Desired airflow table seems too low but works

[ls1vt209]

Ok I have just installed a 220/220 581 lift 112 lsa in my 2000 VT Gen 3 with ls6 manifold, it's manual. Standard throttle body CHE fibreglass OTR and thats about it.

I did RAFIG and the results are somewhat abnormal.

I reduced the desired airflow by the amount suggested after RAFIG it works but the table seems way too low compared to every other tune I have seen etc.

Here is the table

-40 12.870117 0.000000
-28 12.567383 0.000000
-16 12.264648 0.000000
-4 11.959961 0.000000
8 11.657227 0.000000
20 11.295898 0.000000
32 8.593750 0.000000
44 4.796875 0.000000
56 3.440430 0.000000
68 2.742188 0.000000
80 2.200195 0.000000
92 2.187500 0.000000
104 2.187500 0.000000
116 2.187500 0.000000
128 2.187500 0.000000
140 2.187500 0.000000

It works and the car idles but as I said before the values seem way low. I have not progressed much past this with tuning as I want to be sure before going any further

Thoughts does anyone see that this is too low and is there any consequences for it being like it is?

Thanks

[5.7ute]

There are many variables that will affect the amount of desired airflow added by the IAC valve. Hole size in the TB, position of the throttle blade at idle( has the idle stop been adjusted?) airleaks after the TB. Even the hole size in the IAC bypass valve seat
If your IAC count is around 40 with no airleaks behind the TB and drivability is good I wouldnt stress about the values IMHO.

[ls1vt209]

Pretty sure there is no air leaks after the TB. Hole size has not been adjusted (From standard VT GEN3), throttle blade position has not been altered.

IAC count, which specific pid would that be, I have logged steps (GM.IAC) thats it and this gets down to 0, which one in particular should I be logging for IAC count?

When I control timing via DVT at idle and set it to 10 it seems to idle much smoother. I am currently seeing around 7degrees at idle, no matter what I do I can't seem to get it any higher

Attached is my idle log from today.

Cheers
Nigel

[5.7ute]

IAC steps is what you want to log.( like you have been)
Dropping to 0 in the steps will limit control of the idle speed as the IAC valve will be fully closed. This is not a good position to be in.
First thing I would try is to back off the idle throttle stop & see if this will raise the IAC step count when warm. Also make sure your throttle cable isnt hanging the blade open slightly.
What is your map pressure at idle?

[ls1vt209]

Map pressure at idle is 50kpa

[5.7ute]

You think you need to sort out the excess air issue first. Also post up your tune file.

[ls1vt209]

Tune attached cheers

[WeathermanShawn]

Your desired airflow looks really low.

Are you absolutely sure RAFIG was done correctly? I.E., all the scan-tool units correct..metric, etc.

Another way of double-checking your idle air is to compare it against your DYNCLAIR.DMA or CLYAIR.DMA. I can see you have it closed loop. Looks like you still have MAF enabled? In either case, if you change units in your VE Table to g/s..looks like you should have well over 7-8 g/s at 800 RPM and 50 Kpa. It is not always going to line up perfectly, but it should be pretty close.

Either redo RAFIG or suspect an air leak.

[ls1vt209]

Yeah Shaun RAFIG was done correctly however I have since discovered an air leak, which has now been fixed. The PCV line had come adrift and could not be seen on initial inspection.

I will attempt to rectify the situation today flash in the last decent Desired airflow tune then do RAFIG and let you guys know.

Thanks again for your help and support gents

[5.7ute]

No worries, glad you found the culprit.