LQ4 MS3X High idle

[5.3LS10]

Hi all,

I have a LQ4 that was pulled from a running and driving car with no issues. I put an LS6 intake on it and a LS9 cam swap. It is running an MS3X in a fully sequential configuration. I have it running and only getting about 17" of vacuum but the idle is at 1500-1700rpm. Base timing is around 15*. I have lowered down to about 6-8 and the idle comes down but not much.

I do not have the wideband wired in yet (on my weekend to do list) but I set the idle fuel setting just like I would on a carb and shoot for the highest manifold vacuum level.

Attached is the current msq and a datalog of it running. I have setup the IAC according to the MSExtra documentation and have tried both always on and hold current and neither make a difference.

Any ideas what I may have over looked?

Thanks
Shane

[jsmcortina]

Please post a datalog (Datalogging -> Start)

James

[5.3LS10]

I am 99% sure I have the homing direction backwards. I just looked at a 5.3 I have and the homing direction is open. This 6.0 is closed. I will change and post back tomorrow. Also I will look through the megamanual and confirm this.

[5.3LS10]

I made the change and now it seems to idle much better. Only way to get the idle down around 800 is to pull a bunch of fuel out of it and the map is around 11" but if I tune to get the idle around 18" by adding a bunch of fuel the RPM is closer to 1200. Definitely have much more tuning and tweaking to do but this is a good start. Just have to wire in the wideband now so I know where I really am. Smells rich though. I should have more time tomorrow to play with.

[5.3LS10]

I am still having issues. I took a couple different datalogs today and tried a bunch of different settings. I have looked around and cannot see a concrete answer for what the IAC settings should be. I got the ASE tuned so it stays running after startup but I believe the IAC is staying open too much. Very loud noise of rushing air coming from the TB (more than I have heard from other vehicles.) I feel like the IAC is wired backwards. But I have tried switching homing direction from open to closed (supposed to simulate having both coils wired backwards) and I get the same thing. When testing idle vlave no matter settings I have if the number is lower the plunger retracts which I thought should extend to stop airflow.

The longer it runs the louder the throttle body gets and the leaner the car gets and the higher the revs.

Am I incorrect in believing that changing the homing direction will fix this issue? I just confirmed that if I change the IAC steps in the Idle Warmup Duty Steps and the RPM dropped right down. I believe I have both coils wired backwards.

Can someone please confirm my mistake?

I am going to pinout from the top of the IAC back to pins 25,27,29, and 31 and see where I messed up.

Thanks,

[5.3LS10]

25 goes to Pin D
27 Goes to Pin C
29 Goes to Pin B
31 Goes to Pin A

I matches G/W to G/W for the diyautotune harness to the GM LS pigtail
Same iwth the 3 other colors.

So I run in through the in/out test and it works fine. Which tells me they are both wired backwards.... So I think. But only one was wired backwards. I just flipped the one and now it idles like a champ.. i want to kick myself in the face.