How do you set your mixture

[calimedeiros]

Do you guys actually have a tester or is there another way to set the mixture

[The cap'n]

Not enough information for a meaningful answer ..........................

The Cap'n

[tirwin]

I'm assuming you mean on a CIS system. Otherwise what The Cap'n said.

The "proper" way to do it is with an exhaust gas analyzer. I've found that finding shops that still use them can be a bit tricky. Not that it's impossible, but you'll probably need to call around to find one. You can get "in the ballpark" using the dwell meter method.

Are you looking for the dwell meter procedure? Or do you just want to know which method people use?

[calimedeiros]

Sorry yes it's for a cis car
81 targa.
Car is runing good but I'm always curious to see how u guys mess with the adjustments in these things

[dicklague]

I have an MFI car and i use a AFR instrument. It is a wideband and the brand that I really like is the Daytona-Sensors WEGO IV It is very accurate and logs several hours of data as well.

Wideband AFR units have changed the face of tuing CIS, MFI, Carbs and even EFI.

[The cap'n]

OK, then. First, valve adjustment, engine electrics (i.e., "tune-up" need to be good. Engine at operating temp, timing correct, vacuum capsule on the distributor functional with no leaks. From there, you can check the O2 sensor voltage with the sensor wire unplugged. It should be producing between .2 and .6v. To see if it's functioning, blip the throttle a couple of times and see how it reacts. They get old, mostly because people don't think of an O2 sensor as a consumable. If it functions properly, turn the adjustment screw in the sir flow meter a bit , rev the engine for 10-15 seconds, let it idle again and look at the voltage. It doesn't take much to make a significant change. Get it to around .4v, connect the wire and see what happens. You should see a fairly rapid cycling between .2 and .6v. You'll have to hold the RPM up again and let it settle back to idle for an accurate reading. Repeat it a couple of times, making sure it idles for 20-30 seconds (or more) before you read the voltage. You may have to reset the idle speed during the procedure. Note that this procedure is a rough substitute for using a CO machine, but it has worked well for me since CIS with an O2 sensor appeared on the market. Remember: basics set, engine temps up, small adjustments, and allow the idle to stabilize before you take measurements! I have found over the years that these systems rarely need "messing with the adjustments"! When they do, there's usually something else wrong. Too lean and it'll be hard to start, too rich and the idle will hunt.

The Cap'n

[calimedeiros]

Thanks for the information

[Bob Kontak]

The cap'n write up is worth of note. I have done this and it works fine. You do have to "back-pin" the O2 connector when it's connected to test at the end of the procedure. Meaning you have to squeeze a tiny enough wire in there when connected to pull a reading.

I have used tin foil in tight squeezes to back pin.

[stlrj]

Originally Posted by calimedeiros

Do you guys actually have a tester or is there another way to set the mixture

I use a dwell meter to set the mix on my 82 Targa, the way it's done by the pros. I doubt you will get it right backpinning the 02 sensor, but the dwell specs are very specific.

Cheers,

Joe
82 Targa, 87 Carrera

[kshafer1]

This is what I use to set the a/f mixture:

LM-2 Wideband O2 Digital Air/fuel Ratio Meter

BTW: My '79 SC pre-dates the introduction of the O2 sensor

[SoCal911SC]

Is the mixture adjustment screw the same as the idle screw mentioned above?

I have a Delorean with K-Jetronic and there's a small hex screw that you turn. Right for rich and Left for lean. Same on the Porsche?

[tirwin]

Originally Posted by SoCal911SC

Is the mixture adjustment screw the same as the idle screw mentioned above?

I have a Delorean with K-Jetronic and there's a small hex screw that you turn. Right for rich and Left for lean. Same on the Porsche?

No. The idle screw is on the left hand side of the engine (facing it from the back). It's near the throttle cable. The air mixture screw is on the right side. There is a hole to the left of the fuel distributor you stick a long 3mm hex allen wrench into. If you didn't know it was there, you'd never know it was there. If you were looking down on top of the FD with 6 o'clock being the rear bumper, the hole would be at the 9 o'clock position.

[Newfie911s]

Wideband O2 meter that I picked up on eBay for about $150.00.

[Flat6pac]

Originally Posted by SoCal911SC

Is the mixture adjustment screw the same as the idle screw mentioned above?

I have a Delorean with K-Jetronic and there's a small hex screw that you turn. Right for rich and Left for lean. Same on the Porsche?

Yes, there is an idle screw on the throttle body but as the Deloeran, the mixture screw is between fuel dist and the air flow sensor. A small hole to access with a 3 mm long Allen wrench. Rich is. Clockwise and undo the ox sensor to adjust.
Bruce

[Reiver]

Originally Posted by Newfie911s

Wideband O2 meter that I picked up on eBay for about $150.00.

Get rid of the dumb clock and put a wideband meter in place...I monitor my CO on a daily basis and believe me...it can change.
The 30 + year old CIS system is not a very well computer controlled system. It requires monitoring and since many do not get a yearly CO check up are beyond what the factory thought would happen.
I adjust mine regularly and with ease with the on board system...I know the sweet spot.
Injectors clog, valves get dirty, etc. and all effects fuel air ratio.
Assuming a one time check every few years is a big assumption.

[calimedeiros]

Interesting can you show me a pic of this set up and also what are some of the part numbers for this set up