More MFI questions:

[jasonborkowski]

Here's one for "The early S-Man and company".....

Ok; I have adjusted my throttles per the Pelican Parts article. I have also adjusted the air flow of each stack with the linkages disconnected (via a synchronizer). Just as the article admonished, the idle is low..

Using the gas pedal to keep the engine alive, I went for a test-drive..WOW; she runs 10 times smoother! But there was still the ever present black smoke following me#########################

The article went on to say: "If your idle is low, your engine needs A: more air, or B: more fuel".

So, I disconnected the MFI pump linkage (now set at the spec length of 114mm) and found that my engine went right up to 1000RPM and idled great with far less black smoke####

Would this be indicative to my having an overly rich pump, or do I simply need to adjust the throttle stops for more air?

Second question:
Which way do you turn the idle enrichment screw, and the part-load screw to lean out the mixture? I have not touched the MFI pump thus far.., but I intend to do so tomorrow; pending on information.

I'M ALMOST THERE GUYS, DON'T GIVE UP ON ME YET.....

Porsches should run like Porsches, not like weed-whackers!

Jace.

[psychotron]

hi, if you unhook the linkage to the pump and the idle goes up, you are too rich. the part-load is is rich-left, lean-right. the idle adjustment (thru the fan) is just the opposite. when i set part load, i just lean it out a little at a time (1-2 clicks) until it back fires a little on deceleration, then richen it up a little. that has worked really well for me.

[This message has been edited by psychotron (edited 08-11-2001).]

[lsolon]

On my 72, I have the idle set at 900rpm. I adjust it with the car warm and all linkage hooked up.
To lean out the pump on the top end-bihind the allen bolt-turn it clockwise. To lean out the bottom end Behind fan(idle) turn it counter clockwise. Have you aligned the marks on the back of the pump with the FI mark on the the front pully? Have you tried a hotter plug?
Sounds like your almost there

[Peterfrans]

I would suggest that you check the length of the left and right throttle valve push rods before doing anything else (leave the pump rod alone). It seems to me there is some pre-tension in your set up on a warm engine. This will cause the pump lever not getting down to its idle position, which in turn causes you to run rich over the whole rev range. Adjusting those rods should be done on a warm engine btw. On a cold engine, with a correct set up the pump lever will be about 1 degree of its stop.

[jasonborkowski]

You are right, I have to pre-load the MFI pump lever to get the 114mm MFI linkage to connect. However, I've adjusted both the left and right throttle push linkages to the cross shaft when it is in it's idle position. They line up fine, the MFI linkage just seems long..

Should the MFI lever (if you will) be in it's relaxed position (all the way towards the rear of the car) when your MFI linkage mates up; or is some pre-loading required?

Jace.

[jasonborkowski]

Well; I am the proud owner of an almost perfect running 70 911E targa (thanks to everyone on this web-site).

My problem originated at the linkage from the transmission, up through the engine, to the back left pivot. It was simply too short, and didn't allow the throttle to go to the correct idle position; there by altering the position of everything after (Ie. every damn linkage in the engine compartment).

With this found, my engine back-fires through the exhaust quote: like a banshee.
I will drive and enrich the mixture till the back firing upon decellaration subsides.

Once again, I would like to thank everyone who gave their insight to this matter. Now I can drive about town today without the embarassment of a black cloud of smoke behind me.

Guys; the Targa top is coming off, and I'm going to hit the road...


Respectfully;

Jason Borkowski

[lsolon]

That damn rod had fallen off my car at least 4 times when i first bought it. I had to keep bending it, adjusting it until it was finally happy.

[Peterfrans]

Nice to hear you got the better of the MFI. Just so many rods, screws and adjustments to fool around with on a MFI. Keeps life interesting though.

Peter
1970 911S Targa

[Early_S_Man]

The pair of plastic bushings inside the bellcrank that the throttle pull-rod clips to could be worn or partly-missing. Five-minute replacement job.

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Warren Hall
1973 911S Targa
1992 Dodge Dakota 5.2 4X4 parts hauler