Heads/Cam LS1 Idle Surge

[Dscott16]

Hey guys been driving myself crazy trying to get rid of the idle surge on this setup. Its a 2004 ls1 with PRC 225 heads and 228/230 duration .588 Lift cam, 36lb GTP injectors with a t56 behind it. It runs great everywhere but idle.

Ive tried locking timing and fueling. Used Russ K's idle airflow config.
All adaptives should be turned off
The only thing ive noticed is that if I lock the IAC position it hardly surges at all.
I attached a log of the surge it gets worse towards the end and at the end I locked the IAC.


idle surge 2.hpl

2004 gto Idle tune file_0001(closed loop disabled)_002.hpt

[Gyver-it]

In your Engine>Fuel>Transient>Min Fuel Milligrams Tab. Try lowering that value to half of the 0.032 that you have in there now. Looks like you have the 42# injectors, that may take care of it for you.

[Dscott16]

In your Engine>Fuel>Transient>Min Fuel Milligrams Tab. Try lowering that value to half of the 0.032 that you have in there now. Looks like you have the 42# injectors, that may take care of it for you.

I'll give that a try thanks. Also injectors are 36lb GTP's.

[Dscott16]

So changing the min fuel grams had no effect on idle quality. Any other ideas out there?

[kevin87turbot]

It's still a bit rich at idle. I leaned it just a bit. The VE table has some odd spots in it that I smoothed just a bit. I've found that sometimes, when all else fails, change the Over/Under Spark tables to a more aggressive ramp. I incorporated that into this tune. You might give it a try. 2004 gto Idle tune file_0001(closed loop disabled)_003.hpt

[Camaro6]

Did you post the log, I don't see it? You have zero base airflow for p/n. I idle LS cars at 800-810 with a steady idle. Lean is usually the hunt for idle surge culprit. Your MAF is 0 from 0 to 5,000hz. why?

I just did a Monte Carlo LS1 swap with the same mods pretty much except he had 40lb injectors, heads were worked a little, fast intake, and bigger tb. Put down 384tq (3948rpm)/381hp (6136rpm) to the wheels through a 4L70 with 3k yank stall. Load this one and see how idle is. It's you tune with idle items changed.

I really need the stock tune, MAF fixed, and then a log file of the car idling and start to drive area. Let it go into closed loop. My LS1 Firehawk has the same cam size roughly, stock heads, LS6 intake, ported tb - local shop tuned 15yrs ago- it put down 390 through T56 - that was before I had a dyno or messed with tuning.

2004 gto Idle tune file_0001(closed loop disabled)_002 changed.hpt

[Dscott16]

Did you post the log, I don't see it? You have zero base airflow for p/n. I idle LS cars at 800-810 with a steady idle. Lean is usually the hunt for idle surge culprit. Your MAF is 0 from 0 to 5,000hz. why?

I just did a Monte Carlo LS1 swap with the same mods pretty much except he had 40lb injectors, heads were worked a little, fast intake, and bigger tb. Put down 384tq (3948rpm)/381hp (6136rpm) to the wheels through a 4L70 with 3k yank stall. Load this one and see how idle is. It's you tune with idle items changed.

I really need the stock tune, MAF fixed, and then a log file of the car idling and start to drive area. Let it go into closed loop. My LS1 Firehawk has the same cam size roughly, stock heads, LS6 intake, ported tb - local shop tuned 15yrs ago- it put down 390 through T56 - that was before I had a dyno or messed with tuning.

2004 gto Idle tune file_0001(closed loop disabled)_002 changed.hpt

Log of the idle is in my first post just in front of my tune, it almost looks like there the same file.
MAF is zeroed out because im running in speed density only.
Base airlfow is zero in P/N because its a manual.

Sorry i haven't been to active on here its been a bit hard to find time to mess with the car lately

[anniversaryss]

I would start by logging STIT and LTIT or anything that has to do with adaptive idle. Your adaptive idle kicks in around 176 and it seems that's where things seem to take off.

[Dscott16]

Heres a log with stit and ltit logged. I thought all my adaptives were turned off but I guess I wrong. Have way through this log I commanded a set IAC value and locked timing. It seemed to idle pretty decent.
Id guess I just need to tune my adaptives a bit right?

Idle surge 3..hpl

[Jeff7577]

What are the idle fuel trims in closed loop? It seems to be idling on the rich side. Command leaner mixtures through the scanner with timing locked and adaptives off to see if the idle will steady. I just did a BTR stage iv cam with longtubes and had VE at 29 in the idle areas otherwise it would go out of control.

[Dscott16]

What are the idle fuel trims in closed loop? It seems to be idling on the rich side. Command leaner mixtures through the scanner with timing locked and adaptives off to see if the idle will steady. I just did a BTR stage iv cam with longtubes and had VE at 29 in the idle areas otherwise it would go out of control.

You were right! leaning it out made it idle nice and steady. Only problem now is when I enable closed loop it adds fuel back in and creates another surge not nearly as bad though.

[Jeff7577]

You were right! leaning it out made it idle nice and steady. Only problem now is when I enable closed loop it adds fuel back in and creates another surge not nearly as bad though.

Yeah I had to make it go open loop at idle by setting the PE throttle position at 0 up to 1200.