LS1Z28_98

Can someone explain what closed and open loop mean in regard to O2 sensors?

I am having a horrible time keeping properly functioning O2's in my car since putting Hooker LT headers in. 3rd set of O2's in 3000 miles.

I am frying the upstream O2's and getting slow switching codes when SES light comes on.

Does anybody know how to get this right. I have heard a tune would fix it but how?

RedHardSupra

iTrader: (1)

OL == ignoring all O2 inputs
CL == taking O2's into consideration, building STFT and LTFTs and adjusting fueling based on these.

if you keep messing up your O2s, then you're either overfueling or they're too close to exhaust ports. if you dont have a tune (since you're asking about getting one) then i got my money on overfueling.

LS1Z28_98

Well the problem i thought is that the O2 bungs are farther from the heat on the headers then the OEM bungs. But yes, then the o2's go out, it runs VERY rich

Doc

iTrader: (9)

How do you have your exhaust system setup? Is it clamped or welded? I believe your overfueling is due to exhaust leaks. Sensor senses more air = adds more fuel. I bet your fuel trims are adding massive amounts of fuel.

LS1Z28_98

It is Hooker LT that have 3 bolt flanges. The flanges are welded. Then into dual Magnaflow high flow cats, into a custom Y. Then to the back to a Flowmaster 1 chamber racing muffler and stock tips. Its all welded and all in 3 inch pipe. There are no leaks. I thought there were but I did a careful check along with a muffler guy and its all kosher.

LS1Z28_98

ALSO,
how do you get into open loop??

Do you need a computer to get the PCM into open loop and tune it?

RedHardSupra

iTrader: (1)

you don't 'get into' OL, it starts in it by default, so all you have to do is prevent the computer from going into CL.
if you want more on OL/CL read this:
http://redhardsupra.blogspot.com/200...-2-olvscl.html