Alright I installed my autometer a/f gauge last night and went for a spin. I was wondering if the following patters are right.

The gauge when starting the car reads LEAN and then works its way slowly up to semi-rich at idle (heating up the sensor I am assuming).

When Driving at cruise control, the gauge light bounces between the top part of stoich and the bottom part of lean (crossing into rich somtimes).

At WOT it is RICH which is a good thing

But when I let off the gas the light disappears into the lean section and comes back on when I give it more throttle (straight to the rich section).

Is that about right?

 

That is exactly how mine reads which is normal from what I have been told.

 

Sounds right to me.

 

I am quite happy with it if that is the case...took me 3 hours to install my Gauge Pod, Boost Gauge, and A/F gauge...to much wiring...yarg.

 

Do you have auto seat belts?

 

Mine reads about the same except at idle it just reads lean all the time and when I get into it at 4k it goes from 1st bar to of the scale lean. I think my secondaries are not kicking in or something (also get a gas smell when this happens) But the wierd thing is if I lift then smash it again it goes back to where it is supposed to be. Well I guess I should stop with my problems just hoping some one out there had the same prob and could tell me where to look.

 

HOW DID U GET THE PILLAR MOUNT ON RIGHT?? BECAUSE MOST OF MY FRIENDS WIT 89-91'S HAVE PROBLEMS BECAUSE IT WAS MADE FOR 86-88'S... I WENT THROUGH THE SAME WIT MY 91.... AS FAR AS THE AIRFUEL GAUGE... MINES DOES THA SAME..WHAT DOES URS READ AT IDLE?

 

i would rather have a water temp gauge than A/F

 

well a dremal and sometime and two screws and it worked out great just mounted it so that the pod was below the track for the seat belts. I could take a pic and post it sometime today if you like.

 

my 7 at idle reads 1-2 bars green and works its way down slowly. if i let it idle long enough she will go to middle yellow (about 15 minutes of idling). the bouncing back and forth (closed/open loop, i forget which one) has stoped. i always get a steady reading. i have my safc leaned out to -12 at idle (1000rpm) and she idles smooth but still reads rich, it trips me out! how can you tell the oxygen sensor is going bad, i would assume when the reading is sluggish. as soon as i left of throttle the gauge reacts instantly so it seems like my sensor is good. i think i need a better a/f gauge.

 

That is correct.&nbsp 3- and 4-wire heated O2 sensors get up to temp a lot quicker.

This is the ECU going into closed-loop mode:&nbsp the ECU constantly self-adjusts the fuel devliery to run closest to stoic and give you the best gas mileage.


This is the most important thing.


That is correct.&nbsp On decel, the fuel injectors are cut off totally - this helps the revs drop as fast as possible.



-Ted

 

my a/f gauge doesnt bounce back and forth at all anymore. does this mean my ecu is not in closed loop mode anymore to?

 

Yep.&nbsp It runs in closed-loop under light throttle and light load conditions.&nbsp It will also not work if the secondary fuel injectors are triggered - this means the revs has to be below 3,800RPM on the tach.&nbsp I'd say anything over 15% throttle input will cause it to disengage closed-loop mode.

Unless you're running a Haltech?



-Ted

 

My friend's A/F gauge bounces back and forth at idle, from extremely lean to extremely rich. It never stays put at idle, is there something wrong?

BTW, this is on a SC '96 Mustang Cobra.

 

Sounds normal - mine does the exact same.

 

Thanks Ted for the awesome followup.

no auto seat belts...its a Canadian Turbo II =) I never did like auto seat belts.

It was a 97% perfect fit...it looks great and is super solid...I followed the instructions roughly from the fc3s.org site.

I hit 10 PSI last night...no fuel cut...strange...and still running rich

I now hit 7 PSI in 1st gear, 10 PSI in 2nd gear, 8.5 psi in 3rd gear, and I haven't really tested the upper gears to their full extent because I know that fuel cut is there some where... (The car has SO much more power and acceleration in the lower gears, thank goodness for no catalytic converter!)

It was the 89-91 specific autometer gauge pod...but you can't put it just anywhere you want without some modification to it, I had to dremmel one hole bigger too because the boost gauge was not the smaller type..ooops...1 size bigger, but it still fits nice.

You have to put the gauge to where it looks like it is flowing with the contours of the a-pillar (nearer the bottom). If you get it just right you won't have to do any modification.

Its great, I'll post some pics in a few weeks.

 

thanks ted!

 

I installed the 88+ pillar gauge cluster on my 89, go search for a thread on gauge cluster (look for one started by rico5) and you'll see our entire discussion on it.

 

Ignore the gauge until the sensor has had time to reach operating temp, usually about 5 minutes. If you mean at idle, some cars do idle rich, especially if you’ve taken your emissions gear off. No pedal, no fuel, no reading. You get a rich “burst” because of your open vented BOV. That released air has been metered by the AFM so its fuel gets injected. But since the air’s not there, you get a momentary rich condition. Then since you’ve let off (just like above), the injectors shut off, so the gauge reads nothing.

Most of this was answered earlier in the thread y’know...

 

Where did you connect the signal wire to? If it's at the sensor (and not the ECU) then that's probably the problem.

 

The O2 sensor cable has an earthed braided shield around it to protect it from EMI. If you pierce this wire to tap into it, it’s hard not to contact the shield too, effectively earthing the whole circuit and screwing everything up.
I haven’t got S5 wiring diagrams so I can’t give you pin info. But if your new DMM has a continuity tester, you can probe all the ECU wires until you find it. Easy.