Need Suggestions, A Little Stumped
11-09-2019 | 01:40 AM
#1
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Joined: Nov 2019
Posts: 164
From: Montana, Big Sky State
Need Suggestions, A Little Stumped
I own a 1997 Trans Am with the LT1. Honestly I've had alot of problems with the car due to mistreatment over its life. Here's a precursor to my problem. The optispark died on me about five months ago so, I replaced the opti unit with a new AcDelco one, replaced the NGK plugs and put in some new MSD plug wires while I was at it since one was a little burnt up. The car has always had an O2 sensor light on, keep this in mind. The car ran great up until a week ago, it freely revs smoothly in neutral or with the clutch pushed in. However once I am in gear and moving it stutters and jerks quite a bit, progressively more the higher the gear. Once the car is warmed up it seems to not act up as much too. The motor is modified, it's a 383 with cam, heads etc. Would the O2 sensor explain this occurrence at all since the fueling from the computer may be different in neutral as compared to when I'm gear? I already swapped over the ICM since I read about it on another post. Or is it possible I killed another opti in only 300mi worth of driving? Thanks for the feedback
-WhiteWS6
-WhiteWS6
11-12-2019 | 10:11 AM
#2
Administrator
Joined: Nov 1998
Posts: 70,853
From: Hell was full so they sent me to NJ
Re: Need Suggestions, A Little Stumped
What is the specific O2 sensor code...... there are 22 of them in OBD-2 for your car? Pre-cat O2 sensors affect how the engine runs, after-cat sensors not so much. Do you even have cats?
An O2 sensor code can prevent that bank of the engine from going into closed loop in the PCM, which might explain the difference between how it runs hot (closed loop) and cold (open loop for first 3 o 4 minutes).
Do you know the history of the car - like who tuned it?
Where did you find a new OEM AC Delco Opti? They stopped making them at least 5 years ago, switched to rebuilt units with a core charge for returning your old one. And even the rebuilt AC Delco units are getting hard to find. I saw someone recently who found an OEM unit collecting dust on the shelf at a GM dealer, but those finds are very rare.
Revving the engine in neutral withoiut any load on the engine is pretty much useless as a diagnostic. Your engine seems to run worse as engine load increases ("it stutters and jerks quite a bit, progressively more the higher the gear."). Increased engine load puts strain on the ignition system, but you seem to have replaced all the components. Yes, an Opti can go out in 300 miles... carbon tracking can contribute to increased misfires under load. A loose wire becomes a bigger problem. If the ignition system is healthy, then the fuel system becomes suspect. Another issue under load can be plugged cat(s). Hence the question above - do you even have them?
An O2 sensor code can prevent that bank of the engine from going into closed loop in the PCM, which might explain the difference between how it runs hot (closed loop) and cold (open loop for first 3 o 4 minutes).
Do you know the history of the car - like who tuned it?
Where did you find a new OEM AC Delco Opti? They stopped making them at least 5 years ago, switched to rebuilt units with a core charge for returning your old one. And even the rebuilt AC Delco units are getting hard to find. I saw someone recently who found an OEM unit collecting dust on the shelf at a GM dealer, but those finds are very rare.
Revving the engine in neutral withoiut any load on the engine is pretty much useless as a diagnostic. Your engine seems to run worse as engine load increases ("it stutters and jerks quite a bit, progressively more the higher the gear."). Increased engine load puts strain on the ignition system, but you seem to have replaced all the components. Yes, an Opti can go out in 300 miles... carbon tracking can contribute to increased misfires under load. A loose wire becomes a bigger problem. If the ignition system is healthy, then the fuel system becomes suspect. Another issue under load can be plugged cat(s). Hence the question above - do you even have them?
11-12-2019 | 10:58 AM
#3
Thread Starter
Registered User
Joined: Nov 2019
Posts: 164
From: Montana, Big Sky State
Re: Need Suggestions, A Little Stumped
What is the specific O2 sensor code...... there are 22 of them in OBD-2 for your car? Pre-cat O2 sensors affect how the engine runs, after-cat sensors not so much. Do you even have cats?
An O2 sensor code can prevent that bank of the engine from going into closed loop in the PCM, which might explain the difference between how it runs hot (closed loop) and cold (open loop for first 3 o 4 minutes).
Do you know the history of the car - like who tuned it?
Where did you find a new OEM AC Delco Opti? They stopped making them at least 5 years ago, switched to rebuilt units with a core charge for returning your old one. And even the rebuilt AC Delco units are getting hard to find. I saw someone recently who found an OEM unit collecting dust on the shelf at a GM dealer, but those finds are very rare.
Revving the engine in neutral withoiut any load on the engine is pretty much useless as a diagnostic. Your engine seems to run worse as engine load increases ("it stutters and jerks quite a bit, progressively more the higher the gear."). Increased engine load puts strain on the ignition system, but you seem to have replaced all the components. Yes, an Opti can go out in 300 miles... carbon tracking can contribute to increased misfires under load. A loose wire becomes a bigger problem. If the ignition system is healthy, then the fuel system becomes suspect. Another issue under load can be plugged cat(s). Hence the question above - do you even have them?
An O2 sensor code can prevent that bank of the engine from going into closed loop in the PCM, which might explain the difference between how it runs hot (closed loop) and cold (open loop for first 3 o 4 minutes).
Do you know the history of the car - like who tuned it?
Where did you find a new OEM AC Delco Opti? They stopped making them at least 5 years ago, switched to rebuilt units with a core charge for returning your old one. And even the rebuilt AC Delco units are getting hard to find. I saw someone recently who found an OEM unit collecting dust on the shelf at a GM dealer, but those finds are very rare.
Revving the engine in neutral withoiut any load on the engine is pretty much useless as a diagnostic. Your engine seems to run worse as engine load increases ("it stutters and jerks quite a bit, progressively more the higher the gear."). Increased engine load puts strain on the ignition system, but you seem to have replaced all the components. Yes, an Opti can go out in 300 miles... carbon tracking can contribute to increased misfires under load. A loose wire becomes a bigger problem. If the ignition system is healthy, then the fuel system becomes suspect. Another issue under load can be plugged cat(s). Hence the question above - do you even have them?
Thanks so much, WhiteWS6
11-12-2019 | 11:34 AM
#4
Administrator
Joined: Nov 1998
Posts: 70,853
From: Hell was full so they sent me to NJ
Re: Need Suggestions, A Little Stumped
"Insufficient Activity" (P0134)..... or "No activity" (P????)? The code descriptions provided by some scanners are "generic" and not necessarily correct for the specific vehicle/engine. Shoebox's list is basically the list out of the factory service manual.
http://shbox.com/1/Dtcs.htm
You can download a free copy of the 1996 (same as 1997) factory service manual here - courtesy of GaryDoug:
http://www.mediafire.com/?40mfgeoe4ctti
Have you scanned recently for any new codes that may be hiding behind the SES light for the O2 sensor?
You can't really clean an O2 sensor. The exposed metal part with the slots or holes is just a shield. The sensor thimble it inside the shield.
What voltage did you check, and what did you use to check it? The PCM supplies an ~0.450 volt bias voltage. The sensor thimble adds or subtracts from that voltage based on comparing the oxygen level in the exhaust on the outside of the thimble to the oxygen level in ambient air on the inside of the thimble. The ambient air enters the thimble via the hole the wires pass through. If there is anything leaking on the outside of the sensor, like engine oil, or if it has been soaked with something like PB Blaster in order to break the threads loose, the thimble could be contaminated or the air may not be able to get to it.
A 383 ci engine, heads/cam, which probably has larger than stock injectors, is not going to run well with a stock tune. But you indicate this is only a recent problem, so it must have been tuned.
http://shbox.com/1/Dtcs.htm
You can download a free copy of the 1996 (same as 1997) factory service manual here - courtesy of GaryDoug:
http://www.mediafire.com/?40mfgeoe4ctti
Have you scanned recently for any new codes that may be hiding behind the SES light for the O2 sensor?
You can't really clean an O2 sensor. The exposed metal part with the slots or holes is just a shield. The sensor thimble it inside the shield.
What voltage did you check, and what did you use to check it? The PCM supplies an ~0.450 volt bias voltage. The sensor thimble adds or subtracts from that voltage based on comparing the oxygen level in the exhaust on the outside of the thimble to the oxygen level in ambient air on the inside of the thimble. The ambient air enters the thimble via the hole the wires pass through. If there is anything leaking on the outside of the sensor, like engine oil, or if it has been soaked with something like PB Blaster in order to break the threads loose, the thimble could be contaminated or the air may not be able to get to it.
A 383 ci engine, heads/cam, which probably has larger than stock injectors, is not going to run well with a stock tune. But you indicate this is only a recent problem, so it must have been tuned.
11-12-2019 | 12:01 PM
#5
Thread Starter
Registered User
Joined: Nov 2019
Posts: 164
From: Montana, Big Sky State
Re: Need Suggestions, A Little Stumped
"Insufficient Activity" (P0134)..... or "No activity" (P????)? The code descriptions provided by some scanners are "generic" and not necessarily correct for the specific vehicle/engine. Shoebox's list is basically the list out of the factory service manual.
http://shbox.com/1/Dtcs.htm
You can download a free copy of the 1996 (same as 1997) factory service manual here - courtesy of GaryDoug:
http://www.mediafire.com/?40mfgeoe4ctti
Have you scanned recently for any new codes that may be hiding behind the SES light for the O2 sensor?
You can't really clean an O2 sensor. The exposed metal part with the slots or holes is just a shield. The sensor thimble it inside the shield.
What voltage did you check, and what did you use to check it? The PCM supplies an ~0.450 volt bias voltage. The sensor thimble adds or subtracts from that voltage based on comparing the oxygen level in the exhaust on the outside of the thimble to the oxygen level in ambient air on the inside of the thimble. The ambient air enters the thimble via the hole the wires pass through. If there is anything leaking on the outside of the sensor, like engine oil, or if it has been soaked with something like PB Blaster in order to break the threads loose, the thimble could be contaminated or the air may not be able to get to it.
A 383 ci engine, heads/cam, which probably has larger than stock injectors, is not going to run well with a stock tune. But you indicate this is only a recent problem, so it must have been tuned.
http://shbox.com/1/Dtcs.htm
You can download a free copy of the 1996 (same as 1997) factory service manual here - courtesy of GaryDoug:
http://www.mediafire.com/?40mfgeoe4ctti
Have you scanned recently for any new codes that may be hiding behind the SES light for the O2 sensor?
You can't really clean an O2 sensor. The exposed metal part with the slots or holes is just a shield. The sensor thimble it inside the shield.
What voltage did you check, and what did you use to check it? The PCM supplies an ~0.450 volt bias voltage. The sensor thimble adds or subtracts from that voltage based on comparing the oxygen level in the exhaust on the outside of the thimble to the oxygen level in ambient air on the inside of the thimble. The ambient air enters the thimble via the hole the wires pass through. If there is anything leaking on the outside of the sensor, like engine oil, or if it has been soaked with something like PB Blaster in order to break the threads loose, the thimble could be contaminated or the air may not be able to get to it.
A 383 ci engine, heads/cam, which probably has larger than stock injectors, is not going to run well with a stock tune. But you indicate this is only a recent problem, so it must have been tuned.
11-12-2019 | 08:34 PM
#6
Thread Starter
Registered User
Joined: Nov 2019
Posts: 164
From: Montana, Big Sky State
Re: Need Suggestions, A Little Stumped
"Insufficient Activity" (P0134)..... or "No activity" (P????)? The code descriptions provided by some scanners are "generic" and not necessarily correct for the specific vehicle/engine. Shoebox's list is basically the list out of the factory service manual.
http://shbox.com/1/Dtcs.htm
You can download a free copy of the 1996 (same as 1997) factory service manual here - courtesy of GaryDoug:
http://www.mediafire.com/?40mfgeoe4ctti
Have you scanned recently for any new codes that may be hiding behind the SES light for the O2 sensor?
You can't really clean an O2 sensor. The exposed metal part with the slots or holes is just a shield. The sensor thimble it inside the shield.
What voltage did you check, and what did you use to check it? The PCM supplies an ~0.450 volt bias voltage. The sensor thimble adds or subtracts from that voltage based on comparing the oxygen level in the exhaust on the outside of the thimble to the oxygen level in ambient air on the inside of the thimble. The ambient air enters the thimble via the hole the wires pass through. If there is anything leaking on the outside of the sensor, like engine oil, or if it has been soaked with something like PB Blaster in order to break the threads loose, the thimble could be contaminated or the air may not be able to get to it.
A 383 ci engine, heads/cam, which probably has larger than stock injectors, is not going to run well with a stock tune. But you indicate this is only a recent problem, so it must have been tuned.
http://shbox.com/1/Dtcs.htm
You can download a free copy of the 1996 (same as 1997) factory service manual here - courtesy of GaryDoug:
http://www.mediafire.com/?40mfgeoe4ctti
Have you scanned recently for any new codes that may be hiding behind the SES light for the O2 sensor?
You can't really clean an O2 sensor. The exposed metal part with the slots or holes is just a shield. The sensor thimble it inside the shield.
What voltage did you check, and what did you use to check it? The PCM supplies an ~0.450 volt bias voltage. The sensor thimble adds or subtracts from that voltage based on comparing the oxygen level in the exhaust on the outside of the thimble to the oxygen level in ambient air on the inside of the thimble. The ambient air enters the thimble via the hole the wires pass through. If there is anything leaking on the outside of the sensor, like engine oil, or if it has been soaked with something like PB Blaster in order to break the threads loose, the thimble could be contaminated or the air may not be able to get to it.
A 383 ci engine, heads/cam, which probably has larger than stock injectors, is not going to run well with a stock tune. But you indicate this is only a recent problem, so it must have been tuned.
11-12-2019 | 11:47 PM
#7
Administrator
Joined: Nov 1998
Posts: 70,853
From: Hell was full so they sent me to NJ
Re: Need Suggestions, A Little Stumped
Manual or auto trans? What rear axle ratio?
Trying to accelerate hard at low RPM in the wrong gear (second, rather than first) actually puts more load on the ignition system than accelerating hard in first gear. What RPM are you cruising at when the problem occurs? Does it jerk and stutter with constant throttle position, or only when you try to accelerate? Do your hear any knock (detonation) when you try to accelerate at low RPM.
https://www.camaroz28.com/forums/lt1...nature-879835/
Trying to accelerate hard at low RPM in the wrong gear (second, rather than first) actually puts more load on the ignition system than accelerating hard in first gear. What RPM are you cruising at when the problem occurs? Does it jerk and stutter with constant throttle position, or only when you try to accelerate? Do your hear any knock (detonation) when you try to accelerate at low RPM.
https://www.camaroz28.com/forums/lt1...nature-879835/
11-13-2019 | 12:09 AM
#8
Thread Starter
Registered User
Joined: Nov 2019
Posts: 164
From: Montana, Big Sky State
Re: Need Suggestions, A Little Stumped
Manual or auto trans? What rear axle ratio?
Trying to accelerate hard at low RPM in the wrong gear (second, rather than first) actually puts more load on the ignition system than accelerating hard in first gear. What RPM are you cruising at when the problem occurs? Does it jerk and stutter with constant throttle position, or only when you try to accelerate? Do your hear any knock (detonation) when you try to accelerate at low RPM.
https://www.camaroz28.com/forums/lt1...nature-879835/
Trying to accelerate hard at low RPM in the wrong gear (second, rather than first) actually puts more load on the ignition system than accelerating hard in first gear. What RPM are you cruising at when the problem occurs? Does it jerk and stutter with constant throttle position, or only when you try to accelerate? Do your hear any knock (detonation) when you try to accelerate at low RPM.
https://www.camaroz28.com/forums/lt1...nature-879835/
Thanks, WhiteWS6
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