Random/multiple misfire, cylinder # 3
#31
Member
Posts like a V-Tak
Thread Starter
Join Date: Feb 2006
Location: Normal, Illinois
Posts: 42
Likes: 0
Received 0 Likes
on
0 Posts
![zeroburnz is on a distinguished road](https://www.gmforum.com/images/reputation/reputation_pos.gif)
![Default](https://www.gmforum.com/images/icons/icon1.gif)
UPDATE: Today while i was sitting at a light i noticed my battery voltage changing quite rapidly, but still within the limits (not in the red). Could this be a bad alternator or battery/connections.
It seems to follow the noise im hearing from the engine, sounds as if the power isnt being delivered correctly.
It seems to follow the noise im hearing from the engine, sounds as if the power isnt being delivered correctly.
#32
Junior Member
Posts like a Ricer Type-R
Join Date: Apr 2006
Posts: 19
Likes: 0
Received 0 Likes
on
0 Posts
![RMiller526 is on a distinguished road](https://www.gmforum.com/images/reputation/reputation_pos.gif)
![Default](https://www.gmforum.com/images/icons/icon1.gif)
I changed my spark plugs and wires and still had 3 & 5 misfire, then I changed all 3 coils and yeah it runs like new.
If coils dont work it could be a bad module.
If coils dont work it could be a bad module.
#33
Junior Member
Posts like a Ricer Type-R
![Default](https://www.gmforum.com/images/icons/icon1.gif)
We try not to suggest shotgunning 3 coils as a troubleshooting step. If a misfire is suspected, swapping coils around, or swapping in one new coil in each location is a much better alternative.
With ignition problems, checking the primary and secondary coil resistances is something easy to do, as is checking resistance of plug wires and inspecting plugs.
Fueling is rarely the issue with these types of problems. Over 95% are ignition related.
Low alternator output can indeed cause low spark voltage.
With ignition problems, checking the primary and secondary coil resistances is something easy to do, as is checking resistance of plug wires and inspecting plugs.
Fueling is rarely the issue with these types of problems. Over 95% are ignition related.
Low alternator output can indeed cause low spark voltage.
#34
PopaDopaDo
True Car Nut
![Default](https://www.gmforum.com/images/icons/icon1.gif)
The o2 sensor is out of the picture when the engine is cold. The computer doesn't use the signal until it goes into open loop operation (warmed). I suspect your coil packs, be sure to clean those two posts when you have one off. Thats the real connection back to the eec. I had a reoccuring misfire on 6 this past winter and thats what cures it, a light sanding of those two posts with very fine sandpaper.
Thread
Thread Starter
Forum
Replies
Last Post
Ben Cartwright
General GM Chat
2
08-09-2013 09:27 PM