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Well after a lot of troubleshooting I was finally able to figure out what was causing the erratic/inconsistent spark problem.
For those that have the GM 3.3L engine make sure that you have the most up to date MEMCAL because it fixes a bunch of problems that existed with the original MEMCAL the car came with. GM listed a service bulletin for the updated MEMCAL but it was aimed towards Oldsmobile’s with the 3300 since it was made in an Oldsmobile factory.
The updated MEMCAL broadcast code is BLYB 8289.
Hope that info helps!
Well after a lot of troubleshooting I was finally able to figure out what was causing the erratic/inconsistent spark problem.
For those that have the GM 3.3L engine make sure that you have the most up to date MEMCAL because it fixes a bunch of problems that existed with the original MEMCAL the car came with. GM listed a service bulletin for the updated MEMCAL but it was aimed towards Oldsmobile’s with the 3300 since it was made in an Oldsmobile factory.
The updated MEMCAL broadcast code is BLYB 8289.
Hope that info helps!
I went out this morning and took a look at the bolt that you were referring to and it was a little rusted up but not too bad. I sanded it down and cleaned it up real good, put everything back together and started the car and the spark issue was still there.
Just to be sure that the coil packs or the ICM aren’t the problem I hooked up the old ones and the problem still existed so I know that they aren’t at fault.
I also removed the ECM and looked it over and I noticed that it had a slight electrical burning smell. I took it apart and everything appeared to be fine, there were no shorts on the circuit board and the wires and harnesses looked fine but that burning smell is a little suspicious.
Could that smell be an indication that the ECM is bad or is it normal?
I went out this morning and took a look at the bolt that you were referring to and it was a little rusted up but not too bad. I sanded it down and cleaned it up real good, put everything back together and started the car and the spark issue was still there.
Just to be sure that the coil packs or the ICM aren’t the problem I hooked up the old ones and the problem still existed so I know that they aren’t at fault.
I also removed the ECM and looked it over and I noticed that it had a slight electrical burning smell. I took it apart and everything appeared to be fine, there were no shorts on the circuit board and the wires and harnesses looked fine but that burning smell is a little suspicious.
Could that smell be an indication that the ECM is bad or is it normal?
I did sand down the bracket that the ICM sits on but I did not check that stud to see if it was corroded, I probably didn’t see it. I’ll check it tomorrow morning and post back here with the results. Thanks!
I did sand down the bracket that the ICM sits on but I did not check that stud to see if it was corroded, I probably didn’t see it. I’ll check it tomorrow morning and post back here with the results. Thanks!
Thanks for the quick reply! I have tried 3 different sets of coil packs and 3 different ICM’s and the problem still exists (all are AC Delco). A friend of mine owns a salvage yard so I got lucky with testing out those parts. I also tested for vacuum leaks and voltage leaks and didn’t find any. I should also mention that the car has a waste spark setup. Each coil fires 2 cylinders simultaneously (one front bank cylinder and one rear bank cylinder). I did a power balance test by pulling the injector connectors and each cylinder had a similar drop in RPM so I can assume that the fuel is being delivered properly. I checked the wiring and the harnesses and they all looked fine.
I have replaced just about every sensor on the engine with the exception of the knock sensor so could a knock sensor cause a problem like this? I’m not sure on how to test one.
Thanks for the quick reply! I have tried 3 different sets of coil packs and 3 different ICM’s and the problem still exists (all are AC Delco). A friend of mine owns a salvage yard so I got lucky with testing out those parts. I also tested for vacuum leaks and voltage leaks and didn’t find any. I should also mention that the car has a waste spark setup. Each coil fires 2 cylinders simultaneously (one front bank cylinder and one rear bank cylinder). I did a power balance test by pulling the injector connectors and each cylinder had a similar drop in RPM so I can assume that the fuel is being delivered properly. I checked the wiring and the harnesses and they all looked fine.
I have replaced just about every sensor on the engine with the exception of the knock sensor so could a knock sensor cause a problem like this? I’m not sure on how to test one.
They have free wiring diagrams on AutoZone.com. You just have to make a free account and then you can access all the diagrams that they have for your car. They aren’t as complex as other wiring diagrams so you should have an easier time understanding it.
They have free wiring diagrams on AutoZone.com. You just have to make a free account and then you can access all the diagrams that they have for your car. They aren’t as complex as other wiring diagrams so you should have an easier time understanding it.
If it’s a vacuum leak that’s causing the misfire it’ll be most noticeable when the engine is the closed loop idle i.e. the engine is up to operating temperature and it’s at the normal idle RPM. The misfire could exist at higher RPM’s it just may not be as noticeable.
Do keep in mind though that there could be a different issue causing your misfire but vacuum leaks are one of the more popular causes for idle misfires.
If it’s a vacuum leak that’s causing the misfire it’ll be most noticeable when the engine is the closed loop idle i.e. the engine is up to operating temperature and it’s at the normal idle RPM. The misfire could exist at higher RPM’s it just may not be as noticeable.
Do keep in mind though that there could be a different issue causing your misfire but vacuum leaks are one of the more popular causes for idle misfires.
You can also check for vacuum leaks with a spray bottle filled with water. It may not be as accurate as using carb cleaner. I never use carb cleaner when the engine is warm, I always do it when it’s cool and when I start the car up for the first time of the day. This will decrease the fire hazard since the engine and it’s components aren’t hot. Also, a vacuum leak can be found when the engine is hot or cold.
You can also check for vacuum leaks with a spray bottle filled with water. It may not be as accurate as using carb cleaner. I never use carb cleaner when the engine is warm, I always do it when it’s cool and when I start the car up for the first time of the day. This will decrease the fire hazard since the engine and it’s components aren’t hot. Also, a vacuum leak can be found when the engine is hot or cold.