1987Porsche944WithRealLongName

At cruise mine seem to go as low as 14.0 and as high as 15.3
Its a constant dance but my idle afrs usually stay put around 14.6-15.1
Could it be a sign of my o2 sensor slowly dying? I unplugged it and there was a huge difference in a negative way.

At idle you can feel and hear it stumble and pop, it sounds like this
I replaced the plugs a few weeks ago and my compression is good
My TPS specs out perfectly

raleighBahn

are you saying it holds constant at some value above or below 14.8, or rather it is alternating above and below within that range? The latter is normal behavior. The real question is if you have noticed a change from what your steady state is?

1987Porsche944WithRealLongName

It alters within that range. I'm just wondering how wide of a window its supposed to vary in.

Rogue_Ant

Your readings are pretty normal.

Eric_Oz_S2

Mine tend to wander at wot with no O2 feedback as well. Probably because of the gm IAT used in place of the afm sensor, or does this occur with stock motors as well?

Varies by upto 0.5 afr.

Chris White

The O2 correction has a lag in the feedback loop. The O2 sensor is almost 3' from the combustion chamber and the amount of time it takes the exhaust to travel to the sensor means that the DME is trying to adjust the AFR from an exhaust sample that is 'old'. The time lag varies with engine sped and load, Steady cruising is close to the worst situation and the DME will always be over correcting.

Its not a problem - but it can be annoying on some cars. Once you are aware of it you can feel the slight difference in the engine as it oscillates back and forth.

BTW - if you want to go for economy the 8v engine will cruise at 16:1 with no issues. that's steady cruising only - it needs to get richer as soon as you want any power.