Hey, I've noticed that my car (03 cavi) seems to be faster right after I start it, before it is completely warmed up. (I know its bad to run the engine hard until it is warmed up, I don't normally do that) Do you think it is because the engine is running in a different loop mode than normal (I'm pretty sure this is the case, but I don't know much about the operational loops, i.e. when is it closed or open loop)
As a second part, does this indicate that some sort of tuning measures might increase performance a little? What do you think.
P.S. Please don't try to flame me for pushing it before it's warmed up...
see, my '05 sunfire seems to run slower when it is warming up, after it hits the 180 or so degree, it runs like a bat outta hell.
cold air=more dence=more power. when u first start the car the engine bay is full of cold air and thats the air thats getting sucked in.. not humid and hot.
John H [Cavalierkid wrote:]cold air=more dence=more power. when u first start the car the engine bay is full of cold air and thats the air thats getting sucked in.. not humid and hot.
To add to that...your motor is also at a lower temperature (not as hot).
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your engine will perform its best with the engine running at a nominal temperature. the temperature outside and other conditions will always apply as well.
running cold like that will definitely mess things up if you do it a lot. not to say i havent floored it from the start either.
AkA joe m.
Ricer ELIMINATOR!
Yeah, I put a colder thermostat in my car an I noticed how much better it runs esp. ay highway speeds. For 10 dollars, I have been very impressed.
I'll have a sig someday....................
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^ are you guys serious?
I wouldn't be doing that...not to flame you or anything...but oil's viscous properties are quite dependent on temperature...and the clearance in your engine's main/rod bearings is designed around the oils properties at operating temperature...so baggin' your car when its cold is definatly not a good idea.
2000 z24
1985 z28
http://www.cardomain.com/ride/825536
Drain your oil out, you'll notice an insane performance increase!
JimmyZ wrote:Ya know, I've always wondered...
If "cold air is SOOOOO much better than warm air, why aren't there threads all over the place here talking about how much more power people have in the winter? Why aren't Canadians telling Americans (especially those in Texas and Florida) how much their cars suck because they don't have as much power?
I even asked this question here before.
Point is if you're not boosted and you're worried about the temperature of the air going into your engine, you're focusing your energy in the wrong place. Actually, most of the "cold air intake" designs are dangerous to your cars in the summer....they are drawing in the well-heated air off the asphalt and the super-heated water vapor from other car's exhaust.
The test I did on my old car was with the stock airbox, my home-made warm air intake, the stock airbox with a with a "custom cold-air extension" and Alex Peper's OBD2 monitoring software. On an 90 degree day, the stock airbox reported 90-93 degree air being drawn in with the car moving or idle. The warm air intake reported 95-98 degree intake air temperature with the car idle and 90-92 degree intake air temperature with the car moving. The stock airbox with a "custom extension" to place the inlet in the lower bumper area (about 6 inches off the ground) reported intake air temperatures of 97-99 degrees with the car moving or idle. So much for "cold air intakes".
To answer the original question though...engines will seem more responsive when cold because of the open-loop characteristics of the computer's operation. The engine is intentionally run richer and with higer degrees of ignition advance with the specific purpose of making it warm up faster. Those of you with automatic transmissions will notice "slightly increased" performance because the higher density and increased viscosity of your transmission fluid makes pressures build a little slower at the solenoids..making the transmission shift a little later and a little harder.
Thank You Jimmy Z for saying it...I've been trying to tell people the same thing but I guess some don't learn...
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While installing my turbo setup on my car recently I found a plug in so that I can plug my cavalier in to keep the block warm. I wish I would have found this last winter but it will be perfect for me now especially with the turbo. But I do notice a little more vroom out of my car on our Colorado cold winter days and I love it!
~Boost. Its what's for dinner!~
JimmyZ,
That's exactly what I was thinking, but wanted to see if somebody else who knew a little more would have the same thoughts.
Could somebody explain more about how the loops work in each case? Thanks
Jimmy Z is absolutely correct. Timing is advanced and more fuel is dumped for a faster warmup. Its basically what a choke does on a carburated engine. Without the "choke" persay it would tke the vehicle longer to get up to operating temperature and causing excess wear. That the only reason why you feel extra power BlackCav, but im sorry to imform you, your engine will wear out sooner then it would if it was left with the stock thermostat. Engines and computors are designed to run at the stock temperature and are at that temperature to reduce wear on engine components.
To elaborate on the loop operations open loop is were the o2 sensor is monitoring the air/fuel ratio but the computor is ignoring the the sensor. Untill the o2 sees the air/fuel ratio at a point calibrated into the computor then the computoe will then use its information, which is also called closed loop.
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I have an 03 Cavalier 5spd. <img src=http://registry.gmenthusiast.com/images/tinytim12333/timmy.gif> TIMMAY
I never take it over 3k rpm's if I absolutely have to go. other than that when it's warm it's usually up there in the rpm's
JIMMYZ:
Of course the stock air box will have the same temps, it is a "cold air" intake itself...
It's not rocket science.
Doesn't the computer switch into open loop when at WOT? I think I remember this.
Sean wrote:Doesn't the computer switch into open loop when at WOT? I think I remember this.
you are correct the computer does go into open loop and PW is hammered at WOT.
on that note O2 is ignored in open loop, your O2 maybe slow on a scan tool make sure it goes from 100mV up to 900mV and cross counts are around 8-10 at 2,000 rpm.
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