well i got into a conversation with a freind of mine that has had a large amount of background in jbodies, his last before it was parted out, was turboed and had nitris. but back to the point, i asked him about running a cooler thermostat, and he suggested just pulling the thermostat. apperently he did it on his, and did wonders. i was told that it forces the car to stay in open loop. now my question comes into play here, what are the benifits of running in open loop vs closed? are there any disadvantages? just trying to debate what i want to do here, i know the "right" thing to do is go with a cooler thermostat, but at the same time.... if there are no disadvantages to concider, why not?
The ecu should run in cloosed loop when at w.o.t. regardless.
The thermostat wouldn't effect the ecu dirrectly, but indirectly through the coolant temperature sensor.
Running in open loop all the time you will get worse fuel economy
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The ecu should run in cloosed loop when at w.o.t. regardless.
it goes to open loop at wot.
Pulling the T-stat on a street engine is considered a no-no. First, the engine really should be allowed to warm up in order to force condensation out of the crankcase. If moisture is allowed to build in the crankcase it has a negative effect on the engine's longevity. How much of an effect? It depends. Probably not an issue for someone expecting less than 100k miles out of their car. Second, a warm engine with warm oil loses less power to oil viscosity. Cold oil is harder to move and doesn't lubricate as well. Third, you tend to lose efficiency if the engine is too cold. Too much of the heat of combustion is wasted trying to heat the coolant.
The ecm/pcm on most older cars will not enable closed loop until a certain coolant temp is reached. In open loop, a richer AFR and more agressive spark advance are usually used. Combine this with colder intake air temps and the greater air density which accompanies them, and you get more power, especially in midrange. But you use more fuel to do it and you build more deposits in the oil and in the crankcase.
In reality the best way to make power is with cool air and a warm engine. If you can find a way to keep the intake temps down without keeping coolant temps down, you'll be better off. If you need to change T-stats, you should stay with a 180 or above.
-->Slow
Running a cooler t-stat, or even no stat will not make the car run in open loop. It will affect the car getting to operating temp slower. From datalogs I have taken my 2001 Z24 switches from open loop to closed loop at 104 degree's. A stock stat is 180, if you ran a cooler stat (say 160), the car will reach that 104 at the same rate as the 180. Now running no stat will slow the coolants warm up time, but it will still reach the same temps and go into closed loop.
As stated our cars go into open loop under WOT. With HPTuners you can change that as well (if I have heard correctly). I'm a firm believer a cooler motor will run beter (but also agree about the oil temp being warm enough as well). I believe there is a sweet spot for both, and a 160 stat would not hurt either way.
FU Tuning
slowolej wrote:Pulling the T-stat on a street engine is considered a no-no. First, the engine really should be allowed to warm up in order to force condensation out of the crankcase. If moisture is allowed to build in the crankcase it has a negative effect on the engine's longevity.
-->Slow
Sludge buildup comes to mind with dino oil. Also one of the reasons making a quick 5 minute trip to the store can be bad.
ur friend isnt too smart unless hes runnin a race car as weather conditions change and conditions in your motor arent exactly always the same so u shouldnt run off of preset air fuel ratios which is open loop other than havin an o2 sensor which is like a guess n check method I guess u'd say. Ya u could pry get some better numbers by runnin in open loop all the time but if you wan ur car to be a daily driver and want the motor to last a while then u should leave the thermostat in and stay in closed loop and remain in closed loop unless ur goin WOT or if ur engine aint up to runnin temp then ud also be in open loop hope that helped
ok first off i would like to thank everyone on there input. i was just trying to get some facts from somone other than him. he has been very successfull with all his projects, but me being some what anal about things i do, i have cought him cutting corners more than once. just kinda over looked it for the reason its not my car. but i do understand what you guys are saying about the still getting to operating temp and the viscosity of the oil. just trying to get as much knowlege as i can gather.
one over question i guess, instead of starting a new post. i installed the 62mm tb i bought from him, it turns out that his "idle sensor" which is what i think he called it was bad. the cylinder shaped sensor on the front side of the tb, so i changed it for the one off my stock tb, well that fixed the high idle, but i am still seeing the car not wanting to decel as much as it used to if you downshift to slow down. now i dont have a header yet, thats the next to be ordered, i was thinking this could possibly be the reason. just trying to make sure there is no other issues before i start driving the car any distance. thanks for the info guys!
Is the throttle body bored cuz I can't think of any stock 62mm tb. If so then it's possible the throttle plate isn't closing off like it should assuming he made (or had a machine shop make) a new throttle plate. This could also affect idle as well as decellerating if air is coming by the throttle plate. Wish I would have known this last weekend at the meet in Columbia, we could have taken a look at it.
