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Old 12-20-2006, 10:27 AM
Arthur Dalton Arthur Dalton is offline
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Join Date: Aug 1999
Location: Florida / N.H.
Posts: 8,804
I have seen 02 sensor codes come up when either AIR or Trans delay have been BB'ed. Both of these systems are used to get the cat hot as fast as possible from cold start and when they are not working the 02 sensor can get carboned up. I have found a remedy is to do a 3rd gear, under load [ up-hill] hard run to clean the sensor.
try it.............
As DOC says, get an 02 sensor read out .
An easy DIYer test on these HFM units is to disconnect the 02 sig wire [ under passenger rug] . Hook your meter to it and with engine coolant up to temp, take the vac hose off the fuel regulator and plug the line so there is no vac. leak...meter should jump to Rich voltage b/c the fuel pressure is higher than normal with reg test, put that line back on and pull a convienient vac line and look for lean/low condition voltage. [ if you rapidly block this line on/off with your thumb , you will see the sensor voltage change with your on/off blockage,,this will tell you if the sensor is reacting fast.
What you are doing is manually causing the engine to run in both a rich and lean conditions and monitoring the 02 voltage to see if it reacts to your engines inputs. The reason for dis-connecting the 02 sig wire to the ECU is so the engine can not correct your manual inputs while making these test ..kinda like using the engine as a rich/lean condition generating tool............................
A scope is the best way to monitor a sensor, but for guys w/o such, this will give you some basic 02 sensor operation insight..

Last edited by Arthur Dalton; 12-20-2006 at 10:56 AM.
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