what can cause an intermittent rough idle?

[jerseydrew]

for the last week i have had an on and off rough idle. i put some seafoam in the tank and filled up with good gas in case it was some bad gas but it still comes and goes a bit.

[ranger952]

What truck do you have? Sometimes, a rough idle is normal. How much is the tach jumping?Seafoam is a good start, but have you changed the plugs, cleaned the air filter, what octane of gas are you using?

[travis73]

In my experience a 5.3l engine with afm.lol

[jerseydrew]

yup 5.3 afm on a gmt900 85k miles and the tach jumps abut 150 -200 rpms when it does it. run regular 87 gas.

[BlackZ71Silverado]

yup 5.3 afm on a gmt900 85k miles and the tach jumps abut 150 -200 rpms when it does it. run regular 87 gas.

 

 

GM will tell you that it is normal. My 2010 idle is a little shaky sometimes, guess I just got used to it being that way. They all seem to do it for some reason.

[Stevens03]

A dirty throttle body or throttle body blade will cause a bad idle, also a dirty MAF sensor will cause a rough idle.

[jerseydrew]

ok CEL came on today and i read the code, turned out to be a misfire in cyl 1 so i pulled the plug and it looked like it was in the ocean for 10 years. looked like lime scale build up. changed the plugs, all is perfect now.

[elite0259]

yup 5.3 afm on a gmt900 85k miles and the tach jumps abut 150 -200 rpms when it does it. run regular 87 gas.

 

 

Mine does that too :/ I'm at like 89k miles