4th 911, one 73.5 cis, two 77's and this present one the creme de la creme 73 s targa with mfiiiiii!!, original right down to the genuine rubber floor mats, the way it should be.....

I dont know how long I would have gone withought noticeing my error, but I would like to thank you warren and bruce for the heads up and post / threads to wake me up...

I think i've been inside the engine comp't too much of my life!!!!...Any how enough dribble, time for a nice long toooourrr....

By the way, what is your best suggest for octane on these machines, lately i have been useing 89, I know 87 is reommended,but can we go higher, I've been working down from 94 to rid the miss proble....

Well, time to fly, going to see "fast and Furious flick", I'll bet there are no real cars in the movie, just wannabeees!!!!

Thanks s-man......

[emcon5]

Nope, nope, nope, nope.

Fess up, you posted the problem, you need to post the solution. You telling us how you fixed it, may save someone else with the same trouble in the future.

Spit it out, we are waiting.
Don't worry, it can't possibly be as bad as putting your pistons in upside down.

Tom

[s-man]

Well, your right, maybe there are some others having a trouble with co2 poisoning too!!!!

First I must say that all of the main criteria are essentinal before we get to my stupidity. For example.....

1-cap ,wires, rotor, plugs ,coil ,centrifugal and vacuum advance points etc must all spec out...
2- throttle plates must be set on spec.
3- Throttle linkages must spec out.
4- air bypass screws must be free and clear..

All of the above procedures are "CRITICAL" no skipping steps....

5- MFI must be set with a functioning warm up thermostat, without that, your up the creek....I would invest in the specialized tools that automotion has for adjusting, follow the blue book, part load then full load.

6-Check throttle flow with synchronizer to dial in.

7-Check dwell and then timing, and by the way , make sure you use the correct mark for TDC to reference 5 degress atdc!!!!! I know I didn't....Voila my stupidity!!!!!

Somehow, sometime I dont know where????I got it into my head that tdc was the mark on the left, da f***!!! I have been in the automotive business all my life, 4 911's, how stupid could I be?????( Don't answer).

Anyhow, on any other model except the highly overlapped cam on the s'sss, the error would not have been as critical, but here we have such a tight tolerance between intake and exhaust that there is virtually no room for error..

So I hope that I have been of a little light for you still stuck in the tunnel....

S-man, ***Don't forget**** HEEL TOE+ WOT!!!!!