chevy406

I am working through the tune on my heads (AFR205)/cam (224/230 XFI Comp)/exhaust/intake on an LS1 with MN6, and have it all sorted pretty well except for the idle. I still have two areas to improve:
1. On a slow roll through a parking lot, I get surging below ~ 10 mph. What should be considered a reasonable in-gear low speed in a manual before you have to disengage the clutch?
2. I have some problems at re-start when the engine is warm and has been sitting for a few minutes. Typically the engine will surge at idle and/or wont idle until I have driven it for a few seconds.

I have recently been experimenting with a forced open loop at 1200 rpm and below so that I can force a lean idle. I also recently extended the Update RPM Err Time, which seems to have helped the hot idle surge.

I tried to datalog the RAF %error and update the RAF table, but I think that lead me too far and caused more problems. Any tips on configuration for datalogging the RAF?

CTD

Are you HPT?

Also I'm a bit fuzzy about which intake & TB you have, your sounds like stock?

I have a wee bit more cam 228/228 113*, ported AFR 205's. I't will drive most anywhere.

phils C5 vette

I used to have a TR224 cam, and you shouldnt have any drivabilty issues with that set up.

What tuning system are you using.

hex

You will not have to run it in open loop to get that cam to idle. When your fuel correction at idle is about +10-15%, it will be fine. Get that right, and if you have done your basic idle control adjustments, you'll be fine.

SargeZ06

Are you talking about STFTs?

chevy406

Sorry - I am using HP Tuners.
My intake manifold is a FAST 78, ported stock TB and stock MAF.

It's not like my car doesn't idle decently, I just wanted to know what is considered an excellent level. How low RPM should you be able to creep around in a manual car without experiencing surge?

I probably confused the original question when I threw in the open loop idle tuning. I was just experimenting with that to see if I can improve the fuel economy by forcing a leaner idle.

edcmat-l1

How bout posting a log?

FWIW, I can get a bone stock car to surge at parking lot speeds.

CTD

I'm not a pro tuner! Here is a couple things I've found.

Base Running Airflow sounds like a problem. Russ K idle config will help you, I would post but my tunin puter is busted. Easily found over @ HPT. Once you have that set up, start your car cold with the hood closed, don't touch the throttle & allow it to warm up until the fans come on. Shut it off & copy paste over to the Base Running Airflow.

The timing tables between idle & main, I found if those are the same that helps the very low speed. If driving very slowly you may be switching between those two tables, that will help set a surge off.

I just started trying the OL idle, I was having good results with richening by .5 AFR. That should be within range of the O2 R/L switching voltage, then you can run CL.

At this point my Alternator puked causing a bunch of electrical gremlins! This is not a good condition when trying to tune!

chevy406

Let me work on the Russ Kemp RAF scan first and see if I can figure it out without bothering you. I really appreciate the offer though. I know it doesn't benefit professional tuners much to give help to shadetree guys, but that kindness often has a way of paying off in the long term. I tried using his log several months ago, and kept leading me leaner and leaner until the car would barely even idle. I recenly read the sticky on idle tuning on HPTuners forum, and I have several tables to revise now before I run his RAF scan. We'll see how it does now.

I also found another issue this past weekend. My headers are a slip fit into the x-pipe, and they sometimes slip apart and leak. When I got under it this weekend, I found it was leaking again. Now with the pipes tightened up the O2 sensors aren't seeing false oxygen levels, and it is doing quite a bit better on hot start and idle surge.

Thanks for the ideas CTD. I'll spend some time playing with it this weekend. Goodluck getting your laptop and alternator all sorted back out.

tblu92

I have had the best luck with adding a % to the "desired airflow table" to correct for surging--In HP i think it's called base airflow
Also i would add 3* or so of timing to the "base Timing table" in the idle low RPM ranges
For engine starts the ECM is in "open loop" briefly--i always seem to have to LEAN OUT the "open loop fuel normal table" in the hotter temp ranges for war starts--say from 180 on--start by leaning it out by subtracting .50 to the AFR
With some cams sometimes it helps to delete the "DFCO" system(decel. fuel cutoff)--often with DFCO enabled it will want to dye/surge when coming to a stop

phils C5 vette

Tune your VE tables first, then your MAF. They you'll love your car

Bluefire

I hope this isn't considered a hijack. I have an almost identical issue as the OP. I have an 03, A4 Coupe (CAI, AR Headers, 2800 Yank stall). I recently had a H/C build done. I added new 243 heads. I already had the stock LS6 intake. The cam I installed is a 224/230 .585/.595 113.

Car runs great. Park idle is 950, in gear in 775. Cold start has a very minor surge (+/- 100 rpm). When at normal operating temp. there is no surge at all. However, during an "almost warm" restart (coolant temp is in the range of 120 deg. - 150 deg.) It will start fine but, as soon as I put it in gear and start to touch the accelerator, the rpms go up to ~1000 rpms and then it will drop like a rock to ~700 rpms like it wants to surge but it just dies instead.

I am not a tuner (yet). I am just looking for ideas to give to my builder/tuner when I take it back in. I am sure he will be able to eliminate it eventually. I was just wondering if someone had seen this before and knew the precise fix.

Any clue would be greatly appreciated.

Thank you.