Hi,
I'm pretty new to this forum as far as posting is concerned, but I have been reading posts for awhile. I could use some help from someone with some good experience tuning Gen 4, LS engines. For starters, I have a '06 GTO: New engine - .010 over LS2 block and .010 under factory crank. Except for accessories on the front everything else has been modified. Forged AutoTec pistons, forged rods, King Bearings, and the shortblock balanced and assembled by a machine shop in Redding, CA. where the owner loves LS cars and has built lots of these engines over the years. I did the remaining assembly and installation myself. The engine is topped off with Ported GM LS3 heads, BTR Springs, Fast 102 with NW 102 Throttlebody. Also, I installed and degreed a BTR stage 4 LS3 N/A cam (619/595, 233/248, 113 +5). And of course, 1.75" JBA long tubes, a 3600 stall vigilante converter, one piece driveshaft and sturdy rear axles. My previous engine (modded, but with the stock bottem end) was outfitted with the same heads, intake and exhaust but used a 224/236, 114+4 custom grind cam that worked well and was not impossible to tune to get very good idle, low speed and WOT performance. this new engine setup, however, seems to be a whole different animal. When I first attempted to start the car, I had to 'blip' the throttle a couple of times when cranking in order to get it to start - this problem is still persisting and is one of the things I want to correct, although I did turn up the startup air and it helped, but hasn't alleviated the issue - Also, I don't think I should have to set that table all the way up to 64 g/s to get the car to start on it's own - In fact, I'm pretty sure I'm right on that. Once the car has been running for about 30-40 seconds it will idle on its own. OK, Also, the car had terrible surging, to the point that the rpm would swing so low that it would stall. I adjusted the MAF, VE and timing settings to where that stopped and the car idles at 1000 rpm in neutral as well as in gear. Right now, my STFT's ( I have LTFT's tuned out and prefer not to use them) seem to be pretty good at idle, but the idle quality is a little flaky when I turn on the a/c, and I would also appreciate some insight on how to eliminate that as well. I've looked at the a/c airflow ramp in and ramp out tables but I'm not sure how much to add or subtract in order to get started on that issue, or, if I need to make adjustments elsewhere to fix this. I played with the ETC area scaler after reading some posts and have tried a couple of different settings( I currently have it set to 6293, but also tried 6800, and if I remember right, I also tried 7223 but this hasn't helped the starting issue. - I have not tried the original stock setting of 4275 with this throttle body. Additionally, I 'm not quite sure how to proceed on the adaptive idle or follower settings. I do know that I still need to work on VE and MAF tuning but right now I'm trying to get the idle completely seamless as far as staying on RPM target both in gear and in neutral and with the a/c on or off. Also, I would prefer to simply turn the key and have it start without gas pedal assistance (my engine with the 224 cam did this - Always started pretty quickly). So, In a nutshell, I'm trying to get the idle a little bit more solid in all conditions and with the a/c on, in gear and in neutral. Also, there's the starting issue. Once I have those things ironed out I can begin to more thoroughly tune VE and maf and spark -my spark tables are sorta based on my previous engine setup - but the target spark is now 20 degrees at idle. Sorry this is so long, I have also included my current tune and log files.
Thanks in advance to anyone who can help me - I really appreciate it!!
I went over to my shop area today, 05/15, and turned the key, started right up without any pedal - yay! Once it warmed up a little I turned on the A/C and put it in gear - idle drops 100-200 rpm and surges between 700-900 when A/C is applied, especially when in gear and my foot is on the brake like when I'd be stopped at a light. Do the A/C and trans ramp in and out tables affect this, do I need to change those settings to address this issue and what recommendations does anyone have on changes to these? Thx.
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