misfire
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misfire
ive got an 04 ford escape 3.0, its got a cylinder 4, and 6 misfire, all plugs were replaced as well as the 4 and 6 coils, still a misfire, so i pulled the plugs out and grounded them, all cylinders are getting spark. i did a compression test, and all cylinders read around 160, im thinking pull the intake off again and check the injectors? it misfires at idle,and clears up when you bring it off idle
Hotshot
Joined: Jan 2004
Posts: 19,765
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From: St Louis
Before jumping into injectors:
1. Check your fuel pressure to ensure adequate fuel is available.
2. I'd swap the #4 & #6 plugs and COPs with adjacent cylinders, reset the PCM, and re-test to see if the misfires stay in the original cylinders or move. If they stay, then go for injectors. If they move, the new parts are flaky.
1. Check your fuel pressure to ensure adequate fuel is available.
2. I'd swap the #4 & #6 plugs and COPs with adjacent cylinders, reset the PCM, and re-test to see if the misfires stay in the original cylinders or move. If they stay, then go for injectors. If they move, the new parts are flaky.
Logistics Pro
Joined: Jan 2002
Posts: 4,907
Likes: 39
From: suburban atlanta
I would swap the #4 and #6 COP WIRES. It is very easy on some of the early models to lay the COP wires across the cam cover in the wrong direction. It is a common mistake as the wires do not 'look right' in their factory orientation. Putting them on wrong will give a dead miss in both #4 and #6. Swapping should give immediate relief if that is the problem. {I may have the wrong year, but it won't hurt to check.}
Also note that oil in the spark plug wells can cause the COPs to allow the spark to jump directly to the cam cover instead of taking the long way through the spark plug. Oil can affect the insulation effect of the COP boots, and once lubed, they will tend to misfire more often. Pull the affected COPs and check for oil damaged boots. If you have oil, then you likely will need to re-seal the cam cover and wells, and replace the boots. Boots can be purchased separate from the COPs if desired.
tom
Also note that oil in the spark plug wells can cause the COPs to allow the spark to jump directly to the cam cover instead of taking the long way through the spark plug. Oil can affect the insulation effect of the COP boots, and once lubed, they will tend to misfire more often. Pull the affected COPs and check for oil damaged boots. If you have oil, then you likely will need to re-seal the cam cover and wells, and replace the boots. Boots can be purchased separate from the COPs if desired.
tom
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