G8 Idle Help - Small Cam and Converter

[nskaats]

I have a G8 in the shop with a BTR Stage II LS3 Cam that recently got a torque converter install. After the cam install it never would idle the way it should with a stock converter. So the customer decided to put an Ultimate Converter Concepts 3,000 RPM converter in it. Even with the converter it surges all over the place when cold. Once it warms up it'll idle. When you drop it into gear it surges wildly again.

It was originally tuned elsewhere before I opened up shop and always had some idle issues. What's weird is no matter how much I change idle airflow up or down, it seems to do what it wants. It is speed density tuned and open loop idle. Wideband verifed even when surging the AFR is between 14.1 and 14.7 consistently. I've added a couple logs and the tune file. Any help would be appreciated.

[VFL77]

A newb's perspective...
Not many of your IDLE tables are stock...in particular the Integral RPM [2184] is set to a value that will hold it from ever kicking in and I'd try some closer to stock Airflow tables for Integral and Proportional (Adaptive idle).
There's a bunch of other things that 'look interesting', but I'd start there and compare against a stock tune.

[nskaats]

A newb's perspective...
Not many of your IDLE tables are stock...in particular the Integral RPM [2184] is set to a value that will hold it from ever kicking in and I'd try some closer to stock Airflow tables for Integral and Proportional (Adaptive idle).
There's a bunch of other things that 'look interesting', but I'd start there and compare against a stock tune.

Unfortunately I don't have the stock file for this car. I'm still trying to figure out everything that was changed previously. I'll download one from the repository and give it a look.

[Niemer]

I can't open the files at work, but what are the idle proportional and integral enable RPM values? It could be getting into an underdamped condition when the RPM fluctuates outside the limits.

[nskaats]

I can't open the files at work, but what are the idle proportional and integral enable RPM values? It could be getting into an underdamped condition when the RPM fluctuates outside the limits.

[Niemer]

Try bumping the proportional up to 100 rpm. You could also read through this and give it a try, https://forum.hptuners.com/showthrea...e-tuning-guide

[GHuggins]

Do as previously pointed out - your integral won't kick in at all - it's your immediate corrector - it's set to a 4000rpm error before it'll do anything / on top of this your main timing tables are set to 24 degrees - your idle timing is set to 24 degrees = no headroom for the idle corrective spark values to do anything - main timing table needs to be 10 to 15 more than your idle timing - you might also want to set idle timing to something around 12 or 14 degrees to help stabilize it...

Another note to point out - the integral and proportional somewhat work opposite of one another... Higher values on the left side of the proportional table will bring rpms down slower/add more air and timing in... Higher values on the right side of the integral table causes more air to be added in for your rpm corrections... If you have one bucking or trying to jump after releasing the clutch for example - lower the cells on the right of the integral table...

[Area47]

you honestly shouldn't need to touch a lot on the idle side of it. rpm, RAF, startup, and timing. the stg 2 cam isn't that big. drop the timing down at idle to give the corrections more control over it.

[nskaats]

Thanks for the responses. I haven't had time to get back to it yet, going to dig in tonight or tomorrow. I ended up grabbing another stock file to use as a base. I had no idea that much was changed by the previous tuner. I normally don't have to make any major changes on a cam this small.

[lukearmstrong1990]

you need to find an OS that is the same and input all the stock idle parameters including adaptive idle etc.

will be much easier to fix from there as opposed to where you are now.

given the idle TPS and timing it looks to me like the car wants a bit more air. perhaps an air bleed might help. just start small

[nskaats]

So I finally got a chance to dig back into this thing and solved the problems. I've been scattered about and desperately trying to catch up since I got out of the hospital, so this car hasn't gotten much attention.

Onto the solution. I ended up going back to all stock idle tables and starting over. It still did the exact same thing as before. I adjusted the base airflow, proportional and integral tables, corrected the spark tables and still no change. I was back to square one.

On a whim I decided to pull the throttle body off and have a look. What I found was pretty disgusting. Behind the throttle blade was caked in tons of baked on oil. Enough that no air could get around it at idle. So it couldn't breathe at all without significant throttle input, then when you did give it some throttle it would surge. Once the throttle blade closed it would choke and die.

A little cleaning with some acetone and a rag, bolted the throttle body back on, the thing fired up and idled like new.

Lesson learned: Force a catch can on all your customers.

[GHuggins]

I've picked up right at 20rwhp on heavily cammed cars that only had a year of driving on them just doing induction cleanings, so I can believe that