Engine Sputter

[Blue_Oval_Ford]

I have this ongoing sputter that gets worse when I apply a load to the engine only after it is completely warmed up. It also has a rough idle shudder when warming up from 1000 rpm down to 650 rpm sometimes being worse then others. Here is a list of the things I have done so far.

1. cleaned IAC and MAF
2. replaced spark plugs
3. replaced TPS
4. replaced upper intake o-rings
5. did ONP 0012m
6. replaced front O2 sensors
7. seafoam flush
8. replaced fuel filter and checked fuel pump pressure, all OK


I do need to replace the muffler as the sound is much deeper then when I bought it new and will be replacing it as soon as my muffler gets here. On the highway and and at constant speed it runs great with no loss in power just when I give it a lot of gas. Any help would surely be appeciated.

 

[Blue_Oval_Ford]

Ahhhh, come on there has to be someone on here who has experienced this problem.

 

[RickOTR]

Have you replaced the spark plug wires? You said you replaced the two front 02 sensors, what about the two rear sensors? They may have weak readings that very greatly from the two front sensors, I heard this can make the engine act funny. Might want to change the rear sensors. The explorer has a strong history of bad MAF sensors which does not always throw a CEL light. You can only clean them so much before it is replacement time. How old is you battery? A weak battery or one that is 3/4 charged or less won't allow enough electrical current to the coilpack. Thus causing a weak spark and poor power even though it may have a smooth idle. How is your catalytic convertors. A partial or compltely clogged cat will not let the engine breath freely.

 

[Blue_Oval_Ford]

Thanks RickOTR I will see about replacing them this weakend.

 

[jayhawkexplorer]

Dang man, you've spent a heckuva lot money fixing things that didn't cause your problem, at least I assume that since the problem is still there. Might be time to take it to a shop...

 

[Blue_Oval_Ford]

I have taken it to the dealer and a very reputable shop that I have been using for years and they could not find the problem. I have 115,000 miles on the engine so I decided to replace the sensors as regular maintenance. I talked to a Ford tech yesterday and he said always replace the two rear sensors when replacing the two front sensors or it could confuse the computer. Please don't ask me how.

 

[Blue_Oval_Ford]

Well, after checking everything under the hood, I finally found the problem. I have an intake leak between the lower and upper intake manifold because one of the self tapping screws on the lower intake is stripped. Can this be fixed with a larger screw, or should I buy a new lower intake manifold. If so, can I reuse the old seals as there are only 1000 miles on it.

 

[Dakota1358]

If your spending the money on a new manifold why not buy a seal

 

[RickOTR]

Glad you found the problem. Now for the bad news. Generally the problem is not the seals on the lower or upper intake. It's the upper intake itself as Ford had a problem with it warping if not torqued in sequence correctly. I had to replace mine because the ford tech who did the 0012M did not tighten them correctly. Ford refused to pay for it so I bought a used one from the junk yard for $75. A new one is around $850.