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post #1 of (permalink) Old 05-21-2003, 01:50 PM Thread Starter
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Rough Running \'91 - (help for a friend)

My longtime Mountain Biking buddy, Dr. Gonzo is having a bit of a problem. [img]images/graemlins/frown.gif[/img]
As you all know, I'm an infant when it comes to EFI knowledge. [img]images/graemlins/blush.gif[/img]

1991 F150 4X4 / 5.8L EFI / AT(E4OD?)
Here's his text:
"When going up a hill, or accelerating hard, there is a miss.
At idle, or on a flat road, runs like a kitten.
Started just after I replaced the plugs, wires, cap & rotor, fuel filter, air filter, oil and oil filter.
What did I screw up?"

Thanks much folks!
Doug

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post #2 of (permalink) Old 05-21-2003, 02:19 PM
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Re: Rough Running \'91 - (help for a friend)

Maybe a plugged injector??? It could be that all the other stuff you did was only hiding a flaw which chose this time to show up. Murphy's law. Good luck, B.O.B.
post #3 of (permalink) Old 05-21-2003, 04:25 PM
 
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Re: Rough Running \'91 - (help for a friend)

First suggestion I'm sure you already thought of:
Go back through all the plugs/wirs/cap/rotor and make sure they are tight. What are the plugs gapped at? I know some on here have had ok results with widening gap, I found it to be no help.

next take off power to battery, then put it back on after a few minutes, reset the ol puter memory. This will let it relearn as your friend drives around.

Did he save that ol fuel filter? If it wasn't too old, might try putting it back on, see if problem goes away. If so, go return the one just purchased. It isn't a FRAM [img]images/graemlins/censor.gif[/img] is it?

Does he regularly use a fuel system cleaner? Probably a good idea.

if none of those help, then what was suggested earlier...that the problem coincidently began with the tuneup...and the problem is elsewhere. Any codes pop up?
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post #4 of (permalink) Old 05-21-2003, 04:36 PM Thread Starter
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Re: Rough Running \'91 - (help for a friend)

Thanks so far folks.
I did give him <font color="blue">Havack's</font color> code list link.

I was wondering about the fuel filter too.
Especially if the problem is only occurring under load. [img]images/graemlins/crazy.gif[/img]
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post #5 of (permalink) Old 05-21-2003, 06:12 PM
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Re: Rough Running \'91 - (help for a friend)

Wd, i battled that same problem for about 6 months, (seems like thats a common problem area with TFI-IV EFI fords), after i had did a major tune-up and changed many servicable parts on the ignition and fuel system including having my injectors done at an injection shop.

I had no codes, what it turned out to be (and i know there are a few members here using these brands w/o trouble) was first: defective 9mm ford racing wires, and a *german* brand platinum plug set. It would buck bad going up every hill but ran flawlessly otherwise, once i installed a better quality set of wires and delco plugs, it quit doing it...

what brand parts did you use?
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post #6 of (permalink) Old 05-21-2003, 09:46 PM
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Re: Rough Running \'91 - (help for a friend)

Yo Bros ! thanks for the advice. Its my truck, not WD40's so don't blame him for being lame. I'm the newbie.

Anyways, I used Autolite wires and plugs, Fram fuel filter.

So like where do I start ? Fuel or Spark ? I'm heading out to the shop for another fun filled evening of grease monkeying.

Gonzo the newbie
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post #7 of (permalink) Old 05-22-2003, 01:07 AM
 
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Re: Rough Running \'91 - (help for a friend)

Ahh welcome to the board.Welcome to the wonderful(sic)world of EFI.Check all the easy stuff first.Like making sure the plug boots are snug,firing order is correct.Check the codes.Check the fuel pressure at the fuel rail(autozone sells a cheap gauge)disconnect the vacuum line to the regulator and see if FP increases 10#.Check the timing(remove the spout connector)reinstall the spout and rev the engine with the timing light connected,make sure the timing is advancing properly.If you can't find anything obvious I would pull the plugs and check to see if any one cylinder is fouled,recheck the gaps.Maybe one cylinder is not firing 100% but you don't see it until it's under a load.Good luck.Keep us posted.

CB
PS go spill something on dougs shop floor,it's too damn neat.
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post #8 of (permalink) Old 05-22-2003, 12:25 PM
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Re: Rough Running \'91 - (help for a friend)

speaking of Spark Plug Wires ... The way they connect to the plugs ... is that lame [img]images/graemlins/lame.jpg[/img] or what ? just push them on ? Expect that $.05 band to maintain hoop tension for such an important connection ? Is that how the professionals do it? If I were an automotive engineer, that be the first thing I'd design, a positive threaded fastener to hold them 20,000 volt carrying wires to the plugs.

Is there an external diagnostic tool that can detect which cylinder is missing ? can use it while your driving down the road ?

Gonzo newbie, bro not pro
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post #9 of (permalink) Old 05-22-2003, 12:48 PM
 
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Re: Rough Running \'91 - (help for a friend)

Check the ignition as myself and others have suggested, but I tell you what, I am zeroing in on one thing here...

FRAM fuel filter.

On this board, we have already ripped FRAM for there crappy ass oil filters, why should the fuel filters be any different. Do you have your old one still, and is it a fram?
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post #10 of (permalink) Old 05-22-2003, 04:43 PM
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Re: Rough Running \'91 - (help for a friend)

I suppose I should do a Search on 'filters', but I'm lazy ... so if Fram s*cks, what brand filters do you all reccommend ?

While you're at it, what brand spark plugs as well ?

Gonzo newbian
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