I just joined the opti club
08-17-2017, 11:57 AM
#1
Instructor
Thread Starter
I just joined the opti club
Was in the middle of a short errand and my 94 LT1 started bucking and belching and backfiring. I barely made it home. So I threw the MT2500 on it and it's showing a code 16, low/high resolution failure. Did a little research and code 16 looks like opti failure.
I plan to do the work myself but would appreciate your collective wisdom as to whether I'm on the right track.
Btw the car has 33k on it and the PO replaced the water pump and opti in 2007, at 27k. So it got 10 years and only 6k. Work was done by the dealer so I'm guessing they put in a OE replacement at the time.
I'm leaning towards Sac City for a new opti.
Would appreciate any thoughts
Thanks
Bob
I plan to do the work myself but would appreciate your collective wisdom as to whether I'm on the right track.
Btw the car has 33k on it and the PO replaced the water pump and opti in 2007, at 27k. So it got 10 years and only 6k. Work was done by the dealer so I'm guessing they put in a OE replacement at the time.
I'm leaning towards Sac City for a new opti.
Would appreciate any thoughts
Thanks
Bob
08-17-2017, 12:25 PM
#2
Melting Slicks
Was in the middle of a short errand and my 94 LT1 started bucking and belching and backfiring. I barely made it home. So I threw the MT2500 on it and it's showing a code 16, low/high resolution failure. Did a little research and code 16 looks like opti failure.
I plan to do the work myself but would appreciate your collective wisdom as to whether I'm on the right track.
Btw the car has 33k on it and the PO replaced the water pump and opti in 2007, at 27k. So it got 10 years and only 6k. Work was done by the dealer so I'm guessing they put in a OE replacement at the time.
I'm leaning towards Sac City for a new opti.
Would appreciate any thoughts
Thanks
Bob
I plan to do the work myself but would appreciate your collective wisdom as to whether I'm on the right track.
Btw the car has 33k on it and the PO replaced the water pump and opti in 2007, at 27k. So it got 10 years and only 6k. Work was done by the dealer so I'm guessing they put in a OE replacement at the time.
I'm leaning towards Sac City for a new opti.
Would appreciate any thoughts
Thanks
Bob
08-17-2017, 12:40 PM
#3
Advanced
I just installed a Petris Enterprises Optispark and am very happy with it. They also offered a 5 year unlimited mileage warranty which far exceeded anything else anyone was offering. My car is a 93, so it added the ventilation which isn't standard for 92-94.
08-17-2017, 01:58 PM
#4
Instructor
Thread Starter
Was in the middle of a short errand and my 94 LT1 started bucking and belching and backfiring. I barely made it home. So I threw the MT2500 on it and it's showing a code 16, low/high resolution failure. Did a little research and code 16 looks like opti failure.
I plan to do the work myself but would appreciate your collective wisdom as to whether I'm on the right track.
Btw the car has 33k on it and the PO replaced the water pump and opti in 2007, at 27k. So it got 10 years and only 6k. Work was done by the dealer so I'm guessing they put in a OE replacement at the time.
I'm leaning towards Sac City for a new opti.
Would appreciate any thoughts
Thanks
Bob
I plan to do the work myself but would appreciate your collective wisdom as to whether I'm on the right track.
Btw the car has 33k on it and the PO replaced the water pump and opti in 2007, at 27k. So it got 10 years and only 6k. Work was done by the dealer so I'm guessing they put in a OE replacement at the time.
I'm leaning towards Sac City for a new opti.
Would appreciate any thoughts
Thanks
Bob
Just went out and took the connectors off the ignition control module and reinstalled them. With the engine temperature back down to the 140s, it started right up and ran normally. Later, I'll go out and start it in the driveway and let it heat up to see if heat has affected the ICM. It may not be the opti. Now I have to dive into the FSM.
08-17-2017, 02:40 PM
#5
Le Mans Master
So the mystery goes on.
Just went out and took the connectors off the ignition control module and reinstalled them. With the engine temperature back down to the 140s, it started right up and ran normally. Later, I'll go out and start it in the driveway and let it heat up to see if heat has affected the ICM. It may not be the opti. Now I have to dive into the FSM.
Just went out and took the connectors off the ignition control module and reinstalled them. With the engine temperature back down to the 140s, it started right up and ran normally. Later, I'll go out and start it in the driveway and let it heat up to see if heat has affected the ICM. It may not be the opti. Now I have to dive into the FSM.
A cap/rotor fault won't set DTC 16, so if you replace only the cap and rotor, you'll be tearing it down twice.
Most likely cause is the optical sensor is failing when hot, in which case you'll be replacing the distributor. The difficulty then becomes where to buy one that will last.
Live well,
SJW
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vette196 (08-17-2017)
08-17-2017, 03:46 PM
#7
Safety Car
Was in the middle of a short errand and my 94 LT1 started bucking and belching and backfiring. I barely made it home. So I threw the MT2500 on it and it's showing a code 16, low/high resolution failure. Did a little research and code 16 looks like opti failure.
I plan to do the work myself but would appreciate your collective wisdom as to whether I'm on the right track.
Btw the car has 33k on it and the PO replaced the water pump and opti in 2007, at 27k. So it got 10 years and only 6k. Work was done by the dealer so I'm guessing they put in a OE replacement at the time.
I'm leaning towards Sac City for a new opti.
Would appreciate any thoughts
Thanks
Bob
I plan to do the work myself but would appreciate your collective wisdom as to whether I'm on the right track.
Btw the car has 33k on it and the PO replaced the water pump and opti in 2007, at 27k. So it got 10 years and only 6k. Work was done by the dealer so I'm guessing they put in a OE replacement at the time.
I'm leaning towards Sac City for a new opti.
Would appreciate any thoughts
Thanks
Bob
08-17-2017, 03:51 PM
#8
Instructor
Thread Starter
If it set DTC 16, the fault is either in the distributor's optical sensor or the wiring harness (with a very slim chance it's in the PCM).
A cap/rotor fault won't set DTC 16, so if you replace only the cap and rotor, you'll be tearing it down twice.
Most likely cause is the optical sensor is failing when hot, in which case you'll be replacing the distributor. The difficulty then becomes where to buy one that will last.
A cap/rotor fault won't set DTC 16, so if you replace only the cap and rotor, you'll be tearing it down twice.
Most likely cause is the optical sensor is failing when hot, in which case you'll be replacing the distributor. The difficulty then becomes where to buy one that will last.
It is throwing a DTC 16, so I am going ahead with the opti replacement. Will also do the water pump shaft seal and cam shaft seal.
I like the warranty offered by Sac City and the fact that components are made in USA. It's still a crap shoot no matter how you look at it.
08-17-2017, 03:59 PM
#9
Instructor
Thread Starter
Same problem i have. If you have an original opti it will have a stainless disc if not buy a gm replacement from rock auto Do not tamper with the one you remove or it will be a loss of a credit when returned Also MSD is an option and i have both but with my research the GM rebuilt is the way to go. Also see if yours is vented some times the hose works loose and draws in ambient moisture. Blow it with a hair drier on low cool setting to clear any moisture and reattach. Also vent the water pump. Direct the so called vent hole on bottom of pump with plastic tubeing. ( clear would be best so you can see in future if pump has drooling problems) Also on what ever opti you choose blue loctite rotar screws and tape the four wire plug on opti( Heat shrink is better but Scotch 33 plus tape will do the seal} Do not stretch tape it will adhere far better. The o-ring for the cap should be checked and screws blue loctite to furthur water resistat. Good luck!
Good commentary!
I am not sure if mine is vented or not. It was probably built as non-vented but it's hard to see if the replacement was vented or not. I don't see any tubing but it's hard to see in there.
08-17-2017, 06:30 PM
#11
Instructor
Thread Starter
08-17-2017, 06:51 PM
#12
Le Mans Master
The factory unit from 1992 through 1994 was passively vented, via three weep holes in the bottom of the housing. 1995 and 1996 were actively vented, using manifold vacuum to draw filtered air from the intake bellows through the distributor housing.
Some aftermarket replacements for the 1992 - 1994 cars are fitted with active venting. Active venting can also be added to the early units by using the later unit's distributor cap. I would not install a passively vented unit, as the active venting really helps to pull moisture and the corrosive ozone (produced by arcing from the rotor to the contacts in the cap) out of the housing.
If you add active venting to yours, be sure to do it correctly or you might cause more problems than you prevent. You'll need a one-way check valve (installed in the correct orientation) in the vacuum line between the manifold and the distributor, and you'll need to add a fitting to the intake bellows, aft of the MAF sensor, for the inlet air connection. Be sure to route the vacuum lines such that they don't get abraded by sharp or moving parts, and that they don't get pinched closed. If the inlet hose from the bellows gets pinched shut, manifold vacuum will collapse the distributor cap until it contacts the rotor, and parts will break immediately.
It is widely believed that the Mitsubishi optical sensor that was used in the factory units is far more durable than the off-brand sensors. Sadly, the Mitsubishi sensors are no longer being manufactured.
Be advised that it is not possible to install a later housing on an earlier car. The drive coupling to the camshaft is different, as is the timing cover.
I would replace the water pump with a new AC Delco unit while you have things apart, and it's a good idea to add a drain hose to the weep hole in the bottom of the pump, to route any coolant seepage away from the distributor, as was suggested elsewhere in this thread.
This is also a good time to replace all coolant hoses, the serpentine belt, and completely drain (yank the knock sensors) and refill with fresh coolant and distilled water.
Be sure to purge the air from the system as it's being refilled. There are two air bleed valves on the 1994 cars. A cooling system pressure tester can really help to push out any trapped air. Pack the area under the bleed screws with rags to absorb any coolant that escapes, to keep it off the distributor below.
Also consider replacing the plug wires while you're in there. They are a queen royal PITA to replace with everything assembled, but somewhat easier (though still not particularly easy) when you've got it pulled apart down to the distributor. Loosen the power steering pump, and slide it forward an inch or so to gain clearance behind the pump to pass the wires through. And, it might be sensible to change the plugs while you have the wires off, too. The military calls this scenario "mission creep."
Good luck with it.
Live well,
SJW
Some aftermarket replacements for the 1992 - 1994 cars are fitted with active venting. Active venting can also be added to the early units by using the later unit's distributor cap. I would not install a passively vented unit, as the active venting really helps to pull moisture and the corrosive ozone (produced by arcing from the rotor to the contacts in the cap) out of the housing.
If you add active venting to yours, be sure to do it correctly or you might cause more problems than you prevent. You'll need a one-way check valve (installed in the correct orientation) in the vacuum line between the manifold and the distributor, and you'll need to add a fitting to the intake bellows, aft of the MAF sensor, for the inlet air connection. Be sure to route the vacuum lines such that they don't get abraded by sharp or moving parts, and that they don't get pinched closed. If the inlet hose from the bellows gets pinched shut, manifold vacuum will collapse the distributor cap until it contacts the rotor, and parts will break immediately.
It is widely believed that the Mitsubishi optical sensor that was used in the factory units is far more durable than the off-brand sensors. Sadly, the Mitsubishi sensors are no longer being manufactured.
Be advised that it is not possible to install a later housing on an earlier car. The drive coupling to the camshaft is different, as is the timing cover.
I would replace the water pump with a new AC Delco unit while you have things apart, and it's a good idea to add a drain hose to the weep hole in the bottom of the pump, to route any coolant seepage away from the distributor, as was suggested elsewhere in this thread.
This is also a good time to replace all coolant hoses, the serpentine belt, and completely drain (yank the knock sensors) and refill with fresh coolant and distilled water.
Be sure to purge the air from the system as it's being refilled. There are two air bleed valves on the 1994 cars. A cooling system pressure tester can really help to push out any trapped air. Pack the area under the bleed screws with rags to absorb any coolant that escapes, to keep it off the distributor below.
Also consider replacing the plug wires while you're in there. They are a queen royal PITA to replace with everything assembled, but somewhat easier (though still not particularly easy) when you've got it pulled apart down to the distributor. Loosen the power steering pump, and slide it forward an inch or so to gain clearance behind the pump to pass the wires through. And, it might be sensible to change the plugs while you have the wires off, too. The military calls this scenario "mission creep."
Good luck with it.
Live well,
SJW
Last edited by SJW; 08-17-2017 at 07:07 PM.
08-17-2017, 07:09 PM
#13
Instructor
Thread Starter
The factory unit from 1992 through 1994 was passively vented, via three weep holes in the bottom of the housing. 1995 and 1996 were actively vented, using manifold vacuum to draw filtered air from the intake bellows through the distributor housing.
Some aftermarket replacements for the 1992 - 1994 cars are fitted with active venting. Active venting can also be added to the early units by using the later unit's distributor cap. I would not install a passively vented unit, as the active venting really helps to pull moisture and the corrosive ozone (produced by arcing from the rotor to the contacts in the cap) out of the housing.
If you add active venting to yours, be sure to do it correctly or you might cause more problems than you prevent. You'll need a one-way check valve (installed in the correct orientation) in the vacuum line between the manifold and the distributor, and you'll need to add a fitting to the intake bellows, aft of the MAF sensor, for the inlet air connection. Be sure to route the vacuum lines such that they don't get abraded by sharp or moving parts, and that they don't get pinched closed. If the inlet hose from the bellows gets pinched shut, manifold vacuum will collapse the distributor cap until it contacts the rotor, and parts will break immediately.
It is widely believed that the Mitsubishi optical sensor that was used in the factory units is far more durable than the off-brand sensors. Sadly, the Mitsubishi sensors are no longer being manufactured.
Be advised that it is not possible to install a later housing on an earlier car. The drive coupling to the camshaft is different, as is the timing cover.
Good luck with it.
Live well,
SJW
Some aftermarket replacements for the 1992 - 1994 cars are fitted with active venting. Active venting can also be added to the early units by using the later unit's distributor cap. I would not install a passively vented unit, as the active venting really helps to pull moisture and the corrosive ozone (produced by arcing from the rotor to the contacts in the cap) out of the housing.
If you add active venting to yours, be sure to do it correctly or you might cause more problems than you prevent. You'll need a one-way check valve (installed in the correct orientation) in the vacuum line between the manifold and the distributor, and you'll need to add a fitting to the intake bellows, aft of the MAF sensor, for the inlet air connection. Be sure to route the vacuum lines such that they don't get abraded by sharp or moving parts, and that they don't get pinched closed. If the inlet hose from the bellows gets pinched shut, manifold vacuum will collapse the distributor cap until it contacts the rotor, and parts will break immediately.
It is widely believed that the Mitsubishi optical sensor that was used in the factory units is far more durable than the off-brand sensors. Sadly, the Mitsubishi sensors are no longer being manufactured.
Be advised that it is not possible to install a later housing on an earlier car. The drive coupling to the camshaft is different, as is the timing cover.
Good luck with it.
Live well,
SJW
Thanks for the nice write up. Are caps and rotors available for my new opti if I were to try to actively vent it? I'm pretty sure mine is not actively vented. I ordered the Sac City opti, non vented.
Bob
08-17-2017, 08:11 PM
#14
Le Mans Master
Live well,
SJW
Last edited by SJW; 08-17-2017 at 08:11 PM.
08-17-2017, 09:30 PM
#15
Advanced
Everything Steve said is correct. I investigated this for my 92. I am going with the Petris set up and a Gates water pump as they are still made in America. Good Luck.
08-17-2017, 10:11 PM
#16
Advanced
Drifter36, I did not go with a vented Opti. SJW gave some great information. I did use an AC Delco Water pump. I did replace my plug wires. I used Taylor 8mm. I did flush my coolant as well. Also did the serpentine belt. All good to do during this time/repair.
08-17-2017, 10:33 PM
#18
Le Mans Master
If you're going to add a DIY active venting arrangement to a passively-vented distributor, search here for threads about how best to do it. It occurred to me that those weep holes at the bottom of the housing will need to be sealed off...
Live well,
SJW
Live well,
SJW
08-18-2017, 07:11 AM
#19
Instructor
Thread Starter
The factory unit from 1992 through 1994 was passively vented, via three weep holes in the bottom of the housing. 1995 and 1996 were actively vented, using manifold vacuum to draw filtered air from the intake bellows through the distributor housing.
Some aftermarket replacements for the 1992 - 1994 cars are fitted with active venting. Active venting can also be added to the early units by using the later unit's distributor cap. I would not install a passively vented unit, as the active venting really helps to pull moisture and the corrosive ozone (produced by arcing from the rotor to the contacts in the cap) out of the housing.
If you add active venting to yours, be sure to do it correctly or you might cause more problems than you prevent. You'll need a one-way check valve (installed in the correct orientation) in the vacuum line between the manifold and the distributor, and you'll need to add a fitting to the intake bellows, aft of the MAF sensor, for the inlet air connection. Be sure to route the vacuum lines such that they don't get abraded by sharp or moving parts, and that they don't get pinched closed. If the inlet hose from the bellows gets pinched shut, manifold vacuum will collapse the distributor cap until it contacts the rotor, and parts will break immediately.
It is widely believed that the Mitsubishi optical sensor that was used in the factory units is far more durable than the off-brand sensors. Sadly, the Mitsubishi sensors are no longer being manufactured.
Be advised that it is not possible to install a later housing on an earlier car. The drive coupling to the camshaft is different, as is the timing cover.
I would replace the water pump with a new AC Delco unit while you have things apart, and it's a good idea to add a drain hose to the weep hole in the bottom of the pump, to route any coolant seepage away from the distributor, as was suggested elsewhere in this thread.
This is also a good time to replace all coolant hoses, the serpentine belt, and completely drain (yank the knock sensors) and refill with fresh coolant and distilled water.
Be sure to purge the air from the system as it's being refilled. There are two air bleed valves on the 1994 cars. A cooling system pressure tester can really help to push out any trapped air. Pack the area under the bleed screws with rags to absorb any coolant that escapes, to keep it off the distributor below.
Also consider replacing the plug wires while you're in there. They are a queen royal PITA to replace with everything assembled, but somewhat easier (though still not particularly easy) when you've got it pulled apart down to the distributor. Loosen the power steering pump, and slide it forward an inch or so to gain clearance behind the pump to pass the wires through. And, it might be sensible to change the plugs while you have the wires off, too. The military calls this scenario "mission creep."
Good luck with it.
Live well,
SJW
Some aftermarket replacements for the 1992 - 1994 cars are fitted with active venting. Active venting can also be added to the early units by using the later unit's distributor cap. I would not install a passively vented unit, as the active venting really helps to pull moisture and the corrosive ozone (produced by arcing from the rotor to the contacts in the cap) out of the housing.
If you add active venting to yours, be sure to do it correctly or you might cause more problems than you prevent. You'll need a one-way check valve (installed in the correct orientation) in the vacuum line between the manifold and the distributor, and you'll need to add a fitting to the intake bellows, aft of the MAF sensor, for the inlet air connection. Be sure to route the vacuum lines such that they don't get abraded by sharp or moving parts, and that they don't get pinched closed. If the inlet hose from the bellows gets pinched shut, manifold vacuum will collapse the distributor cap until it contacts the rotor, and parts will break immediately.
It is widely believed that the Mitsubishi optical sensor that was used in the factory units is far more durable than the off-brand sensors. Sadly, the Mitsubishi sensors are no longer being manufactured.
Be advised that it is not possible to install a later housing on an earlier car. The drive coupling to the camshaft is different, as is the timing cover.
I would replace the water pump with a new AC Delco unit while you have things apart, and it's a good idea to add a drain hose to the weep hole in the bottom of the pump, to route any coolant seepage away from the distributor, as was suggested elsewhere in this thread.
This is also a good time to replace all coolant hoses, the serpentine belt, and completely drain (yank the knock sensors) and refill with fresh coolant and distilled water.
Be sure to purge the air from the system as it's being refilled. There are two air bleed valves on the 1994 cars. A cooling system pressure tester can really help to push out any trapped air. Pack the area under the bleed screws with rags to absorb any coolant that escapes, to keep it off the distributor below.
Also consider replacing the plug wires while you're in there. They are a queen royal PITA to replace with everything assembled, but somewhat easier (though still not particularly easy) when you've got it pulled apart down to the distributor. Loosen the power steering pump, and slide it forward an inch or so to gain clearance behind the pump to pass the wires through. And, it might be sensible to change the plugs while you have the wires off, too. The military calls this scenario "mission creep."
Good luck with it.
Live well,
SJW
I have a new AC Delco wp ready to go in. Just did a complete flush with new knocks, a month ago and decided not to replace the WP at that time. I will change out the plug wires. I need new looms since the retainers are long gone.
The weep hole in the WP is tiny. I guess I'll drill and tap it for a larger fitting. As it is, a barbed fitting jammed into the weep hole will reduce this even further.
I'll keep posting with some photos, as the job progresses.
Bob
08-18-2017, 09:17 AM
#20
Le Mans Master
Great info, Steve
I have a new AC Delco wp ready to go in. Just did a complete flush with new knocks, a month ago and decided not to replace the WP at that time. I will change out the plug wires. I need new looms since the retainers are long gone.
The weep hole in the WP is tiny. I guess I'll drill and tap it for a larger fitting. As it is, a barbed fitting jammed into the weep hole will reduce this even further.
I'll keep posting with some photos, as the job progresses.
Bob
I have a new AC Delco wp ready to go in. Just did a complete flush with new knocks, a month ago and decided not to replace the WP at that time. I will change out the plug wires. I need new looms since the retainers are long gone.
The weep hole in the WP is tiny. I guess I'll drill and tap it for a larger fitting. As it is, a barbed fitting jammed into the weep hole will reduce this even further.
I'll keep posting with some photos, as the job progresses.
Bob
Good luck with the job. It's a nuisance, but if you're good with your hands you'll get it done. Getting the damper off of the hub is likely to be the biggest challenge. Hopefully, it won't be seized with rust.
Live well,
SJW