96 XLT Rough Idle

[maxx31]

this one has even 2 mechanics stumped thus far!

The truck idles rough(a slight shake to the engine itself). So far NO CODES at all!

plugs,wires,pcv,IAC,air filter,vacum lines,TPS, all checked and replaced...NO GOOD YET

Last year I did get a CODE for the driver side O2 sensor which I replaced. Passenger side has never been replaced but i am getting no codes anyway this time around.

I've been told it may be the EGR valve or the FPR?

what would be the symptoms for these failing?

NOTE: i had the upper intake gasket replaced as well. I have to say the mechanic pissed me off as he left the EGR unplugged and I drove it around like that for 2 days. BUT- i did not notice a difference between then and now with it plugged in! Should I be able to unplug the vacum line from the EGR with the engine running? should it make a difference?? THANKS

 

[RickOTR]

I am having the same problem as you. I wounder if it could be a bad EGR valve.

 

[cjbarron5]

iac?????? clean it and check it.................vaccum leak???????????? well worth checking.....i would have a star tester put on it so you can "see" what all the electrical components are doing....iat????......coil pack AND its ground???????

 

[maxx31]

Egr?

i wish i knew a way to test the egr valve. anyone?

 

[bmxking5]

http://www.explorerforum.com/forums/showthread.php?t=115948&highlight=egr+valve

it is the fourth post down. hope this helps.

 

[performancenut]

Clean the MAF sensor- a quick and easy process which may be a contributing factor and which probably needs done for routine care anyway

 

[maxx31]

thanks but

i have already cleaned the MAF. List of things done:

fuel filter, plugs, wires, TPS, IAC, checked vacum lines(No apparant leaks), temp sensor,PCV,air filter, Fuel Injectors Flushed, O2 sensor Driver Side only.

Idle is slightly rough at times. I also noticed- right before coming to a complete stop, the trucks engine seems to idle down roughly for a split second or two???

The IAC (which was replaced last winter) had a bit of carbon in it, a few shots of carb cleaner fixed that. I would not think it's defective already? I did notice a small rubber seal sticking out more on one end of the bore than the other in the IAC body, is this normal? does anyone have a close up pic of the IAC Internaly? The other possible culprit- EGR!

thanks

 

[maxx31]

Help Anyone??

Thanks!

 

[TPLYNCH]

The IAC may need cleaning again. Give it a shot and see what happens.

 

[maxx31]

cleaned IAC again...same problem

I've cleaned the IAC again, and double checked all vacum lines- no good...same problem. Another thing i am noticing is: when stopping from a steady rpm (at a stop sign) the trucks engine idles down roughly for a split second or two??? what could this be?

anyone out there experience this? thanks

 

[cjbarron5]

did you check the iac to make sure it works?

 

[maxx31]

how can i test it?

how can i test the IAC? thanks again!

 

[cjbarron5]

pull off the iac and apply power and ground to the prongs where it plugs in WARNING DO NOT APPLY POWER LONGER THAN A SECOUND OR YOU COULD BURN UP THE SOLINOID

 

[lightnin]

Little old thread. But I am having the same problem. I replaced egr, egr sol., cleaned IAC, and still does it. But when I sprayed carb cleaner around the intake it Idles up. Gasket or cracked upper intake? Have anyone tried this?