michael/edge

i live in wyoming and the mornings can be pretty cold.

so when its anything 20 degrees to -35 i cycle the plugs twice. the truck always starts with no problem. when it starts it runs instant at a grand rpm. my exhuast is fairly loud. so while it is reving up loud about every 30 seconds it sounds like it misses or cuts out for a split second.

warmer mornings my truck runs normal then revs up to a grand.
my dads 03 never revs up right it start. his always runs normal then in later warm up time it revs up to a grand for like 10 seconds then back to normal..


so my question is why is two 03 trucks running differnt. is mine missing or what is it doing.

my truck has 60,000 miles. never had a problem with it other then a lift pump. i do have little mods but currently it has been return to stock. the truck runs great. no lack of power. i pull a circle j horse trailer that is double walled and put 5 horses in it and no problem pulling at all. the truck has never been pushed to its limits with chips. got a superchip only casue it was given to me for free and i never use the thing. i keep it for checking codes.

justin mcfall

it could be your grid heater cycling. This will cause the motor to sound like it is missing for a second. More load on the engine.

PoorMansCat

My 06 model does the same thing... If you have the defrost on, it could be the a/c compressor cycling. Remember, a/c compressor is running when the defrost is selected.
It could also be the grid heater cycling..
If its the grid heater cycling, sit in the truck and watch the voltmeter while listening to the exhaust. If the exhaust stumble happens when you see the needle moving then its the grid heater.
The reason two different trucks may act differently may very well have to do with different versions of programming loaded into the two trucks. One may have a more aggressive cold mode strategy than the other.

michael/edge

thanks guys.. cause i always turn the defrost on and let it warm up for 10-15 min and then take off

Jeff in TD

If your dad plugs in, in some temps it will prevent the truck from going into high idle when it would have otherwise.

Sounds perfectly normal. If you have an exhaust brake, turn it on, and it will warm up much faster.

etn550

When I worked at CAT it was common to have many different software versions in the ECM for the same model and year. Manufacturers make a lot of changes on the fly.

I would not be too concerned about it. Actually, I think yours is the better version going straight to 1000. Mine does that too.

Jeff in TD

Yeah, I enabled PTO control, so I can get mine to do that when I want.

jbeach6

are they supposed to go to 1000 rpm at first start? mine just idles normal

michael/edge

like everyone has been saying i think it depends on the program. mine right at start on a really super cold morning goes to 1000 rpm at instant start.. warmer mornings it runs at idle then to 1000 rpm for awhile and then back down......the days i plug it in it never revs up just stays at idle

Jeff in TD

Yeah, it had to be around 0 f, but both my 06 and the 03 I had would go straight to high idle when it was that cold.

1-2-3

Do you plug your truck in overnight?

michael/edge

latlely i been plugging it in at night. our highs zero and night its dipping to -14 with no wind. and during the day it stays plugged in all day.