Might be a stupid question but.....?
Thread Starter
Racer
Joined: Nov 2005
Posts: 410
Likes: 1
From: Amherst NH
Might be a stupid question but.....?
I was just wondering, how would you know if you would only firing on 7 cylinders?? Is there a code for this? I only ask because while troubleshooting a recent problem I pulled an ignition cable to reach something else. When I cranked the car I had forgotten to plug the ignition cable back in. The car still fired up fine and to be honest I would never have known the difference. I didnt get any codes for it either. So I ask, how would you know if you botched a spark plug or wire and were only firing on 7?? Thanks 
Supporting Vendor
Joined: Mar 2008
Posts: 1,762
Likes: 14
From: Cumming Ga
I was just wondering, how would you know if you would only firing on 7 cylinders?? Is there a code for this? I only ask because while troubleshooting a recent problem I pulled an ignition cable to reach something else. When I cranked the car I had forgotten to plug the ignition cable back in. The car still fired up fine and to be honest I would never have known the difference. I didnt get any codes for it either. So I ask, how would you know if you botched a spark plug or wire and were only firing on 7?? Thanks
Instructor
Joined: Jun 2008
Posts: 220
Likes: 0
From: Somers Point New Jersey
floor that sucker. You will know. It may not be so obvious at idle, but when you want power and can't get it, you'll know. And I am sure the code is there, it is just pending meaning it noticed the problem but it hasn't been happening long enough to put on the light.
Tech Contributor
Joined: Dec 2006
Posts: 10,962
Likes: 29
From: Van Buren Arkansas
Wounded Warrior Escort '11
A cylinder not firing will usually set a code in the PCM and you should easily feel it trying to drive it. Most people with a good ear will hear it not running correctly either.
Tech Contributor
Joined: Dec 1999
Posts: 32,910
Likes: 2,402
From: Anthony TX
CI 6,7,8,9,11 Vet
St. Jude Donor '08
Several things happen when the engine has a cylinder that isnt firing. The problem can be caused by a number of reasons:
Bad plug
Bad wire
Low or no compression
bad valve
bad valve spring
Bent pushrod
ETC>>>>>>>>>>>>>>>
If the PCM detects a cylinder misfire,,What you will see is this:
The PCM will set a P-0300 DTC if the mis is detected. That DTC will ONLY display during that period of thime that the engine is running. If you turn the ignition OFF,,,it will reset. Yes you can read the DTC while the engine is running!
If the PCM detects a mis-fire and sets a DTC ir will cause the "CHECK ENGINE LIGHT (CEL) to flash.
Like it was previously recommended, if you LOAD the engine, the misfire will show up more.
BC
Bad plug
Bad wire
Low or no compression
bad valve
bad valve spring
Bent pushrod
ETC>>>>>>>>>>>>>>>
If the PCM detects a cylinder misfire,,What you will see is this:
The PCM will set a P-0300 DTC if the mis is detected. That DTC will ONLY display during that period of thime that the engine is running. If you turn the ignition OFF,,,it will reset. Yes you can read the DTC while the engine is running!
If the PCM detects a mis-fire and sets a DTC ir will cause the "CHECK ENGINE LIGHT (CEL) to flash.
Like it was previously recommended, if you LOAD the engine, the misfire will show up more.
BC
