missing while accelerating hard
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Joined: Mar 2011
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missing while accelerating hard
Hey guys new on the fourm I have a 2005 sport trac 135k on it 4.0 v6. It runs great as long as you dont put your foot into it. Once you do it hesitates and surges, engine light flashes while this is happening and finally stayed on, code was cylinder one miss fire. So I changed fuel filter,plugs,wires, cleaned mass air flow sensor. Still no diff and its flashing the engine light and saying #1 miss fire again. Iam puting on a new pcv valve today but where do I go from here. Any help would be great and I think Ive read as much as I could from previous post which is why I have done the fixes that I mentioned Thanks,Eric
Logistics Pro
Joined: Jun 2009
Posts: 4,808
Likes: 83
From: Cedar Rapids, IA
Welcome to the forum!
Does your 2005 Sport Trac really have plug wires rather than CoP ignition? If CoP, did you change all coils? If not, then try swapping the coil with another and the plug with a different cylinder. See if the misfire code follows the coil, plug, or stays with the cylinder. If it stays with the cylinder then you need to either swap the fuel injector with another cyilnder or perform a compression test. If you have access to a scan tool with datastream mode you could also monitor the bank 1 short term fuel trim (STFT) and oxygen sensor voltage to see if it is running lean or rich and if the PCM is attempting to compensate for it.
-Rod
Does your 2005 Sport Trac really have plug wires rather than CoP ignition? If CoP, did you change all coils? If not, then try swapping the coil with another and the plug with a different cylinder. See if the misfire code follows the coil, plug, or stays with the cylinder. If it stays with the cylinder then you need to either swap the fuel injector with another cyilnder or perform a compression test. If you have access to a scan tool with datastream mode you could also monitor the bank 1 short term fuel trim (STFT) and oxygen sensor voltage to see if it is running lean or rich and if the PCM is attempting to compensate for it.
-Rod
Cargo Master
Joined: Aug 2003
Posts: 3,263
Likes: 92
From: BC Canada
Looks like you did all the expensive stuff, but why not pull the plug, that is the window to how that cylinder is firing..... did you know that marginal plugs will misfire under pressure... in the old days we cleaned and tested plugs in a pressure chamber.... many that looked good, failed.. Philip
Logistics Pro
Joined: Jun 2009
Posts: 4,808
Likes: 83
From: Cedar Rapids, IA
Okay, even though you have new plugs and wires, it is possible that the new plug is cracked or the wire is bad/not seated, and coincidentally it's on cylinder #1. It's also possible that the coil feeding cylinder #1 is weak and doesn't provide a strong enough spark. Swapping items around as mention above is still applicable, and if there is another plug wire that happens to be similar in length to the wire for cylinder #1, swap them around temporarily as well.
-Rod
-Rod
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