Why can't things get weird when it is warm out?

[MarkEkberg]

Truck in sig, added smarty last spring. 210K on the clock

When cold truck will cycle to high idle. After a couple min at high idle it begins to miss every once in a while, then starts to chug chug chug after another couple min.

I have noticed a slightly longer crank time to start but nothing major.

Am I headed down the road of injectors?

 

[jhenderson]

I also get a slight miss on high idle, but it doesn't get any worse. Try reloading a stock program and see what happens.

 

[Alan Reagan]

This will sound kinda strange but I posted last year where mine had a miss at high idle sitting still. It also had a miss that was noticeable when pulling long hills. Turned out to be a faulty fan clutch. The clutch was turning on and off very quickly and putting a noise spike on the Engine Load Line. The dealer here couldn't figure it out and they replaced injectors, throttle body, sensors and more. I'm an electrical engineer and on at least three occasions, showed the tech the noise spike on the computer diagnostic system. It was a very consistent spike on the screen that should not have been on a signal line. Finally, they gave up and sent me to another dealer in Perry, GA. Within 15 minutes, the tech had figured it out. You might try disconnecting the fan clutch to see if that is the problem. I would have never thought that could have been my noise issue but it was.

 

[MarkEkberg]

I will save this link. That is a interesting point. I know sometimes when running the ac I can feel the fan cycle at highway speeds.

 

[cerberusiam]

A blip that sounds like a miss in high idle when cold is pretty normal. It is just the grid heaters activating or releasing most of the time. It is much mor enoticeable whne you have an open free flowing exhaust. Sometimes that could also be telling you it is time for batteries or cleaning connections, any disruption or spike in the power supply will cause little blips in idle quality.

I don't know what a chug is but is might be the same as lope for some people. It is not unusual in high idle cold for the engine to sound like it is loping. It is the ECU evenly splitting the injection events to warm up faster. As long as it is not spewing clouds oif thick white smoke when it does htis likely not an injector issue. It is compeltely normal with a CAT installed to see some good amounts of white smoke 5-10 seconds after startup, just the CAT converting the exhaust to H2O, as it come sup to temp. Steam is a lot thinner than fuel smoke from a bad injector, pretty easy to see the difference.

With a CAT white smoke form a bad injector won't gag or burn eys, usually doesn't without a CAT either is one is used to diesel smoke. Defimitely will smell like raw diesel fuel where steam just semlls like normal exhaust.

 

[User113]

2003's don't have CATs, do they? Or is this an acronym for something that escapes me?

 

[Prairie Dog]

2003's don't have CATs, do they? Or is this an acronym for something that escapes me?

Most did not but I think maybe the Ca. 250 HP version.

 

[MarkEkberg]

No CAT on mine. Supposed to warm a little this weekend. Might fire her up to see whats up.