2004 Ford F-350 Misfire

Tiny
NICK04350
  • MEMBER
  • 2004 FORD F-350
  • 5.4L
  • V8
  • 4WD
  • AUTOMATIC
  • 40,000 MILES
Truck has brand new plugs and coil packs runs great most of the time. Problem I'm experiencing is if the truck is let sit for 2-3 days undriven unstarted when started it idles incredibly rough and runs rough up until 2500 rpm then settled out and will stop when it gets warm and after it has been driven a little bit
Friday, October 9th, 2015 AT 6:05 PM

7 Replies

Tiny
HMAC300
  • MECHANIC
  • 48,601 POSTS
Check fuel pressure with a gauge and for a vacuum leak like hose off etc. Auto parts rent gauge should be 35-45 psi key on only. Also check fuel module on center cross member if its' all corroded connections, replace with one from ford as it has stilts to add to stop from happening as the old one will break in two making it useless anyhow.
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Saturday, October 10th, 2015 AT 6:26 AM
Tiny
NICK04350
  • MEMBER
  • 5 POSTS
I will look into those. Any chance you think it could be the iac valve? I've cleaned the MAF and the throttle body also. I was told by a friend it could be leaking injectors I just don't know where to start about the injectors other than to replace them all. What do you think?
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Saturday, October 10th, 2015 AT 12:40 PM
Tiny
HMAC300
  • MECHANIC
  • 48,601 POSTS
Replacing injectors is an expensive fix misfires are very hard to diagnose as it can be a basic engine problem as well as sensor bad. With what I've given you to check, other than that take to a local pro as that will be your cheapest option. It sounds screwy but these are hard to diagnose and he will know what to do with a scanner to fix the problem. But at same time it can be a basic problem as well.
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Saturday, October 10th, 2015 AT 1:24 PM
Tiny
NICK04350
  • MEMBER
  • 5 POSTS
I've had the codes read the truck isn't sending any error messages at all no engine or chassis codes
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Saturday, October 10th, 2015 AT 1:27 PM
Tiny
NICK04350
  • MEMBER
  • 5 POSTS
That's what makes me believe its a leaking injector or injectors and I've changed injectors in a 6.0 diesel I can change a triton one. And I don't think injectors are that pricey for these motors are they?
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Saturday, October 10th, 2015 AT 1:31 PM
Tiny
HMAC300
  • MECHANIC
  • 48,601 POSTS
$70-80 each for new and $27-30 each at rock auto so you are talking about at least $250 with tax. And it may not be them either.
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Saturday, October 10th, 2015 AT 2:00 PM
Tiny
NICK04350
  • MEMBER
  • 5 POSTS
I know it may not be them but I have a hook up at summit racing and may get a set of bigger injectors for it just for what ever power gain they may bring with the tuner I have but have not installed. With the tune put on and the exhaust and cai it lt may spice it up some but I plan on replacing and checking any possible cause of this.
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Saturday, October 10th, 2015 AT 2:19 PM

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