Another beginner needs help. Idle / rpm hang issues

[SirNemesis]

Hi guys,

I'm having a lot of issues understanding idle and even though many people have given great advice, it still just isn't clicking in my head. I figure a post on this forum begging for help is my best option. This isn't to say that the people who have helped in the past haven't done a great job, just that it’s still a whole other language to me.

OK, so what I've got. I'm driving a 2002 Holden Statesman with several modifications. This I'm sure is the cause of most of my issues as I'd struggle to tune a 100% standard car, and I feel I've really jumped into the deep end trying to tune something with a lot of areas that need attention.

Holden Statesman’s are only available as a factory automatic. I've converted mine to a T-56 manual. I've also converted it to an L76 6-litre with a 227/234/113 cam. I'm running without a MAF, with a CAI and decent exhaust system. I'm using a FAST 92mm cable throttle body, L76 standard injectors (39lb I think?) and a Lingenfelter crank signal converter. I think that’s all the mods that should make a significant difference to the tune, but I'm happy to go into detail on anything else if it helps.

My tune was provided by an Australian tuner as a base tune, and from a power perspective it goes very well and makes good power. The problem is the low rpm drivability and idle isn't up to scratch.

I have been driving it as-is for several months, with little modifications here and there to try and make it more friendly, but it seems no matter how hard I try any changes I make give the opposite to desired result. Today I opened the throttle stop screw a little more which has stopped my car stalling when approaching an intersection. This has helped immensely, but I still have idle hanging issues when changing gear and before I reach a complete stop, and obviously isn't the best way to go about things as now I sit with 0 IAC steps on a warm idle. The car also still drops in RPM and tries to stall when trying to park and occasionally when doing a U-turn.

I've posted my current tune and a couple of log files from today. If someone could please explain to me how I can use these logs to make positive changes to the drivability to the car that would be greatly appreciated. I'm also interested to hear any changes to the tune that someone would recommend, and why they would recommend them. Also, if I'm logging incorrectly and should be doing something different, please let me know.

[WeathermanShawn]

Welcome to the Forum:

I am not as well-versed with the Holden Platform(s) and running MAF-Less.

But, I must say you have a very well-written summary and description of your concerns.

You should get a lot of assistance during the next week.

How do you like that cam?

[gmperformancecentre]

try this
make sure you have a copy of your current tune to go back to if this doesn't help
also return the throttle stop screw back.
do you also have the Lingenfelter crank signal converter away from any heat source.

[DrkPhx]

If the above changes don't work, I would completely disable the the Throttle Cracker (TC) table (which would disable the Rolling idle tables) and rely on the Throttle Follower (TF) tables. This works for me especially well on M6 cars with aftermarket cams. The TF tables are different between the LS1 M6 and A4 cars so maybe start with LS1 PCM M6 values as a reference. If you disable the TC, you may have get a rpm dip when pressing in the clutch or it may drop too fast to idle. In that case you will have to increase the TF airflow values and delay, but decrease the decay rate. This will slow the rate to a stationary idle. The opposite is true if you want to reduce the hanging idle. I also noticed you have some pretty big spark swings at idle. Look at the Idle Overspeed and Underspeed spark tables to reduce the swinging.

BTW - There is an excellent idle tuning tutorial on this board that deals specifically with these issues. It's well written and worth the read.

[joecar]

showthread.php?4661-Idle-Tuning-Helpful-Info-Inside

[SirNemesis]

Welcome to the Forum:

I am not as well-versed with the Holden Platform(s) and running MAF-Less.

But, I must say you have a very well-written summary and description of your concerns.

You should get a lot of assistance during the next week.

How do you like that cam?

Thanks WeathermanShawn. I've been holding off on asking these questions for a long time now, but I finally feel as though I've got enough free time to stop and learn a few things about tuning instead of just patching up problems.

I like the cam, but I'd in all honesty I'd like any cam. It brings a smile to my face every time I go over 4000rpm, but I'd be even happier with it if it easier and smoother to drive in lower RPM / light throttle situations. My previous setup was an LS1 with a 220/220/112 which wasn't as much fun as what I've got now.

try this
make sure you have a copy of your current tune to go back to if this doesn't help
also return the throttle stop screw back.
do you also have the Lingenfelter crank signal converter away from any heat source.

Thanks gmperformancecentre. I've tried your adjusted tune and it seems to have improved, but I think its too soon to tell as I'm still trying to find the ideal throttle stop screw position. I'm not sure if this is a problem with my tune aswell, but I have a lot of trouble finding a throttle stop position that allows both cold start without throttle assistance and driving without rpm hanging. I've always had the issue where my IAC steps would max out at 310 yet the car would still struggle to get the RPM up on a cold start.

I'll keep driving it around and post up some logs over the next couple of days.

If the above changes don't work, I would completely disable the the Throttle Cracker (TC) table (which would disable the Rolling idle tables) and rely on the Throttle Follower (TF) tables. This works for me especially well on M6 cars with aftermarket cams. The TF tables are different between the LS1 M6 and A4 cars so maybe start with LS1 PCM M6 values as a reference. If you disable the TC, you may have get a rpm dip when pressing in the clutch or it may drop too fast to idle. In that case you will have to increase the TF airflow values and delay, but decrease the decay rate. This will slow the rate to a stationary idle. The opposite is true if you want to reduce the hanging idle. I also noticed you have some pretty big spark swings at idle. Look at the Idle Overspeed and Underspeed spark tables to reduce the swinging.

BTW - There is an excellent idle tuning tutorial on this board that deals specifically with these issues. It's well written and worth the read.

Thanks DrkPhx. I'll try tweaking/disabling the TC values on the weekend to see how it behaves. I've tried this before a while back and it resulted in my car stalling while reversing out of the driveway, but I'm sure there are ways that I could work around that if need be.

showthread.php?4661-Idle-Tuning-Helpful-Info-Inside

Thanks joecar. This guide has been very helpful to me in theory, but not in reality. I've read it multiple times and it's helped to give me a better understanding of how TC and TF function, as well as sparks effects on idle swing but unfortunately any changes I've made to my tune after following this guide have resulted in the opposite than desired outcome. Without doubt I'm looking at the symptoms of a problem and trying to patch them instead of actually focusing on the cause.

[WeathermanShawn]

Sir:

Are you 100% sure your MAF is failed? Where is your MAF DTC?

I don't know if it is standard procedure to be manipulating the Throttle Screw. Seems like that will make it hard to diagnose whether it is tune related or mechanical. I.E., your tune could look perfect, but if your are manipulating the Idle airflow in another fashion..how will we know what is controlling your Idle Air.

Your modifications and conversions make this out of my league, but those are a few general thoughts.

Good luck.

[SirNemesis]

I'm about as sure as a beginner tuner can be. C2901 and C2903 are set to 1 and the MAF is unplugged, which I think is right.

I know playing with the stop screw isn't the correct method and once I've got it back to where it should be it won't be touched again. I believe the idea is to have the IAC steps sitting at around 60-80 steps on a warm idle, which is about where I have them now.

[WeathermanShawn]

Sir:

I realize you have your MAF physically removed. But, check out this thread about MAF DTC's. Without one present, you will still be using the MAF Table..http://forum.efilive.com/showthread....l=1#post119580

Granted, sometimes DTC's will not be stored in the log (BBL according to 5.7ute). So here is the easiest way to check. In Table C6001 change P001-P003 to A: 1 Trip, Emissions Related. In Table C6002 change P001-P003 to MIL.

You should see the MIL 'light-up'. Then log.

I would hate to see you go tho all this trouble, and find your airflow and fueling was all coming from the MAF. That would obviously effect your Idle.

Like I said, your tune is complicated..but that is an easy sanity check..

[5.7ute]

SirNemesis, I had the same issues as you shooting for 60-80 steps at warm idle where there wasnt enough airflow at a cold start at 310 steps. I found leaning out the mixture at idle to help, along with some major work in getting the base idle solid.
What you could also do is open up the IAC passage in small increments, being careful not to damage the pintles seat but this would be a last resort.