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Discussion Starter #1
can running open header (edelbrocks) wipe out a new o2 sensor??

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hmm dont think so, just get an incorrect reading because ussually it reads more lean than the actual engine is... thus the computer feeds more fuel which gives you a rich burn

what year vehicle? and FI?
 

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it`s a 94 ss 4.3 cpi.

i changed over to headers and gutted cat while the trans was out for rebuild. when the trans was finished i fired it up open header to check line pressure.

i figured it was the o2 sensor. becaulse after warm up when the comp switches over to closed loop it miss off idle bad and blips when idling. the only other computer related part i changed was the temp sender which still has the wires disconected becaulse of a different connecter. i thought the sender was just for the gauge but it just occured to me that the comp might also need to read off of it.

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If ya disconnected the one at the manifold next to the t-stat which
has a black and yellow wire setup, you disconnected the main sensor
for the ride going into closed loop. It's the CTS, and the engine will
stay in open loop or limp-in mode until you get it hooked back up. The
engine will stay in open loop until you get the o2 hooked up again.

If the o2 is disconnected or not hooked up to the y-pipe it will not
allow the engine to go into fuel managed closed loop. The ECM
takes reading from the CTS, a warmed up over 600* o2 sensor,
and the timer before it will even think about going into closed loop.

After it gets it's basic voltages from the CTS, the o2 and times down,
it will go into closed loop to moniter the other sensors. If one major
one is out of voltage, it will go into limp-in mode. If you have a
later 94 where it's OBDII with a MAF, it evens get more readings
from these components and more to determine if it's good to go and
stay in closed loop. If ya have gutted the cat and have a post cat
o2 sensor, it'll set a code, but will still stay in closed loop, I believe.
 
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