We'll I got the truck back last thursday. I met my deadline for graduation. As I started filling it up with 91 octane I've been experiencing some idle issues. Truck runs good past 30 anything below 10/30 it kinda bogs down, My tuner said it'll need to be data logged and see whats going up, I thought if I run all this fuel out this weekend and try 87 to see if it makes a difference. The tuner said it was tuned to run 87 and 91 octane. Kinda thinking it's something to do with the fuel not understanding. I ran it around for a couple days to see the difference and I can't figure out anything.

Enough of me telling whats going on, have any of you guys experienced this. It might need fine tuning possibly but I don't know, my tuners has issues with idling. Hope this issue gets fixed.

Another thing the I do warm up the truck int he morning for a good 30 minutes, once the trucks warmed up and ready to go after driving it awhile it goes away, it only happens early in the morning. and sometimes in the afternoon like after school.

 

Sounds like something with open loop tune...

 

Clean the MAF with some of that special cleaner from the parts store and clean the TB.

 

I thought in open loop before it warmed up it ran in speed density..... Which would eliminate the maf from the equation...

 

Nope, two different things.

Closed loop uses feedback from the O2 sensors to keep the AFR at stoich, open loop does not use the O2s for feedback.

Speed density computes airflow by using a model based on engine size, rpm, manifold pressure, and temperature. The MAF actually measures the airflow with a sensor. Stock systems are a bit of a hybrid setup using both. Vehicles with a maf use that mainly for the fueling below a certain rpm with speed density as a check, and only the maf above that threshold.

 

Ok so i had a gross misunderstanding, always thought open loop was speed density without o2 input and ignoring maf due to the cold idle causing more air to be pulled in. Skewing maf readings