New CAM and Idle Assistance

[Behold]

I have just fitted a new cam. Its quite a large cam so its affected the running a lot. It runs fine, little lean nothing an AutoVE will not sort out.

I am trying to sort the idle out.

It will idle and holds at 800 as expected but after a rev or slow down from speed. I have sorted out the fueling in the VE for idle and this has helped a lot. but I assume I need to sort out the spark table. it ticks over at 65-68KPA should I increase the spark to match similar to 30-35 ish. (27degrees I think).

Which spark table is it? is it the Base Spark table. B5932 B5933?

Anything else I need to think of?

Also on start it really struggles with out any throttle. is this a fuelling issue or is this my throttle body needing a larger pilot hole?

anything I should particularly log? I am starting to trawl the forums but any help would be good.

[joecar]

How big is the cam (indur/exdur lsa +adv)...?

[joecar]

...
Which spark table is it? is it the Base Spark table. B5932 B5933?
...Yes, base spark in G and in P/N.

[Behold]

the cam is

282/294 (230/242@/.5)
LSA 115 and +2 Advance

I made some changes. Throttle Cracker and startup airflow correction tables. and the idle learning to 4.3. and It certainly runs a lot better than it did. it starts and idles well with a nice sound to tick over. on a spirited stop it does drop to 2-400 RPM and may not always recover unless I blip the throttle.

could it be its struggling air? or should I be looking at leaning it out a bit more. currently its bang on 14.7 AFR

I have not touched the spark yet.

[joecar]

230/242 115 +2

this cam has 6* overlap, so maybe bump desired idle speed to 900 rpm.

Yes, maybe try more desired air.

What intake manifold and throttle body do you have...?


How are you determining the AFR (wideband...?)...?
Generally, as overlap increases, at idle, wideband will tend to read leaner (unburnt fuel and oxygen passing thru), so yes try going a bit leaner that what you see.
If you don't have catalysts, try to see if you can smell unburnt fuel in the exhaust, this will tell you if it's not lean.

[Behold]

Sorry for the delayed reply.

So it's a LS6 intake and ls1 TB. I have followed the tutorials and played around with settings. The RAFIG table is tuned and spark bumped up.

It idles a bit better but still stalls coming off throttle or after blipping. It actually idles really smooth at 800-850-900 and 950.

So I'm lost. Do I just need more air in on idle. Do I ream out the blade hole? If so how much at a time? File it or drill it?

It's the most annoying bit. Any load as well can cause it to die. Often the spark is stable. And at 500rpm can recover. But often drops to 1-200. If I get on the throttle it will catch and stay running.

[joecar]

...

It idles a bit better but still stalls coming off throttle or after blipping.

...This sounds like Throttle Follower...

[ProperTuningOG]

What is the IAC holding at when at normal idle no load? Sounds like there isn't enough base airflow. On DBC the IAC is there to help control Idle not totally control, I mean its there to ramp in and out of idle. It can not do that quickly so there has to be proper base air. I deal a lot with off road race, huge loads at idle and have come up with my own method for the cars running well down low and not dying. I get enough airflow so when there is no load the last bit of idle RPM is spark trimmed. So when load is placed spark returns and air can be added by IAC as it is needed. The way I see it all base engine load has to be taken care of without idle air trim.

This is what I deal with. They go from all out....
https://photos.smugmug.com/2016/U4-China/i-sqvfJVg/0/M/1475608304.jpg.1024x683-M.jpg

To technical rock crawling. Here is a shot of the steering setups that draw massive parasitic load down low.
https://photos.smugmug.com/2016/U4-China/i-Xmv52t9/0/M/IMG_1938-M.jpg

That one had a bad day. DOM housing didnt like the skying out. LOL. These were both from an event I was at in China the past 3 weeks, babysitting 10 cars.

Plenty of other examples in HERE (http://photos.team208motorsports.com/2016).

[joecar]

Your pics are not showing up...

[ProperTuningOG]

Your pics are not showing up...

Really, they show up fine with all devices logged in and out here. Country issue?

[joecar]

Might be my internet...

[Behold]

IAC hold the RPM at the RPM set (800 or 900 had been tested) I need to check IAC steps.

I need to log idle field again (this weekend) to see what its doing now.

Base Air seems to be set right. Its about 14.7-8 on tickover maybe a little too rich still if the WB is miss reading a bit. but any leaner it seems to not like it as much. I have added and removed spark with about 21 degrees being the best on tickover. it floats from 16-23 I think as it ticks over. tick over is actually

Follower as @joecar says could be to blame. not fully sure as even if its been ticking over and I turn the wheel. and it can stall under load from the PAS. No throttle touched. this is more of a problem when warm.

[statesman]

Have you tried what was suggested to you here?...


I get enough airflow so when there is no load the last bit of idle RPM is spark trimmed. So when load is placed spark returns and air can be added by IAC as it is needed. The way I see it all base engine load has to be taken care of without idle air trim.


This will work provided you make your spark corrections a bit more aggressive.

[Behold]

sorry for going a bit quiet. Lots going on.

I have*tried Spark*corrections, RAFIG setup and Follower alterations.

The issue is better but not 100%.*Still coming to a stop from speed (30+) no throttle touched on deceleration it will likely stall.
Warm its worse and seems more likely*to stall*from the same*scenario.

if its about to die I can recover from 400RPM or less (seen 250rpm before)*with a kick of the throttle.

I know many say bigger holes or moving the*blade is not right to*do but surely there is merit to need this? the older LS1 with cable*either uses a stopper on the blade or a hole in it. some a combination of both IIRC.*
Having worked on*another*vehicle with a larger than stock cam that was tuned (not by me) to not stall using follower.*It just seems a*hack to cause it to hang to increase likely hood to not stall.*This*is an LS3 with ETC so it can hold the throttle open effectively making a larger hole.

I'm really at a loss and maybe my ECU tuning limit right now to get any better result and I do just wonder how much*we are trying to*fix an issue that has a physical*engineering limit.*Don't get me wrong I fully belive the ECU needs altering hugely to match the new modifications but surely its*like*trying to electronically alter the intake pipe to a larger diameter to get more air in. you cant do that.

I might be opening a can of worms here! Thanks all

[statesman]

Post your tune file.

[rich24v]

sorry for going a bit quiet. Lots going on.

I have*tried Spark*corrections, RAFIG setup and Follower alterations.

The issue is better but not 100%.*Still coming to a stop from speed (30+) no throttle touched on deceleration it will likely stall.
Warm its worse and seems more likely*to stall*from the same*scenario.

if its about to die I can recover from 400RPM or less (seen 250rpm before)*with a kick of the throttle.

I know many say bigger holes or moving the*blade is not right to*do but surely there is merit to need this? the older LS1 with cable*either uses a stopper on the blade or a hole in it. some a combination of both IIRC.*
Having worked on*another*vehicle with a larger than stock cam that was tuned (not by me) to not stall using follower.*It just seems a*hack to cause it to hang to increase likely hood to not stall.*This*is an LS3 with ETC so it can hold the throttle open effectively making a larger hole.

I'm really at a loss and maybe my ECU tuning limit right now to get any better result and I do just wonder how much*we are trying to*fix an issue that has a physical*engineering limit.*Don't get me wrong I fully belive the ECU needs altering hugely to match the new modifications but surely its*like*trying to electronically alter the intake pipe to a larger diameter to get more air in. you cant do that.

I might be opening a can of worms here! Thanks all

Excuse if totally irrelavent to your cause....
Does seem to be a fair amount of stuff that just doesnt work when going maffless....I assume you refer to my ls3 E38?....BTW very grateful for your help getting up and running to point I'm not too scared to try changes myself.
The table we modified was B1860 Airflow dec rate ?....I'm not actually sure this did the trick, more likely as you got closer with the VVE at the same time that was more help. ( It still suffered stalling with small parking manouvers ect.)
I subsequently made bigger and bigger changes to that table with little/zero affect.

Couple of days ago I compared the B1829 Min Idle Airflow table with the HPtune table after coverting the units ect. The HPtuner table numbers at low rpm were almost double, so I mirrored the settings into B1829
Bingo....sort of....drop to idle now behaves like the hptune where rpm will drop to just below target (not as much as before) and pick up by ~120rpm above target before settling to target after about 7 secs or so.
Still an annoying idle hang period, and I know it's probably viewed as a bodge, I will try reducing the table bit by bit. For now though it's much better than before and a lot less likely to stall on me.

[Behold]

20697

Played a bit to day.1 thread movement on my Throttle stop has massively resolved the issues. Still not perfect and 2 threads was too much it hung quite a bit. but I guess a new RAFIG tune will be needed now air expected will be more that it should be.

Thanks

[spy2520]

I've had that issue and played with idle settings alot. I think I'm around 24* and 13g/s with much improved results. Cam specs are 236/238 on a 113 LSA. Leaning out the idle cells in the VE table also seemed to help.

[Behold]

I solved it in the end. Still needs fine tuning but opening the throttle plate a fraction ( I really mean a fraction) and it now idles like a dream. No hanging no stalking easily unless turning the wheel a lot on parking.

I'm sure it can be made better but it's worlds apart from before. I tried advance, leaning. Nothing worked.

[spy2520]

Yeah I forgot to mention I did have to drill the TB, tried opening the throttle plate but I guess with this cam it just needed too much.

[5.7ute]

I found dropping idle timing to around 13 degrees, using a more aggressive spark correction and drilling the blade to give 30 - 40 steps at warm idle fixed all my issues. You can drive off from a complete stop with little to no throttle input using this method. This is a 236/242 ls3.