i have a couple a questions about the two loops. lets say the car is running fine in closed loop no codes ect.. as well its running fine, preset tables in open loop. whats the advantages of closed loop in this situation as far as performance?

 

closed loop is when the engine starts to read the sensors. Ultimately, this will tune the engine for normal driving much better then a table ever will.

If you think of an engine in open loop as an old school carb with a brain, you are real close.

 

Closed loop is used to obtain low emissions, high fuel economy and cooler combustion temps.

These help to provide more $$ for the high performance of Corvette driving.

 

so closed loop could be robbing hp in the name global warming?

 

I don't like 65Z01s answer... it's no where near accurate enough to give an honest representation.

In short, God, no.

However, to a degree, yea, but the idea is still to be closest to perfect air/fuel ratio so not to waste the stuff... that's why you get a custom chip tuned to your engine.

When the engine reaches redline, and the throttle is wide open, then tables kick in again... In between, the TPS, IAT, MAP (or MAS), O2 and knock sensors keep things in check.

What I don't get is the desire to go fast and destroy our air all the same time... being fast and being emission legal are not mutually exclusive.

 

i understand where your coming from but seems to me the after market parts people arent very ozone friendly and they sell alot of violation. so maybe closed loop does achive its goal even with the darkside`s part list.

 

bogus has the right idea.. tables will kick in for power enrichment.. basiclly it goes into open loop at wot and reads the ve tables for fuel.
o2 sensor is not allowed to make adjustments in the mode. there is really no diffence to be in open or closed loop at this point..

the problem i ran into with my car was because of the very aggesive cam, closed loop tuning was nearly impossible.. the overlap of my cam was throwing the o2 sensor into a frenzy. throttle responce was next to zero. im a fairly knowledgable tuner and no one could get it run even decent in closed loop at lower rpms.. so what i did was disable closed loop and tune my ve tables with a wide band.. at this point my tune is at about 95% and it run good and my fuel ecomony has not suffered much at all..


my general plan was to tune it as lean as possible to run well and idle and part throttle and for max peformance at wot..

i have no desire to go fast and destoy the ozone, as bogus said..

by no means will a car running in open loop be as efficent, emmision wise, as closed but i did my best to be as close a possible.

over the winter i will be adding a fast engine management system, then problem sovled..

 

Sorry for the missed communication on this issue.

Actually closed loop on a stock engine should not rob power and when you go to WOT it should not be poluting, if properly tuned.

Actually we get the best of both worlds from our fuel injected and computer controlled engines. During "normal" street driving we have good power and exceptional milage from an efficient fuel burn. Yet when we call on the horses by snapping the throttle open the power is there.

I run my C4 with full emissions equipment and still have very nice power when it's called for. A well modded and setup L98 will take you into the low 12s and still be very streetble and emissions friendly (except on the Left Coast).

 

so can you burn a eprom for open loop operation and achive the same et`s? not worried about to much mpg.

 

yes you can... you probably wont pass emissions. but et's will not change if tuned properly.. some have even gained in open loop.

 

If your running cats you need the closed loop swing from rich to lean for the cats to operate properly.

Your original question was if the car is running fine in both open and closed loop, then what are the advantages of running closed loop for performance.

You have to understand that you are only in open loop under certain circumstances. Usually when you first start the car, till the o2 gets hot enough, WOT, and on cold startup till the coolant temps get hot enough.

So really your only basing your "runs good" on these above situations. Most times when you start the car, there is a timer hot and cold based that expires, and you are then in closed loop. You may very well find out that your car runs horrible if you would lock the BLMs (which is an easy way to disable closed loop).

What I am trying to get at and to answer your question is there is really no reason to lock out closed loop, and if you have cats you will probably suffer in the end. If your running a HUGE cam, then yeah there are some advantages, but in the end, you should be able to work around it.

When you go WOT, the o2s are ignored so closed loop is not being employed at that time anyways to effect performance ***
I put the *** there cause there are some things happening at the moment before you go WOT that can play into things, but for all intense purposes and for sake of this discussion the 02 do not play a role.

My recommondation would be use the closed loop as it was intended. Its probably the main advantage of a FI car over carb - you can have the best of cruise type fueling and also WOT>

 

for most purposes closed loop is best..

for me.. it was much easier to get it to run good in open.. i may have been able to get closed loop to work for me but not successful so far.

 

im having the same problem in closed loop. went to the heated o2 ect... the car will hesitate,stumbal and seems like its starving for fuel at times. replaced the tps, iac, map, temp works, had a chip burned which fixed a rich condition i was having. short list of parts. 383, 224/230 cam,58mmtb,stock injectors,all msd iginition,superram,longtubes, gutted cat. runs great in open loop.

 

you sound like a canidate for a wide band O2.

 

whats the difference? wider range of operation? how much does it cost?

 

a wideband is for tuning purposes only. unless it is hooked into a dfi or fast system, then it can be used for target a/f ratio..

i have a tune that will work for your car.. if you have the ability to burn your own chips and you give me all your specs, i can send it to you. it will be close to your needs..

 

thanks, but i dont have the stuff to burn chips. dvd`s yes and my partime bussiness is pc repair so i might have an idea of how to do it but i would need the software and hardware. how much would it cost to get set up for something like this? pcmforless just burned a basic chip for me which cleared up some issues i was haveing.

 

moates.net will have all you need to burn.. you will need a burn 1 and a gp1 adaptor kit.. 256k chip work the best for out cars but you can use 512k chip also. about $130.00

 

AMEN even.

 

but most people dont even realize that a simple 02 could save the ozone or that the very ticket they buy to lets say, watch an nhra event is promoting the depletion. beats me.