The check engine light has been on for about a month and I have just noticed a very rough idle while I am at a stop light. Just a couple days ago the truck just completely shut off for some reason and luckily I was able to restart it quickly. Do you all have any suggestions on what the problem might be. It is a 98 5.4 v8 with 100000 miles on it.

 

Hole in the rubber elbow in the back of the engine. It's the vacuum side of the PCV hose. Get the whole hose from your dealsership, it comes with the elbow, plastic tube, and i think a pcv valve already in it.

(Just a experienced educated guess, btw)

 

thanks Jeff I'll be sure to check that out.

 

If its that, you should be able to hear a vacuum leak if you put your head back there near the firewall on the passenger rear of the engine with it idling. Feel around the tube with your hands and you should be able to see what im talking about. If its not that, it could be that your AC evep. drain doesnt have the tube on it that keeps the condensate from dripping on the Bank1 O2 body, killing the heater in it.

 

jeff, exactly where is the vaccum tube located and where so i listen in for a leak?

 

Jeff is right, I just replaced my whole assembly from the pcv valve all the way to the idle sensor. It cost about $ 33 or something like that from the dealer. The easiest way to find the elbow, is find your pcv valve on the motor.....follow it back, its a little of a strech if you have short arms like I do, but the idle sensor is back on top of the motor....feel the rubber elbow there and more than likely you will feel the dryrotted piece of tubing. Like Jeff said, you should be able to hear it or use something to spray back in there, as it sucks you will hear the motor idle smoothly. It very easy to replace, no clamps or anything just rubber fittings, and yes it does come with a new pcv valve. That will take care of the check engine light and make her run alot better!!

 

Is there any chance some fuel injector treatment could clear this problem up?

 

If the check engine light is on or has flashed and you haven't disconnected the battery then go to Autozone and have them read the code for free. Could be vacuum leak or something else entirely.

If you haven't changed your plugs/wires yet it could be that as well.

 

No, injector cleaner wont fix the hole in your PCV tube