Rough idle every once in a while

[crsevns90]

New here and I have a '98 2.5 Ranger with 56,000 miles. I just changed all plugs and wires, and installed a new IAC valve. My problem is that once in awhile while the truck is ideling it will shake like a misfire and drop about 200 rpm's. Happens at stoplights too once in awhile and it gets very annoying! Suggestions? Any help is appreciated!

 

[Vonrak]

try having your alternator checked, mine was having a sputter like that and had my alt tested . found out the regulator/rectifer was bad. Put a new alt on and now it runs great.

Vonrak

 

[68Ranger390]

it sounds like a EGR valve that is opening or sticking open intermitally,
when at idle open the EGR valve with your finger or put vaccuum on the fitting to see if that causes the same symptom

 

[crsevns90]

I tested the egr valve and no change. It is operating the way it should. When I am watching the engine idle I can see it shake a little about every 10 seconds, other than that it idles smooth as can be. When I hold the rpm's at about 2000 there is no misfire or anything, and again it runs very smooth. Anything else I should look for? Thanks!

 

[68Ranger390]

did your problem begin after your tune up? if so clean and gap your old plugs and try that,,, also I have seen a fuel pressure regulator that dripped a drop of fuel on occasion and cause a flooding miss that cleared up as soon as the drop of fuel was burned, and wasnt noticeable above an idle,,,,

 

[skyking]

Try the mass airflow sensor. Mine was giving me fits. I have a 98 2.5 with 89,000 miles on it. Finally figured this was the problem. Disconnected it "before" I started it up. Ran smooth just like nothing was wrong. So I put a new MAF sensor in. Runs very well now. Thought some one from this website would of new of this problem. Kind of disappointed. Oh well, I figured it out. Good luck

 

[exigent]

Is it you a/c kicking in? Dont forget it runs when you have the defog/defrost on too. If that is the case Id bet the ac needs service.

 

[jobar]

x2 when my a/c is on my truck drops about 300 rpm and picks back up about 7 sec. interveals. Thats at idel, when I turn the a/c off it runs like a champ. Its gotten to the point where I cant drive with the a/c on or the truck shuts off while driving.

 

[tylerh]

there is a tsb for the idle on the 2.5 there is a idle kit available from ford just google ford ranger 2.5 low idle and it should come up