Do i need a Performance Chip if i put a 160* Thermostat in my car so it dont mess my computer up. I have a 1985 Trans Am 5.0 TPI Auto.

 

The stock programming requires the coolant temperature sensor to reach 176ºF for full closed loop operation. A 160º 'stat probably doesn't quite get the temperature it should.

 

There's no benefit to running a 160 degree stat. It sets the minimum temp, not the operating temp. It will just cause you to come out of closed loop more often. Run at least a 180.

 

A thermostat that cold won't do anything for performance. It will just make it drink fuel like an alcoholic that just won on the bar's VLT machines.

The stock 195* is a little warm IMO, but the 180* is the best choice, especially for a stock-ish engine. This is what the LT1 and LS1 came with from the factory. The engines were designed and set up with tolerances and components designed for an engine running in the 190-210* range. A 180* thermostat will put it right around the lower end of that range.

(**just a little side note, the 160*/180*/195* rating is only when the thermostat starts to open... it is not fully open untill about 10-12* above that rated temp.**)

 

Vader, idk, but i watched my car go into closed loop at 161.2*. I waited and waited and thought for sure closed loop did not happen until 166*? Seems like they go into closed loop on a "timed" basis?

 

What benefit would i exp. going to a 180* thermo vs my present 160?

 

I am changing to a stock chip too vs my current hypertech stg.2.

 

I tried a 160 in my tbi, but it drank gas, so I switched back to 180. I know you have a tpi, so take it for what it's worth. I also have my cooling fan hooked to a toggle switch so I can keep my coolant temp at 180, and not let it go to 225 degrees. I just reach under and flick the switch.

On the other hand, my carbed 305 seems to like the 160. Mileage didn't change, and I have better throttle response when warm. I have a fan switch for it also.

 

what year is your tbi ?

 

92

 

what are you using for a 180 thermostat?

 

What am I using? Please be specific.

 

Stock programming, temperature dependent parameters:

CTS < 14.7̊C (58̊F) for 75 seconds;
CTS >14.7̊ (58̊F) and < 40.7̊ (105̊F) for 51.4 seconds;
CTS >40.7̊C (105̊F) for 12.5 seconds;
O2 >0.699V & O2<1.99V for 10 seconds;

Coolant Temperature Sensor Related Parameters
BLM enabled between 50̊C (122̊F) and 140̊C (284̊F)
Cold spark advance disabled above 56̊C (133̊F)
Hot spark retard begins above 116̊C (240̊F)
Highway Mode spark advance > 59.8̊C (140̊F)
Knock sensor disabled below 66.5̊C (152̊F)
Power enrichment at base A/F ratios > 56̊C (133̊F)
Target IAC idle RPM >80̊C (176̊F)
IAC multiplier at 1.0 (base) > 32̊C (90̊F)
Knock Control enabled > 67̊C (153̊F)
EGR Duty-cycle enabled at 56̊C (133̊F)
EGR Duty-cycle at MAX >80̊C (176̊F)
TCC lockup enabled >50̊C (122̊F)
SHIFT light enabled >50̊C (122̊F)
Diagnostic communication enabled at 70̊C (157̊F)
DTC 43 enabled > 90̊C (194̊F)
Cooling fan #1 enabled at 107̊C (226̊F)
Cooling fan #1 off at 104.7̊C (220.5̊F)
Cooling fan #2 enabled at 115.2̊C (239.5̊F)
Cooling fan #2 off at 110̊C (230̊F)
Cooling fan duty cycle at 100% at 80̊C (176̊F)
Acceleration enrichment multiplier at 1.00 below 80̊ C (176̊F)
Acceleration enrichment multiplier at 0.75 above 80̊ C (176̊F)[/color]
Acceleration enrichment multiplier at 0.50 above 104̊C (220̊F)
Acceleration enrichment decay factor at 25% below 80̊ C (176̊F)
Acceleration enrichment decay factor at 40% above 80̊ C (176̊F)
Acceleration enrichment decay factor at 50% above 104̊ C (220̊F)
Acceleration enrichment decay factor at 60% above 128̊ C (262̊F)
Fuel limiting factor timer at 217 counts below 80̊ C (176̊F)
Fuel limiting factor timer at 169 counts above 80̊ C (176̊F)
Code 13 (oxygen sensor fault) enabled above 70̊C (157̊F)
Code 14 (CTS high fault) enabled above 130̊C (266̊F)
Code 32 (EGR fault) enabled above 30.5̊C (87̊F)
EVAP canister purge enabled above 70.3̊C (158.5̊F)
Hot closed-loop timer enabled above 70.3̊C (158.5̊F)
Rich/Lean O2 offest at 16 counts between 20̊C (68̊F) and 92̊C (197.5̊F)
A/C clutch disabled above 150̊C (302̊F)

That third to the last line shows why your scanner is reporting "Closed Loop" but it is not FULL Closed Loop as I stated several years ago.

 

what brand of 180 thermostat are you using?

 

I am using a 180* thermostat made by "Stant". I don't remember whether I got it at advanced auto or NAPA.

 

is motorad fail safe themermostat any good?

 

I don't know which is better. I just know mine doesn't stick... yet. I have heard of thermostats that are designed to stick open if they fail. I am skeptical. I just watch my gauges, and I will pull over before I fry the engine.

 

So according to your data the engine leans out at 197.5??

 

I put a 160 degree thermostat in my 87gta because the stock 195 kept my car running at 220, but now my car runs about 155 if my digital temp gauge is correct and goes through the gas. I figure the car is running rich off the 02 sensor. I bought a 180 degree thermostat the same time i got the 160 to try out. Now that i can tell mileage is reduced i will try the 180 out! I would have thought the 160 degree thermo whould have delivered a running temp about 175-180 but it seems to run way to cold.

 

My crossfire did the samething with a 160 thermostat but it also caused my car to overheat. But with 180 it now runs in closed loop

 

WOW... soooo tired of bad 160* info
I have run a 160* Tstat in all my fun cars with ZERO issues for 20 yrs. Esp the iron head cars,
Take that back, if you have to E test your car (I hear they pass) or your a skinny person thats cold all the time and need your heater set on hell from sept to april leave the 195 in your car.
ZERO MPG change with the 160*. Unless you run your car harder because it picked up a bit of power.
Some say when the temps drop outside, you use more fuel with a 160* , thats true and false. ALL cars, no matter what the t-stat is, use more fuel when you cram more cold dense air in the motor, DUH.
I still don't understand how people say the 02 sensor goes into open loop because of the coolant temp???
IIRC, The 02 uses EXHAUST temp, a timer in the ecm and I think a coolant temp of 100* to kick on. A 160* is NOOO problem.
If you want a 160 in your car use it, as long as your electric fans are set properly for it.

 

I love how my car runs, but it seems to use more gas. It could be my imagination as I can only afford to fill it up half way and the bottom end of the fuel gauge always runs out quicker (it seems) than the full-half way mark. My 25 year mechanic buddy thinks the car running that cold will run rich because it operatives off the 02 sensor until the car his its programed running temperature that the ECM is programed to lean out. According to him, unless I reprogram or chip the ECM my car will always run richer off the 02 sensor because the cars computer thinks its still warming up. I may stick the 180 in and see how it does. I have 3 thermostats sitting around and the 195 is definitely to warm.

 

P.S.
Even with my 160 degree thermostat and cool running 155-165 degree temp., my cars heater blows hot still.

 

The bottom of the tank is kinda shaped like a triangle soo it will seem like you use fuel faster just because of the shape. Watch how much your putting in the car, gallons wise. your prolly only putting around 5-6 gallons in and itll show half tank or close. you have a 15.5 gallon tank. soo your really putin in close to a 1/3rd instead of a half tank.

 

yeah well 5-6 gallons on a good day! lol. I will put 15-5 dollars in (depending on how empty) and get about a half tank. Maybe I'll wait until I can actually fill it all the way and see what it does. I assume the ECM is programmed to lean out the system once it reaches a certain temp and if it never reaches that temp it would want to run richer?

 

maybe your gauges are inaccurate. When i ran a 160 thermo my car stayed at about 170 ish. I remember it hitting 200-210 on a 100 degree day once.

 

Well its been cool out here in Idaho so i have not had the chance to see how my car runs on a hot day, but with the 195 thermostat i was always sitting at a solid 220 degrees this winter weather i was sitting still or on the freeway. Its possible this thermostat is also opening a little sooner than what the 160 should do. I bought it at autozone. I may just wait as Summer is here and it should start to get hotter out. Then i will also want to get my AC working and that will also heat things up.

 

that happened to me as well

 

my car is a 1983 crossfire injection 305ci V8


my friends snap on Modis scan tool showed that it was never operating over 156 degrees on an average day and it was jumping in and out of closed loop. it was running rich all the time . my car never ran in closed loop unless it 90 degrees plus outside. when it was 90 degrees or higher outside the operating temp was around 210-220 degrees.


for you to run a 160 thermostat properly you need a performance prom chip or ebl flash computer, or the computer is going to think that it still has a 195 thermostat in it.


the 180 thermostat, the crossfire motor stays in closed loop and better gas mileage. it does not go above 200 degrees . even when it was 90 degrees out during the last couple of days.

 

these wre desgned to run at 220 degrees. 220 is normal oprerating temp

 

The modis uses the factory sensors for its info and we all know how these sensors and gauges are perfect...
Even with a factory 195 T-stat, if these car idle very long they will jump in and out of closed loop. If it goes open loop going down the road you have other probs than to cold of a T-stat... Weak spark,leaky inj, tbi or carb on the dr side. If your car has headers it will happen worse. Heated 02s work wonders and are fairly cheap.

I'm not sure if the cease-fire has a mech or electric fan? Either way you are correct, the fans (clutch and electric) need to work with which ever T-stat you chose.

With a 180* t-stat the fan (If electric) should come on @ 200°F/Off @ 185°F.. You shouldn't be running at 200*, maybe splitn hairs a bit, buuuuut.

 

my 1983 CFI has a mechanical fan with no thermostatic clutch .
for a crossfire it is very reliable.


the 1982-1983 F-body CFI's has a mechanical fan.

the 1984 corvette 350 CFI has an electric fan.


its probably running at somewhere between 190-200 degrees

i had a weak spark caused by the 160 thermostat. it fouled my plugs. I have new plugs in there and my TBI's don't leak.

 

Weak spark isn't from a 160* t-stat, it would be from a bad coil or maybe even to cold of a plug. (of course this assumes the carb is properly tuned)
If you have to run the engine that warm for a complete burn your masking a small problem someplace.

Thank you for the early car info. I'm kinda thinking you may also have a copper or brass rad? I don't remember when they switched? They run a bit warmer than the aluminum rads, IIRC
Its been a veeeery long time since I messed with a clutch fan, are they RPM or temp controlled? Both? I know they don't spin as hard going down the road.

 

Fan clutch is temp controlled. Bi metallic spring on the leading edge changes fluid passages that the silicone runs through to lock and unlock fan.

 

This is a great discussion.

 

I thought thats what controlled it...

 

the fouled plugs came from the 160 thermostat causing a rich condition. my spark is excellent.

my car has electronic fuel injection and does not have a carburetor. the crossfire throttle bodies are in sync / balanced.

the previous owner removed the clutch fan and put in a direct drive fan.
my mechanical fan is on all the time when the engine is running.

a clutch fan could be either rpm or temperature driven.

I have a new stock replacement radiator from spectra. I don't know what is made out of.

 

yeah for an ASE Exam

 

This is not a great discussion.
I get tried of telling people this, efi cars dont have chokes, right. The ecm uses the coolant temp sensor (instead of a choke) to richen or lean the air/fuel ratio, if your running at 155* going down the road its like having the choke half closed. Is that good for performance?
If you have a 195* stat & its running 220 going down the road then you have a air flow problem, like a missing air dam or debris in front of the radiator. Or your gauge is not working right.

 

[QUOTE=KITT1983;5250601]the fouled plugs came from the 160 thermostat causing a rich condition. my spark is excellent.
[QUOTE]

I highly highly doubt the 160 is the plug fouling prob.
In closed loop, your O2 ultimately controls the A/F ratio, not a 160* T-stat.
Exhaust gas/combustion temp controls the non heated O2 sensor and if its going open or closed loop, not a 160* t-stat.
In open loop, the ecm uses the coolant temp sensor to help richen or lean the air/fuel ratio from set programing. (maybe you have a bad/flaky ECM coolant temp sensor?)
Your car would be the 1st in my almost 30 yrs of wrenching on cars that Ive seen or heard of with this problem.
If you foul plugs because of a 160* you do have another issue someplace.

I do understand that your car has TBI units an not a carb. They are both similar in that they have a wet intake and generally poor fuel distribution.

A direct drive fan robs the most power,(and its like wiring a electric fan to stay on all the time). I saw a dyno test on them and read the same thing about them many times. I would put a clutch fan back on.

 

According to Vader's info above, the coolant temp determines open or closed loop. Once the ECM is there, it's looking for the O2 sensor to report rich/lean switching. But the O2 can only switch rich/lean at a certain minimum temp, determined by exhaust temp if it's a single wire, non-heated type.

 

I think (id have to check my service manual) the temp is 100*, a certin amount of run time and 600*(?) exhaust temp lets the computer switch to the O2 for AFR control. (I'd have to dub check)

 

the minimum temperature for entering closed loop was 165 degrees on my car confirmed by modis

with the 160 thermostat it never went beyond 156 degrees

where can i get a heated O2 sensor for crossfire ?

 

You will need a 3-wire O2. These were used on early 90's V6 S10 pickups. 2 of the wires are a heat circuit (12v ignition and ground), and the 3rd wire will be the signal.

 

you mean like this one

http://www.summitracing.com/parts/CEI-103025/

 

I use the Bosch universal sensor for an 89'ish Mustang 5.0, it comes in 3 different wire lengths and the price usually varies between 35-55$
I have the part number(s) someplace in the garage..


Kitt: What does the factory service manual say your computer needs to see for your O2 circut as far as operating perameters??
I'd bet your car never saw over 155* due to the fan being a improper direct drive.

 

It never went above 156 degrees. It uses all sensors not just the o2 sensor for operating parimeters

 

I'm not asking what your car did. I'm sure it was cold because you have the wrong fan and its pulling air as long as its running.

What does your factory service manual say the ECM is looking for while in open loop to switch to closed?
How many seconds/mins of run time, coolant temp and O2 exhaust temp?
I did a quick search and couldn't find the info.