thinking about open loop...
05-20-2004, 12:09 AM
#1
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thinking about open loop... I've been pondering about running my car strictly in open loop. I'm with nogo in that dealing with these damn O2s are becoming a pain in the butt. So, I'd like to know what the pros and cons are to running full open loop.
Also, what's involved in tuning a car for open loop aside from changing the WOT tables?
Also, what's involved in tuning a car for open loop aside from changing the WOT tables?
05-20-2004, 06:38 AM
#2
Open loop involves a good A/F setup and adjusting the VE table to get right.It does take time to get right.I've seen alot of people going open loop tuning lately when it's not needed.Have also seen a few people wreck there motors from not tuning open loop right.(mostly gas washing)My rule is when you go over a Cam size of 245/245 on a stock ci engine open loop can work great.
05-20-2004, 08:31 AM
#3
The pro's and con's of open loop are actually not that different.
The tables setup inside of the PCM run the car very accurately without the O2 sensors. Suprisingly, a good collection of countries (typically Middle East) recieve these vehicles without O2 sensors.
The downside of running open loop is that you don't have a safety net (the LTerms) to bring your fueling back into spec if you don't know what your doing. However, I have never seen a car blowup due to open loop operation. Just keep your Injector Flow Rate Table within reason and your MAF table within reason (+/- 5-8%) and you should be fine. Additionally, pay attention to the 'normal' signs of excessive lean or rich conditions. Does the exhaust make your eyes water? (rich/lean) Does the car hesitate on take off (lean). What do your plugs look like? As long as you pay attention you shouldn't be washing out your cylinders or running excessively lean.
A large mistake that many people make is that they presume that the overlap is causing the excessive LTerms and not a vacuum leak. However, once the car goes open loop it will run excessively lean if there is a vacuum leak. With that being said, make sure that your have absolutely NO vacuum leaks prior to taking the car open loop.
Whether or not you should be running open loop is dependant on the type of cam that you are running as well as the type of exhaust that you are running. It can be said that x/y size of cam requires open loop operation, but there are alot of other factors that come into play.
If you tuned WOT fueling properly the first time (ie your Lterms locked at 0) then the WOT fueling should be the same in open loop operation.
Good Luck
The tables setup inside of the PCM run the car very accurately without the O2 sensors. Suprisingly, a good collection of countries (typically Middle East) recieve these vehicles without O2 sensors.
The downside of running open loop is that you don't have a safety net (the LTerms) to bring your fueling back into spec if you don't know what your doing. However, I have never seen a car blowup due to open loop operation. Just keep your Injector Flow Rate Table within reason and your MAF table within reason (+/- 5-8%) and you should be fine. Additionally, pay attention to the 'normal' signs of excessive lean or rich conditions. Does the exhaust make your eyes water? (rich/lean) Does the car hesitate on take off (lean). What do your plugs look like? As long as you pay attention you shouldn't be washing out your cylinders or running excessively lean.
A large mistake that many people make is that they presume that the overlap is causing the excessive LTerms and not a vacuum leak. However, once the car goes open loop it will run excessively lean if there is a vacuum leak. With that being said, make sure that your have absolutely NO vacuum leaks prior to taking the car open loop.
Whether or not you should be running open loop is dependant on the type of cam that you are running as well as the type of exhaust that you are running. It can be said that x/y size of cam requires open loop operation, but there are alot of other factors that come into play.
If you tuned WOT fueling properly the first time (ie your Lterms locked at 0) then the WOT fueling should be the same in open loop operation.
Good Luck
05-20-2004, 10:25 AM
#4
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My mods:
stock heads/internals 2001 A4 Z28
F1 Cam (226,224 591,563 112) 918 springs / hardened pushrods
Hooker Jethot coated LTs
ported Oil Pump
Rollermaster 2x timing set
3 inch ORY with cutout prior to axle
whisper lid / K&N filter
FTRA kit
stock MAF
160 thermostat
3000 stall converter
custom ROCK-ON transmission
based on what you guys have said I'm not sure I should run in open loop just yet. Correct? Thanks for the input!
stock heads/internals 2001 A4 Z28
F1 Cam (226,224 591,563 112) 918 springs / hardened pushrods
Hooker Jethot coated LTs
ported Oil Pump
Rollermaster 2x timing set
3 inch ORY with cutout prior to axle
whisper lid / K&N filter
FTRA kit
stock MAF
160 thermostat
3000 stall converter
custom ROCK-ON transmission
based on what you guys have said I'm not sure I should run in open loop just yet. Correct? Thanks for the input!
