First ? on the 90-95 Zr-1s what does their performance key do?Does it run at 300hp when key is in Econ mode?Is there a large seat of the pants difference when key is switched from Econ to Performance?
Second ? is when I have my a/c on the car runs hotter.Is this normal?I would think it would be running cooler as the fans are on.Even at highway speeds it runs 20 degrees hotter than when the a/c is off.I'm going to be replacing "radiator" cap & opening up bleeder when car is warm to see if that helps with car running hot.I also turn the heater on when temps reach 235 degrees which brings temps back down to 220 degrees.I hate doing that as its been hot & humid here lately.I checked for debris inbetween radiator-its fine.I also checked for coolant leaks-none.It has fresh coolant & a 160 degree thermostat I installed last summer.Engine runs good with no smoking.Am I going to have to bite the bullet & buy a Dewitts to solve these running hot issues?

 

200 hp are the specs I've seen with Valet Key on.

a/c should be cooler. It's either got debris blocking the condensor or it's plugged up internally. Check operating pressures with a manifold gage set or the a/c pressure signal with a scanner. If the high side is greater than 220 at speed, it's one or the other. Heater core should have coolant flow through it at all times. That might drop it a degree or two.

 

The Valet key/performance key/power key (whichever term you like! ) activates the secondary butterfly plates which are located in the secondary intake runners in each cylinder head. The second set of fuel injectors are also controlled by the same key. The system operates using vacuum from the engine and/or electric vacuum pump.

With the key in the "Normal" position, the secondaries and the second set of injectors are deactivated and the engine only runs on the primary set of intake runners and injectors. Power is then limited to only around 200-220 HP.

Once the key is turned to the "Full" position, the "Full Engine Power" light in the DIC (1990 ZR-1 only) or the LED next to the power key (1991-1995 ZR-1's) is turned on and the secondary butterfly plates and second set of injectors are enabled. Now the full 375HP (or 405HP for 93-95) is available for miles of Perma-grins!!

Yes, you should be able to feel a big difference with the key on compared to off when you accelerate. If they both feel similer, even when accelerating aggressively, then the secondary system is not activating properly, which almost always means you have a vacuum leak preventing the secondary actuators from opening the secondary intake plates. A lot of ZR-1 guys just remove the secondary intake plate system completely and have the ECM chip reprogrammed.

You said you checked the radiator for debris, but did you completely remove the shroud and the radiator to do so? If not, there are areas you can't see with the shroud on where crud can collect. I also recently read a thread about someone finding a lot of crud in the second evaporator thing (not sure what it's official name is) mounted under the plastic shroud at the firewall where the A/C line goes in. The radiator overflow/fill tank has to be removed to get to it.



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Thanks for the answers200 hpWhat does that feel like(when in econ mode)?I haven't removed the shroud & I will remove it & make some type of adapter to spray water in that area.I did like from the side between the condenser & radiator & there was no debris there.I didn't check the fins on the condenser or radiator though.I'll do that & clean the fins & hopefully it improves.Wonder what the quarter-mile time would be in econ or valet mode on those Zr-1sIs it harmful to drive them in econ or valet mode?

 

UPDATE-I've been driving my car the last few days & its been hot & humid.I've been in stop & go traffic also.The engine never got to 240 degreesI believe another fan is kickin in at around 237 degrees so the temp goes downAlso had a/c on & no overheating issues.Now I can stop worrying & turning on the heater-which sucks when its hot out.I still haven't cleaned out condenser & radiator but will after I install the throttle body bypass which I've had since last summerAnyone think I'll gain any HP from doing this?