2001 Ford F150 truck idles rough

Check behind the throttle body. There is a vacuum hose that has a 90 degree bend in it. They are known to dry rot and cause a vacuum leak. Check that and let me know what you find.

Joe

I have changed that one, is it long black hose that goes to a black thing on the fire wall with a green cap. also there is small black hose about 6" long off the bottom of that black box.. also a little tiny plastic hose that comes off that and goes to the passenger side. i have not changed that line or any other little lines.

I think vacuum is the problem. Check all of them closely and let me know the outcome.

Ok I will do I use carb cleaner to spray on them?

Well I took carb cleaner and sprayed every little vacuum line that I cooked see. I could not find a problem. the truck was running and did not change when I sprayed the line fittings. could the alternator be messing things up it is is under voltage???


I see there is plenty of problems with this truck and engine size. plenty of people are having the same issue.

I am going to replace the egr valve to see if it is the problem. I took it off and sprayed the inside with carb cleaner and got some black stuff out of there. hopefully this will tale care of the problem.

I just replaced my egr valve and the pcv valve and still nothing. The rpms drop less but more often now when sitting still and in drive and foot on the brake. I did see the little black rubber hoses on my tiny vacuum lines looked dry rotted. But haven't changed them out yet.

I would like to say is that couple of months ago I did a tune up. I changed out my spark plugs so I had to take the driver side fuel rail off and the fuel injectors. would that be a problem now??

I would focus on the vacuum hose you mentioned. If you had done something wrong with the tune up, it would have started right away. Also, as far as the fuel injectors, do you smell any raw fuel? I want you to check one other thing. Since the tune up, make sure none of the plug wires may have moved and melted on something causing a miss.

No I do not smell any fuel at all. When I reinstalled the fuel injectors I lubricated the oring before I installed them back in. Ok I will check those things. I saw on another blog that some one checked a valve on the EFI and it was dirty. Where would that be located ??? I could not find it in my chiltons manual.

I'm not sure what valve they are talking about. Many times people will clean the MAF. I will check my manual to see if I can find anything about a valve.

well I did change out four short black rubber vacuum lines and my problem slowed down. well from the start of my project my rpms were sitting at 900 rpms and now after all I have done it sits around 600 to 700 rpms. now instead of dropping 5 rpms and back up it goes about 1 rpm to about half rpm drop. and when i am cruising speed it only acts up between 45mph to 60 mph. if I am sitting still at a drive through window and move up and stop it bogs down and back to normal.

i dont know if you have answered me before on this question or not but could it be an electric issue with the alternator?? by the way nothing is showing any codes at all. i had a computer hookes up twice and nothing shows.

The "no codes" is what is leading me to believe there is a problem with vacuum. As far as the alt, if the battery was run down very low, it could.

What shouldi do now? I can't think of anything else to do? Today when I was driving it seems like I have no problems at idle anymore but just between 50 to 60 mph range. It feels like the engine is bucking slightly. Maybe a different issue.

have you checked fuel pump pressure?

No I haven't. I have thought about that. I can rent a thing from
Autozone i think.

Yes, they usually will lend them to you. You pay the cost of the tool and then they refund the money when it is returned.

Thanks for the help but I am done searching for the problem. I am going to take it to garage.

If anyone that is reading this and have he same problem. I took my truck to the garage and it is an ignition coil that went bad not a vacuum problem.