Help Please; '70 2.2L Engine

[dwood]

I've spent a lot of time the past few days poking around the engine compartment of my new (old) 73E with a 70 2.2 S engine. I just realized a couple of things are missing, and was wondering how critical they are....

Both items of concern are on the Pelican exploded view at http://www.pelicanparts.com/911/911_Parts/1969/fuel_injection_big.htm

First, the angled air-intake pipe to the filter (exploded item 40) isn't there. How critical is it other than to avoid the possibility of water entering? I park underground, and have no intentions of driving in the rain. Either way, I should probably replace it. Any idea where I can find one?

And second, the actuating screw and locknut for the speed switch (exploded item 51) are missing. I hope this explains my 'farting' at idle and deceleration. Is there are reason for these to have been removed? Anything I should be aware of before I replace them? And the silly question, what size screw/locknut do I need? And finally, is the correct adjustment procedure to screw down until the switch engages at idle, then turn the screw another 1/2 to 3/4 turn and tighten the locknut?

Thanks in advance,
Dave...

P.S. Still looking for spark plug and oil recommendations for this engine. Grade and conventional vs. synthetic. Will be VERY low use vehicle (mostly weekend cruising), fair-weather only in Toronto.

[This message has been edited by dwood (edited 05-21-2001).]

[Early_S_Man]

Dave,

First of all -- those are carbs in that diagram, the Pelican title to that page is WRONG!!! I hope there's not too much besides the air cleaner on that page that matches your engine's induction system!

And, if the cover/intake to your air cleaner housing is gone ... your engine hasn't been getting filtered air at all! So, yes, by all means, get or fabricate a replacement ASAP!

Assuming that your engine does still have MFI and not carbs ... the best thing to do is download and print everything at the following Pelican page:
http://www.pelicanparts.com/techarticles/911_MFI/TipMFI.htm

It is a lot of material to digest, but just be thankful it is still available!

------------------
Warren Hall
1973 911S Targa

[BK911]

Dave,

The link you posted is for carbs. Do you have carbs or fuel injection? If you have carbs I don't think the speed switch is necessary and the farting could be due to a lean mixture. I have a 2.2T with carbs and no speed switch and the car runs great. No farting except by driver!

Sorry I couldn't be of more help!
BK

[dwood]

Thanks for the quick responses, and thanks for the complete MFI links!

I'm pretty sure I'm still getting filtered air. In the proper diagram at http://www.pelicanparts.com/techarticles/911_MFI/MFIdiagram2.jpg, I have everything there including the final outside cover (#4) except that it doesn't have the elbow on it; it's open where the elbow is shown.

On the switch, I took another look, and found that in addition to the screw and locknut missing, it's also disconnected! I found the two wires I think go to the switch (white / red stripe). Can someone explain how this switch is supposed to operate? The Haynes manual talks about the Speed Switch and a Microswitch, but the relationship isn't clear.

Sorry to keep bugging you guys.... I sure hope I'll eventually (hopefully sooner rather than later) be able to contribute rather than just drain on the group!

Thanks again,
Dave....


[This message has been edited by dwood (edited 05-21-2001).]

[This message has been edited by dwood (edited 05-21-2001).]

[Early_S_Man]

Dave,

Well, you answered your own question as to why the microswitch was disconnected! It is shorted out, and MUST be replaced! With a shorted switch there would be a rather limited operating zone for the engine between idle and 1800-2000 rpm ... as in [/b]NO FUEL TO THE INJECTORS above 1500 rpm![/b] I guess the previous owner decided he could live with backfiring, as opposed to an 2000 rpm rev limit! Apparently he didn't want to spend the money to fix it.

Explanation of circuit logic for Speed Switch + Microswitch + Cut-Off Solenoid/Magnet:

Refer to items #11, #13, & #15 in the following circuit (also in Haynes on p. 219) schematic: http://www.pelicanparts.com/911/911_Parts/Electrical/911_electrical_1971_Part-2.jpg

Item #11 is the Speed Swictch, and is mounted on the engine 'console' in close proximity to the Voltage regulator. It gets the same ground-pulse signal from the distributor that drives the CDI-unit and tach. It is 'activated' and closes a set of relay contacts at 1500 rpm, and the relay contacts do not open up until rpms fall to 1300 rpm.

Item #15 is the Microswitch mounted on the throttle body, and operated when throttle rod is at rest, i.e, throttles closed!

Item #13 is the Cut-Off Solenoid (or magnet) mounted on the injection pump.

The need for the fuel cut-off during overrun is farly easy to understand, since the MFI injection pump operates primarily based on engine rpm and throttle position ... there is no air flow or vacuum input! So, an electronic relay operates when the engine rpm is above 1500 rpm and provides switched 12 Volt power, fed to the Microswitch. So, an overrun condition exists ... meaning the engine is above 1500 rpm and the throttles are closed, the Microswitch provides 12 Volt power to the Cut-off solenoid, causing the fuel to the injectors to be stopped while the engine speed drops to 1300 rpm. The difference in the switching action on rising rpms vs. falling rpms is called hysteresis, and the electronic action of the circuit with different thresholds on rising and falling triggers is called a Schmidt Trigger.

This interupted fuel supply is why properly-operating MFI cars always get better gas mileage than Weber-equipped cars -- even found to be the case empirically in 906E race cars at Le Mans!
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Warren Hall
1973 911S Targa

[This message has been edited by Early_S_Man (edited 09-08-2001).]

[Early_S_Man]

Dave,

I just did a search at Stoddard's part number look-up on the 901.613.106.00 Microswitch and came up empty.

Since 'Microswitch' is a company name and standardized product line second-sourced by many companies for the military in the '60s and '70s, I should be able to find a replacement in some electronics supplier catalogs!

------------------
Warren Hall
1973 911S Targa

[dwood]

Thanks again Warren....

I checked the switch again, and it seems OK (I think I originally checked the mounting screws instead of the bottom blade connectors; oops.....). Anyway, the switch seems OK, except one of the bottom blade connectors is missing. I've already fixed that.

The wiring from the switch to the cut-off solenoid is fine, and the wiring from the switch back to the RPM transducer is also OK. But, I checked for 12v at the wire from the transducer with the idle above 1800rpm (with the throttle lever), and nothing. I pulled the transducer and opened it up, and everything looks OK. No obvious circuit problems on the rpm transducer board. Maybe I didn't rev high enough.

My next step will be to reinstall the transducer and try again (I cleaned the leads), and if that doesn't work, I'll have to check the other wiring to the transducer (power source, ground, and signal from distributor, I think...). Hopefully I'll be able to get all that going, and then the only question left will be the shut-off solenoid.

If I apply 12v to the solenoid lead, should I be able to hear a 'click' if it's working?

Thanks again for the help,
Dave....


[This message has been edited by dwood (edited 05-22-2001).]

[This message has been edited by dwood (edited 05-22-2001).]

[Roland Kunz]

Hello

Easy check as far i remeber.

Let the engine run and rev it over 2500/min.

Hold the throttle from the enginbay at that rev. Use your left hand and press the switch while the engine is still at over 2500/mn.

Now the enginerev should drop to 800 - 1000 for a sec and then speed up automatically to 1600 - 2000 and fall back again. It will always cycle beetween those marks even if you have full throttle then. ( Don´t try it with more then you need.

If it will not work the system has a failure.

First would be to short the switch just by connecting the spades. And then look if you have power on the selenoid.

Very easy to track down to the tachometer unit.

The microswitch is a Klöckner ( brown bakelit ) or Wherle ( black ) unit and was used at Mercedes Benz MFI too.

Mostly Bosch dealers stock them too.

They have very rarly failures. Mostly if the rubberboot is missing or craked.

If everything brakes you can adopt the 911/964 convertible top switches. Make sure the amperage will suit up.

Grüsse

[Early_S_Man]

Bump... for famliarization related to WARNING thread.

[Early_S_Man]

UPDATE -- I had a new spare mil surplus, Unimax brand 'microswitch' on hand of 1963-vintage, 15 Amp variety that is an exact-fit replacement, minus the 'Faston' tabs and the rubber cap/seal.

A search of elecronic supplier catalogs found the following replacements for the MFI 'Microswitch' ... that turns out to be a standard USA size and mounting configuration dating back to the early 1960s:

Allied Electronics ia source for all of the following switches ...

http://www.alliedelec.com/

SelectaSwitch (mfg by Microswitch 15 Amp rating)-- BZ-2RQ1-A2

C&K Compnents, Inc. --
15 Amp rating - HBS2KCB4SJ055C-5
20 Amp rating - HL2KJC3J055C-5

Omron --
15 Amp rating - Z-15GQ-B7-K
20 Amp rating - A-20GQ-B7-K

All of the above have screw terminals and will need to have 1/4" quick-disconnect or 'Faston' terminal lugs attached to mate to the 911 wiring harness.

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

[brittbolen]

Reading the spec sheets for the C&K part HBS2KCB4SJ055C it is not an exact fit replacement, or at least not for the Kissling Sulz/Calw part that came off of my 70E. The other 2 parts don't have full dimension specs on the Allied Electronic's pages but I think they're not going to fit either.

Granted all I have to do is make a bracket and i'm set, still beats $120+ for a porsche part.

Has anyone else tried using these parts to replace the MFI microswitch?

B

[rexav8r]

Just posting FYI, the last post to this thread prior to yours was in 2001, 6 years ago.

I do also have a '70E but I'm not near my car/stuff, sorry.

Nice to see Roland's post though. I would definitely trust what he had posted.

[304065]

Roland was Der Mann!

For as often as the microswitches break I'd happily pay $120 just to find the right one.

[brittbolen]

I realize this thread is _ancient_ but enough other threads point here, that I thought it would be useful to keep the comments in one place...