160 deg thermostats for TPI's have had some controversy.
I have an '89 IROC with a hypertech stage 2 chip and160 stat.

Should I be concerned about staying open loop, running rich or chronic overcooling with the stage 2 chip for which the 160 was recommended?

I can't get a straight answer from hypertech.

 

i have this chip and this problem with my car.

ok so i have the hypertech chip which turns on the fans at 160 and if its summer time and i'm running a 160 degree thermostat great keeps the engine nice and cool, i didnt have any problems with the car running rich, i wouldnt say it was overcool. in the summer with the ac on and windows up in traffic it was still over 180 or so, you cannot keep these cars cool enough in the summer time. now thats its cool out though a 160 degree thermostat sucks, no heat for the car or at least not enough. so i switched to the 180 degree thermostat which gives me some nice heat in the car but the fan will stay on none stop since the thermostat will close before the fans turn off.

do i think you should be concerned with staying open loop or not or overcooling? well i am going to switch to a seperate fan switch so i can change the settings on the switch rather then having my fan running when it is 30 degrees out, but still be able to turn it down in the summer when i need that cooling really bad.

check in the tech articles for info on cooling fan control.

 

I actually have one of those in my car right now, and recorded the data from it to work and back home from there. It never went into open loop, wasnt running rich at part throttle it was actually lean (although its an 86 chip with a 91 engine, I think that the 86 fueling is pretty lean) and the EGR was working too. Looks like the EGR started working at 117F and was mostly functional (78%) at 165F, which is about where the temp runs.

When my engine was stock, it did run rich. Hypertech claims this isnt the case, but I know thats not true. I havent looked in the chip to see if they modified the fuel tables or not, but something tells me they didnt.

 

Thanks for the info guys.

I store my car in the winter so I'm not too concerned about passenger heat...I just don't want to cause any premature failures(dual cats etc.).

Does anyone know what is reprogramed on the stage2 chip vs the stage 1 chip on a 5-speed application?