2004 4.0 Rough idle

[jahcdp]

Hello everyone. I am new to this forum and ii am looking for some help. I have a 2004 4.0 that has a consistent rough idle. I have changed the plugs, wires and coil pack. Even double checked the firing order to be sure all was correct on the engine to the coil. Replaced the EGR valve and put on a known good throttle body and still has a rough idle. Pulled the intake and replaced the gaskets and checked all hoses for vacuum leaks. I am at a loss as too what to try next. I have sprayed the exhaust bolts going to the cats and I am going to back them down to see if I have a stopped up converter. If that doesn't work does anyone any suggestions. All help now would be appreciated.

 

[donalds]

Sounds like its time for a smoke test
With the info you gave us is sounds like a vacuum leak

 

[jahcdp]

Sounds like its time for a smoke test
With the info you gave us is sounds like a vacuum leak

Where can I get a unit to do that. I pulled all the vacuum hoses off and tested individually and found no issues. Guess I need a smoke machine?

 

[donalds]

Google Search

www.google.com

 

[jahcdp]

Google Search

www.google.com

Thanks, going to build one and see what happens. I'll post back here when I get it built. Thanks

 

[imp]

Hello everyone. I am new to this forum and ii am looking for some help. I have a 2004 4.0 that has a consistent rough idle. I have changed the plugs, wires and coil pack. Even double checked the firing order to be sure all was correct on the engine to the coil. Replaced the EGR valve and put on a known good throttle body and still has a rough idle. Pulled the intake and replaced the gaskets and checked all hoses for vacuum leaks. I am at a loss as too what to try next. I have sprayed the exhaust bolts going to the cats and I am going to back them down to see if I have a stopped up converter. If that doesn't work does anyone any suggestions. All help now would be appreciated.

In this day and age, the old-time failures are often overlooked. I would look for a burnt exhaust valve. This can be checked by holding a folding matchbook open against the end of the exhaust pipe. If the matchbook flaps back and forth with exhaust gas pulses, pulled against the pipe by suction, a failed cylinder (valve) is indicated.

 

[TechGuru]

Hello everyone. I am new to this forum and ii am looking for some help. I have a 2004 4.0 that has a consistent rough idle. I have changed the plugs, wires and coil pack. Even double checked the firing order to be sure all was correct on the engine to the coil. Replaced the EGR valve and put on a known good throttle body and still has a rough idle. Pulled the intake and replaced the gaskets and checked all hoses for vacuum leaks. I am at a loss as too what to try next. I have sprayed the exhaust bolts going to the cats and I am going to back them down to see if I have a stopped up converter. If that doesn't work does anyone any suggestions. All help now would be appreciated.

I see idle air control valve is missing from this list.

What spark plugs are you using? I would not use any but the Motorcraft SP500 and be sure to gap them properly, they do not come pre-gapped.

Is your service engine soon light on?

Is this a FlexFuel model? If yes, I would run though a full tank of E85 thought it to give everything a good cleaning.

 

[LMHmedchem]

What spark plugs are you using? I would not use any but the Motorcraft SP500

I have seen this posted before a few times. What is the reason for needing the Motorcraft platinum? I have used the Bosch 9006 double iridium for quite a while now. Is that going to cause a problem? I haven't noticed anything since making the change.

LMHmedchem