Random mutiple missfire.
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Junior User
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Random mutiple missfire.
My truck is a 2000 ford f150 4x4. I put a used engine in it awhile back and it has ran great with no problems at all until recently. The engine has around 114000 miles on it. The truck runs fine while I am driving it until I am going up a hill and the engine kicks down into it's lowest gear after a few seconds the service engine soon lights start flashing and when I have the codes read it reads multiple random misfire. I installed new plugs and replaced coil four here not very long ago. I have put on a new idle air control valve. I have had the fuel pressure checked and everything is good from what we can tell. I replaced the fuel filter also. After replacing the fuel filter it seemed to straighten up for a short time and wasn't doing the flashing. Now it's all started again and I am at a loss. I also ran a can of sea foam through the booster hose and one can through a tank of gas. I am at a loss and can not seem to figure it out. I am hoping someone can tell me something I may have missed. The only thing I haven't done is put it on a computer that will go deeper than the scan tool we used. If any one knows anything that might help please let me know.
Lead Driver
Joined: Sep 2006
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Well, let it me put it his way, the flashing CEL is telling you the misfires are likely to be passing un-burnt gas through the cylinders to the cats endangering them from over heating by burning the gas in the cats.
Lose a cat assembly and your costs go up dramatically.
Your attempts at finding the cylinders causing it is not good enough.
There are 8 coils and boots to be the cause.
.
You need to use a Scanner with a fault trap function and/or a mode 6, test 53 ability to look at all cylinder monitors for the offending cylinders.
.
If you take it to a shop they must do it the same way or just guess costing you parts.
As the code tells you along with the CEL flashing, ignition is the cause.
Diagnose the problem the right way and it will be found.
Good luck.
Lose a cat assembly and your costs go up dramatically.
Your attempts at finding the cylinders causing it is not good enough.
There are 8 coils and boots to be the cause.
.
You need to use a Scanner with a fault trap function and/or a mode 6, test 53 ability to look at all cylinder monitors for the offending cylinders.
.
If you take it to a shop they must do it the same way or just guess costing you parts.
As the code tells you along with the CEL flashing, ignition is the cause.
Diagnose the problem the right way and it will be found.
Good luck.
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So you think my problem is still somewhere in my coils. I will have to find someone with the right scan tool to check it out for me. I was thinking of putting all new coils on it anyway. I am fixing to hopefully trade the truck off but I didn't want to pass the problem on to someone else.
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Junior User
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I fixed all of my problems by having to have the converters cut off my truck. they were so stopped up the truck could not breath at all. I had them taken off and it fixed every problem I had and not even the check engine light is on anymore.
Lead Driver
Joined: Sep 2006
Posts: 7,907
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If the truck ran ok in the past, it was the misfires that melted the cats by passing raw gas and burning in the cats.
Cats that bad should have set codes 420/430.
With no cats these codes will return or set as a result.
Reason is the ratio of the rear to front Ox sensor switching is monitored by the PCM.
When this ratio is out of limits the codes are set.
This means you can't just not use them in a proper exhaust system.
Been there before and seen it happen.
Good luck.
Cats that bad should have set codes 420/430.
With no cats these codes will return or set as a result.
Reason is the ratio of the rear to front Ox sensor switching is monitored by the PCM.
When this ratio is out of limits the codes are set.
This means you can't just not use them in a proper exhaust system.
Been there before and seen it happen.
Good luck.
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Junior User
Joined: Feb 2013
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I have not done anything with the o2 sensors. Eventually the sensors may burn out and send the codes but as of right now no it has not sent codes. The code for the multiple miss fire is back but that is the only one. The truck did not run fine before I cut the cats off. It has always had a lack of power when I had to get on the gas. But I am sure the miss fire made them worse. But as I said right now I do not have a code for o2 sensors. I am going to install non fowlers on the back to sensors just to get them out of the stream of heat they are not use to. I hear that helps them last longer but if I am not getting codes for them then why do it.
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