Dialing in low LSA cam idle

[blkscooby]

Here's my current tune after 2 weeks of work. Its getting closer, feels much smoother than it looks.

2008 G8 GT
Comp Cams Thump 219/233 .553/.536 109 LSA, 103 ICL +5
LS9 springs
Comp Cams 7.425" rods
DOD intact
Ported TB
Ported stock exhaust manis
cat delete pipes
TR6 plugs gapped at 0.040"
Homemade 4" CAI
Homemade catback w/ x-pipe

Car runs real good, idles just a little rough, has slight jerk in 6th gear decel under 1,500 RPM. I think the random knock (new this week) is due to an issue with my catch can.

I currently am running MAF only, DFCO off, DOD on but not activating for some reason.

Comments? I followed 5_Liter_Eater's idle air tuning guide with limited success a few days ago. I just feel like I'm chasing my tail with the idle air.

This log was my morning commute. I changed the extension on the log to .hpt since it exceeded the file size

[IDRIVEAG8GT]

M cam has more duration and is down on a 112 LSA. When I get home I'll throw up my tune for you. It's the Airfow numbers that should get you about right. Also the cab shake at idle, well can be adjusted with spark idle numbers, but it won't lope quite as nicely.

As for your bucking issue, what size is your stall? Mine starts getting shitty around 1,200 rpm with a 2,800 stall supercharger converter.

[IDRIVEAG8GT]

Try the airflow and idle base spark advance control on for size. Don't use the spark under/overspeed tables though unless you want it to shake your brains out lol.

[02Ls1]

Yea i have tune 112 lsa's cam's and the airflow is greater than yours on your tune i have no problems on surging.

Hey IDRIVEG8GT, your is running on SD mode?

[blkscooby]

Stock stall. I have the light bucking just about taken care of in my latest revision (one past what I posted).

Thanks for posting the tune.

[IDRIVEAG8GT]

Yea i have tune 112 lsa's cam's and the airflow is greater than yours on your tune i have no problems on surging.

Hey IDRIVEG8GT, your is running on SD mode?

That's because you use throttle as your primary idle control. I use spark, which creates a much niftier cleaner chopping lope.

And yes 2.5 bar. Set on 9 psi now lol.

[IDRIVEAG8GT]

Stock stall. I have the light bucking just about taken care of in my latest revision (one past what I posted).

Thanks for posting the tune.

That cam on a stock stall is going to net terrible low end performance IMO. Next mod equals stall change, then your problem will be completely cured.

[blkscooby]

This is Rick's (G8-4-Speed) old cam. He also ran it with a stock stall. Honestly, it's not really bad at all. If I can get the idle just a little smoother, I'll be happy. It doesn't push at low speed braking to a stop.

[blkscooby]

Actually the low end is awesome. It performs like a Torquer cam. Off idle response is great and really gets the car moving.

[blkscooby]

Here are the logs from this morning's commute. IDRIVEAG8GT- I copied over your idle air min table and followed your idle spark and low RPM, low load spark table. Also zeroed out the cat warmup spark adder tables as I am catless also.

I need to look at the fuel trims though. I noted that they are +12% when in coastdown and not sure why. I'm running MAF only right now and I've had this MAF tuned for a long time. Either the VE table (which needs more work) is affecting the fueling still or the change in spark advance in low load, low RPM is the cause. Obviously I can't have a huge spike in the low RPM MAF table so I will probably have to switch back to pure VE for a while and dial that in.

The idle choppiness and spark variation was worse with the increased air in the idle min table vs. where I was. I think it has too much air now. But the coastdown in 6th was better. I think if I drop the timing in this area more, the light surging in 6th gear coastdown will go away completely.

[blkscooby]

Yeah it had too much air at idle, was surgin like mad. Good news is I am startign to understand how the changes I amke will affect the tune. I believe I will have to work on the idle under/over speed since the idle is so choppy.

[blkscooby]

What causes "Stability Control OFF" message to light on a G8? This appears at idle now.

[SultanHassanMasTuning]

thats caused due to the cam, in relations to TPS. PMed you the solution

[IDRIVEAG8GT]

I figured it's a low vacuum code.

[IDRIVEAG8GT]

Huh, usually tight LSA's net crappy low end. Um, I'm sorry the idle air didn't work. Did you hit the TB cleaned button in the scanner to relearn the values?

When I converted to 2.5bar SD I actually had to remove 30% idle air flow or else my car would stick around 1,000 rpm, even though I commanded 800.

Lol I thought I said not to copy the idle under/over speed tables unless you wanted it to chop like mad.

The smoothest factory tables you can run concerning spark is that from a 2008 Sierra Denali. They're set extremely close to each other in spark recovery and will get you where you want to be. Download a tune from the repository. To change the way it lopes increase/decrease idle airflow at the rpm it idles. Setting the idler airflow purposely a bit low nets the smoothest idle possible, as it forces the EXM to manipulate the spark control and advance the base numbers completely. Try a base idle timing of 16 degrees and see how you like it.

[blkscooby]

Huh, usually tight LSA's net crappy low end. Um, I'm sorry the idle air didn't work. Did you hit the TB cleaned button in the scanner to relearn the values?

When I converted to 2.5bar SD I actually had to remove 30% idle air flow or else my car would stick around 1,000 rpm, even though I commanded 800.

Lol I thought I said not to copy the idle under/over speed tables unless you wanted it to chop like mad.

The smoothest factory tables you can run concerning spark is that from a 2008 Sierra Denali. They're set extremely close to each other in spark recovery and will get you where you want to be. Download a tune from the repository. To change the way it lopes increase/decrease idle airflow at the rpm it idles. Setting the idler airflow purposely a bit low nets the smoothest idle possible, as it forces the EXM to manipulate the spark control and advance the base numbers completely. Try a base idle timing of 16 degrees and see how you like it.

I didnt use your over/under tables. Mine are basically still stock.

I havent used the TB cleaned button, will have to do that. I used the 5L Eater method last night again and honestly, during the tuning with the idle airflow table zeroed, it idled the best it ever has.

I also worked the VE values again as I was getting +25% at idle. Thats much closer too but I wasnt sure how much of that was from unburnt fuel escaping into the exhaust. I have +8* overlap. I also played with advancing the end of injection boundary by 12-13* and it seemed to make the exhaust stink less like raw fuel.

Honestly, it was running fairly good on Friday morning then I dropped it off and had new tires mounted. After is when I started getting the stability light and stalling. I just realized this morning I hadnt changed the tire dia info as the new tires are shorter than the old. Maybe has nothing to do with it but I was just trying to think of what changed.

Later I'll look at the 2008 Denali tables for comparison. My spark tables are pretty smooth and I'm commanding 17-18* at idle now.

[IDRIVEAG8GT]

Got an idle log handy?

[blkscooby]

Here's where the tune is at now. I believe the tire dia being off was causing some of the issues I noticed on Fri. Also, disabled PO0086, PO0101, PO0106 tests, reset the TB through the VCM controls this morning. The car is back to driving well and almost being where I want it.

I am getting +25% at idle, in neutral. I've worked on the VE table for over a week, so its much closer too but I wasnt sure how much of that was from unburnt fuel escaping into the exhaust. I have +8* overlap. I also played with advancing the end of injection boundary by 12-13* and it seemed to make the exhaust stink less like raw fuel. Should I continue to increase the end of injection timing boundary until this lean condition goes away or should I work on the VE table? It seems that changing the VE table in this area didn't have an affect on STFT. Before I advanced EOIT the other day, at idle the exhaust hurt my eyes but the rest of the VE table was dialed in. I advanced EOIT 13*, exhaust is better but now VE is off (to be expected I guess).

Attached are 3 logs from my morning commute. Log 1 in the beginning once the car warmed up and log 3 toward the end have idling in them. the rest is driving.

[DSteck]

Post your cam timing events, particularly intake valve opening point at 0.006.

[blkscooby]

Here is the cam card.