Weird rough idle every few weeks shortly after starting.

[DocShultz]

So every few weeks my new to me 2003 4.7l with just over 100k will start idling rough as if it has no/little fuel making it to the engine (reminds me of my lawn mower when I shut off the fuel line and run it until it dies; it will surge just before it dies) but the RPMs don't seem effected on the dash and a no codes are thrown and it hasn't killed the motor yet. This only happens when the engine is cold and I am not moving, as soon as I start driving away it is fine. The last time it happend I had just put the truck into reverse but had not started moving, the time before that I was in park when it happened; in both cases the truck started fine and idled fine and it was only after 10-15 seconds that the rough idle began.

Searching over the forum, I have found similar rough idling symptoms from others, but often its when they are moving slowly or happens when they come to a stop while driving. My issue seems to occur within the first minute of starting the truck. Does anyone have an idea as to what this may be?

Thanks in advanced.

 

[Rampitt]

have you tried cleaning the air filter, TB IAC sensor? ran any fuel injector cleaners? checked the plugs make sure they are burning good? best way to start trouble shooting.

 

[DocShultz]

have you tried cleaning the air filter, TB IAC sensor? ran any fuel injector cleaners? checked the plugs make sure they are burning good? best way to start trouble shooting.

Air filter looks good. I have run seafoam through the gas tank, but not specifically injector cleaner. I will check the TB IAC sensor and check the plugs this weekend. Anything in particular I should do to check the TB IAC?

Thanks for the response.

 

[Rampitt]

Air filter looks good. I have run seafoam through the gas tank, but not specifically injector cleaner. I will check the TB IAC sensor and check the plugs this weekend. Anything in particular I should do to check the TB IAC?

Thanks for the response.

I would get some brake kleen to clean the tb and just blow out the sensor.

Sent from my LG-H901 using Tapatalk

 

[DocShultz]

I would get some brake kleen to clean the tb and just blow out the sensor.

Sent from my LG-H901 using Tapatalk

Well, I asked the gentleman I bought the truck from if he had changed the spark plugs and he said he had replaced them about 5 months ago, so those are good. I removed the TB and gave it a good cleaning, lots of buildup. The IAC valve was very dirty, but I didn't want to screw with it to much, the idle channel where the IAC goes was even more gummed up and I did clean that out. I will see if that solves my problem. My idle RPMs went from 600 to 700 after cleaning, so it appears cleaning it did have an effect. Hopefully my random issue is gone, but only time will tell.

Thanks again for the quick response.

 

[Dbowling19]

I'm trying to find out myself my threads don't seem to be getting replies , my truck is doing the exact same thing, I've cleaned TB, and throttle position sensor . still does it from time to time 2003 4.7

 

[Dbowling19]

Mine does i t too, I'm stumped as to what it is, I noticed the lights dim too

 

[DocShultz]

I'm trying to find out myself my threads don't seem to be getting replies , my truck is doing the exact same thing, I've cleaned TB, and throttle position sensor . still does it from time to time 2003 4.7

My problem has appeared to go away. If you are still having that surging I would replace the IAC valve and see if that fixes it.

 

[PdPuNOme]

Having similiar issue where randomly when i start the truck cold or warm it doesnt get up to idle rpm's and usually surges up to normal but sometimes dies out. I have a spot less tb , ports, iac etc as I deep cleaned it and monitor it every 3 months as i am very crazy about keeping all my chrysler vehicles tb clean.

i did throw in a new map sensor recently other than that and the iac maybe a leaky intake manifold i would suspect.

 

[FullForceRam]

If I may interject here, coming from a good friend and neighbor of mine who worked as a mopar and GM mechanic for over 30 years, do not use brake clean on cleaning your throttle body.
Mopar makes a specific cleaner for throttle bodies. It's only $6.

 

[evanj5]

Mine seems to now and again run rough after maybe an hr or so of use or at least once it's warmed up... These engines....well the 3.7 and I believe the 4.7 were designed to run copper plugs....if the throttle body is clean and all the sensors are clean ID look at the plugs and coil packs.....if that doesn't work fuel filters and injectors....I'd hate to think fuel pump but you never know..

Sent from my XT1254 using Tapatalk