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1987 - 1996 F150 & Larger F-Series Trucks 1987 - 1996 Ford F-150, F-250, F-350 and larger pickups - including the 1997 heavy-duty F250/F350+ trucks

'91 f150 4.9 2wd

 
  #1  
Old 03-06-2011, 01:05 PM
joecarpenter
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'91 f150 4.9 2wd

First let me thank the Admin and those who are much more mechanically savy than I.

About a week ago my trusty Ford died at a stop light. After being towed to a trustworthy mechanic whom I've used before, a bad ignition module was to blame. After a quick turn-around from the shop, (my truck is my livelihood as I'm a carpenter with a truck full of tools) I drove her a few days and noticed a little less power and a slight miss under load, (pulling a hill). Last weekend I changed plugs. No improvement. The other day I changed wires with a high quality set. No improvement. I used a injector cleaner which a friend recommended. Still no improvement. I need all the power this 4.9 has due to the weight I carry around everyday, plus it is a 5 speed. I bought the truck new in 1991 and she has 224,000 miles. No smoke, very little oil consumption.

I wondered If my mechanic could have altered the timing installing the ignition module. There is a layer of gook on the timing indicator so I know he didn't time it old school. I wish I was more mechanically inclined so I need help here from you Pro's. What is going on? Thanks in advance....
 
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Old 03-06-2011, 02:00 PM
77h0t_r0d_wrecker
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Definitely sounds like an ignition timing problem, but there has to be a reason that it now has altered timing just after installing an ignition module and the distributor wasn't moved...

Try pulling codes... see if anything comes up. If no codes come up, I'd try unhooking the neg cable on the battery for a half hour to let the computer reset. It could be possible that it was altering the ignition timing to compensate for a failing module... remember i said POSSIBLE, lol. Plus it couldn't hurt, and it's free.

I'm not too familiar with the OBDs on the early fords, so I don't know what sensors the ecu relies on to determine ignition timing. It could be that one of those sensors is failing as well. Maybe someone else can chime in on that...

I'd try resetting the comp first if there's no codes though. Please report back!
 
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Old 03-06-2011, 04:23 PM
joecarpenter
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Thanks,

Tomorrow I'm basically off so I will stop by a Auto Store that will get the codes for me, not that I'll know what they mean. Also getting a well overdue alignment.....I will report back as thats how we all learn, right?

Thanks again
 
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Old 03-06-2011, 07:48 PM
77h0t_r0d_wrecker
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Originally Posted by joecarpenter View Post
Thanks,

Tomorrow I'm basically off so I will stop by a Auto Store that will get the codes for me, not that I'll know what they mean. Also getting a well overdue alignment.....I will report back as thats how we all learn, right?

Thanks again
Idk if the auto store will be able to pull codes for you. Around here they usually only pull codes on 96 and newer OBD2 systems. If you search around you should be able to find out how to pull the codes yourself and find out what they mean.

And you're most welcome. Please keep us (at least me lol) updated!
 
  #5  
Old 03-07-2011, 07:00 PM
joecarpenter
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Ahhhh Master, It is better to teach a man to fish than to give him a fish....I seeeee.

Seriously, you were spot on...Auto store can't pull the codes....my mechanic can but seems like I read where there's a "how to pull codes" for dummies like me. (I will research that.) Something like jumping the self test connectors STO and STI and doing the key on, engine off test and read the flashing of the check engines light? Is that right? I'm on it..... going to my mechanic is too easy...ha.

I'll try and do the above mentioned and report back in a day or two....If you can enlighten me further please feel free.

Thanks Again

Grasshopper
 

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