LS Engine Idling Issue

[ItDoRun]

Finally got my car started (after 8 years of building) but it won't idle at all. I have to feather the pedal to keep it running. Also noticed my volt meter on my New Vintage gauges is only showing 8 volts when running. Fan 1 comes on in the key on position. Let's start with the idling issue first though. I do know hat PSI programmed my ECM for the wrong style MAF. Would that be causing the issue? I talked to Gary at PSI this morning and he said the car would still run like it is.

2008 6.0L short block
LS3 heads
LS3 Intake
Custom cam/springs
Stock valve train

Ok, where do I start with the idling issue?

[Vega$69]

Check the port on the drivers side of the intake just behind TB. Should be plugged

[ItDoRun]

Check the port on the drivers side of the intake just behind TB. Should be plugged

It's capped.

[ItDoRun]

How does the voltage play into this? Or does it make that big of a difference?

[Vega$69]

I would 1st look for vacuum leaks and open ports on the intake. Ports on the rear for the booster etc. also check that TB and O ring are snug.

Is the MAF sensor installed?

What have you done regarding tuning for you set up?

[ItDoRun]

I would 1st look for vacuum leaks and open ports on the intake. Ports on the rear for the booster etc. also check that TB and O ring are snug.

Is the MAF sensor installed?

What have you done regarding tuning for you set up?

I checked all the vacuum/PCV hoses and they're all tight. I'll check the TBthis evening. Yes, MAF is installed. PSI did a start up tune when I purchased the ECM.

[ItDoRun]

I need to get a fuel pressure gauge installed. I'm sure there's probably some air in the fuel system as well.

[TomM]

The 8 volt thing is a problem. Where did you pick up the wire to the gauge? Is your alternator charging when it is running? What is your battery voltage running and static?

These engines use a lot of power to run everything, it might just be this simple...

T,

[ItDoRun]

The 8 volt thing is a problem. Where did you pick up the wire to the gauge? Is your alternator charging when it is running? What is your battery voltage running and static?

These engines use a lot of power to run everything, it might just be this simple...

T,

I need to check it this evening to see if it's charging or not.

[ItDoRun]

The 8 volt thing is a problem. Where did you pick up the wire to the gauge?

T,

I tied it into the pink 12V wire from the instrument cluster wiring.

[ItDoRun]

Static is 11.52V, so that's a problem. Since the car won't idle, I'll need another hand to check while running.

[Vega$69]

Voltage is probably not the issue.

If you have a custom cam and ls3 top end on an LS2 the canned tune from PSI will not do the job.

You can have it tuned or data log and send the for to Mike Norris or somebody to re-tune for your set up.

[ItDoRun]

Voltage is probably not the issue.

If you have a custom cam and ls3 top end on an LS2 the canned tune from PSI will not do the job.

You can have it tuned or data log and send the for to Mike Norris or somebody to re-tune for your set up.

Futral Motorsports spec'd the cam for it and they're going to tune it for me on the dyno. I spoke with them today and they can go ahead and put a good tune in it now and then finalize it on the dyno in a few weeks.

[GregWeld]

Low voltage - and the wrong MAF programmed - and not knowing your fuel pressure.... these are all things that EFI doesn't like.

EFI is a very PRECISE system - and needs to have things right.

Put a charge on your battery -- get the right start up tune - and get a gauge on the fuel pressure and make sure it's adjusted to WHAT THE TUNE calls for (it's programmed in) before you start making other changes or wasting your time chasing issues that might not be issues.

[ItDoRun]

I guess it just needed to run a bit for the ECM to figure itself out. I had the ECM tuned last Friday cranked it up and still had the same issue of not idling. Haven't touched it agin until yesterday evening and I cranked it, held it at about 1100 rpm for a few minutes and after easing off the the throttle, it started idling. It idles low at around 500rpm but they'll fix that on the dyno.

[Vince@Meanstreets]

yeah, it helps to have a heat cycle on it or two.

[GregWeld]

I guess it just needed to run a bit for the ECM to figure itself out. I had the ECM tuned last Friday cranked it up and still had the same issue of not idling. Haven't touched it agin until yesterday evening and I cranked it, held it at about 1100 rpm for a few minutes and after easing off the the throttle, it started idling. It idles low at around 500rpm but they'll fix that on the dyno.



IF it's EFI -- which it is -- you should never have to hold the throttle.... it has a "choke" system built in via fueling etc and an IAC (Idle Air Controller). Apparently these are set wrong -- or you have something else that needs touching up.

I've installed a couple LS / GM controller motors -- they fire off instantly and run like little kittens... I've never had to do a thing to them to get them to run the first time.

[cjsgarage]

I've done a bunch of these and there's 6 or 7 things to adjust on aftermarket cams, especially those with low lobe separation angles. They have to be monitored a couple times during cold and hot starts to get it perfect... even after you bump up timing and dial in the air volume per cylinder.

The computers do "learn" within a few blocks one direction or the other. The more you let it idle, the more it will learn. The dyno tune should take care of it.. but the idle tuning part hopefully wont tie up precious dyno time. I just let it sit in the bay for that stuff.