LaughaC

I bought the 't-wrench' to adjust my mixture for the winter, but I cannot find the adjustment screw and my book is not specific enough. Does anyone have a picture?

DGaunt

It is between the rubber boot that connects the throttle body to the airbox and the fuel distributor. There is not much room there which narrows the possibilities a lot. You are looking for a small hole about 3/23 in idameter. It might have a plug with a wire handle in it, but most of them got lost forever ago.

Before you mess with the mixture, make sure you know which way is leaner/richer. Make really small adjustments and rev the engine between adjustments to let it settle. Why are you trying to adjust it anyway? Most problems have nothing to do with mixture, though you can mask a problem for a time by richening the mixture--but I am not reccomending that. Also, the adjustment really only affects idle so if you have a higher speed problem, you have to look ensewhere.

Good luck.

emac

Dave
Right on with everything -- however you should have mentioned the he should NOT leave the
wrench in if he rev's the engine.

Ernie 81 SC

DGaunt

Good point emac! D'oh!

redidrum

Ask E-Mac why he knows?

john70t

The CIS adjustment shouldn't be necessary, but if so it should be done with a gas analyzer. No way to tune it "by ear", and the adjustments are very fine. The most common suggestion has been to disconnect the O2 sensor(which trys to adjust the mix to a preset curve) to richen it slightly, and there may be something else causing what now seems like a lean miss- such as low fuel pressure or bad wires etc...
Also if the engines aren't kept at higher rpms and lugged like a daily driver, they can gum up quickly.

Peter Zimmermann

Laugh: What year/model is your car?
Pete

Peter Zimmermann

john makes the best point of all, that "T" wrench is useless without an exhaust analyzer. However, since CIS, there are some misconceptions about "lugging" and "keeping the revs up." First of all, CIS and later cars, when using high quality oil (KENDALL GT1, Mobil 1, etc.) and high quality fuel (Chevron w/Techron) don't gum up in anything less than the most extraordinary conditions. Any CIS and later car can handle traffic, and traffic jambs, with ease. Keeping the revs up doesn't matter, as long as a floor of about 2200-2500 revs is used in the lower gears in town. Obviously, 3K rpm is better in third or fourth because you're pushing more air out of the way. Taking the car up to 5 or 6K before shifting, in commuter traffic, will do two things; wear out the car, and wear out the driver. Commuting can be done easily with a shift point in the 3800-4000 range. Believe it or not, shaft chatter inside the trans, while truly "lugging" a CIS or later car (driving at 1200-1500 revs) will cause eventual premature bearing failure in the trans. Obviously these suggestions/opinions only scratch the surface of a very deep and complex subject, but I'm afraid there isn't enough room here to be more complete.
Pete

Lorenfb

I. Key points to check before setting the mixture:

1. the system pressure
2. the warm control pressure

II. Mixture evaluation:

1. disconnect O2 sensor
2. check Lambda unit for 50% duty cycle
3. monitor CO & CO2 at idle & 2000 RPMs

III. Set mixture and do step II #3.

IV. Connect O2 sensor & do step II #3. Then monitor the O2 sensor for varying voltage
between (about) .25 volts to .75 volts.

LaughaC

Wow, what great advice! I forgot to subscribe to this string and didn't expect to see so many answers today. Many thanks to all of you.

Okay, here is some more relevant info:
My car is a '77, so there is no O2 sensor, but it runs great. However, when temperatures drop below 60' it surges at little at idle. I put a new fuel accumulator on the car not long ago, and I've notice the warm up regulator appears to have a missing vacuum hose on the right side when looking at it. If anybody knows where this line is supposed to connect it may solve the problem before I mess with anything else.

It sounds like I've been running lower RPMs than I should in traffic. I live in the country and only have 2 stop lights per day to deal with, so it will be easy to adjust this habit. Running between 2200-3800 in each gear will be a pleasure.

john70t

CIS is great, but it is pretty sensitive to vacuum leaks. If its missing, plug that vacuum leak and find out where it goes (mabye to the carbon canister?). A few overlooked rubber maintenance items are the fuel distributor boot and injector o-rings. The throttle butterfly, EGR valve(have one?) and inside the fuel distributor should be cleaned ocasionally too with a spritz of carb cleaner which can possibly get slightly gummy.

LaughaC

Thanks. Mine has no EGR but I'll read up on recommended maintenance cleaning. Right now I have about a 50 RPM idle surge when outside temperatures drop below 60' F or so.

I have had no luck finding the vacuum line that goes on the empty warm up regular nipple. My guess is that the the manifold end is in its proper place and the loose end is hidden somewhere out of site.

DGaunt

Maybe Mr. Zimmerman cna enlightne us on the vaccum line routing from the WUR?

Peter Zimmermann

Dave & Laugh: Porsche fooled around with those warm up regs, they're not always hooked up the same. The '77 might have one that comes off the top, next to the electrical plug, but it might not. Also, there is a chance that there is a small vacuum hose off the bottom, at the middle of the narrow side that faces the airbox, or not. If it's got the small diameter one, there might be a place for the larger one at the top, with nothing connected there. The best thing to do is look carefully at any hose nipples that the reg might have, and try to determine if anything has ever been on them. If in doubt, leave it alone, especially if the cars cold starts well!
Pete

john70t

To add to the above.... but from a historical perspective..... Back in.the late 70's/early 80's was the advent of the (glorious) oxygen sensor and smog laws. Mainly the exhaust Catalytic Converter controlled this technowlogy, along with something to control what was going into it (CPU/computer controlled mixture).

This was supposed to clean up the "SMOG" in the air over our major cities