Dixit

iTrader: (1)

Now Ive tried this about 4-5 times and still cant get the car to run simply at idle without dying in the garage.

I really want to drive the car without the MAF and in SD mode to get the VE table inline as close to possible instead of trying to do it with the MAF on.

Now the last owner had the cam installed and tuned, but who knows how well that tuner did it. All the info I see online about tuning the idle always talks about regular throttle bodies and adjusting the screw, but C5s have electronic throttle and no way to adjust a screw to open the blade up.

I have a 228/232 .600" lift 112lsa Crane Cam. It idles just fine now with the MAF, but without it will barely stay on and idles around 400rpm to where I turn it off cause its sounds horrible.

My STIT and LTIT is almost at 0 but that still didnt help me.

Can anyone point me in the right direction on where I should make my changes to account for the correct idle airflow with this cam without a maf?

Here are some screenshots of my tables with the current settings.





Here you can see whats it showing at idle.


Now here Im not sure if this is right or wrong, but the IAC Position is always showing at 310. My TPS at idle never drops below 3%, never.


Again any help on this would be appreciated. I know the people who made the howto's on the LS1Tuning docs did a great job, but didnt help the many of us that have drive by wire throttle bodies, maybe we can get that added in there.

Dixit

txhorns281

iTrader: (12)

Chances are you are running very rich. Try bumping your idle up 200 rpms from where it is stock if you already haven't, just to keep it running. Also, multiply your VE at 400, 800, and 1200 rpms by .8 in order to lean out. You will not keep the VE in this condition, but just for sake of keeping the car running for the initial data run this should help out. Also make sure your IFRs are what they should be. That is also a source of fueling confusion.

Bryan Wilkinson

iTrader: (1)

Here is a small suggestion.

Instead of screwing around with the VE table. If the car was running good with the MAF, go to the injector table, and select the entire row. Use the + and - symbol to adjust the amount of injector flow.

The VE table was good before. its kind of odd, though, I would think that MAF or no MAF, fuel would not have to be changed to run.

I literally just unplugged the MAF and it started right up.

405HP_Z06

iTrader: (11)

Send me your tune and let me take a look at it. I'll do my best to get you fixed up.

z06_pwr@mac.com

Dixit

iTrader: (1)

Thanks for the replies. Ive already lowered my 400, 800, 1200rpm VE table significantly to help resolve my hotstart issues with my cam. I no longer have that problem because Im not dumping all that extra fuel in there. So dont see the culprit being that.

I was always told to never mess with the IFR table unless you truly have made a change on that like injectors.

My idle is running at 900rpm right now and have no problem there.

405HP_Z06 - I sent you my BIN file, thanks for your help.

Dixit

Phil99vette

iTrader: (11)

We had problems at first getting the car to idle in SD mode. We played with the 400 800 and 1200 cells for about 30 minutes before it would idle without any assistance. Keep working with the car in SD mode to get the idle down, it takes alittle tweaking. Mine was way off with S2 heads and a big cam but now it purrs like a kitten.
Phil

YellowToy/A

iTrader: (1)

In am with him ^

look in the chart mode and watch you o2s and make sure they are switching.

txhorns281

iTrader: (12)

This be a truth... run the correct IFRs that reflect your injectors true rating.

jimmyblue

iTrader: (11)

Can't make out the year on this car but is it one with
both a primary and a secondary VE table? If so you
probably want to start by copying the appropriate
(every other) lines of the Primary (which should be
the main airflow term in normal idle operation) onto
the secondary (where you would end up looking in
event of a MAF failure). A straight tune might have
"fixed" the primary but left the secondary as-was?

Later years don't use the secondary table anymore.
Anyway, check it out.

RedHardSupra

iTrader: (1)

wow, i just had a very similar situation on a big head/big cam car, and no matter what i set in the tables, this thing would die in SD, but it would be fine in MAF.
another trick i found to work, is to disconnect the IAC sensor.
I did the 60/80/90% multiplication trick once, and it didn't change anything. should i keep doing it over and over? isn't it a bit much? what is a VE value on a idling cell for a car with a very well flowing engine?

Phil99vette

iTrader: (11)

Here's what I did....
- Started with the stock VE secondary table which we know to be high @ idle with a cam
- Lower the 400, 800 and 1200 in the 40 50 60 70 cells by 95% and start
- If the car won't idle reduce more. It will eventually start to stumble and than once the tune is right, it will idle somewhat choppy due to the richer 13.0 vs the normal commanded 14.7 with a MAF.
- My cells ended up in the mid to high 30s for the 60 and 70 cells where my car idles and once the table was done the peak numbers went to ~105. The correct IFR and offset tables are key.
- Once the secondary table was done which is what is used on a 2 table system, I put that data into an excel table and calculated the averages between the cells and input that into the primary table. Its pretty dang close.
Phil

BTW: My car idles 60-75 @ 800 and 1200 and those cells are in the high 30s to very very low 40s(<41)

Phil99vette

iTrader: (11)

Oh and make sure you reset your fuel trim

Phil99vette

iTrader: (11)

Your LTIT and STIT shouldn't have any values.No matter what you input your car is always going to be adding fuel. I had this exact same problem.

WS6FirebirdTA00

iTrader: (33)

is this an issue with the vettes drive by wire tb? im gonna be starting on tuning my cam and just trying to follow along some of these thread to see different issues. do you have any logs you can send? i was having troubles getting my fuel injectors to get proper idle. if you send me your tune and log i can see if i can point out a few things that helped me, might not work but its nothing that will hurt.

budchevy358@yahoo.com

Dixit

iTrader: (1)

This is a 2k2 Z06. Only has a Primary VE table, no secondary.

Ive reduced the 400 800 and 1200rpm but 50 60 80% respectively from the stock VE table.

I just dont understand why my IAC Position always shows 310 and the TPS never gets to 0%, lowest Ive got it is 3%. Is this because of the cam being a big aggressive? Is it even possible on drive by wire TBs to get the car to idle fine without opening the TB at all?

I think I ned to work on that part before I keep messing with the VE. I got a feeling that the TPS is opening to about 3% because the MAF is reading the air and STIT is commanding the IAC to push up the TB since for some reason its maxed out the IAC at 310.

Am I making any sense or just blowing smoke?

Dixit

Dixit

iTrader: (1)

Ive got 100s of scans and tunes. Since Ive been messing with this nonstop. What type of Scan you want? One of just at idle during cold startup upto normal temp with the MAF on? What PIDs you interested in?

Dixit

WS6FirebirdTA00

iTrader: (33)

if you have some of just idle with o2s, injectors pulse width, rpm, map, and if you have dynamic airflow and fuel trims that would help too. i made about 40 different tunes trying to get my injectors better before i decided to throw the cam in to see if that might help things out lol

Phil99vette

iTrader: (11)

The stock IAC park reset position is 310 from the factory. It won't change no matter how long you log or how far off your fuel trims are.
Phil

Dixit

iTrader: (1)

BIN file

Scan at Idle during warmup for 5mins

Scan at idle of car warmed up

Scan at idle of car warmed up and then driving. This one you can tell when I start driving from looking at the speed PID.

The O2s seem to look like they are switching fine at idle, but Im sure if they supposed to look like that or a bit better. I also got the Dynamic Airflow PID on there as well.

Dixit

Dixit

iTrader: (1)

So would you say its normal for my TPS to be showing 3-4% at idle? Or can I bring that down to 0 by asjusting the IAC steps somehow?

Dixit