Part throttle hesitation, stumbling, bucking, etc.

[gorblimey61]

I've been experiencing part throttle hesitation for a while now, but its gotten progressively worse. Its really bad in passing situations, ascending hills, pulling away from lights, etc. Its gone from minor hesitation to stumbling and bucking. Its not throwing any codes either. I've replaced the fuel pump, fuel filter and fuel pressure sensor to no avail. I seem to remember reading that there was an issue with the early fuel pumps, but replacing the pump didn't alleviate the problem at all. Going by the old air, spark & fuel theory I'm now wondering if its an ignition problem. Plugs perhaps? They're OEM and I have 108,000 miles on the odometer. I suppose another culprit might be the coils. I also thought it could be an injector issue, but I'm not sure because I'm not getting any codes. Any info or input would be greatly appreciated!

 

[CJ-]

My car bucked under light acceleration and decel when the airfilter popped off the intake tube. I guess unexpected turbulence and the MAF dont agree.

 

[BruceH]

I've been experiencing part throttle hesitation for a while now, but its gotten progressively worse. Its really bad in passing situations, ascending hills, pulling away from lights, etc. Its gone from minor hesitation to stumbling and bucking. Its not throwing any codes either. I've replaced the fuel pump, fuel filter and fuel pressure sensor to no avail. I seem to remember reading that there was an issue with the early fuel pumps, but replacing the pump didn't alleviate the problem at all. Going by the old air, spark & fuel theory I'm now wondering if its an ignition problem. Plugs perhaps? They're OEM and I have 108,000 miles on the odometer. I suppose another culprit might be the coils. I also thought it could be an injector issue, but I'm not sure because I'm not getting any codes. Any info or input would be greatly appreciated!

No matter what you need new plugs. 108k is too much.

 

[redfirepearlgt]

Original plugs in a 4.6 3V? You better do some research on the procedures for replacing them. They are a 2 piece plug (the ground strap housing is crimped to the plug). The ground strap housing for no better term builds up carbon between the bottom and the head. Carbon builds up around the plug and causes it to seize in the head. When you remove it the crimped portion (ground strap housing) and sometimes a portion of the porcelain stays in the head and you need a special extraction tool to complete the job. There are some methods and a TSB training video youtube around on 3V 4.6 and 5.4L spark plug removal if you google them. Most ignorant move Ford ever made. 2nd most ignorant was not putting a Tremec in the 2011+ cars IMHO.

 

[gorblimey61]

Yeah, I know I waited too long to change the plugs and I'm aware of the difficulties involved in removing the two piece plugs. I'm going to try using Seafoam Deep Creep for a while to hopefully dissolve some of the carbon and I'm also going to buy the Lisle removal tool. With regard to the air filter I have a K&N flat filter in the stock airbox so I can pretty much rule that out. Thanks guys for the rapid responses. This forum is a great resource.

 

[BruceH]

Original plugs in a 4.6 3V? You better do some research on the procedures for replacing them. They are a 2 piece plug (the ground strap housing is crimped to the plug). The ground strap housing for no better term builds up carbon between the bottom and the head. Carbon builds up around the plug and causes it to seize in the head. When you remove it the crimped portion (ground strap housing) and sometimes a portion of the porcelain stays in the head and you need a special extraction tool to complete the job. There are some methods and a TSB training video youtube around on 3V 4.6 and 5.4L spark plug removal if you google them. Most ignorant move Ford ever made. 2nd most ignorant was not putting a Tremec in the 2011+ cars IMHO.

The design was changed to a nickel plated barrel after the first year or so. Not all are going to be the same difficulty to get out. The Autolite plug is still the only reliable plug option for the early heads.

Yeah, I know I waited too long to change the plugs and I'm aware of the difficulties involved in removing the two piece plugs. I'm going to try using Seafoam Deep Creep for a while to hopefully dissolve some of the carbon and I'm also going to buy the Lisle removal tool. With regard to the air filter I have a K&N flat filter in the stock airbox so I can pretty much rule that out. Thanks guys for the rapid responses. This forum is a great resource.

Good luck with the plugs. What year is your car? It makes a difference on which generation of HT plugs were used by the factory.

 

[stkjock]

Looks like he has a 06 from prior posting

 

[BruceH]

Looks like he has a 06 from prior posting

Probably a double whammy. IIRC the non nickel plugs were still used in 06.

 

[05roush0090]

Change plugs

 

[86GT351]

I've been experiencing part throttle hesitation for a while now, but its gotten progressively worse. Its really bad in passing situations, ascending hills, pulling away from lights, etc. Its gone from minor hesitation to stumbling and bucking. Its not throwing any codes either. I've replaced the fuel pump, fuel filter and fuel pressure sensor to no avail. I seem to remember reading that there was an issue with the early fuel pumps, but replacing the pump didn't alleviate the problem at all. Going by the old air, spark & fuel theory I'm now wondering if its an ignition problem. Plugs perhaps? They're OEM and I have 108,000 miles on the odometer. I suppose another culprit might be the coils. I also thought it could be an injector issue, but I'm not sure because I'm not getting any codes. Any info or input would be greatly appreciated!

Plugs are a must. Have you scanned it to see if there are any codes? Even with the light off there can be codes stored.

 

[gorblimey61]

Luck was on my side. I got all eight plugs out without breaking any. The Deep Creep definitely helped. She runs like new again! Thanks for all the responses. If I showed you what the original plugs looked like y'all would want to smack the crap out of me.