Jerking hesitation - Sort of urgent

[410Fortune]

How many miles on the truck Hartman?

Also dont keep throwing $$$ at it.
Jerking like that is usually:

fuel pump or relay

Also could be the 02's, especially with a CEL, it will run rich or lean and either load up or starve you for gas.

Could also be a clogged cat, could be a bad plug or wire, but your best bet is to pull the codes...get in the zone...

90% of the time the CEL will point you in the right direction.....

 

[Hartman]

How many miles on the truck Hartman?

Also dont keep throwing $$$ at it.
Jerking like that is usually:

fuel pump or relay

Also could be the 02's, especially with a CEL, it will run rich or lean and either load up or starve you for gas.

Could also be a clogged cat, could be a bad plug or wire, but your best bet is to pull the codes...get in the zone...

90% of the time the CEL will point you in the right direction.....

My truck has 142,500mi.

I went to Autozone and they said they couldn't read the code because the CEL ONLY comes on after driving a minute or so, it isn't constant. Whatever my problem is, it doesn't effect the idle, doesn't trigger the CEL when in idle. The only symptons are slightly sluggish accel and jerking when you keep your foot on the gas but leave it in the same position (not pushing down or letting up). The fuel pressure is fine, the fuel pump turns on fine on startup, and startup itself is fine. I'm leaning against plugs and wires because I figured they would make the idle at least a little rougher than normal.

 

[410Fortune]

They always do that, your CEL is not on, we cant pull codes, BS! If you push them they willhook up the scanner and they will likely get codes. Just because the CEL is not on does not mean codes are not in memory.

Have you tried re-setting the battery?
Did you test the fuel pressure? Just because the pump is running doesnt mean pressure is at par, and the regulator is working.

It never hurts to check the plugs and if you are going to check them you mine as well replace them! But I know from experience that these driveability types of issues are hard to track down and once you are done throwing $$$ at it, you usually still have the problem, of course you also usually end up with a full tune up!
hahaha

 

[Hartman]

The guy at Autozone did do the test and he got a 111 every time (normal diagnostic code). I have reset the battery a few times. I tested my fuel pressure and it's right at 35 psi where it's supposed to be.

I'm ordering plugs and wires because they are due anyway. We'll see what happens.

 

[Runnin'OnEmpty]

Hartman, that's a new one on me. A CEL will always leave a trouble code in memory, unless the battery has been disconnected to erase it. After the battery disconnect, the code will be gone until the CEL comes on again. Could you have disconnected the battery and then had the code read (with no CEL lit in between)?

Your description of the problem happening at a steady throttle cruise, still leads me to suspect a MAF problem or worn-out TPS sensor. Try unplugging the sensors and spraying the connectors with WD-40, then re-plug. See if that changes anything. Ford has had problems with their MAF connectors in the past.....

 

[uwbradley]

Hartman, that's a new one on me. A CEL will always leave a trouble code in memory, unless the battery has been disconnected to erase it. After the battery disconnect, the code will be gone until the CEL comes on again. Could you have disconnected the battery and then had the code read (with no CEL lit in between)?

Your description of the problem happening at a steady throttle cruise, still leads me to suspect a MAF problem or worn-out TPS sensor. Try unplugging the sensors and spraying the connectors with WD-40, then re-plug. See if that changes anything. Ford has had problems with their MAF connectors in the past.....

Is WD-40 an effective cleaner for cleaning the connections between the MAF and the car's computer? I have never heard that before, are you saying to seriously unplug the MAF from the truck and spray WD-40 on the connections?

Brad

 

[410Fortune]

wd-40 the wd stands for Wire Dryer
WD-40 is an electrical contact cleaner, its perfect for that application.

I personally have never had problems with the MAS connector

 

[xploda01]

hartman, i have a 96 4.0 and i have a very similar problem, sometimes it will act up like you've described and sometimes it wont. now i know i have original catalytic converters and i know they need to be replaced after 130k miles. the explorer has been running a little on the hot side and i know my cooling system is up to par. I have reason to believe that my problem lies with old catalytic converters that are too clogged to allow for proper exhaust exit causing the engine temp to rise a little. Are you running a little on the hot side?....not over heating but a little warmer than its supposed to be?

 

[Hartman]

My engine temp is fine.

I have tried to remove the MAF sensor to clean it, but only one of the bolts is a security star, and the other just looks like a round rivet and I have no idea how to remove it. Sort of frustrating.