Intermittent Spark Please Help
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Junior User
Joined: Jan 2006
Posts: 95
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Intermittent Spark Please Help
I need some help dealing with an intermittent spark causing a misfire. Have swapped out the front coil with a known good coil and still the same problem. Cylinder 2 & 3 fire better than 1 & 4. I have a slightly rough idle and a stutter at times. It feels like the truck holds back when running most of the time. Other times the truck does not miss and runs great. I have put a voltmeter on the crankshaft sensor and it shows about .65 volts at idle and increases with rpm. Have checked ground from the coil frame to the battery ground and it is good. Checked resistance between ECM and triggers on coil looking for a bad connection or corrosion, but came up with no resistance on the wires.
Using a timing light on various spark plug wires it appears that this is happening on both coils, just worse on the intake side plugs. If you take the wire loose and put a plug on the end grounded to the power steering bracket, the spark is consistant, even though it is not when in the engine. The plugs and wires have less than 1k on them along with timing belt, #3 fuel injector, air filter, fuel filter, and PVC.
Please Help
Using a timing light on various spark plug wires it appears that this is happening on both coils, just worse on the intake side plugs. If you take the wire loose and put a plug on the end grounded to the power steering bracket, the spark is consistant, even though it is not when in the engine. The plugs and wires have less than 1k on them along with timing belt, #3 fuel injector, air filter, fuel filter, and PVC.
Please Help
Moderator
Joined: Jan 2004
Posts: 13,851
Likes: 111
From: SW Va
Well I suppose it's possible the coil pack is electrically breaking down, maybe internally, so why not pull it & take it by your avorite autoparts store for a bench check & see if it'll pass muster.
Does it miss more often when hot, or wet, rather than when cold, or dry????
If it's a hot problem or wet problem, take a hair dryer or spray bottle of water with you when you bench test it & see if you can replicate the failure mode.
Was it doing this radom miss thing BEFORE you replaced the coil, plugs & wires????.
Does it miss more often when hot, or wet, rather than when cold, or dry????
If it's a hot problem or wet problem, take a hair dryer or spray bottle of water with you when you bench test it & see if you can replicate the failure mode.
Was it doing this radom miss thing BEFORE you replaced the coil, plugs & wires????.
Logistics Pro
Joined: Jan 2002
Posts: 4,907
Likes: 39
From: suburban atlanta
Check the grounds on the coil pack. They are noted for not being happy when they are not grounded. You may have to use a wire to connect all the ground points together so you have a good common ground. I have heard of people leaving one of the mounting bolts off, and causing a problem that appeared only after leaving the garage, as the ground would be decent enough at the start, but degrade over time...
Scout around this site for other problems w/2.5 ignition. I remember one post that yakked about the 'dual plug system' and when the plugs were disabled, and when enabled. I don't remember the details....
tom
Scout around this site for other problems w/2.5 ignition. I remember one post that yakked about the 'dual plug system' and when the plugs were disabled, and when enabled. I don't remember the details....
tom
Last edited by tomw; Feb 22, 2006 at 11:10 AM. Reason: spelling
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