A friend has an 02 Z06 w/ a 383 in it. Car Runs great it just surges real bad ay idle. (Like everyones). He has a pretty big cam init 242/247 605/619 w/ a 112 lobe seperation. Another problem is he has an aluminum flywheel. Can some people that has motors simalar to this please chime in or log there tunes for me to look at. He is running open loop and closed loop.
Thanks Ronnie
Can you post a tune for this car?
How do I get the tune on here?
Lets see if this worked
more than likely he is rich, do a search on Russ idle config, also search on open loop at idle.
Also here is a good place to start for idle tuning
http://redhardsupra.blogspot.com/200...le-tuning.html
but getting the fuel in order is the biggest concern. Also his spark is probably jumping around like crazy.
injector size, tb size, IAC or DBW TB?
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Guys thanks so much This helped alot. I have a question. Can you lean a car out by telling the computer that you have a larger flow rate on the injector. Someone told me this works. If the computer thinks the flowrate is higher it squirts for less time. Does this make sense? What is the easyest way to lean a car out?
I see your thinking but that isn't right imagine at higher rpms do you want it to squirt less fuel then also?, tune the VE and the MAF, then if still having problems use open loop idle.
So larger #'s in the VE means more air(leaner)?
let's see if I can get this one (total newbie here)...the ve is a model of the (breathing) air filling the cylinders and fueling is proportional to ve (open loop) so that higher values will demand more fuel.
Is this correct? Sounds perfect
VE is a ratio of how much air is going through the engine vs how much air there could be going through the engine. Our VE is calculated by VE, displacement and a chemical constant for specific heat of dry air. When multiplied by MAP and divided by Temperature of the aircharge, it gives us actual airmass. VE by itself is a normalized airmass meaning it is a airmass at a given pressure and temperature.
the way I look at VE is that it is a percent of air in the cylinder, I know its a simplton version but it works for me. If you raise the table the car thinks there is more air in there and thus gives it more fuel. If you lower the table it thinks there is less air and therefore gives you less fuel. So to get a leaner a/f at idle you need to lower the VE table so that the car squirts less in. you also need to worry about fuel trims etc as they can try to sway your a/f back to 14.7 or at least what it thinks is 14.7
Just from trial and error I don't really even trust my wideband at idle, I think I catch pulses of air either from overlap or just the low idle that throws it out of whack, Damn the big cams!
If car is in open loop does it just read the VE table and nothing else.? If I shut off the 02 sensors the car will not surge. Another thing how do you tell when it is scanning if it is in closed or open loop?
Well it reads the VE and the MAF to calculate whatever it believes is how much air is in the cylinders, if you disable the MAF it reads only VE, if you disable the VE it reads only MAF which is why its important to try and make the two match up as close as possible IMO.
There is an open/closed loop status bit that you can set but I have found that its not entirely accurate, the best way is to log your fuel trims if you don't see any short term trims my guess is you are in open loop. To be 100% sure of this reset your trims and you won't have any long term fuel trims or short term fuel trims.
FWIW I had to do what you did and disable closed loop/narrowband 02's at idle. By having them enabled it tried to make the car waaaay to rich as it tried to adjust fuel trims to match what it thought was 14.7 a/f.
Read this thread for info on open loop idle.
http://www.hptuners.com/forum/showthread.php?t=5585
Also make sure to search on "Russ idle" and use his config file to get your RAF inline.
There is also the adaptive idle overspeed/underspeed spark settings which left at stock sway spark too much in order to try and keep correct idle speed.
In the end though I think its too much fueling that causes the surging.
I tried this. It seems to work better. I had to lower the CRANKING VE also. It was reading this table because it was richer then the Main VE. this makes no sense to me. If it says cranking should it only work when the key is turned to cranking?
for me I didn't have to alter Cranking VE at all, I don't see why you should have had to either to be honest. Did you make sure and disable fuel trims when you tried the open loop stuff?
which brings a question to mind. how long does the PCM stay in the cranking VE table? when does it switch to the main VE table to help control idle?
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