ah ok i see, i wasnt sure but i thought there was a short time without it lol. oh well.

 

New problem. after sitting in traffic or a drive through for more than two minuts, sometimes less, it starts surging hard during acceleration, but clears up after a minute of driving. does it almost every time. idle doesnt change, only acceleration. and i mean hard surging. I put a new IAC on it, cleaned maf, iat sensors, pcv is fine. no vacuum leaks, I changed my tune, still nothing, fuel pressure is good, a/f stays good. im stumped. i've been trying to fix this for over a month, no luck

 

A guess??? I see idle increase after sitting for a while at a light when it is hot. Is it possible that the pcm uses a timer or ACT to increase the idle, or do the cats need more air for their correct operating temp?
It could be that the pcm commands this correction and it is slow to change? You might log fuel source to see that it comes out of idle fueling.

 

I don't have it set to increase idle speed. And i don't have cats so my tune is set for that, And it just started one day so I dint see it being tune related

 

Mine does the same when the battery is low or I am pulling to much amps at idle(lights,A/C radio all on)! You can change the voltage and timer on PRP.

 

May be an intermittent cam or crank sensor. Used to happen alot with the 7.3 diesels.

 

Just a guess, probably not the problem, but would the fact that it's cooler out now effect the tune ? Running with the heat on ? Yea, kind of a long-shot, but I get a surge @ idle, -sitting at the light when turning up the heat. Doubt that's the problem, but the air is cooler now.

Otherwise, I would look for an open/chaffed MAF wire maybe.

Does it do this cold ? If not, maybe an O2 wire.

 

It does it when its 40* like tonight, or 90* like a month ago... I dont see it being tune related because it just started doing it one day, my o2 sensor readings stay the same during surging, maf readings are dead on too, just goes along with the rpm change... if it were a cam or crank sensor wouldnt it throw a code?

 

when u datalog have u looked at crank or cam sensor voltage during a movie play back when it surges

 

Dpfe?

 

I think that's extinct under that hood

 

my truck was doing that once and I had melted the EGR wire

 

It might be an off the wall guess but maybe a bad tank of gas. I think your truck acted funny before when you had a bad tank.

 

What is your idle set at? I forgot to turn my idle back up after i adjusted my tune with my programmer and it did wierd **** like that. It was idling at 550ish and would surge, i guess it was the cams not liking low idle. Good luck finding your problem man.

 

Not necessarily. The diesels didn't throw codes if it was intermitent. If the sensor was dead then yes, I think it was p0340.