Hey guys, after I did my engine swap I went and had a dyno tune done on the truck. After the dyno portion, me and the tuner went riding in my truck and as I drove he logged and made fine adjustments to the fuel trims and whatnot to help with mpg's. This tune was done by a very reputable business and person. Well every since the tune my truck has acted weird while doing 0-part throttle pedal usage in first and second gear. When the truck is coasting down a little downgrade to my house(when I am actually on the brake a little) or coasting through a parking lot when it should be at a stable idle it will sometimes fluctuate from a high side of 1,000-1,200 rpm's and then at a moderate speed will drop to about 500 rpm's causing the AC to cycle off and blow warm air. Pretty annoying on these high humidity days. It does it fairly often and only in 1-2 gear. Like j said earlier, I can be in first gear and let off the throttle to start to coast to a stop or even hit the hit the brake and the trucks rpm's will drop below the set idle speed and automatically cycle off the AC. For the tune he set my idle a little high until I do my 80e swap and get a higher stall tc in it. The idle in park with AC on is about 800-850 and in gear it drops to about 750. In the tune also extended how long my truck holds each gear before it shifts, I feel like it holds first a little longer than I would like so I am going to have readjusted closer to stock when I go back to try and get the hunting rpm's issue sorted out. But about the gear adjustment part, sometimes it's like the truck gets confused when to up shift and down shift when I am at part throttle or have just let off the gas. Under light throttle my truck will shift out of first at about 14mph, if I was to accelerate slowly and let off the throttle at like 13 mph it would upshift quickly and then after it slowed down just a couple mph it will downshift kinda aggressively and clunk. It's almost like there is kind of a meshing range when he tuned it to upshift and downshift. The main concern for now is the hunting rpm's so my truck will run normally and my AC will function like it is supposed to. When I go back I am also going to have my idle turned down some since I will be doing the 80e swap in a couple months. The engine is a 5.3 that was bored a little, 216/224 .553"/.553" 112+4, ported healthy 799 heads, 10.8:1 cr, stock truck intake and throttle body. Does anybody have any idea about my rpm issue? I sorta feel like the engine is hurting for air because this 95% of the time happens when I have just let off the throttle. Thanks in advance guys and sorry the post is so long just wanted to give y'all as much information as possible.

 

It needs more tuning, there are numerous issues going on there with the tune.

 

What are you thinking? I am on the guys schedule for october 12 and hopefully he is willing to take the time and really find the issue instead of just wanting to raise the idle even more and call it a day.

 

Anyone else have and ideas?

 

Post the file if you have it.

 

I dont have it. The guy who did my dyno tune has it saved on his laptop he uses for all his tunes.