Too early to tell. The temps are at 40 F now outside
But when the weather warms up it should show some benefits.

I gotta dig into the FSM'* in great depth pertaining the PCM for someone anyway. Lemme look in greater detail at it.

If the O2 sensor has no effect on your timing advance, and only AFR, you should be golden. My idea some time ago when we didn't know alot was to set this up as a 'happy ****'. In the cockpit.

A switch would change me over from 'real' to a simulator when I wanted it.

Souds like a good idea, im hoping this trick will work

Well, we can test it on OBD1 and 2 now. Maybe we should.

Taking advantage of the 80° Florida weather with Don on the phone in his 91LE, with his IAT disconnected the scantool thinks the temp is 61° (the PCM 'cold' operation limit), and with it connected it reads 80°.

Sensor disconnected (tricked to 60°) Don achieved timing advance of 48° (max peak 49°) with TCC lockup. Unlocked was also 48° if he feathered the throttle.

Sensor hooked up and reading 80° IAT temp, timing advance was 44° max. That'* a difference of 4° of timing advance which roughly equates to 12hp.

HOWEVER, we don't know what would happen long-term with the PCM, which is the question. It would appear that in hotter weather, there would be a greater delta (difference) and that more hp could be gained with hotter air temps (ambient).

Silverbullet and I can't test this for confirmation as our ambient air temps today are in the 40'*.

The OBD2 and the L67'* (both gens) will probably be more restrictive in timing advance due to risk of KR and emissions.

On my 95 when you unplug the IAT.......The computer runs at a baseline 40* temp.....Only thing I have notcied from doing this is a SES and a lil bit better idle in 90*+ weather.

But did you ever scan for timing advance? And will it actually advance the timing if it knows the sensor is disconnected? Don'* 91 PCM may not react the same as our OBD1 PCM'* or the OBD2.

I did, but it was probably right after our main meets, and now I can't really remember what the number was....I'll see if I can remember and post back

I am not just unplugging my IAT sensor and removing it. I am using a resistor in its place to simulate 40 F and trick the Computer.

IIRC, there won't be any added timing effect cooler than 60°F, but I'll have to look it up to be sure.

However, simply disconnecting it will tell the PCM to default to 60°, as Don did a couple posts above.