02 Xls 4.0 slight rough idle

[luvsspeed]

I have a 02 xls 4.0 with 105k on it and it has a slight rough idle. Its nothing major that really anyone would notice, but I do. I'm used to a smooth idle with cars and this is not my only car. All of the following was changed in May at about 102k. Plugs (oe), fuel filter (oe), wires (autolite I believe). I don't remember if the slight rough idle was there before those where changed, I didn't notice until they were changed. It feels more like its stumbling, like a random misfire. Well Thursday I was thinking that it cant be a misfire, since it hasn't thrown a code since I started to notice it about 4 months ago. Well Friday it throws a code P1151. The last time I had this code it was due to the fact that I was getting crappy gas from this one gas station. Once I figured that out I stopped going there. I thought that it couldn't be from bad gas since I was on the same tank for over a week and I go to the same place. I cleared the code 100 miles ago and didn't come back yet. I also cleaned the MAF sensor. I know it works because I forgot to plug it back and and the truck didn't even start. Once I plugged it back it in, it started fine. I had read that there is a vacuum line that is prone to cracking coming of the of the intake manifold, but the only detailed pictures I have seen for it are for the V8 and not the V6. I could not find that shaped hose on my V6. The only hose that I saw that could be it was a long hose running from the right side corner of the intake manifold by the fire wall to some where on the left side of the engine. When I went to go and check it the printed information coating turned to powder as soon as I touched it. I did the carb cleaner trick on that hose, all vacuum lines that I could see, and what I believe was the EGR valve and there was no change in the idle. Can anyone help me solve this problem? Thanks for all the help in advance.

 

[swshawaii]

2 Door Sport? If so, here's the "notorious" PCV elbow. GL

http://www.explorerforum.com/forums/showthread.php?t=314670

 

[luvsspeed]

2 Door Sport? If so, here's the "notorious" PCV elbow. GL

http://www.explorerforum.com/forums/showthread.php?t=314670

No its a 4door xls. Now I saw that thread before, but that picture is so up close I don't have anything in that picture that I can reference.

 

[D Hook]

I have the same problem so I'd be curious to know about the elbow and its' location.

 

[luvsspeed]

2 Door Sport? If so, here's the "notorious" PCV elbow. GL

http://www.explorerforum.com/forums/showthread.php?t=314670

Is that even the same engine?

 

[swshawaii]

Same engine, different configuration. Check out these threads. GL

http://www.explorerforum.com/forums/showthread.php?t=222601

http://www.explorerforum.com/forums/showthread.php?t=356647

 

[luvsspeed]

Same engine, different configuration. Check out these threads. GL

http://www.explorerforum.com/forums/showthread.php?t=222601

http://www.explorerforum.com/forums/showthread.php?t=356647

Yea I saw that page about the ecu flash. I don't think that's it since I never really noticed that rough idle before the tune up. I could be wrong though. I will try that hose coming from the evap system as well as look for that other hose with the bend. I would like to think it is a hose somewhere though. With the summer heat down here, I have found a lot of rubber dry rotted and cracked on this truck in the past 3yrs or so. It wouldn't surprise me. Its raining here today so I will try and check tomorrow and post what I find. Thanks for the information.

 

[luvsspeed]

Ok here's an update.. I could not find any damaged vacuum hose that could be causing this issue. The one hose that I thought could be causing the issue, I unplugged an capped the hole on the intake and it still had that little stumble at idle. I thought about changing the PCV valve, but there is no way I can get my big hands and tools back there... If that's the issue I'll just let the dealer deal with it. If its the plugs or fuel filter well since I just had them do it in may, that's there issue to fix. If its the wires ill just let the dealer diagnose those and take those back were i bought them from. That hose that has seem to been a problem on other 4.0's I don't even see on mine, unless its all the way in the back and I just can't see it.