Truck bucks around 50 mph and some hills?
- Thread starter mrpenguin
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I was just researching online and there's a lot of talk about MAF, coil packs, plus and wires, O2 sensor. I just bought this truck used from a dealer 3 mos ago. They did plugs, wires, and timing belt. There was an issue shortly after the timing belt... for some reason the serpentine belt and alternator belt came off when driving. The truck lost power and died. The dealer fixed it. Ran fine until yesterday when the bucking started. It really only happens between 50-60 mph and going up hills in OD. If I mash the gas pedal it'll do it then too.
Lester Lugnut
New member
I went through this back in the spring - 1995 Isuzu Rodeo 3.2 liter V6
Vehicle started up nicely - idled smoothly. Ran great at city speed.
Get on the highway and accelerate slowly OK. Once I tried accelerating up around 60mph, vehicle would start breaking down. Same going up a hill.
This vehicle is OBD-I. No readily available scanner to read any meaningful data. Dealer scanner was all that was ever available.
Research revealed bad Ignition Coil Pack. This vehicle has a set of 3 packs.
Your vehicle may have individual coils for each cyl. and should be ODB-II. If that's the case, a good scanner might point out the offending cylinder if a bad coil is indeed the case. Usually you'll get a code if this is the problem with an OBD-II vehicle.
Vehicle started up nicely - idled smoothly. Ran great at city speed.
Get on the highway and accelerate slowly OK. Once I tried accelerating up around 60mph, vehicle would start breaking down. Same going up a hill.
This vehicle is OBD-I. No readily available scanner to read any meaningful data. Dealer scanner was all that was ever available.
Research revealed bad Ignition Coil Pack. This vehicle has a set of 3 packs.
Your vehicle may have individual coils for each cyl. and should be ODB-II. If that's the case, a good scanner might point out the offending cylinder if a bad coil is indeed the case. Usually you'll get a code if this is the problem with an OBD-II vehicle.
Sukirman
New member
Same experience
My truck, an '01 2WD Limited did that too, loses power, misfires or hesitates under acceleration, especially going uphill (60mph and around 2000rpm). Very annoying. Threw some codes last week (P0300, P0303 and P0442) Changed the spark plugs, spark plug wires and the PCV valve and grommet last Sunday and it is now running smoothly again. Will also install a new fuel filter this weekend. Hope this helps!
My truck, an '01 2WD Limited did that too, loses power, misfires or hesitates under acceleration, especially going uphill (60mph and around 2000rpm). Very annoying. Threw some codes last week (P0300, P0303 and P0442) Changed the spark plugs, spark plug wires and the PCV valve and grommet last Sunday and it is now running smoothly again. Will also install a new fuel filter this weekend. Hope this helps!
BlackWorksInc
New member
I would make sure the plugs are correct for the vehicle and they are gapped correctly, most plug wires have the date of manufacture printed on the wires (at least the Toyota/NGK/Denso ones I have seen used) so you can verify if they have been changed out recently.
Coil Packs could be an issue as well. Out of curiosity when you say "bucks" do you mean like the vehicle misfires or that it loses power and sort of falls flat on it's face momentarily. One more question, even if you are not going up a hill or accelerating hard; if you say drive on the freeway for an extended period of time does it also start to exhibit this "bucking" feeling until it cools down?
Coil Packs could be an issue as well. Out of curiosity when you say "bucks" do you mean like the vehicle misfires or that it loses power and sort of falls flat on it's face momentarily. One more question, even if you are not going up a hill or accelerating hard; if you say drive on the freeway for an extended period of time does it also start to exhibit this "bucking" feeling until it cools down?
CrazyNorwegian
New member
The fuel leans out a bit at higher rpms which make it easier for a weak spark to ignite. I had the same problem on a 98 mustang I used to own. The first time it was due to bad spark plug wires. The second time it was due to a bad coil pack. I first thought it was the spark plugs, so I replaced them. The problem seemed to go away at first. But, after a day of driving, it would return as the spark plugs eventually fouled up again.
Squirt
New member
Mine was doing the exact same thing. I searched for over a year replacing parts here in there (that were aged and probably needed replacing anyway) but none were the solution. Couple of days ago took it to the muffler shop and had them replace both cats (mine has California emissions) ALL of my power came back have none of the hesitation or bucking at certain speeds. I don't know how many miles you have on yours but it would definitely be worth a look.
who done it
New member
Yeah for me it was an exhaust leak, O2 sensors couldn't read correctly with the leak. The car would buck quite a bit when the gas was applied heavily.
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