1995 LT1 Auto
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1995 LT1 Auto
Team my 95 is getting to rich ones warm up , new opti, ICM, both O2 sensors, cables and plugs, cars runs good cold and in minutes start running rich I can smell the bad mix coming from exhaust, I have 120psi of compression not sure if that could cause that issue , also I scanned the car and all I have is EGR code because it was deleted by previous owner , my mechanic suggested that could be a bad PCM but I don't want to spend more money in stuffs that I don't need , please any advice.
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Joined: Nov 1998
Posts: 71,086
From: Hell was full so they sent me to NJ
Re: 1995 LT1 Auto
Is the “SES” light on?
Check the coolant temperature sensor in the water pump housing. If it’s indicating colder than actual temperature, could cause the PCM to richen the A/F ratio, and prevent the PCM from going into closed loop. If you have a scanner that can read real time data from the PCM, look at the coolant temperature to see if it looks correct. You could also check the 5 volt reference signal provided by the PCM, and measure the sensor resistance - ohms vs. degrees - using Shoebox's procedure:
4th Gen LT1 F-body Tech Articles
You could also check the fuel pressure to see if it indicates a leaking fuel injector, or leaking fuel pressure regulator. Put a pressure test gauge on the Schrader valve. Turn key to “RUN”, pump should prime for 2 to 3 seconds. Pressure should reach at least 40 PSI at pump shutoff, and pressure should not drop rapidly after the pump shuts off.
What brand O2 sensors did you buy? AC Delco work best. The cheap stuff from eBay or Amazon are Chinese junk and could be causing the problem, if it started after you replaced them.
Faulty PCM is very rare.
Check the coolant temperature sensor in the water pump housing. If it’s indicating colder than actual temperature, could cause the PCM to richen the A/F ratio, and prevent the PCM from going into closed loop. If you have a scanner that can read real time data from the PCM, look at the coolant temperature to see if it looks correct. You could also check the 5 volt reference signal provided by the PCM, and measure the sensor resistance - ohms vs. degrees - using Shoebox's procedure:
4th Gen LT1 F-body Tech Articles
You could also check the fuel pressure to see if it indicates a leaking fuel injector, or leaking fuel pressure regulator. Put a pressure test gauge on the Schrader valve. Turn key to “RUN”, pump should prime for 2 to 3 seconds. Pressure should reach at least 40 PSI at pump shutoff, and pressure should not drop rapidly after the pump shuts off.
What brand O2 sensors did you buy? AC Delco work best. The cheap stuff from eBay or Amazon are Chinese junk and could be causing the problem, if it started after you replaced them.
Faulty PCM is very rare.
Thread Starter
Registered User
Joined: Apr 2024
Posts: 10
Re: 1995 LT1 Auto
Is the “SES” light on?
Check the coolant temperature sensor in the water pump housing. If it’s indicating colder than actual temperature, could cause the PCM to richen the A/F ratio, and prevent the PCM from going into closed loop. If you have a scanner that can read real time data from the PCM, look at the coolant temperature to see if it looks correct. You could also check the 5 volt reference signal provided by the PCM, and measure the sensor resistance - ohms vs. degrees - using Shoebox's procedure:
4th Gen LT1 F-body Tech Articles
You could also check the fuel pressure to see if it indicates a leaking fuel injector, or leaking fuel pressure regulator. Put a pressure test gauge on the Schrader valve. Turn key to “RUN”, pump should prime for 2 to 3 seconds. Pressure should reach at least 40 PSI at pump shutoff, and pressure should not drop rapidly after the pump shuts off.
What brand O2 sensors did you buy? AC Delco work best. The cheap stuff from eBay or Amazon are Chinese junk and could be causing the problem, if it started after you replaced them.
Faulty PCM is very rare.
Check the coolant temperature sensor in the water pump housing. If it’s indicating colder than actual temperature, could cause the PCM to richen the A/F ratio, and prevent the PCM from going into closed loop. If you have a scanner that can read real time data from the PCM, look at the coolant temperature to see if it looks correct. You could also check the 5 volt reference signal provided by the PCM, and measure the sensor resistance - ohms vs. degrees - using Shoebox's procedure:
4th Gen LT1 F-body Tech Articles
You could also check the fuel pressure to see if it indicates a leaking fuel injector, or leaking fuel pressure regulator. Put a pressure test gauge on the Schrader valve. Turn key to “RUN”, pump should prime for 2 to 3 seconds. Pressure should reach at least 40 PSI at pump shutoff, and pressure should not drop rapidly after the pump shuts off.
What brand O2 sensors did you buy? AC Delco work best. The cheap stuff from eBay or Amazon are Chinese junk and could be causing the problem, if it started after you replaced them.
Faulty PCM is very rare.
Yes SES turn on in seconds , thanks for the info I am going to check all that , regarding O2 sensors previous owner replaced them not sure the brand but I will.check , I bought the car like that it looks like previous owner never had luck finding the issue he throw a lot of new parts but nothing, again thanks I Will update once I check everything.
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Joined: Nov 1998
Posts: 71,086
From: Hell was full so they sent me to NJ
Re: 1995 LT1 Auto
If the SES light turns on and stays on, did you or your "mechanic" scan for codes? Should have been the first step by the mechanic.
SCAN FOR CODES NOW ! ! !
Note that your 95 has a 16-pin OBD-2 style DLC, but the PCM is OBD-1
SCAN FOR CODES NOW ! ! !
Note that your 95 has a 16-pin OBD-2 style DLC, but the PCM is OBD-1
Thread Starter
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Re: 1995 LT1 Auto
I did download scan 95 and i have 0 codes all I saw is that , I am not an expert and yes once SES light is on remain on .
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Joined: Jul 2005
Posts: 9,507
From: Okemos, MI
Re: 1995 LT1 Auto
Looking over the electrical faults, I’d expect to see codes for EGR and EVAP.
EVAP (evaporative emissions) in particular is likely what’s causing the smell. I know close to nothing about how it works on an LT1 car, so I’ll let Fred take it from here.
EVAP (evaporative emissions) in particular is likely what’s causing the smell. I know close to nothing about how it works on an LT1 car, so I’ll let Fred take it from here.
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Re: 1995 LT1 Auto
I will scan again , i am learning how to use the tool , thanks for all the advice .
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Posts: 71,086
From: Hell was full so they sent me to NJ
Re: 1995 LT1 Auto
Use the “DTC” tab for codes.
The electrical fault tab shows three faults, in green.
Figure out how to run a data log, according to my guidelines.
https://www.camaroz28.com/forums/com...-guide-886891/
Note my hesitation to do these data log reviews, because people aren’t willing to make a commitment to work with me to find the problem. If you don’t follow the guidelines, don’t answer my questions, don’t give me all the info about the car and known modifications, I’ll drop the review like a hot potatoe. I've been burned too many time recently.
The electrical fault tab shows three faults, in green.
Figure out how to run a data log, according to my guidelines.
https://www.camaroz28.com/forums/com...-guide-886891/
Note my hesitation to do these data log reviews, because people aren’t willing to make a commitment to work with me to find the problem. If you don’t follow the guidelines, don’t answer my questions, don’t give me all the info about the car and known modifications, I’ll drop the review like a hot potatoe. I've been burned too many time recently.
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Joined: Jul 2005
Posts: 9,507
From: Okemos, MI
Re: 1995 LT1 Auto
As I think more about it, I think you should check the wiring and connector for the evap purge solenoid. That electrical fault says that the circuit is open, which means it’s not connected. You want to make sure it’s connected and that the wiring is in good condition. If it is, then the solenoid itself has likely failed, in which case you should replace it.
The solenoid mounts to the intake manifold, and looks like this: https://a.co/d/09J0SG2W
If you need to replace it, the link above is a quality part at a good price. Feel free to shop around for a better price, but as with all sensors, the OEM supplier (ACDelco) is generally the one to buy.
Replacement is simple: disconnect the sensor and the vacuum lines, then remove. Installation is the same in reverse.
The solenoid mounts to the intake manifold, and looks like this: https://a.co/d/09J0SG2W
If you need to replace it, the link above is a quality part at a good price. Feel free to shop around for a better price, but as with all sensors, the OEM supplier (ACDelco) is generally the one to buy.
Replacement is simple: disconnect the sensor and the vacuum lines, then remove. Installation is the same in reverse.
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Posts: 10
Re: 1995 LT1 Auto
As I think more about it, I think you should check the wiring and connector for the evap purge solenoid. That electrical fault says that the circuit is open, which means it’s not connected. You want to make sure it’s connected and that the wiring is in good condition. If it is, then the solenoid itself has likely failed, in which case you should replace it.
The solenoid mounts to the intake manifold, and looks like this: https://a.co/d/09J0SG2W
If you need to replace it, the link above is a quality part at a good price. Feel free to shop around for a better price, but as with all sensors, the OEM supplier (ACDelco) is generally the one to buy.
Replacement is simple: disconnect the sensor and the vacuum lines, then remove. Installation is the same in reverse.
The solenoid mounts to the intake manifold, and looks like this: https://a.co/d/09J0SG2W
If you need to replace it, the link above is a quality part at a good price. Feel free to shop around for a better price, but as with all sensors, the OEM supplier (ACDelco) is generally the one to buy.
Replacement is simple: disconnect the sensor and the vacuum lines, then remove. Installation is the same in reverse.
I will do it and replay you back , thanks
Thread Starter
Registered User
Joined: Apr 2024
Posts: 10
Re: 1995 LT1 Auto
Use the “DTC” tab for codes.
The electrical fault tab shows three faults, in green.
Figure out how to run a data log, according to my guidelines.
https://www.camaroz28.com/forums/com...-guide-886891/
Note my hesitation to do these data log reviews, because people aren’t willing to make a commitment to work with me to find the problem. If you don’t follow the guidelines, don’t answer my questions, don’t give me all the info about the car and known modifications, I’ll drop the review like a hot potatoe. I've been burned too many time recently.
The electrical fault tab shows three faults, in green.
Figure out how to run a data log, according to my guidelines.
https://www.camaroz28.com/forums/com...-guide-886891/
Note my hesitation to do these data log reviews, because people aren’t willing to make a commitment to work with me to find the problem. If you don’t follow the guidelines, don’t answer my questions, don’t give me all the info about the car and known modifications, I’ll drop the review like a hot potatoe. I've been burned too many time recently.
I will do it and reply you back , thanks
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