99 Grand AM

[sforce1]

I have a 99 grand am Code p0300 Random/multipal cylinder misfire detected i have removed and cleaned the crank sensor and the cam sensor and changeed the plugs still same code any help?

[GTP Dad]

Welcome to AF!!

First of all it would be helpful if you posted the engine size. If you have a V-6 replace the wires. If you have a 4 cyl. replace the connectors that connect the housing to the plugs. Random misfires can also be caused by bad coils but I suspect your issue is due to wires.

[sforce1]

Originally Posted by sforce1

I have a 99 grand am Code p0300 Random/multipal cylinder misfire detected i have removed and cleaned the crank sensor and the cam sensor and changeed the plugs still same code any help?

Sorry about that engine size is a 4 cyl 2.4L

[sforce1]

Thanks GTP Dad
I will try the wires will let you know if it works.
Sorry again about not posting the engine size 4cyl 2.4L

[sforce1]

I replaced the connectors on the plugs still same code is there anyway of checking the coil packs. thanks for any help

[sforce1]

I just replaced both coil packs still same code I noticed there are some cracks in the coil pack housing could this be the problem. Please any help

[GTP Dad]

Yes, if the housing is cracked it can cause misfires, I would replace the housing. Sometimes a random misfire can be a real issue trying to track down. If this doesn't work you may have dirty injectors causing the issue, if they are not pulsing correctly or are extremely dirty they can cause problems.

[sforce1]

New problem with car code p0420 Catalyst system eff.below threshold {bank 1} any help with this 2.4L

[GTP Dad]

Bad cat! I would try the O2 sensor first but this sounds like the cat is going bad however if the O2 sensor is giving false readings you will get the same code.