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Fordanswerman, Auto Service Technician
Category: Car
Satisfied Customers: 3306
Experience:  Ford Engine Master/Transmission Master/Chassis Master=Ford Senior Master also Diesel 7.3/6.0
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2000 Ford excursion: v10..runs rough..#5 & 8 coil packs..injector

Customer Question

2000 Ford excursion v10 runs rough after warm. It's as if the coil packs are failing but only after the engine is warm. Already replaced #5 & 8 coil packs and #3 injector. I have suspicion that this might relate to o2 sensors but do not want to continue trial and error parts replacement. Is there a known issue to look at or should I be looking at carbon build up at 60,000 miles?

Optional Information:
2000 Ford Excursion V10

Already Tried:
Coil packs, fuel filter, fuel injector, plugs, injector cleaner (additive)

Submitted: 11 years ago.
Category: Car
Expert:  Fordanswerman replied 11 years ago.

Thanks for the question.

Is there any fault codes in the computer?

The o2 sensors would be the last thing to look at unless you had a code in the computer for it.

Has the fuel pressure been checked?



Customer: replied 11 years ago.
Reply to Fordanswerman's Post: No codes on computer after replacing coil packs. The O2 sensor thought was based on a TSB I found for rough idle and hesitation. Vehicle runs strong when cold. I have a 1995 E250 with V8 that had similar problem which ended up being the TFI. I have operated a fleet of lincoln limos for 15 years and never run accross this problem. This vehicle also randomly blows a 25 amp fuse connected to the Vehicle theft circuit funny thing is vehicle will continue running but will not restart after the fuse blows?
Expert:  Fordanswerman replied 11 years ago.

Well, it sure does sound like the it might be in the fuel system.

I would try replacing the fuel filter first if it hasn't been done for a while. If it still does it, I would get the fuel presssure checked, because as you know these v-10 suck a lot of gas, and the fuel pump needs to be at its best.

Also, you might want to try to unplug the MAF or mass air flow sensor and drive it to see if it is any better. If it does, you can try to clean the MAF sensor wire where the air goes through.



Customer: replied 11 years ago.
Reply to Fordanswerman's Post: Already tested fuel pressure and replaced filter. I will trie the MAF today and reply accordingly. Maf is fine also tried IAC and still same. Did I mention it only does this at low RPM? I also replaced air filter. I am at a loss!
Expert:  Fordanswerman replied 11 years ago.

Thanks for checking that for me.

I did find the TSB you're talking about, but your concern is well after it is warmed up. This is what the TSB says:

Some F250-F550 Super Duty and Excursion vehicles equipped with a 5.4L or 6.8L engine, and some E350/450 vehicles equipped with a 6.8L engine may exhibit a rough idle and/or hesitation when accelerating. This may occur intermittently within the first 2-3 minutes after start when engine is not warmed up (ie., conditions other than hot restart). The condition is more likely to occur at ambient temperatures of approximately 60° F (16° C) and higher, and may be aggravated by an unmetered air leak or exhaust leak.

This is saying during the first periods of warmup. So I don't think this is your concern.

You may want to unplug the vacuum line going to the egr valve and see if this makes a difference. I have has a few of these egr valves cause some headaches in the past before.

Let me know how that works.



Customer: replied 11 years ago.
Reply to Fordanswerman's Post: I considered the EGR valve but dismissed it as it's function seemed mute since the computer did not code it. I will give it a try today and get back to you.
Customer: replied 11 years ago.
Relist: I still need help.
The problem still persists after trying all suggestions.