Still running rough.

[Nas1]

So I changed the plugs and coils on my 99 Expy and though she runs alot better she is still running rough during acceleration and sometimes while cruising. What else can it be? There is no service engine soon light. The PCV valve looks like it is in bad shape so I will be getting a new one today but I can't think what else it can be. Any insight would be greatly appreciated.

 

[walnuts4x4]

try looking for a vacuum leak... especially the rubber elbow

 

[Nas1]

Ok put in a new pcv valve and still running rough and at times jerking. Oddly it also has its times when it runs perfect. But anyways the Service Engine Soon light finally came on so I will be taking to my local Advanced Auto Store tomorrow to see what codes come up.

 

[walnuts4x4]

if its one of these Rough Idle? CEL?, P0171,P0174

try Lane24's link
http://expeditionforum.com/showthread.php?t=10745

 

[mic_1011]

try fuel filter??

 

[Nas1]

Ok so I got back from advanced auto and got codes p0171, p0301, & p0308. Now 0171 said running lean in bank 1 and 0301 & 0308 is a misfire in cylinders 1 & 8. Is it possible that the plugs went bad. I put in new plugs back in February but did the coils just a few days ago. Could bad coils cause the plugs to go bad again?

 

[98EXPY 5-0]

I changed my plugs and wires and it was ok for a while, then acted up again but not as bad. Finally got a CEL and it was cylinder 3. Changed COP again and loaded it up with dielectric grease. Now its smooth.

 

[Nas1]

Changed plugs 1 & 8. The electrode looked like a white powdery color which means they were exposed to a lean running condition. The truck runs much better now. Still idles a little rough, not much though. On light acceleration she feels smooth as butter, on medium acceleration it's a little rough, and hard acceleration is really rough. Time to start looking for that vacuum leak.

 

[superexpy]

Changed plugs 1 & 8. The electrode looked like a white powdery color which means they were exposed to a lean running condition. The truck runs much better now. Still idles a little rough, not much though. On light acceleration she feels smooth as butter, on medium acceleration it's a little rough, and hard acceleration is really rough. Time to start looking for that vacuum leak.

Did you check the other plugs to see if they too had the white powdery color on them? if they do then id suspect the PCV elbo on the back of the intake is cracked. I have seen this a million times. Also how I have found vacuum leaks on mine in the past is remove the vacuum hose on the left side of your throttle body and blow through it. If it doesnt hold pressure, you got a leak.

 

[TheGuyWho]

Fuel filter!!!!!

Should be a cheap & easy fix…

 

[Nas1]

My next day off from work is this coming monday. I will do superexpy said to try and find that vacuum leak and will also change the fuel filter for good measure. I will keep you guys posted.

 

[Jeffintampa]

mine is rough to just on Idle, 2002 new plugs and coil, still rough, Number 5 misfire code sounds number 5 only has 90 lbs sounds like a valve job is in my near future

 

[Petrafire]

i also have a 99 and have the same problem is there a HOW TO for the fuel filter?