Took a long ride up to N.H. this weekend and noticed an odd hesitation / shutter. I noticed this at highway speeds approaching an incline/hill. Just before the truck would down shift, it would bog down/hesitate a bit and shutter a lot probably around 2000-2300 RPM. After down shifting the engine would run fine. Gas mileage for the trip was fine and power seems normal. The plugs and wires have about 20K on them and no check engine lights. Tranny fluid level is OK. The truck is a ’97 F150 XLT 4X4 4.6L engine with 88K miles. Any thoughts?

 

It could possibly be some slight slippage of the lock-up clutches making it chatter.
Jimmy

 

That is also consistent with a misfiring cylinder. If you're sure the new plug wires are good and routed correctly, I would next check the coil(s). Also, its unlikely, but possible, that something is wrong with the plugs.

I'm assuming the transmission fluid has been changed at the recommended intervals (30K), with the proper fluid. If not, that is the first thing to do. If your transmission calls for "Mercon V", and anything else has been used (including Mercon), that could also be the problem.

 

The truck ran fine after changing the plugs and wires around 20K ago. I do not have the coil on plug style and no check engine light. If a coil was bad I think I would have significant power loss. So would it be reasonable to rule out a misfire and routing problem?

Tranny fluid is due for a change (last change was 40K ago) so I will do that tonight.

Anthing else I should check while I am at it?

 

Misfires can be minor and intermittent or major and constant, but it does seem like the first thing is your trans.

Good Luck!

 

Thanks guys, these forums are great!

 

Thanks guys, these forums are great!

 

dtharrett,

I disagree with the tranny theory, but completely agree with the Plugs and wires. I feel you are having a misfiring plug. I've seen lots of 97-98 f150s with the 4.6 that have "tranny problems" that are cured by plugs and wires. Most exhibit simmilar symptoms as your truck does, in overdrive, with light throttle, the engine sputters and shakes a little. When the plugs were changed were double platnium plugs used, and were the wires replaced with high quality ones? Single platnium plugs are used a lot because they are way cheaper, but they don't last long at all. Also check your number 4 plug to see if there is any antifreeze or water on it. The heater hoses are notorious for leaking and filling up the number 4 plug (last one in on the passenger side). Since plugs and wires are significantly cheaper and easier to fix than a tranny, i'd definately change them first. use high quality wires and double platnium plugs. Aftermarket is just as expensive as motorcraft so use the motorcraft ones. I think you'll be very very happy with the end result.


Dube

 

Thanks for the info. The plugs and wires came from Ford however that does not guarantee quality. I fully intended to change the tranny fluid the other day but ran out of time. This weekend I will check the resistance of the wires and pull a few plugs. I also still plan to change the tranny fluid, as it is due for a change anyway. I will post the results next week.

 

Interesting thread here. My 03 Super Crew has a fairly pronounced shudder as i back it up the driveway...a slow speed operation! Anybody else noticed a shudder while in reverse?

 

I am getting the exact same shutter/hesitation that dtharret describes. I have 75,000 miles on a 2001 Supercrew with the small 8 cyl engine. Took it to the dealer and they ran a diagnostic finding only one registered fault - slow engine sensor. They could say if this was the problem so I did not have them replace it. My guess was plugs and wires, but the dealer said they seemed fine?

Once the truck downshifts all is fine.

Gil

 

Probably should have posted the results a while back... I ended up changing the plugs and wires again and this helped a bit but the shutter was still there. Changed the tranny fluid and all has been fine for a few months.

 

Hi Gil and welcome to the forum
Have you ever replaced your spark plugs or are they the originals still? Quite often a misfire wont show up in the shop. Your dealer can drive it with their WDS scan tool hooked up and watch the power balance to see if there is a misfire.

 

My '97 F150, 4.6L, 2WD does the same after a long highway run at 65 mph or more. I have had the transmission rebuilt by "Level 10" for use in a 800 hp application and still found shutter after a long highway run. I also replaced the plugs and wires with no avail. I have used synthetic fluid since the rebuild with no shutter after speed run change. I felt the fluid was foaming and used a transmission oil additive "Greased Lightening" to control the shutter with great success.

 

Thank you for all the replies. The same dealer changed the transmission fluid at 30K and 60K. At 75K the plugs and wires are original as the dealer said they were OK. since I mentioned the plugs and wires, if they wanted to gouge me they could have agreed?

I had a '96 F150 and went 160,000 with no motor or tranny issues. Maybe I should have kept it???

Today the tuck drove with little shutter. I am curious what the warm weather will bring? If it doesn't get worse, I'll wait till the 90Kservice and decide what to do.

Thanks, Gil

Gil