What is your question?
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What is your question?
Misfires during acceleration...coil packs n plugs are brand new..
What makes this problem better or worse?
Misfires upon acceleration
How long has your 1999 Ford Crown Victoria had this problem?
A few days
3 Replies
Hello, It is right behind the airbox. Smoke test and watch around the intake manifold gasket. Before replacing more parts, like the ICM, remember that misfires can occur due to fuel, air, spark, or compression issues.
Be happy to help with this problem - however you're going to need to get the trouble code numbers read and post those numbers here for more help. The code numbers will tell us which cylinder is misfiring - also if the problem is in the primary circuit (going 'to' the coil) - or possibly in the secondary circuit (defective coil) .. Once we have identified the actual cylinder(s) that's causing the problem - diagnoses becomes a LOT easier.
I can tell you that “misfire upon acceleration†is indicative of an ignition misfire - and it is usually within the secondary circuit (bad coil) .... Coil primary (feed circuit) isn’t affected by the extra load of engine acceleration - and doesn’t come and go. Now - if NO code numbers are present - a *professional quality* scan tool will show misfiring cylinders on live data screen - - that particular test may be required. One more common problem is moisture in the spark plug tubes .. Obvious when the coil is removed - *spark plug boot wet*..
IF ‘you’ wish to try ‘diy’ diagnosis - Here are a couple of video links that should help: https://youtu.be/ho3Kyps2i34 https://youtu.be/2LnMZyqfLKw The first link will show how to diagnose a primary ignition circuit ‘trouble code’ - if present. The second will show how to diagnose a secondary ignition circuit ‘trouble code’ - if present. Do not know your auto repair skill level - may need *hands-on* assistance from qualified personnel. â–ªï¸You have got a *defective ignition coil* - OR - ‘possibly’ moisture in the spark tube(s)â–ªï¸ Good luck to ya!
Side note: The intake manifold issue on the 4.6 liter was coolant leak related due to a split in the composite material at the thermostat housing area. I'm not aware of a vacuum leak from the intake that would cause a running condition concern. I would lean towards secondary ignition issues - or a cracked spark plug. I've had trouble with "aftermarket" coils by the way, I lean towards using Motorcraft coils.
Yes, there is a common crack on the composite intakes, then there's the coolant line that snaps off on the rear, then there is the seal on the water pump to heater hose pipe under the manifold. Those are all coolant related, but the intake manifold is a common vacuum leak on the modular ford v8. The ford 4.0l v6 has sealing issues as well, but it's a two piece plenum. Lots of good stuff to think about here for maintenance of the cooling system on this, and all modular ford vehicles, especially with the composite crossover pipe.
Where? on the driver side fender?
You know what, I was looking under the wrong car. The engine control module on that vehicle replaces the ignition control module. The camshaft sensor and the crankshaft sensor report their position at all times, and the engine control module tells the coils when to fire. But, really, the 4.6 liter is notorious for intake manifold leaks.