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-   1997 - 2003 F150 (https://www.ford-trucks.com/forums/forum25/)
-   -   Truck Jerking/Studdering Around 45-50 mph (https://www.ford-trucks.com/forums/1017128-truck-jerking-studdering-around-45-50-mph.html)

97flairside 12-11-2010 04:03 PM

I've tried it, but because this doesn't happen all the time i haven't been able to replicate it. What did you have to do with your truck when you found out it was dropping out of OD?

CharlieBravo 12-12-2010 03:30 PM

Push the override button to turn off the od. You may still have a slight buck but at least you wont get whiplash.

97flairside 12-12-2010 06:46 PM

besides that, did you have to rebuild the tranny or anything? im going to goto autozone tomorrow and see if they can find any pending codes.

CharlieBravo 12-12-2010 08:15 PM

In my case no. Tranny still going strong.

Boydp 12-12-2010 11:58 PM

Ok, so guys, I too am experiencing the same herky jerky motion about 45 mph, but...I can also feel a misfire. A definite miss when I put the engine under a load, if i gently put a load on, herky jerky, if I bury the pedal miss fire. I was totally convinced that it was ignition. So I pulled every coil, every plug, and of course it was not until the very last plug I found a boot with a hole burned through it. I was so satisfied that I found the smoking gun, but that wasn't it! This thing still jerks around and misfires and does not throw a code, if anything its worse. I have tried so many combinations to make it throw a code and it wont do it. I have ran the scanner in the pending mode, nothing. I hate the idea of pulling each COP one at a time to eliminate the problem, most likely because I don't think I will find the problem like that. I have read vacuum leaks? weak coils, a positive charge in the freakin anti freeze? I just don't know that to do next. Thanks for letting me rant.
Bp

Bluegrass 7 12-13-2010 12:42 AM

Now it's time to listen.
You have at least one low output coil.
Again, here is the reason you have the miss.
At speeds between 45 and 60, the EGR system opens and causes a very lean air to fuel ratio.
This come about because the program that calls the EGR into operation causes a very lean fuel to air mixture by commanding the fuel injection to cut back as well as advance the ignition timing in addition to the exhaust being gated into the intake making the mix leaner yet. Exhaust gas does not burn the second time..
The results of this "normal" condition is a rise in coil voltage requirement because.the mix is in the 20 to 1 range and must have higher coil reserve voltage to fire the mix. A failure to fire is a missfire at that time.
This situation is not a "hard fault" so does not set a code because it is cancelled in memory as soon as the operating conditions change.
So, the next time this happens you get the same result over again;
it is a proven fact.
If you do not approch the fault in the proper way, have fun and enjoy the missfires.
Replace the offending coil or have them tested for output to find the one causing the hassle.
You may see this stored in another part of the program then again you may not.
It takes a good scanner not a reader to see anything and to "TRAP" the fault while running when it happens.

ncranchero 12-13-2010 05:01 AM

Exact same symptoms as my 98 had. Had a bad plug wire. Agreed, you will find a bad/weak coil. It emulates trans shudder when it first starts going bad but, in my case anyway, it deteriorated rapidly to way worse than shudder could ever be.

97flairside 12-13-2010 07:28 AM

im going to check the wires on my truck today after work as longs as its not raining. I had a wire rub off the coating 18 months ago. It was rubbing on the upper radiator hose support.

ncranchero 12-13-2010 07:34 AM

Check the resistance in the wire with a VOM.

Boydp 12-13-2010 11:24 PM

Bluegrass, thanks for the info. I am listening and you make total sense. A couple of weeks ago I pulled all the COP's and plugs. When I read the plugs I saw a very lean running engine. It surprised me. So again, what you are saying makes total sense to me. I have a mix of OEM and aftermarket COP's There is 130k+ on the OEM's. I dont know that would make a difference because many say to stay away from the aftermarkets. So I ask, does that hold true for some of the performance aftermarket COP's, say like the MSD's. I think someone earlier in this thread or maybe another said to replace the entire set! I freaked because thats like $750 worth of coils from the dealer. I found a pretty good deal on ebay for an MSD set. Thats why Im asking. For $300 and free shipping I would spend that much at the dealer for them to TS and replace one COP. Then like some other guy said, another coil fails two weeks later. Hey, thanks for your help.

phil6608 12-14-2010 04:34 AM

Last time I checked Rockauto. RockAuto Parts Catalog

They had the Motorcraft COPs for 46.?? a piece.

You wont find a better COP then the stock ones!

97flairside 12-14-2010 05:57 AM

dam that is cheap, but I have coil packs. Those are listed $70 each.

phil6608 12-14-2010 06:34 AM


Originally Posted by 97flairside (Post 9683356)
dam that is cheap, but I have coil packs. Those are listed $70 each.

Yeah, I was talking to Boydp.

Your lucky,,you only have 2 to worry about. :)

Boydp 12-14-2010 03:04 PM

Phil6608,
Thats a great price and I bit the bullet. I ordered a set, should be here by Friday. I know what Im doing this weekend. I'll let you guys know how it comes out.

Boydp 12-18-2010 09:48 AM

Yea!!! Bluegrass! I replaced the COP's, new o-rings on the injectors and all is good. I did not replace the plugs because I installed Motorcraft Platinum plugs less than 30k ago and they looked fine.
Thanks Bluegrass


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