part throttle hesitation/jerking?
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part throttle hesitation/jerking?
I've noticed a part throttle problem. At speeds from 60kmh to 90kmh or so if the truck is given a bit of throttle in top gear, without a downshift, it feels like the truck is jerking or hesitating. The truck is a 99' with about 124 000kms.
No codes, so I assume it isn't a misfire. Bad gas? I doubt that as I thought I felt this a month ago.
I was going to start with the MAF and then look for vac leaks.
Could it be the lock up convertor? I watched it last night when I came home from work. When the problem occurs the tach stays steady.
At full throttle or even when it downshifts I can't feel anything wrong. And at light throttle it runs very well.
No codes, so I assume it isn't a misfire. Bad gas? I doubt that as I thought I felt this a month ago.
I was going to start with the MAF and then look for vac leaks.
Could it be the lock up convertor? I watched it last night when I came home from work. When the problem occurs the tach stays steady.
At full throttle or even when it downshifts I can't feel anything wrong. And at light throttle it runs very well.
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After much searching on the great forum I believe it is a COP or two going bad. I guess I should pull all of them and see if there is any water in the wells and apply some dialectric grease.
Anyone have any luck with the cheapo ebay cops? I am leaning that way because I'm cheap.......
Anyone have any luck with the cheapo ebay cops? I am leaning that way because I'm cheap.......
6th Gear
Joined: Apr 2010
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i had experienced the same problem you were having. The misconception is that all miss fire codes will trigger the Service Engine Light. This is not always the case. I did have a miss fire with no SEL. I took it to where I work and it pulled a Miss fire code again the SEL did not come on. It ended up being a coil pack. I like you thougt it was bad gas and a vac leak. I went ahead and bought a ignition tester (dummy plug) just to make sure since the coil pack is like 49.99. Hope this helps. Good lucks
Larry B.
Larry B.
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Cleaned the MAF, pulled all the coils and applied some dialectric grease, fuel filter is 4 months old.
I have no codes or pending codes. Ford dealer wants $150 to run their diagnostic.
So, ebay coils for $94 are on the way. I will throw a few of the old coils in the tool box for long trips.
I am sure this is a weak coil since it won't fire under load.
I have no codes or pending codes. Ford dealer wants $150 to run their diagnostic.
So, ebay coils for $94 are on the way. I will throw a few of the old coils in the tool box for long trips.
I am sure this is a weak coil since it won't fire under load.
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Joined: Dec 2009
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From: Statesville, NC
Thanks saskdiesel for posting your question. I've been having the same problem but just haven't had the time to research it. Part throttle acceleration up hill at low RPM. I too was thinking plugs or coil. Just didn't want to spend that much cash and be wrong. Time to save up and get it done.
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Thanks saskdiesel for posting your question. I've been having the same problem but just haven't had the time to research it. Part throttle acceleration up hill at low RPM. I too was thinking plugs or coil. Just didn't want to spend that much cash and be wrong. Time to save up and get it done.
If this was my old FJ40 I would change all the plug wires and go from there.
This feels just like a wire going bad.
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The $94 ebay COPS arrived and I installed them one by one until found the bad one, which was #8.
So I installed the rest and it runs great. I put the 9 good coils in my parts box and I will have some spares on vacation.
These cops came with the boots and were ready to install. How long they last is anybody's guess but if I keep my bill the seller stated he would replace any defective coil as long as I own the truck. They look the same as the originals and were the same dimensions. Boots are interchangeable with the Ford cops.
I found out a few things. A coil has to fail completely before a code in registered. Misfires from a bad coil won't set a code and in my case no pending codes either. Of course I could have spent $150 at the dealer and had the misfire count read but I would still need a cop and the cheapest jobber cop I could find was $48 plus the boot.
So $968 for dealer parts or $94 for ebay parts? Time will tell.
So I installed the rest and it runs great. I put the 9 good coils in my parts box and I will have some spares on vacation.
These cops came with the boots and were ready to install. How long they last is anybody's guess but if I keep my bill the seller stated he would replace any defective coil as long as I own the truck. They look the same as the originals and were the same dimensions. Boots are interchangeable with the Ford cops.
I found out a few things. A coil has to fail completely before a code in registered. Misfires from a bad coil won't set a code and in my case no pending codes either. Of course I could have spent $150 at the dealer and had the misfire count read but I would still need a cop and the cheapest jobber cop I could find was $48 plus the boot.
So $968 for dealer parts or $94 for ebay parts? Time will tell.
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Thought I would update this seeing as I won't be driving this truck anymore.
I drove about 12000 kms this year with the ebay coils and lots of it was towing. No problems to report. If I was doing this again I would not hesitate. Seeing as the boots are worth more than two ebay COPs with boots at my dealer, it's a lot of savings.
How long will they last? My stock ones had about 110 000 kms when I first noticed this so if they last that long it will be a real bargain.
But I kept a few of the old COPs in the tool box when traveling....
I drove about 12000 kms this year with the ebay coils and lots of it was towing. No problems to report. If I was doing this again I would not hesitate. Seeing as the boots are worth more than two ebay COPs with boots at my dealer, it's a lot of savings.
How long will they last? My stock ones had about 110 000 kms when I first noticed this so if they last that long it will be a real bargain.
But I kept a few of the old COPs in the tool box when traveling....
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