misfire

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I have a 2003 ford f150 with a 4.2 liter engine.It had slight misfire at load .It seemed to be worse when it rained.Replayed plugs,coil and wires.It has one coil pack for all cylinders.Now the misfire is much worse used bosch Iridium plugs could that cause an increased misfire?
 

patfan

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There are no codes.Hook up to snap on scanner with live data couldn't find any problem.This was a old mechanic who has worked on it before.This was a week ago he is way behind because one of his employes left suddenly the week before
 
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Originally Posted By: patfan
bosch Iridium plugs could that cause an increased misfire?
Yes! When it happened to my truck, it was explained to me: those spark plugs require a higher amperage to arc.
 
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Noticeable misfires with no codes on an 03 Ford doesn't sound right. Did you get a misfire count on each cylinder? Did you get the fuel trim?
 
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Originally Posted By: Trav
Noticeable misfires with no codes on an 03 Ford doesn't sound right. Did you get a misfire count on each cylinder? Did you get the fuel trim?
Our fleet trucks throw a misfire code at the slightest hint of a problem. Modern engines (most any that are OBDII) are pretty much the same. I agree there should be an MIL...
 

patfan

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There is no code started about three weeks ago just on occasion under load.I replaced the plugs, wires,coilpack. I changed them because it seemed to do it more when it rains.I have used ngk irdiums before with no problems
 
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Originally Posted By: patfan
There is no code started about three weeks ago just on occasion under load.I replaced the plugs, wires,coilpack. I changed them because it seemed to do it more when it rains.I have used ngk irdiums before with no problems
At this point its all guessing, you need date when its happening. Actual misfires throw misfire codes but look at the misfire count on all cyl. Have you checked the fuel pressure? This is a good article. http://www.underhoodservice.com/tech-feature-detecting-misfires-in-obd-ii-engines/
 

patfan

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When it does it the whole engine shakes .it will do it every time you press the gas pedal no codes have yet to show
 
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That doesn't have to be misfires. I have seen a partially melted cat do that but still worked well enough not to throw a cat inefficiency code. If you left your foot in it and keep it shaking they will usually pop a PO300 for random misfires No saying that is the problem just info for the sake of it. Real time data is the only real answer, you don't throw parts at something like this.
 

patfan

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It was the spark plugs put autolite double platinum plugs misfire went away will never use bosch plugs again
 
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Originally Posted By: patfan
It was the spark plugs put autolite double platinum plugs misfire went away will never use bosch plugs again
Thats great and all but what doesn't make sense is there were no codes. An actual misfire count would have been helpful in figuring out what exactly was the issue with the Bosch plugs. I for one am curious as to what was going on to misfire with no misfire codes. I just but Bosch +4 in a VW Beetle 2.0 and its smooth as glass. Misfire count of zero and all 4.
 
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Originally Posted By: Trav
Originally Posted By: patfan
It was the spark plugs put autolite double platinum plugs misfire went away will never use bosch plugs again
Thats great and all but what doesn't make sense is there were no codes. An actual misfire count would have been helpful in figuring out what exactly was the issue with the Bosch plugs. I for one am curious as to what was going on to misfire with no misfire codes. I just but Bosch +4 in a VW Beetle 2.0 and its smooth as glass. Misfire count of zero and all 4.
Fords in that era wouldn't always set codes for misfires. Ask OVERKILL. His Expedition blew a plug out, but he still needed to drive home- misfiring the whole way. No code. I've seen it too. You're right though- looking at the misfire counter or cylinder contribution would be a dead giveaway.
 
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Originally Posted By: Trav
I just but Bosch +4 in a VW Beetle 2.0 and its smooth as glass. Misfire count of zero and all 4.
IIRC Bosch is the oem for VW, so it would make sense that the recomended bosch of any type would work well.
 
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I read OEM was Bosch or NGK for the US market and Bosch or Beru for the German. Autolite copper came out of this one (obviously not OE) but it was not misfiring either. It doesn't matter now, without some real live data its all guess work as to what the real problem was with them. I am interested only because it had a misfire that only got worse, it didn't start with the Bosch.
Originally Posted By: OP
003 ford f150 with a 4.2 liter engine.It had slight misfire at load .It seemed to be worse when it rained.Replayed plugs,coil and wires.It has one coil pack for all cylinders.Now the misfire is much worse used bosch Iridium plugs could that cause an increased misfire?
 
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