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| | | | Joined: Aug 2017 Posts: 76 'Bolter | | 'Bolter Joined: Aug 2017 Posts: 76 | Is there a simple test I can do to see if all cylinders are fireing whilst the engine is running.Can you tell by the sound if one is not fireing on a V8.Thanks in advance. | | | | | Joined: Aug 2000 Posts: 1,438 'Bolter | | 'Bolter Joined: Aug 2000 Posts: 1,438 | You can remove one plug wire and see if it stumbles. Put it back on then try another.
Dennis
40 Chevy 1/2 ton
| | | | | Joined: Mar 2014 Posts: 4,485 Moderator, Electrical Bay | | Moderator, Electrical Bay Joined: Mar 2014 Posts: 4,485 | Or before you do that you could hold the palm of your hand about 1/2 inch away from your exhaust pipe while it is idling. If one isn't firing you will feel a distinct and evenly spaced "puff, puff, puff" feel and then you can narrow down the problem cylinder.
~ Jon
1952 1/2 ton with 1959 235 | T5 with 3.07 rear end
| | | | | Joined: Feb 2004 Posts: 29,787 Kettle Custodian (pot stirrer) | | Kettle Custodian (pot stirrer) Joined: Feb 2004 Posts: 29,787 | A little more accurate procedure than just pulling plug wires is called a "power balance test". It takes an accurate tachometer and a vacuum gauge. Set the speed to a fast idle, maybe 1000-1500 RPM and monitor the manifold vacuum. (NOT distributor vacuum- - - -tap into the main plenum under the carburetor. Each time you disconnect a plug wire, record the RPM drop and the vacuum change. In some rare instances involving burned intake valves or a sticky EGR valve, the RPM might actually speed up when a wire is disconnected. Usually, disabling a good cylinder will cause a drop in RPM and vacuum, while disconnecting a low-powered or dead cylinder will not have much of an effect. If you also happen to have an exhaust gas analyzer connected, you'll see a rise in unburned hydrocarbons when a good cylinder is disabled.
Jerry
"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!
| | | | | Joined: Jul 2008 Posts: 326 'Bolter | | 'Bolter Joined: Jul 2008 Posts: 326 | If the engine has headers, you can use an infrared thermometer to test for a cool/cold cylinder.
SimS | | | | | Joined: Jun 2006 Posts: 693 'Bolter | | 'Bolter Joined: Jun 2006 Posts: 693 | what Jerry describes is how modern cars via OBDII monitor and report on misfires (P0300-0310 codes) | | | | | Joined: Dec 2008 Posts: 1,922 'Bolter | | 'Bolter Joined: Dec 2008 Posts: 1,922 | If you suspect it, it's probably got a dead hole.
Throttle response is slow with some engine shaking - which gets worse with more load? | | | | | Joined: Mar 2002 Posts: 9,115 'Bolter | | 'Bolter Joined: Mar 2002 Posts: 9,115 | On my 216s, I have used a household wire tester that is meant for identifying live wiring and outlets. I hold it near each plug and I can watch it firing. The first time I used it looking into a bad miss at idle, it didn't light up on #5. I replaced the wire with no difference observed. I replaced the plug and it lit up on 5. It was a shorted plug. | | | | | Joined: May 2018 Posts: 11 New Guy | | New Guy Joined: May 2018 Posts: 11 | Ok one more suggestion... If the problem is spark related you can check each wire with a timing light.. If one of the wires doesn't cause the light to fire then you have an ignition issue leading to that cylinder..
Last edited by 53BarrelHauler; 09/19/2018 2:57 AM.
1953 3100 Mariner blue (some anyway)
| | | | | Joined: Mar 2002 Posts: 9,115 'Bolter | | 'Bolter Joined: Mar 2002 Posts: 9,115 | If you have a shorted plug like I did, the timing light will flash regardless. | | |
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