Check engine light, code P0101

I finally got it! You are exactly right, vacuum leak. I do not know how I did not find it the first five times, probably because of dirt etc. Because this time I took my shop vacuum and air gun and loosened up/sucked up most of the dirt around the intake manifold and then I used brake clean to check for vacuum leaks. Right by cylinder number one there is what must be a good size leak. Once I sprayed in that area a few times the truck started stuttering (for lack of a better word) pretty good. I think that is what did it, the brake clean cleaned away the rest of the dirt that must have been partially blocking the leak. But now that I sprayed brake clean in that area a good five or so times you can clearly hear a vacuum leak. So as soon as I find a set of the updated gaskets that will not cost an arm I will order them. Put them on soon as they come and see how it idles, then I will call the rough idle a confirmed fix. Thank you for everything you have helped me with to get me to this point I appreciate it very much!

Alright, so I installed the new gaskets. The old ones were leaking bad, on the old gaskets I can see where dirt was partially blocking the vacuum leaks and I mean really only a few of the gaskets were not leaking. There was tons of dirt around the gasket surfaces. So I got the gasket surfaces and all under the manifold all cleaned up, cleaned up the intake ports too along with the ports and everything on the manifold itself. First start up after replacing the gaskets it was still idling rough but it got better and today it has went to basically an intermittent rough idle. I had a couple times today where it took a few tries to start. Also, I still have the engine kickback on hot starts. Looking at what I know, I I know it is getting air. So it has got to be either spark or fuel right? The readings from the O2’s at idle get up to 0.800 volts so as far as I know this means it is getting plenty of fuel? So if this is true, and if the rough idle and hard starts have the same cause, then it would be spark? Oh also, I forgot to mention earlier in the post, the long term fuel trims at idle are now as follows, bank 1, 4.7% bank 2, 0.8%.

Oh alright, thank you. I will look into this!

Alright so sometime in the next few days I am going to go down to my buddy’s shop and we are going to clean the fuel injectors. He has one of those tools you were talking about. Also, I was wondering if there was a chance you knew what the spark timing advance is supposed to be around at idle on this truck?

Alright thank you. I had to kind of pause on this for a few days to get some stuff done for state inspection. But I will post an update once I get the injectors cleaned. I think before I get the injectors cleaned tho I might take the fuel rails off at the shop just to take a peek inside the rails because I read on a few forums about people having a rough idle due to rust/corrosion in the fuel rails on these trucks. I am going to look into that more in the meantime. Have you heard of such a thing happening?

Alright thank you. I will make sure we closely inspect everything, planning on getting that done tomorrow. I will let you know the results.

Absolutely. On my way down to get that done now. So I will post results later or first thing in the morning. But I have a question before I forget, so the radiator fan in this truck as far as I have noticed basically has two speeds (it will turn on low when the engine is running and speed up about twice as fast or so, for example when idling for a while) well once in a while lately once I start the engine cold it will kick on at the higher speed. Any idea of what could be causing this?

Alright so it has happened just about every day since I posted that, sometimes once a day sometimes two to three times. I checked the temperature every time with the scanner and half of the time it was around 115 degrees and the other half it was cold start and at outside ambient temperature witch has been around seventy degrees lately. When this happens I will start it, the fan will immediately be on high and it will stay on high until I have driven for a minute or two at at least thirty five mph. Also I got the injectors cleaned and for the most part is has been running better, but once in a while maybe a few times a day If that (I drive a lot) I will still get an Intermittent rough idle at normal operating temperature. It is not quite as rough as it was before though. But it is always with the engine hot. It runs like a charm when it is cold.

No I have not. I usually do everything myself with help from people like yourself when needed, but for a couple reasons one being I have loved working on vehicles since I was a kid and two money has been tight. I am currently trying to save up money to go to UTI. I think I might start poking around with it before I jump into anything. Maybe start by hooking my multi-meter to the output from the PCM to the fan and see what I get when it is on low and high. Then start plugging into different inputs to try and figure out where the “high on” signal is coming from.