Noob 07 5.3/E38 initial tune help

[SS8UUP]

Hello all,

I'm helping a buddy with his truck. We swapped an 07 LY5 5.3/4L60E and E38 ECM into his 68 Chevy truck. The motor was originally dod so all that was removed and a stock LS1 cam from an 02 firehawk I had sitting on the shelf was put in it. Initial basic tuning to remove VATS, codes etc was done and the motor fires up and runs. other than the small cam swap and exhaust mods the motor is bone stock as it was pulled for the donor vehicle.

GenIV 5.3
4L60E
E38 ECM
02 f-body LS1 cam
LS7 lifters
918 springs
cone air filter
mid length headers
no cats
full true dual exhaust out the back with H-pipe


The main issue is that it will idle around 750ish rpm but if you so much as bump the throttle it immediately jumps to the 2,000-2,500 range and will gradually climb in RPM from there. the only way to bring it down short of turning it off is to put a load on the motor such as cranking the power steering to full lock or dropping it in gear at which point it will slowly drop back down to normal. when it is high reving the VCM controls in the scanner have no effect and will not allow me to command idle down. I saw the sticky about idle info, Bill makes quick mention of GM having bugs and issues of idle wandering off and sticking there but its from a 2006 post with no follow up info.

This is my first E38 to mess with, all of my experience was with the 411 PCM in F-bodies years ago so I am pretty rusty with HPT although I was never very good to begin with. I was going to work on logging and adjusting the VE tables but with the high idle and jumpy throttle it has me concerned with driving it just yet.


If anyone can steer me in the right direct on where to start it would be appreciated. the tune and a couple logs are attached if that helps.

Stuart

[5FDP]

How is the fuel pressure, good pressure at spec?

Have you checked for vacuum leaks yet because those long term trims are maxed out at 29%.

[SS8UUP]

How is the fuel pressure, good pressure at spec?

Have you checked for vacuum leaks yet because those long term trims are maxed out at 29%.

I had him go double check it, the fuel pressure is at 55psi with it running. hes gone over it twice for vacuum leaks with negative results, that was my initial thought also.

[Covert1]

I just uploaded a stock tune to the repository from my 08 LY5 with DOD. You could use it for your base tune, turning off the DOD in the program, change base idle, p/n and in gear idles to 750 then add 10% to the min airflow and startup tables. Should get you running decent then tune from there. Or just compare with what you have.

[SS8UUP]

I just uploaded a stock tune to the repository from my 08 LY5 with DOD. You could use it for your base tune, turning off the DOD in the program, change base idle, p/n and in gear idles to 750 then add 10% to the min airflow and startup tables. Should get you running decent then tune from there. Or just compare with what you have.

thank you, it?s much appreciated. I?ll give it a look and work up from there. I just found out that the ECM and motor he?s using came from different donor vehicles so it will be good to checkout your file and start fresh from a known correct file for his LY5.

[newbie1987]

I just uploaded a stock tune to the repository from my 08 LY5 with DOD. You could use it for your base tune, turning off the DOD in the program, change base idle, p/n and in gear idles to 750 then add 10% to the min airflow and startup tables. Should get you running decent then tune from there. Or just compare with what you have.

QUICK QUESTION !!!
How does one go about uploading a tune to the repository??? always wondered cause i have a bunch of them people might benifit from.
if theres a page that shows how to do this please point me in the right direction please....thanks

[JayRolla]

QUICK QUESTION !!!
How does one go about uploading a tune to the repository??? always wondered cause i have a bunch of them people might benifit from.
if theres a page that shows how to do this please point me in the right direction please....thanks

Only stock OEM tunes are now allowed on the repository. I believe due to the EPA regulations.