4.0 troubles

[RyanD2]

Hi Guys,

I'm just looking for ideas on troubleshooting my 2000 4.0. For a while it has been running alright but having a rough idle, lately that has turned to it running like hell when pressing on the accelerator

I have had the upper intake gaskets changed as well as plugs / wires. The rough idle is still there and I've looked all over for a vacuum leak but can't find one. Codes that are constantly being thrown are 1151, 1152. The 02 sensor has been changed in bank1. I will try the plugs / wires again if necessary as they were changed about 8 mos ago.

I know there's an exhaust leak but I doubt that would be causing all these issues, but I could be wrong.

My next step is to take it to another shop (this will be the 3rd) to get this resolved. Figures a month after paying it off all these issues get worse.

Thanks in advanced for your help.

 

[martin]

you might try cleaning the maf. instructions in tech library.

 

[Big Jim M]

Running like hell when pressing on the accelerator is a sign of plug gap also. Put the proper Motorcraft plugs in there with the proper gap. That is another place to look...Ok?
Big JIm

 

[BlackBII]

Is the exhaust leak BEFORE the O2 sensor?

The O2 sensor likely didn't need to be changed, as it was just detecting the lean condition, not the cause of the lean condition.

Could be Vaccum leaks, Low fuel pressure, dirty injectors....etc.

How do the plugs look? Any darker or lighter than the rest?

 

[RyanD2]

Yeah I need to check the gap. I know they're not Motocraft plugs, thats a no-no.

As for the leak, its after the 02 sensor. Basically where the muffler meets the connecting pipe to the cat.

Would checking the TPS be worth it?

 

[Doom's Day Custom]

check out the alternator and make sure it is putting out enough juice because that whats was the samething happening to my truck!!!

 

[RyanD2]

Just posting an update, I changed the plugs / wires today, made sure to gap them at 0.52. No change in ride / idle. I did notice that the vacuum hose going to the throttle body was in pretty rough shape, brittle, I'll need to replace this but wondering if it could be contributing to the issues.

 

[hauser775]

Try changing out the fuel filter. If its old and clogged then the engine may not be getting enough fuel. My 4.0 was running rough and I changed out the filter and it runs much better. I don't know what those codes refer to so I could be way off.

 

[cdogg179]

had some idle problems myself.

first time ended up being "throttle control pump" I think... on driver side of upper intake mani . Ive also had recuring broken plug in number 4 but pretty sure thats cause I tend to go tooooo deeeeep in da creek.
Not sure about code numbers, I go to oil can henrys and they pull em for free; Always says im runnin lean. dang,ole waterd down gas. switched to super and she loves it;light still comes on from time to tim but no more idle problems...
just a little mudd in the cylinders to get rid of now...OOOPS

 

[RyanD2]

The plugs looked fine, no physical damage and appeared to just have the usual wear. I did toss in some "better" gas and it appeared to help out a bit. I'm still thinking it is all caused by a vacuum leak, most likely the intake gaskets. At this point the truck only sees about 50 miles a week so I'm not pressed to get this done ASAP, but it would be nice to squash it once and for all. Fuel filter definitely needs to be changed as I've never done that since I've had the truck. I've read the articles on how to change it but is it really as easy as it seems?

 

[hauser775]

replacing the fuel filter is very basic and is done with a couple hand tools