Running open loop question.
Thread Starter
TECH Resident
Joined: Aug 2003
Posts: 948
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From: orlando, florida
Running open loop question. Is open loop the same as speed density mode the reason i ask is because i was thinking about programing my car to run in open loop all the time. when the car is in open loop it idles perfect, part throttle acceleration is smoother and full throttle is smoother. It just all out runs better. I get no KR so it`s not running lean. will it hurt anything doing this? 
Any comments are appreciated. 
Any comments are appreciated. 
TECH Addict
Joined: Nov 2001
Posts: 2,207
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From: College Station, Tx
Open loop can be run either in SD or MAF mode. Open loop just means your car is ignoring the o2's - no fuel trims.
Speed Density means your car calculates fueling based off the manifold pressure, rpm, displacement, air temp, etc. this is as opposed to maf mode, which simply measures the massflow of air going into the engine (instead of calculating it).
Speed Density means your car calculates fueling based off the manifold pressure, rpm, displacement, air temp, etc. this is as opposed to maf mode, which simply measures the massflow of air going into the engine (instead of calculating it).
Thread Starter
TECH Resident
Joined: Aug 2003
Posts: 948
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From: orlando, florida
So when you start the car in the morning it`s just ignoring the o2s I did notice that when the cars in open loop the l-trims and s-trims read 0? Any ideas why it runs so much better when in open loop?
Closed loop is going to set it to stoich (14.7:1) and
this is only best for emissions; better economy leaner,
better performance richer. Richer makes a smoother
idle and more power. Cold engine may also get some
more spark advance and enrichment than normal
operating temp.
this is only best for emissions; better economy leaner,
better performance richer. Richer makes a smoother
idle and more power. Cold engine may also get some
more spark advance and enrichment than normal
operating temp.
Thread Starter
TECH Resident
Joined: Aug 2003
Posts: 948
Likes: 0
From: orlando, florida
any time i shut the car off for a few minutes even if i`ve been driving it for 20 min and just run into the store when i start it again and start driving it runs great and then it goes into closed loop and the car starts running totaly differant. I can tell the instant it goes into closed loop.
TECH Regular
Joined: Nov 2001
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Originally Posted by ChrisB
Open loop can be run either in SD or MAF mode. Open loop just means your car is ignoring the o2's - no fuel trims.
Speed Density means your car calculates fueling based off the manifold pressure, rpm, displacement, air temp, etc. this is as opposed to maf mode, which simply measures the massflow of air going into the engine (instead of calculating it).
Speed Density means your car calculates fueling based off the manifold pressure, rpm, displacement, air temp, etc. this is as opposed to maf mode, which simply measures the massflow of air going into the engine (instead of calculating it).
ChrisB, is there a way to know if my car is running in SD or MAF mode? Can autotap help?
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On The Tree
Joined: Oct 2002
Posts: 141
Likes: 0
From: eastside
Originally Posted by ChrisB
Open loop can be run either in SD or MAF mode. Open loop just means your car is ignoring the o2's - no fuel trims.
Speed Density means your car calculates fueling based off the manifold pressure, rpm, displacement, air temp, etc. this is as opposed to maf mode, which simply measures the massflow of air going into the engine (instead of calculating it).
Speed Density means your car calculates fueling based off the manifold pressure, rpm, displacement, air temp, etc. this is as opposed to maf mode, which simply measures the massflow of air going into the engine (instead of calculating it).
chrisb,
does this mean you can set the car to open loop, take out the stock O2s, and put in a wideband full-time? i was told that the computer still needs the stock O2s for part throttle. is this true? TIA.
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