Rough idle and Loss of Power.

drag214

Well-Known LVC Member
Joined
Apr 30, 2009
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Location
California
I got a problem. Rough idle, feel like a missfire. When I accelerate, I can't notice it. When the car shifts into 4th and is under a load (like going up a hill), there is a strong shutter and loss of power. If I continue to hold steady on the gas pedle, the shutter will be acompanied by the flashing "Check Engine" light. But I have no codes and can't isolate the cylinder. The ignition coils have less that 30,000 miles on them. New fuel filter, spark plugs, and air filter.
I tried pulling the plug on the injectors one at a time to see if one affected the performance any less than the others. The results were pretty much equal across the board.
I performed a compression test and the largest differance I found was Cylinder #2 145psi and Cylinder #5 189psi. Is that with-in tolarance?
I can't figure what the problem could be.
 
I foregot to mention...
1998 Lincoln Navigator 5.4L V8 with 170,000 miles. Well maintained.
 
Hate to say it, but it sounds like a misfire. Just keep driving around you'll get a CEL pretty soon. That's what happened to mine. All the coils are starting to go out one by one. I know you said your coils are not very old but I'd rather it be one of those than an injector or something worse within the cylinder.
 
Just an update. Took her in to the dealer. The #3 ignition coil was bad. They hooked up to a diagnostic tester and performed the test on a dyno under a load.
 

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