well i just did EGR, power steering and flushed the cooling system and added a 180 t stat. now the car is running right at the line between 100 and 220, about 160 degrees by my calculations. so is this too cold or just right. since i have a 180 stat im gona guess that the gauge isnt that accurate and that the car is at about 180. what temp does closed loop activate??? any thoughts??

 

When is it at 160*, in traffic or on the highway. Most will say that 160* is a little cool for emissions purposes and your mpg will be a little less. But I would rather have my car running at 160* than 220*(the way our engines were made to run at).

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'86 IROC
T-TOPS, TINTED WINDOWS, BRAKE LIGHT BLACKOUTS
GM GOODWRENCH 350
EDELBROCK TES HEADERS
3" Hooker CatBack w/Aero Chamber muffler
EDELBROCK 600CFM CARB.
KN AIRFILTER
ACCEL HEI DISTRIBUTOR
160* Stat
3:73 Posi
Rebuilt 700R4
B&M Megashifter, 5" Autometer Tach w/shift lite

 

If I were you I'd be concerned about being in open-loop mode, which will definetely affect your mileage.

However, on the plus side at least you're not doing 220 all the time.


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Trevor
87 Z28 - LG4 - 305
Hedman Headers, Y-Pipe, Dynomax Exhaust, K&N Open Air Filter

http://immortaltk.tripod.com/z.html

 

actualy the 1/4 mark on the temp guage it 170* or 175* i think. the guage is non linear. thats why the first half goes 120* difference, while the second half is 40* (i think) difference. mine runs right past the first 1/4 mark while on the highway, and runs warmer when im going slower.

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- David
88' GTA 5.7L TPI MODS---> air foil, K&N, Shift Kit, 180* therm, TB bypass, Gutted CAT, Flowmaster 80 Series

 

My gauge reads colder than the motor actually is too. Says its 165 but its actually closer to 190. Finally seems to get accurate at 220. Strange but once you know about it not something to worry about.

 

My car has a 160 t-stat and it runs at around 160. I get 27 mpg on the freeway and 20 mpg doing a mix. So I wouldn't worry about gas milage.

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1991 Z28 305 auto, homemade CAI, air foil, power pulleys, ported plenum, hypertech chip, hooker cat back, kyb shocks, PF brake pads, STB, SLP headers, 3" catco cat, spohn lca's, 4th gen 5 star wheels, 14.687@ 96.449 mph

 

im not really worried about gas milage as much as peformance. i want it to run as cool as posible while still being in closed loop. ah well, i guess i need to get an auto x ray and see what shes doing. i do have to say she is hauling a$$ though.

 

At 160 degrees, the ECM should be in closed loop. The oxygen sensor is the deciding factor of when it goes into closed loop. When the sensor temperature reaches 600 degrees, the ECM will then go into closed loop.
But because the fueling level is calculated by the ECU with the input signals from the TPS, CTS, MAP or MAF, the O2 sensor, and the MAT sensor, the fuel curve will be on the rich side if the engine is too cold.
Other functions of the coolant temperature signal are: Idle speed adjustment via the IAC, spark advance, electric cooling fan operation, EGR, etc.