RPMs do not return to idle..

[KMS]

..when pushing in the clutch and coasting to a stop. I know the tuner who did my car was a bit new and had to send some files back and forth to get my car right, but he really spent a lot of time (likely learning) on my car and wanted to make sure everything was right since his shop was also new.

I'm just wondering if he missed a couple things or if that's normal.

Banckground: it's a 228/232 112+2 so it's not the craziest cam out there, and it never dies, never hesitates to start, but the rpm's on a cold start are 1000-1100 for up to 60 seconds before it settles down to 850. Hot start is normal. The gas mileage has gone down, but that may also be due to my right foot. Very little surging, but some in 1st gear and idling through a parking lot.

[eficalibrator]

Without seeing more solid data, I'd wager that the airflow estimate is skewed, and as a result, so is the delivered running airflow in gear (dashpot function). Some guys mask this by shifting the commanded airflow in the RAF or throttle cracker tables, but the real solution is to properly map both the injector and airflow tables in the first place.

[KMS]

they do return to idle eventually, but not until I come to a stop. THEN they drop. I don't know if that makes anything different or not. I will be doing a new top end so I'll get it retuned by someone much more knowledgable. Hopefully they go through all the tables. If you know anyone in the chicagoland area you'd trust let me know. I am also willing to travel to the right person.

[Black_Knight]

they do return to idle eventually, but not until I come to a stop. THEN they drop.

I had the EXACT same issue and my tuner was able to fix it. So one thing I can say for sure is that what you are experiencing is an actual problem that can be fixed.

[WelderMike27408]

sounds like mine when creech tuned it........dont know what to tell you other than find an experienced tuner to look at it.....
my motor blew less than 1500 miles after my h/c/tune ...piston came apart and it was running so hot and had ungodly ignition timing advance the pistons got soft....and four of the sleeves were lifting....
guy who fixed the tune still has the origional tune log saved....i may post it ......

[Eskimo]

I don't think the cold idle at 1100 is a bad thing at all... help get some heat into the engine...

The RPM's hanging though, I have the same issue on mine after we adjusted the throttle stop on the blade to help it start better.

I haven't looked into it much, but I believe there's a value for idle speed when the when vehicle speed >0 ?

[edcmat-l1]

Too much base idle airflow. Idle trims kick in when you come to a stop and that pulls it down to idle.

[Alvin]

^ yep, in GM's wisdom they disabled STIT's until VSS = 0 so if the desired airflow tables are off it will not correct it until you come to a complete stop.

[redhardsupra]

yup, tune your RAF and you'll get a lot closer.