Having issues with "stuttering" and don't know what it is
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Junior Member
Joined: Jul 2023
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Having issues with "stuttering" and don't know what it is
howdy y'all!
I recently picked up a 2005 F150 Lariat with a 5.4 V8. With about 133k on it and beyond the typical east coast rust, it's in pretty good shape.
now to get to the main issue...
When I'm driving uphill, only uphill, it stutters/jerks between 1200rpm and til I hit 2000rpm. It's super annoying and I'm going to be moving back to Montana, towing a horse trailer in less than a month.
Once I hit 2,000rpm it doesn't do it and it doesn't do it on the flat or going downhill.
Initially a mechanic friend said to try replacing the fuel filter. I did that, no change. Then I did some Googling and read it could be the COPs. But when I spoke to my father-in-law (who's a recently retired Toyota master mechanic of 40+ years) about my theory, he said a bad COP would throw a check engine light. Where my dash only has an ABS and E-Brake light stuck on because of a bad speed sensor in the back.
Another friend who's worked for a Ford dealership for a while in sales and works on beaters with heaters in his free time, says it could be a spark plug. Which if that's the case, I'm dreading replacing them. I've heard horror stories and with my luck, I'll break one off and spend the rest of my day fishing it out.
So most of all, I'm interested to know what y'all think. If it's spark plugs I'll have my friend help and if it's a COP problem I'll do it myself. I went to a pick n pull and got 7/8. I just couldn't get the back passenger side one and it was too hot out to keep wasting time trying for it.
Also, another minor issue I've noticed. The driver's side seat and foot pedals don't have power. I checked the maxi fuse and it looked okay. Then again I'm not super familiar with maxi fuses, I drove a Toyota and old school Blazer before this. Could it be a bad relay...?
Thank you all in advanced!
I recently picked up a 2005 F150 Lariat with a 5.4 V8. With about 133k on it and beyond the typical east coast rust, it's in pretty good shape.
now to get to the main issue...
When I'm driving uphill, only uphill, it stutters/jerks between 1200rpm and til I hit 2000rpm. It's super annoying and I'm going to be moving back to Montana, towing a horse trailer in less than a month.
Once I hit 2,000rpm it doesn't do it and it doesn't do it on the flat or going downhill.
Initially a mechanic friend said to try replacing the fuel filter. I did that, no change. Then I did some Googling and read it could be the COPs. But when I spoke to my father-in-law (who's a recently retired Toyota master mechanic of 40+ years) about my theory, he said a bad COP would throw a check engine light. Where my dash only has an ABS and E-Brake light stuck on because of a bad speed sensor in the back.
Another friend who's worked for a Ford dealership for a while in sales and works on beaters with heaters in his free time, says it could be a spark plug. Which if that's the case, I'm dreading replacing them. I've heard horror stories and with my luck, I'll break one off and spend the rest of my day fishing it out.
So most of all, I'm interested to know what y'all think. If it's spark plugs I'll have my friend help and if it's a COP problem I'll do it myself. I went to a pick n pull and got 7/8. I just couldn't get the back passenger side one and it was too hot out to keep wasting time trying for it.
Also, another minor issue I've noticed. The driver's side seat and foot pedals don't have power. I checked the maxi fuse and it looked okay. Then again I'm not super familiar with maxi fuses, I drove a Toyota and old school Blazer before this. Could it be a bad relay...?
Thank you all in advanced!
Senior Member
Joined: Jan 2020
Posts: 4,330
Likes: 1,090
From: utah
Spark plugs. 95% of the time on this engine it's a worn or weak plug/s.
get a set of new boots for the OEM coils if that's what still in there and just change out the boots (I used densos at like $30-40 for a set of 8)
As for the seat/pedals if the fuses are good the things to check would be the ground connection behind the kick panels and I believe there may be a wire splice in the door sill area that is prone to corrosion and coming apart from previous posts iirc.
get a set of new boots for the OEM coils if that's what still in there and just change out the boots (I used densos at like $30-40 for a set of 8)
As for the seat/pedals if the fuses are good the things to check would be the ground connection behind the kick panels and I believe there may be a wire splice in the door sill area that is prone to corrosion and coming apart from previous posts iirc.