Awhile back I scanned my car and noticed that my air intake temp sensor was not working. It was reading -40 degrees F. So, I replaced it.
My car instantly started running rich as hell from 0 to 8 pounds of boost. We are talking like 10 flat on the AFR. Which doesn't make sense, because you would think that the car would richen up when it sees -40 degrees, not when its a normal temp.
So, Ive been doing something thinking... Maybe my coolant has something to do with it. I run a fluidyne radiator and a 160 degree thermostat. Im thinking that now all the sensors are functioning properly the car is trying to adjust itself for what they are reading. Unlike before it probably wasn't making any corrections because the air intake temp sensor wasn't working.
My theory is.. is that since my coolant is very cold and my intake air temp is colder than normal, that the car doesn't have a chance to fully warm up.
When our cars are cold, the engine tends to dump more fuel until its warm. Well, if the car never gets fully warm (according to the ECU) then it will run rich as shit.
#88003, "RE: Air intake temp sensor / Coolant Temp / Rich Boost.. Questions.." In response to Reply # 1
Originally posted by siueclipse Called Mitsu. They say that you should not run a colder thermostat because the car will run like shit and stay in an open loop mode and be too rich at all times.
...and the closed loop cutoff is 150*. Even at near-freezing temps the last winter the car ran, at 70+mph on the freeway with a 16-* tstat, i never saw colder than 175* coolant temps.
Fuck Mitsu and what they think.
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'95 Eclipse TurboGS (garage deco) '95 TSi AWD (restoring a survivor) '97 Talon ESi-T (poor impulse control) '99 Eclipse RS-T (daily beater) '13 Evo X (mostly stock) '17 Sienna (Middle Aged Dad Mobile)
#88005, "RE: Air intake temp sensor / Coolant Temp / Rich Boost.. Questions.." In response to Reply # 1
Originally posted by siueclipse Called Mitsu. They say that you should not run a colder thermostat because the car will run like shit and stay in an open loop mode and be too rich at all times.
You're engine isn't exactly stock either. Fuck Mitsu... they don't know what they're talking about. As far as the ECU is concerned, anything over 150 degrees is fully "warmed up". Doug
#88010, "RE: Air intake temp sensor / Coolant Temp / Rich Boost.. Questions.." In response to Reply # 4
I understand that my motor isn't stock. Mitsu says the stock temp is 195 degrees. They say that using a 180 degree thermostat would be ok, but not recommended. They certianly do not recommend a 160 degree stat.
I bought a 195 degree from Autozone. Im going to change it out in the next day or two and I will report and see if it made a change in my system.
It will be worth the $10 in parts just to check out the theory.
#88014, "RE: Air intake temp sensor / Coolant Temp / Rich Boost.. Questions.." In response to Reply # 4
Originally posted by WickedESi Open Loop = good, close loop = bad. Closed loop is the destroyer of engines.
Depends on the application. If the stock ECU is in closed loop mode it will seak 14.7, not good when you add more than a pound or two of boost pressure. With a MS many people run closed loop under all conditions with the aid of a wideband.
#88028, "RE: Air intake temp sensor / Coolant Temp / Rich Boost.. Questions.." In response to Reply # 8 Jul-19-05 04:16 AM by WickedESi
Originally posted by ner947
Originally posted by WickedESi Open Loop = good, close loop = bad. Closed loop is the destroyer of engines.
Depends on the application. If the stock ECU is in closed loop mode it will seak 14.7, not good when you add more than a pound or two of boost pressure. With a MS many people run closed loop under all conditions with the aid of a wideband.
Isn't close loop on a aftermarket ECU essentially what they call "auto tune".
Joel Baldridge, ASE Certified Master Technician, Audi Certified Expert Technician
#88002, "RE: Air intake temp sensor / Coolant Temp / Rich Boost.. Questions.." In response to Reply # 0
Yeah it does. When the temps are below 170-180 the ECU richens up the motor to get it up to operating temp faster. You can put a 10k 5W POT in series with the coolant temp sensor and set the right temp by using the data logger.I would post a diagram but I don't know how.
#88031, "RE: Air intake temp sensor / Coolant Temp / Rich Boost.. Questions.." In response to Reply # 11
Originally posted by tim96rs Yeah it does. When the temps are below 170-180 the ECU richens up the motor to get it up to operating temp faster.
No. it doesn't. Open loop cutoff, as stated above, is 150*.
______________________________ If a sentence found online has 35% misspellings or greater and includes at least two racially charged expletives, chances are it is a YouTube comment.
'95 Eclipse TurboGS (garage deco) '95 TSi AWD (restoring a survivor) '97 Talon ESi-T (poor impulse control) '99 Eclipse RS-T (daily beater) '13 Evo X (mostly stock) '17 Sienna (Middle Aged Dad Mobile)
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