Well its 0 degrees where i live in good old iowa and just a few days ago it was like 40-50 degrees. Well my truck is idling rough and when it does it the lights go dim and the tacometer will go down and then back up then will go back to normal and then repeat. It only does it when it is cold last time it was below 20 it did it but not as bad. But on top of this my check engine light is on. So i took it to autozone to see if they could tell me what it could be and they said i had a fuse blown so they couldnt check it. Im kind of thinking it could be the mass airflow sensor but i have no idea. Does anyone have any idea what this could be.

 

The fuse is the cig. lighter fuse which also powers the OBII connector, replace the fuse and get the codes read and post them here, the exact codes, not what they think it might be.

 

JCR 56 is correct, we need the exact codes if any.

What engine do you have and how many miles?

Most likely the IAC (Idle Air Control) needs cleaning. Do an advance search and you find a post on how to clean/lube the IAC valve.

 

Get battery checked out. alternater might be charging cold battery and leaving enough voltage to run computer. That's where i would start looking.

 

I am having a similar issue with mt 01 Expd. It is throwing 0174, and 0171 (lean bank one and two codes). I have cleaned Mass Air, and throttle body, replaced egr, PCV, and AIV along with all corresponding plumbing. I also have a high pitched whistle, that comes and goes. Would have to think Vacum leak, but completely spraying engine with Starting fluid doesn't show anything. Rough running only when truck is almost completly warmed up, and outside temp below 30 or so.

 

it could be the battery because when it does it it dims. im not able to go back to autozone today but my dads friend is a mechanic and he is going to take a look at it this coming week for me. I am going to bring up all of these suggestions to him and i will also get him to give me the code so i can post it for you guys for further advice.

 

o also i have the 5.4 v8 and it has 199,xxx miles. I know its a lot but its my baby and up till now nothing was really bad except for the normal stuff like brakes and what not

 

Have you checked the PCV elbow at the back of the throttle body? that is the most common cause of those to codes together a vacuum leak there..