98 F150 4.6 problems under load
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New User
Joined: Dec 2011
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From: Moncks Corner, SC
98 F150 4.6 problems under load
Hey folks, it's been a while since I've been here but that could be a good thing right? I've got a 98 F150 2wd, automatic, 4.6, 330k, not the 7700 package, no codes. It starts and idles fine and seems to drive ok at low speeds but under a load or up a steep hill it starts to pop and sputter and so on. Plugs and wires are new. Any suggestions or more info needed?
Elder User
Joined: Mar 2010
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Does it actually feel like an ignition misfire, or more like just a rumbling ? Those coils fail a lot less often than the cops. Just a couple of easy things to check :
1. Next time it starts acting up, using your left foot, tap the brakes while still accelerating. If the problem goes away, it's likely the torque converter. My '99 did the same thing, depending on your description.
2. Check all the plug wire to plug connections. A lot of the replacement sets have to be firmly snapped onto the plug. Often, the boots grab so tightly that it's a little harder to engage the metal clip.
3. Check for coolant in the plug wells. Long Q-tips work nice for that.
4. If nothing shows up after the above 3 things, drive it somewhere that will cause the problem, and try to run it long enough to trip a code. It might be a coil failing, but the problem is usually short term, and may not set a code . A longer duration episode may set a code, and at least narrow down which coil pack.
It could easily be something unrelated to ignition, but most of those would pretty readily trip a code. Just for one more thing off the list, check battery voltage under load.
Dave
1. Next time it starts acting up, using your left foot, tap the brakes while still accelerating. If the problem goes away, it's likely the torque converter. My '99 did the same thing, depending on your description.
2. Check all the plug wire to plug connections. A lot of the replacement sets have to be firmly snapped onto the plug. Often, the boots grab so tightly that it's a little harder to engage the metal clip.
3. Check for coolant in the plug wells. Long Q-tips work nice for that.
4. If nothing shows up after the above 3 things, drive it somewhere that will cause the problem, and try to run it long enough to trip a code. It might be a coil failing, but the problem is usually short term, and may not set a code . A longer duration episode may set a code, and at least narrow down which coil pack.
It could easily be something unrelated to ignition, but most of those would pretty readily trip a code. Just for one more thing off the list, check battery voltage under load.
Dave
Cargo Master
Joined: Dec 2004
Posts: 2,232
Likes: 3
From: NE Texas
As always, Bluegrass is on the right track. Check fuel pressure first thing. If you don't have a guage, Auto Zone will loan you one in their tool rental program.
When was the last time the filter was changed?
When was the last time the filter was changed?
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New User
Joined: Dec 2011
Posts: 11
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From: Moncks Corner, SC
Thanks guys, I'll give that a shot. Being that it has 330k on it and LKQ is running 50% off memorial day weekend I may opt for a lower mileage PI 4.6. My father in laws mechanic believes there's an issue with the timing chain pensioners or guides but I couldn't hear any excessive noise up there. I'll give the fuel thing a shot but will probably still take advantage of the sale!
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