My1997 F-150 - 4.6 SC will jerk or hesitate several times under light load - say at 45-50 on a flat road. Give it some gas, or kick off the overdrive and the problem disappears. Any clue where to look. or start.

I would like to find the source before this changes from a minor irritation to a major problem.

Thanks

 

I was wondering if you ever found a remedy to your problem. I started having this problem yesterday, and I am getting ready to leave in a few days for a trip. Any help would be great!

 

This one is tough. With the O/D off the engine is forced to run at a higher RPM, which would make me think that there is possibly a fuel delivery problem. When is the last time you change the fuel filter?

Since nothing is far enough out of specification to trip a check engine light, I would start with changing the fuel filter and running a good injector cleaner on tank of gas #1. On tank of gas #2, I would follow up with a decarbonizer to blow out the cylinders (RXP orange bottle available at any auto parts store) If it persists, then going through and cleaning the engine /emissions control devices would be in order. I.e. checking vacuum lines and air filter , cleaning IAC, Throttle Body, EGR and ports, MAF and DPFE hoses.

If you take it to the dealer, they will just do routine maintenance like a fuel system cleaning, filters and possibly fluid swaps followed up by the infamous CND (could not duplicate recommend major tune-up)

 

Sounds like you may just have some water in the gas. Try some STP gas treatment to see if it clears up. Also, get gas from a different station for a while. I have found several gas stations that had problems with their tanks. Just switching to gas from elsewhere solved the problems.

 

Thanks for the replies Throttle and deep6blue. I don't know if this makes a difference or not, but it is a 2001 5.4L V-8 with 64,000 miles on it. Now that the "gas" comment was made, the day it happened, I ran the truck till the low fuel light came on. I filled up, and as soon as I pulled away from the station, is when all the jerking around started happening. I guess I will try the STP additive and change out the fuel filter tomorrow. I have to drive 3.5 hours Wednesday to get home for Christmas, so does anyone think some major damage can be done?

 

Without truly knowing what the problem is we cannot say if real damage might occur.

If it is bad gas, that 3.5 hour drive should give enough time to get alot of gas out of the system. Refill when you get down to half tank and add the STP additive. It should clear things up a little.

 

Change your spark plugs and check to see if any of the coil packs have gotten wet....This happened to me (A/C condensate had the #4 coil boot and plug completely submerged). A new set of plugs and shot of dielectric grease in the boot of each coil pack solved the problem.

My "miss" was most noticeable around 1500 rpm in OD under slight load.

It never set a code and it was at the local dealership for a week. They never found it. I just made the decision to change the plugs and that's what I found.

My truck is an '02 5.4 4x4.

Hope this works for you, too.

Sidewinder

 

check the O2 sensors also. my O2 senor went bad, and the truck would often studder under load. the truck never threw a light, but ford found the code. the O2 sensor tells the PCM how to lean the fuel. also, if the truck never does it when its cold(like in the mornings) this could point to the O2 sensor. the truck runs in an open loop in the PCM until the truck reaches operating temps.

 

I had the exact same problem, and I spent crazy money and time trying to get it fixed. Here is what finally did it for me. I changed the fuel filter, and I ran some fuel injector cleaner through it. Then, I had to change the spark plug in the cylinder that had been missing, because when it didn't fire, it caked up a bunch of crap on the plug, so it fired intermittently. Sounds like you had some junk in your gas tank, and when it got so low, the junk was pulled into the fuel line, and it restricted your gas flow. Have the code checked at your local Auto Zone (or another parts store if you don't have an Auto Zone, just call around and find who will read your codes for free), change the fuel filter, run some fuel injector cleaner, and change the plug in the cylinder that's misfiring. That's what fixed mine, anyway. That was an annoying misfire, too, but like you, when I left the overdrive off on the highway it seemed to run better, maybe because the truck was forcing gas through the clogged filter. Try this, and if it doesn't work, then post back, and we'll take it from there.

 

I've had a similar problem before and it turned out to be a bad sparkplug wire.

 

Also have to remember that the tranny has an unsure spot at about that speed.

 

I also had the exact same problem after driving too far with the low fuel light on. I wasn't a block from the gas station after filling up when she started jerking and more throttle didn't help. I let up on the gas and in about 6 blocks it cleared out. I posted the same question and was told about sediment in the tank. I changed the fuel filter and haven't had the problem since. My truck is a 97 Expy, 5.4 thathad about 90,000 or so on it at the time.

 

Following the advice in this thread I ran a can of K44 fuel injection cleaner through the tank and the results were inmpressive.

The hesitation is gone (for now). Mild black exhaust was seen fro a few hard accelarations - perhaps some contaminants being burned off ?

I will try to update this when I have refilled the tank with clean gas.

Thanks for the help!

John

 

First of all hello to everyone...I am new to this post. I am having the same problems with my 1997 F150 4x4 it has the 4.6, at first it was only hesitating in O.D. and when under light loads then it got so bad that the check engine light came on...took it to Auto Zone and they said the code was for a mis-fire in one of the cylinders. I had new plugs and wires put on, run a bottle of fuel treatment through the tank and installed a K&N air filter. I have not had the light to come back on but still having the hesitating??
What do you suggest I try next without having to do all of them at the same time???

1 Fuel Filter
2 O2 Sensor
3 EGR Valve

Thanks for any help.
Anthony

 

Posted this under the Transmission board but this thread sounds like the problem I'm having as well -

I have a similar problem with my 1996/5.0L although mine seems to be tied into the RPMs. In any gear if the accelerator is lightly pushed when the engine is between 1500-2000 RPM it sounds like the truck is going over rumble strips. Its not continuous - it will do it for about 2 seconds then stop, then another 2 seconds and stop. Another wierd thing is that it will not shake as badly if premium gas is used versus regular. Adding fuel injector cleaner to a tank of premium produces the least amount of shaking while regular fuel will rattle your fillings. Very strange.