Lurching/bucking/hesitation @ 1300-1600 rpms
08-31-2016, 11:18 AM
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Lurching/bucking/hesitation @ 1300-1600 rpms
Need your help, please! I have 89 f150 xlt lariat, 4x4, extended cab, 302, with 5 speed. It has 109k miles. In the last 1,000 miles, I replaced the fuel tanks, pumps, including pump on rail, clutch, IAC, tps, and cleaned throttle body. I also had the map checked out. You see I love my truck.
Here's my issue: when driving between 1300 and 1600 rpms, it hesitates and bucks when I go from coasting to acceleration. It also exhibits similar issues when I back off the gas or de-celelerate at same Rpms. Sometimes i hear a clang in 2nd gear, when this happens. The bucking/jerking is most noticeable in 2nd gear, but can be experienced in all gears, but less so. It runs fine, except for this annoyance. Mechanic says its the tranny, due to age and wear.
My question:
1. Is the mechanic correct, or is there something else that could be the cause ?
2. What would a rebuilt tranny run in material and labor cost ?
I bought this truck in 91 with 33k miles. Dealer put in a new short block at 49k, due to metal filings in oil pan. Frame is in very good shape and body has slight rust. Interior is 98% condition. That's why I was willing to invest so heavily in my red baby !
Would appreciate any and all thoughts, ideas, comments. Please help !
John
Here's my issue: when driving between 1300 and 1600 rpms, it hesitates and bucks when I go from coasting to acceleration. It also exhibits similar issues when I back off the gas or de-celelerate at same Rpms. Sometimes i hear a clang in 2nd gear, when this happens. The bucking/jerking is most noticeable in 2nd gear, but can be experienced in all gears, but less so. It runs fine, except for this annoyance. Mechanic says its the tranny, due to age and wear.
My question:
1. Is the mechanic correct, or is there something else that could be the cause ?
2. What would a rebuilt tranny run in material and labor cost ?
I bought this truck in 91 with 33k miles. Dealer put in a new short block at 49k, due to metal filings in oil pan. Frame is in very good shape and body has slight rust. Interior is 98% condition. That's why I was willing to invest so heavily in my red baby !
Would appreciate any and all thoughts, ideas, comments. Please help !
John
09-01-2016, 08:00 PM
#2
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Welcome to the site!
I suppose stranger things have happens, but something doesn't sound right if you have a manual tranny. Not well-versed on failure modes of manuals, but can't envision what would be happening inside the gearbox to cause a hesitation or a bucking issue. Your clutch replacement within the last 1,000 miles does raise an eyebrow as a possibility with a loose or failed pressure plate allowing the clutch to irregularly slip and grab.
Can't help much on costs - my automatic was about $1500 to rebuild in 2007, with the shop doing all the work - pulling, installing, etc.
Suggest to ensure it's not something going on with the motor, because hesitation and bucking are more up the engine's line of acting up, although not so much in deceleration - pull the computer codes, check the ignition side of things - wires, plugs, cap, rotor, perhaps double-check your rail fuel pressure.
Good luck, and keep us posted.
I suppose stranger things have happens, but something doesn't sound right if you have a manual tranny. Not well-versed on failure modes of manuals, but can't envision what would be happening inside the gearbox to cause a hesitation or a bucking issue. Your clutch replacement within the last 1,000 miles does raise an eyebrow as a possibility with a loose or failed pressure plate allowing the clutch to irregularly slip and grab.
Can't help much on costs - my automatic was about $1500 to rebuild in 2007, with the shop doing all the work - pulling, installing, etc.
Suggest to ensure it's not something going on with the motor, because hesitation and bucking are more up the engine's line of acting up, although not so much in deceleration - pull the computer codes, check the ignition side of things - wires, plugs, cap, rotor, perhaps double-check your rail fuel pressure.
Good luck, and keep us posted.
09-01-2016, 09:07 PM
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Wde, Thanks for thoughts and comments. I failed to mention that the truck was also tuned, plugs,etc. In last 1k miles. The rail fuel pressure was low, so that was replaced last week. That's the same time when the mechanic said the uneven acceleration and deceleration at low ROMs was due to tranny wear. He called it HITCHING. Like you, I felt it might be something engine or fuel related. I'll ask him about the pressure plate. I think you might be on to something. I'll repost after I talk to him. Thanks for the ideas.
John
John