Scan Tool Indicates ECM in OPEN and CLOSED LOOP at Temperature (and driving)
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Joined: Oct 2010
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From: CT
Car: 1987 Camaro IROC - Completely Stock
Engine: 305 CI
Transmission: 5 Speed
Scan Tool Indicates ECM in OPEN and CLOSED LOOP at Temperature (and driving)
Hello, I posted this in the engine section as well but wanted to make sure all bases covered:
My 1987 Camaro IROC has been off the road for 8 years but recently returned it to service - engine is lacking power and running rough (smooth at idle). A check with a scan tool indicates no trouble codes but at idle shows an OPEN circuit at times and CLOSED at times (even after warming), and both LEAN and RICH Steady (doesn't switch back and forth like it is supposed to).
After 75 miles of test driving the performance is still the same - sluggish, no power and almost stalls when you let your foot off the gas - had the scan tool connected and the engine goes into the OPEN loop and both RICH and LEAN, and then CLOSED loop both RICH and LEAN at speed (varies with throttle).
It is also noteworthy that the fuell filter has been replaced, fuel injector cleaner added (Chev. Techtron) and the air intake checked for obstruction. Also, I montored the oxygen sensor values and they change with throttle and there are no "dead" values for things such as the coolant sensor, etc. Four of the eight plugs were changed (didn't look bad) and the rotor cap and rotor corrosion was cleaned off and connections checked).
Can it be that I have a bad computer or would it more likely be an oxygen sensor issue?
Thanks in advance! I really appreciate any help.
Tom (CT)
My 1987 Camaro IROC has been off the road for 8 years but recently returned it to service - engine is lacking power and running rough (smooth at idle). A check with a scan tool indicates no trouble codes but at idle shows an OPEN circuit at times and CLOSED at times (even after warming), and both LEAN and RICH Steady (doesn't switch back and forth like it is supposed to).
After 75 miles of test driving the performance is still the same - sluggish, no power and almost stalls when you let your foot off the gas - had the scan tool connected and the engine goes into the OPEN loop and both RICH and LEAN, and then CLOSED loop both RICH and LEAN at speed (varies with throttle).
It is also noteworthy that the fuell filter has been replaced, fuel injector cleaner added (Chev. Techtron) and the air intake checked for obstruction. Also, I montored the oxygen sensor values and they change with throttle and there are no "dead" values for things such as the coolant sensor, etc. Four of the eight plugs were changed (didn't look bad) and the rotor cap and rotor corrosion was cleaned off and connections checked).
Can it be that I have a bad computer or would it more likely be an oxygen sensor issue?
Thanks in advance! I really appreciate any help.
Tom (CT)
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