Lean Idle

Holden/Delco Tuning. ALDL, OBD 1.5. Circa 1989 to 2004.
lowace
Posts: 59
Joined: Thu May 18, 2017 8:22 pm
cars: 1964 Eh holden and daily series 3 vs 5.0 ute

Lean Idle

Post by lowace »

Hi guys just wondering if some one could point me in the right direction with the idle on my vs s3 v8 ute, I am using the enhanced code and when its idling warm it tends to sit around the 1.17 lambada which is really quite lean. I have tried changing the fueling in that area on the map and also tried the afr targets on the idle chart but it doesn't seem to change much. Is it worth worrying about it ?
immortality
Posts: 3416
Joined: Thu Apr 09, 2009 12:31 pm
cars: VH, VN, VS, VX

Re: Lean Idle

Post by immortality »

VS s3 tune is much like the ecotec V6 so there should be an option for Open loop Idle somewhere I believe.
lowace
Posts: 59
Joined: Thu May 18, 2017 8:22 pm
cars: 1964 Eh holden and daily series 3 vs 5.0 ute

Re: Lean Idle

Post by lowace »

Yeah there is and I have adjusted the table but it doesn't help for some reason. Its only when its fully warm that it does it.
immortality
Posts: 3416
Joined: Thu Apr 09, 2009 12:31 pm
cars: VH, VN, VS, VX

Re: Lean Idle

Post by immortality »

Turn off the open loop idle and see what it does then.
lowace
Posts: 59
Joined: Thu May 18, 2017 8:22 pm
cars: 1964 Eh holden and daily series 3 vs 5.0 ute

Re: Lean Idle

Post by lowace »

immortality wrote:Turn off the open loop idle and see what it does then.
I'm still quite new to this tuning, where do I turn it off I've had a look and m not quiet sure how its done.
Thanks heaps for your help
immortality
Posts: 3416
Joined: Thu Apr 09, 2009 12:31 pm
cars: VH, VN, VS, VX

Re: Lean Idle

Post by immortality »

Should be an option flag to select open loop idle.

What engine mods/tuning has been done?
lowace
Posts: 59
Joined: Thu May 18, 2017 8:22 pm
cars: 1964 Eh holden and daily series 3 vs 5.0 ute

Re: Lean Idle

Post by lowace »

Has a mild cam on completely stock bottom end, a stroker is planned for early next year. The only external bolt ons are a set of pacemaker extractors.
It does have issue on cold starts in the mornng also where it is hard to start runs really rough and is hesitant to take throttle, it is running quiet rich on cold start around the 13.1 which I thought would be normal during cold starts.
Here are the cam specs
Hydraulic Roller
ADV In 290 EX 297
@50 In 216 EX 220
112 Lobe sep
Lift .308 on both
immortality
Posts: 3416
Joined: Thu Apr 09, 2009 12:31 pm
cars: VH, VN, VS, VX

Re: Lean Idle

Post by immortality »

TBH it sounds like it actually needs more fuel. Engines start up really rich and then progressively lean out as they warm up before they go into closed loop operation.

Open loop literally means the PCM measures the amount of air entering the engine and then adds the amount of fuel to achieve the set AFR target on the open loop table. Seeing as you have a cam the airflow characteristics will be different to a stock engine. It will probably also want a little more timing in the idle/low rpm area of the map as the engine won't be quiet as efficient with the cam.

Do you have a WB O2 sensor fitted? If not, disable open loop idle once the engine is warm see what the fuel trims are doing and adjust accordingly. Once it's running well in closed loop with very little variation in the fuel trims then try open loop idle again and see what it does then.
User avatar
Holden202T
Posts: 10311
Joined: Sat Feb 28, 2009 9:05 pm
Location: Tenambit, NSW
Contact:

Re: Lean Idle

Post by Holden202T »

open loop idle has nothing to do with the fuel side, its purely the pcm controlling the idle speed, by adjusting IAC and timing to achieve the desired idle rpm.

if its lean at that point it will need the tune adjusted to suit..... being that its got a cam in it and exhaust it probably would be lean.

not taking throttle on cold start is another good sign its lean, and 13.1 cold its probably not rich enough (depending on the temp) it will more than likely want to be 13.5 to 14 on warm idle i'd suggest.

and I wouldn't be surprised if the tune will want a slightly higher idle rpm too.
lowace
Posts: 59
Joined: Thu May 18, 2017 8:22 pm
cars: 1964 Eh holden and daily series 3 vs 5.0 ute

Re: Lean Idle

Post by lowace »

Thanks heaps for the replies its much appreciated as I'm still learning. The temps here in Orange lately have been in the minus region so I will try and get some more fuel in and see what that does, its interesting as I have the idle speed at the lower temp range set to 1200rpm but it doesn't seem to try and get to it. It runs really well other than the fact it could do with some more comp but that will come.
Post Reply