We have 2 1997 F150's with all the same problems. It's actually kinda funny.

One problem is that they both hesitate around 20-30mph and then pick up after 30mph. We can floor them and they accelerate, but no where near how it should, then they pick up and move.

One truck is a 1997 F150 4.6 V8 automatic tranny 110k miles, well kept. Has EGR code on check engine light. Truck does shudder every now and then.

The other is a 1997 F150 4.2 V6 standard tranny 90k miles(est), no idea how well kept just bought it, P1537, P1538, P0401, P0171, P0174.

Any ideas?

 

Same EGR code, same shudder on 2001 4.2 and a 5 speed. Replaced EGR valve and vacuum controller, but no changes. Let me know what fixes yours.

 

Check your COP's and spark plugs. Sounds like one (or more) of those is your problem. Check with a voltmeter.

 

Thanks for the replies.

The 4.6 recently got new plugs, wires, coil pack, pcv, iac, royal purple oil+ k&n filter, air filter, and BG 44k.

The 4.2 got new plugs, pcv, air filter, royal purple oil+ k&n filter, and air filter.

We plan on getting new EGR for both trucks

What are COPS? I started a thread awhile back asking if there was another thread to decipher the abbreviations but no luck. I am constantly getting lost with these lol.

We cleaned both TBs today. WOW the 4.6 was COMPLETELY clogged from the EGR to the TB. Unbelievable. The previous owner used to pour Seafoam down the vacuum lines to prevent this from happening but it obviously didn't work(I figured it wouldnt plus I would think it wouldnt be good for the lines) Haven't put it all back together but will update tonight on how it went.

 

Oh and I just realized that both TBs have a sticker on them saying not to clean inside of the TB bc they have a special coating. Uh....never seen that before. Did I screw them up?

 

"Oh and I just realized that both TBs have a sticker on them saying not to clean inside of the TB bc they have a special coating. Uh....never seen that before. Did I screw them up?"

I doubt it, most good cleaners these days say safe for coated systems. Look on the can. I doubt you messed it up if not just don't make a habit of using cleaner that is not safe for coated systems. But one must ask, why would Ford (or anyone) put a coating on the TB that could be harmed by normal clearners? Think about it, gasoline has a lot of ethanol these days and ethanol will eat up a lot of things.

 

My F150 is not my life center so I speak many other languages. What is TB and Cops. (to me, one is a disease and the other is one to watch out for when playing on the street) Most honorable posters; Please translate.
In the back of my mind, I am suspicious of a dirty MAF sensor, but don't know what to use to clean it. I am also thinking of checking the steel line from the EGR to the exhaust manifold for clogs. This is new to me. I am used to carbs and HEI ingnitions.

 

TB is throttle body. No idea on COPS. CO positioning sensor?

Well, the 4.2 runs worse when first started, but runs smoother at idle than before after it warms up. Possible IAC?

The 4.6 runs smoother period but it didnt clear the EGR code so we will replace the EGR and check for more clogs as mypvtidho said.

 

I know your problem because it just happened to me but before that...

TB-Throttle Body
CAI-Cold Air Intake
COPS-Coil over plug(Spark Plugs)

There are more but these should get you through your problems.

98 4.6 Same exact problem.

Replaced:

Fuel Pump
Fuel Filter
Fuel Filter Lines
Coils Packs
Coil wires
Spark plugs
MAF
PCV Valve
?!?!?!?!?!?!!?!?!?!??!?!?!? Gues what it was...

MAF. End of story the thing runs like a raped ape. Quick Throttle Response it gets down and gets after it.... Good Luck... BTW (which means by the way) to test cops : Start motor and pull one by one. If its a good one you will hear the motor change, Idle up or down slightly. If its a bad one obviously you wont notice a difference. Thank Westtnfx4 for that little test

 

Looks like you threw some money at it before the MAF. Thanks for the tip, I will give it a shot.