maplelakeduckslayer

My truck hasn't run 100% for several years now, and just last winter I realized that when it gets say 20's or below, it idles higher. Approx 800 rpm. And this is once warm after driving a long time, not higher rpms after startup. So not super high but it's noticeable. This is one of many symptoms I have noticed that must be the reason my truck doesn't run right. Another symptom is my truck constantly sounds like it has a boost leak, but i can't find anything. I've looked and looked and looked.

Any chance an intake manifold gasket could explain it? I know vacuum leaks can cause a high idle, but I have checked everything a ton of times. The only things that I can think of that would cause the air leak sound is waste gates or the intake gasket, assuming I haven't missed anything in any other checks. When I build boost it sounds normal up to about 3-4 psi, above that it sounds like air leaking from a tank instead of a smooth, high pitched whistle I should hear.

Truck has 167,000 miles, hope I am getting close to figuring it out. But I don't get any engine codes which I feel I should get a lean code if I have a vacuum leak. It's really frustrating when it hasn't run right for years and doesn't throw any codes. Doesn't matter what tune is in the truck, stock of aftermarket, it does the sound, higher idle, doesn't run right, no codes.

Ideas?

maplelakeduckslayer

Forgot to add I did try shooting propane all around the intake gasket this summer, and didn't get any change in idle. But summer is when idle is normal. Could the warmer temps seal a leak better, and it would only leak while the intake is pressurized? Maybe in colder temps it's not sealing as well so it leaks at idle too? Guess I could try the propane again now that it's cold

05 super

My old 97 would rev up in the cold while driving..too the point i needed to ride the brakes to slow it down.
Possibly a leak around the throttle body or the throttle body itself? Dirty or sticking open abit.

maplelakeduckslayer

Just tightened the hose to the tb a few months ago and cleaned it like a year ago, was barely dirty. Unless there's an internal issue in the tb that controls it, I dont think that's it. But tough to say for sure with zero codes to go off of. I could just replace it, just getting tired of throwing parts at it

05 super

sounds like something is shrinking in the cold and sucking air..I dunno man.

maplelakeduckslayer

So frustrating, feels like I'm so close but cant quite figure it out. It's -3 F tonight and it is running like it should. Tons of power and there's no air leak sound. Just smooth powerful acceleration with faint high pitched whistle, instead of the sound of air coming out of a hose. It did this same thing a couple winters ago...drove right for 3 days. When it warmed up it ran like crap again.

It's a completely different truck when it gets this cold, you can hear the difference. In temps above 0 idle bounces around, runs rough, has poor acceleration, sounds like air is leaking as boost builds, etc. Below 0 the air leak sound is gone, just smooth linear power with a crisp turbo whistle, smooth steady idle, etc.

Any other ideas? When it runs like it does tonight it just pisses me off even more because this is the way it should drive every day, but I have been driving it years not running right and unable to figure it out.

BRUTE448

that sir is strange! i would think gaskets expanding would seal up, opposite of your experience. but in the cold its better.

hope it gets resolved, here for the sub'd to thread and a bump to the top as i have buds with eco's who mite run into this.

maplelakeduckslayer

Ya not really sure. 1st I will recheck all tubing/charge pipes, etc again and check my vacuum reading at idle when its cold so I have something to compare to when it warms back up. Going to go back to the stock thermostat soon and see what that does. Also going to investigate the water pump and make sure it is moving coolant...never had an overheating issue but maybe if its not moving the coolant in hotter weather it creates hot spots in the engine causing it to run poorly, and in the really cold temps that doesn't happen. Probably start with those things, and if none of those works maybe replace the wastegates. Only other thought is maybe the colder temps increase oil pressure and keeps a worn out timing chain tighter and the timing more consistent. A lot of this is grasping at straws but I really have no other directions to go, I've been trying to fix this issue for 3+years

maplelakeduckslayer

One interesting observation tonight with the truck running well. About 6 months ago I cut out my catalytic converters to see if they were clogged and causing my issues. Cutting them out did nothing to help, and although some have said with off road down pipes the truck didn't throw cat efficiency codes, mine did on both banks. Tonight when I checked the codes, the only one that was throwing the efficiency code was bank 1...passenger side. So I guess with the colder air drivers side is now running efficiently...but why? I gotta check o2 readings but guess this means passenger side is running rich. So now to try and figure out why one side is good and one isn't and how that correlates to tge colder temperatures

BRUTE448

were the cats flowing fine when checked?

my bud chased is 2004 5.4, spark plugs, coil packs, oil viscosity, turned out to be clogged cats.

but to me, i dont think thats your problem. sorry can't be of more help