I’m having some start up, idle, and coast down issues

[ss44]

I’m having some start up, idle, and coast down issues. 2005 GTO A4, LS3 480 crate motor (LS Hot Cam), stock converter, headers, UD pulley, 42 lbs injectors, LPE 58x/4x to 24x/1x trigger adapter. On startup it surges up to about 1300 then seeks for a couple of seconds before idling about 900 and during coast down about 1200 gets a surge then settles back down. I was advised to adjust the Airflow Final Minimum up a couple of g/s but then my idle goes high into the 1000 plus range. However, the surging on start up and coast down go mostly away. I could live with the car as is but the wife is very unhappy. I puffed the LS2 and wifey replaced with new LS3 crate, so making her happy is very important.

Everything other then Idle/coast down seems fine. F/A 12.7 -12.8 WOT and conservative timing was 438RWHP/428RWT.

GMPP Hot Cam Specs P/N 88958733 LS Hot Cam I: 219 I: .525 E: 228 E: .525 112 Same cam as in kit P/N 12480033 E: 228 E: .525

[RWTD]

First, nice going on this engine (for those that don't know, it's just an LS3 with the LS Hot Cam). Cool! That's a strong motor.

You have a few issues going on:

#1: You have the LS7/LS3 injectors. However, your injector values are COMPLETELY wrong, so that's one of the issues.

#2: You have a stock VE table, and since the factory system runs a hybrid of VE and MAF, but a TON of VE around idle and part throttle, this is your other issue.

#3: You've completely hacked your Idle Adaptive Spark Control Overspeed and Underspeed tables, thereby NOT allowing enough idle spark correction to take place.

#4: Your Idle settings are also contributing to this, more than likely. I also think your idle speed is too low. What converter do you have in the car?

On another note, you've raped your PE table, and your MAF High table is jacked up.

Okay, I know I sound a bit rough here, but I don't mean to be. I'm also gonna help you out, and build you a new starter tune to work from! Here's what I need from you:

1: What CAI and MAF you're running, and if it's the stock MAF let me know if it has been descreened or not.
2: What brand/model and size of tires are you running? I think you've adjusted your tire height wrong (just a minor tidbit).

[RWTD]

Okay, here's a new test tune for you to use and test. The car should immediately crank, idle, and just plain ole run better. I want to hear all of your feedback to let me know how it is reacting.

Are you familar with datalogging, such as fuel trim logging, etc.? Do you have a wideband?

Lemme know!

[ss44]

Thanks, will check it out tomorrow. The injectors are 42LBS and the tire size is was factory, but who knows what GM did. Again Thanks for the help and will report back tomorrow evening.

Ooops forgot to answer the other questions, Stock screened LS2 MAF and a K&N CAI. Yes, i have a wide band, and as far as Fuel Trim logging, not so sure. This is my real first attempt at a tune, a friend helped with WOT on his Dyno, and i am trying be a little safer as the previous tuner was most likely the cause of the melted LS2 piston.

[ss44]

Haven't had it out yet, but it did idle much better off the bat. Starts flawlessly every time with no seeking for the idle rpm. However, it was shaking the exhaust pipes to the point they were rattling.

I bumped the idle up by 50, and adjusted the Base Idle Spark Advance to 23. Idle is much much better now. And now the tune it reacts the way i expect when i make a change.

Currently i cannot find an adapter for my WB and will be off soon to get it.

Now i am a rookie tuner and you input would great appreasated and maybe there are better ways to get the idle smoother that i don't know about.

Thanks,

LS3GTO

Included about 1 min of idle and current tune with my adjustments.

[Cantalope Kid]

RWTD - Could he benefit from downloading and using the Idle Config.? LS3 (i.e. Virtual VE) is outa' my league right now I believe.

[RWTD]

Do you have the stock converter? If you do, with an idle speed much over 700 rpms you're probably going to find that you're going to have to apply a LOT of brake at idle to keep the car from moving at a standstill.

As for logging, you are logging way too many things that aren't needed. Please use this attached config file to log with (I don't have any of the trans pids listed, but we can add in those later). I'd like 2 separate logs at idle, one in park and one in drive, and both for at least 1 to 2 minutes each, and at full ECT operating temps (18x to 20x range).

Speaking of logging, your fuel trims look perfect at idle. Your LTFTs are only around -4.x.

I've attached a new tune. Let's just keep naming the files in succession, so this new one is test3, and your next one will be test4, etc. I've also reset all your speedo and trans mph settings back to stock, as you said you had the stock tires. Please read my post here to understand why:

http://www.hptuners.com/forum/showth...771#post171771
(post #4)

Regards,

[ss44]

Yes Stock converter, that is why i was so worried about getting the idle back down.

Been having a new issue with my LC-1. IE it doesn't seem to be correct, I replaced the sensor but it is still the same. IE reading 21.9 in atmospheric air and 13.0 at idle. My son seems to think he knows why, and he will be looking into it this weekend.

[RWTD]

I believe you just need to calibrate it. Anytime you lose power to it you have to recalibrate it in open air.

[ss44]

Here are the requested logs. These were taken in park and drive with test tune loaded.

Other question, is my LC-1 stoned or what? or is that the .75 error.

Thanks again.

[RWTD]

Those look perfect to me. You're around -4.x to -6.x % at idle in both Park and Drive. You could scale a lil on the MAF transfer in the idle areas by a .98 to .96, then interpolate between vertical bounds out a cell or two higher than those, but right now I wouldn't even worry with it.

Do you have an open filter under the hood? Your IATs are SOARING at idle, and most likely due to the fact that you do not have any airflow moving over the front of the car. Some heatwrap could do wonders to help that (the IAT is in the MAF on your car, and it gets heatsoaked by radiator and engine and manifolds). Once you start moving you'll see the IAT drop a lot.

Now do this for me, since you have an auto, go out in 3rd gear, and do some steady state cruising at 30, 35, 40, 45, 50, 55, and 60 mph for me. Hold each point for at least 10+ seconds, and then post me up that log here (try to get 2 logs, if you can).

P.s. I'm sure your wife is a LOT happier now, 'eh?

[ss44]

Today's update, removed 100 RPM from idle and added 2 degrees to idle spark advance base. Car is now back to idling rough, but i needed to reduce idle. Added two degrees of idle timing to help rough idle. Included current PCM load, two cruising logs and 2 idle logs.

Thanks again.

[Astona]

hello, and thank you RWTD, SS44's wifey here. Just wanted to thank you for your assistance with tuning out GOAT. Your assistance has been extremely helpful. Again thank you

[ss44]

Ok, back on the Wideband issue. It reads 15.7 - 16.0 at idle. The wideband is an LC-1 and all reading were the same with both sensors. I used this thread to set offset for the GTO - http://www.hptuners.com/forum/showthread.php?t=11018. Now with that said, i installed the WB in my sons 98 camaro and it read 14.8 at idle (no Cat) and 2008 HHR 14.9 post cat. So i assume that LC-1 is working normally.

So, idle is still in need of some adjusting (still a little rough) and AFR is 15.7. HELP!!!!!

I included a 6 min Park idle run with WB installed and logged.

[RWTD]

What is your AFR reading at cruise at a steady state, say 50 to 65 mph? My initial assumptions, if it's not actually a calculation error in your math, or a faulty sensor (you said you replaced it tho), is that the wideband is getting erroneous readings at idle due to the overlap in the cam.

[ss44]

Drove it to work AFR remained about the same amount off as it was at idle. So i am assuming either offset or a voltage problem. and i was using the LC-1 profile included with HPTuners as well. Next i will run a direct line for the WB to the battery and see what then.

[ss44]

Ok, found the issue...Cracked o2 bung. So now we can return to normal tuning issues.

[RWTD]

That's good to hear!

Okay, using my previous tune without any changes, get me the idle log again and also the steady state log.

Thanks!

[ss44]

Will do, currently at work and i will get the idle logs and cruising logs tonight.

Thanks,

[ss44]

RWTD,

Here are the best logs i could get today. We are 20 mph rain, you know the kind you can only drive 20 mph in? Current tune is your ss44_05gtoa4_rwtd_test3.hpt. But here they are.

Idle still a little high, would like 650 - 700, but i can't have it shake my wifes teeth out. Some surging 1000-1250ish low speed cruising, 20 mph through the neighborhood.

Thanks,