nine-eight

iTrader: (7)

as the title says, I am completely new to EFI live, and I am trying to fine-tune my car. spent hours reading, learned a lot, but now I have some specific questions. finding out more and more that this is going to be a very long learning process.


the car has been email-tuned by slowhawk, and is running very well for the most part. what is left are little nuances that I dislike and want to eliminate.

the car is a manual 6, forged 347, with trickflow cnc 215 heads, professionally ported Fast 90/90 combo, and the VRX5 cam (236/238 .601/.605 lift; 113 lca)

I have all the boltons and supporting mods, i.e. fuel injectors, asp underdrive, oil pump, ls-7 lifters/trick flow pushrods, and the Kooks long tubes with the kooks catted Y and an electronic cutout.

okay... so...

1. as it is now, the car exhibits a light surging whenever I cruise at lower rpms. the range seems to be about 1500-2100 rpms.
it is subtle enough that you can almost ignore it, but I am building a daily-driveable car and the surging goes completely against what i've built the car for. as those of you with manual transmissions know, 1500-2100 is where you cruise at 20,30,40, and 75 mph.....so id like this to go away and I have no idea what i should start looking at.

I still have the stock 3.42 gears, and will be upgrading to the 3.73's sometime in the future. i know this will help the problem by raising my cruising rpms, but thats not the point. i feel like the car is running improperly when it surges, and I want to know what it is and what i can do to correct the problem.



2. what should my 02 sensors be reading at WOT? as it is now, i sit at .895 for one bank and .910 for the other... the car runs great but id really like to know where the rich/lean limits are so that I know what is within acceptable limits. i plan to get a wideband, but that is a couple months away and until then, I want to feel comfortable driving the **** out of this thing.

3. whenever i start the car up, i let her idle and warm up a bit. she has a decent idle at 900 according to the pcm, (the wildly inaccurate tach shows 1100.... anyway... ) right when you fire it up, whether its warm or cold, it has a steady idle for a few moments, then it starts to surge. its about a 50-150 rpm sweep at most. even when the car is completely warm it does that at idle... anyone? please?

4. lastly, i have a bucking below 1500 rpms. essentially, i have to either be accelerating, or decelerating whenever i am below 1500. if i try to make the car creep along at anything under 10 mph, it has a violent buck. i feel like this, as well as my idle and driving surge, are all related to the same problem and I realize most of it is related to the moderately large camshaft. my head tells me that the cam shouldnt be too large to not be tuned the way I like, given that its nothing along the lines of say, the vindicator, and it is sitting in a fully built h/c motor that should be able to swallow a cam of this size and run comfortably.


i'd be grateful for any input i can get here. im not sure where to start.

thanks for reading the novel!

ringram

Hi dude, all the problems are related, basically idle transition. You will need to look at idle airflow and probably timing. You can use the bidirectional controls to alter timing and see what works best then flash them in.

If you goto here http://forum.efilive.com/showthread.php?t=4661
You will get loads of good info on sorting out the idle. The forum is also an excellent mine of info and your questions will be answered and more.

BTW: WOT sensor reading looks fine.