engine misfire

Hi ll. My 98 Ram 1500 4X4-5.9, off an on has the check engine light coming on. Took it to the auto parts store,and the code was- engine misfire ,cylinder#5, I have changed the plugs and wires,and it did it
again this afternoon. My question is, could the injector be acting up? it did stumble a little,like it did before,and if it is the injector ,can just one be replaced? Is it a easy job to do in the driveway? Also I do use medium octane to high octane gas, also used injector cleaner once when this started. Thanks for any information,and for letting me post. This is been a occurance for about 3 months or so. snipped-for-privacy@webtv.net.
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It's possible the injector could be clogged or malfunctioning, and that would certainly cause a mis-fire. Yes, they can be replaced pretty easily, and you can replace just one. To do so, you'll first need to remove the pressure from the fuel rail - either through the test port (middle on driver's side) if so equipped, or simply pull the fuel pump fuse and run the engine until it dies. Remove the electrical connector from the desired injector, then unbolt the driver's side fuel rail from the manifold (couple of bolts hold it down), and gently rock it to free the injectors from the manifold (they're just pressed in with O-rings around them). Don't lift too much, because the electrical connectors on the other injectors are still attached. If they don't provide enough slack, disconnect them as well. Remove the clip that's holding the injector to the rail, and remove the injector. Put the new one in (lube the O-rings with a little petroleum jelly, so they don't tear - lube the O-rings on the other injectors, as well), re-install the clip, seat the rail back into the manifold, bolt it back down, plug everything back in, and you're all set.
Before buying a new injector, you could simply swap say #1 and #5. and see if the misfire moves to the #1 cylinder. If it does, you know you've got a bad injector. If not, you're not out the $$$ for a new injector, and know you need to look elsewhere (like a compression test and/or leakdown test).
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Thanks for the information,will give it a try.
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Tom Lawrence wrote:

If it is the injector would the computer know it was misfiring on #5?
--
Ken



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Sure - just as it would know #5 was misfiring due to lack of spark, or lack of compression. The PCM won't know WHY the cylinder is misfiring, just that it is. It does this by sensing a slight loss, then increase, in crankshaft RPM via the crank position sensor.
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Tom Lawrence wrote:

That makes sense. For some reason I thought it would only read a misfiring plug. Thanks.
--
Ken



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Changing the spark plugs will most likely fix the problem short term. The real fix is rerouting the spark plug wires per a Chrysler service bulletin on cross firing. Don't remember the SB number. This is what I did to fix my sister's 98 Dodge 1500 with a 5.2L engine that had this code. It has worked for over 100,00 miles now. John
On Fri, 26 Jan 2007 21:28:17 -0600, snipped-for-privacy@webtv.net (el jr64) wrote:

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