Bad oxygen sensor ?

[David Cooley]

It sounds like a plugged fuel filter, fuel pump starting to go bad, or 
plugged fuel sock.  The drop at WOT is indicative of leaning out...  You 
need to get a fuel pressure guage on the system and clip it under the 
windshield wiper blade and see what FP does at WOT...  My suspicion is it 
will slowly drop as the O2 volts do...  I suspect the old O2 sensor may not 
have been reacting properly.
Just to make sure, run a wire from the engine block (ground) to the O2 
sensor shell (use a hose clamp to hold it) and try again...  Could also be 
the headers not having a good ground.



At 12:59 PM 11/08/2000, you wrote:
>I did several 1/4 mile runs after I installed my Edelbrock headers and 
>brand new o2 sensor. First and second gear are nice smooth 900mV range 
>ramps. Once it hits third gear is starts descending rapidly to about 400mV 
>and stays down until I let off the throtle. I wish I was at home so I can 
>show you the exact Diacom graph. I tried giving it more fuel (almost 95 in 
>the VE tables) between 90-100 KPA but it still does this. The engine runs 
>fairly well at WOT, but I cant really tune it w/out gettting some accurate 
>info from the sensor. My old 80K mile o2 sensor in the exhaust manifolds 
>didnt do this at all. Could this indicate a bad sensor ? I should mention 
>at idle it goes from 40-50 to 800-900 almost every 1/2 second. It does 
>this at light cruise too. Maybe it's time for a heated sensor ? Still 
>downt explain the WOT weirdness though since it should be nice and hot.
>
>
>
>p.s. I know Bruce already answered this on the thirdgen.org message board, 
>but I wanted some more opinions :)

===========================================================
David Cooley N5XMT Internet: N5XMT at triad.rr.com
Packet: N5XMT at KQ4LO.#INT.NC.USA.NA T.A.P.R. Member #7068
I am Pentium of Borg... Division is Futile!
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