LS3 Stroker(416) race car engine wont idle under 50c water temp

[bubbajohnny352]

I currrently have a LS3 Stroker in my race car. Its a 416 cube 11:1 comp pump 98 fuel, higgins heads, fast manifold, dry sumped, 1.7/8 headers small lunati cam 247/255 651 tho lift 108 LSA. Says its a hydraulic roller to suit carby. im running it with a fast manifold 90mm TB. Car will not start without pushing the throttle pedal, and will not idle unless u hold your foot on the throttle til it gets to around 50c water temp. It smells very rich at idle, burning your eyes rich if you know what i mean.
Any help appreciated

[twenglish1]

Post a datalog of it running as well.

[2xLS1]

Cyl vol is wrong. That effects a lot on a P01 calibration S/B .8521275. Might be why some of the VE numbers are so high. I've never seen that much idle air flow in any tune in over 20 years of tuning. 52-34 g/sec is a lot. System options say cable throttle body. What brand? Fast or Chinese? Zero the catalyst heating spark. You sure the injector data is correct? If I had to guess it is probably the aftermarket throttle body and or IAC passage. It is full time open loop. Is that your intent? Looks like it might be an EFILive COS by the OS number but not sure being an Aussie model.

[bubbajohnny352]

Its Running a 90mm Holley TB with cable 24 tooth reluctor. I noticed it is full time open. Im new to this so dont know what i need. Im fitting a wide band before i go out next. Not sure if the dry sump is playing around with the vacuum at idle as well as its set up to scavenge vacuum.
thanks for your help

[Alvin]

Its Running a 90mm Holley TB with cable 24 tooth reluctor. I noticed it is full time open. Im new to this so dont know what i need. Im fitting a wide band before i go out next. Not sure if the dry sump is playing around with the vacuum at idle as well as its set up to scavenge vacuum.
thanks for your help

Those throttle bodies are not great. FYI. They have especially choked IAC passages. Some people try porting them. I suggest a NW throttle body.

For American GEN 3 Car OS (most) the most you can put in this table is 39 g/s Anything above that and there is a bug or whatever you want to call it where the IAC goes full closed (0)

On early American GEN 3 stuff that limit is lower. On some trucks it's around 28-32g/s. I have no idea if holden is the same but i would suspect it is.

Capture.PNG

Watch IAC position especially at key on. Compare it to that table. See if the Holdens have the same issue. I'll bet they do.

[bubbajohnny352]

whats a NW TB

[Alvin]

Nick Williams Throttle body. He's got the best throttle body IMHO. He's been doing it for a long time and had a tune/build shop so he's quite aware of what makes a throttlebody good or not.

[bubbajohnny352]

we just fitted a NW onto my mates 6 litre race engine with really good results.Ill check it out..Cheers

[Alvin]

mind that BRAF limit I explained earlier. That is problem number 1

[edcmat-l1]

What injectors are in it? Looks like 60 or larger lb. per hour. Transient isn't right for ones that big. Minimum and default pulse width don't look right for big injectors. Short pulse adder doesn't either.

As Alvin said the BRAF is way too high. I'd bet it's shutting the IAC. Need to get those numbers down to where they make sense and then figure out what it needs.

The smell is most likely from the injector data being off. And I'd assume there's no cats on this.

Does it have any exhaust on it at all?

[bubbajohnny352]

exhaust is 1.7/8 headers 4 into 1 into twin 3" about a foot long into single 4" into single straight thru 4" muffler out the side of the car.my main concern is the no idle and the richnes down low. cant even start it in the shed.

[bubbajohnny352]

mind that BRAF limit I explained earlier. That is problem number 1

I ran the car, it pretty much started to idle. havent changed anything apart from a new water temp sensor and new iat sensor. stills runs rich as fu... but it idles

[edcmat-l1]

exhaust is 1.7/8 headers 4 into 1 into twin 3" about a foot long into single 4" into single straight thru 4" muffler out the side of the car.my main concern is the no idle and the richnes down low. cant even start it in the shed.

You need to get the injector data straight first. You have to be able to control big ass injectors at very low pulse widths ACCURATELY.

And it's always gonna stink real bad down low with that cam. It's not rich. You can't smell rich. The chemical definition of rich is high CO. CO is colorless and odorless. You can't smell rich. You're smelling unburnt and half burnt hydrocarbons. They're mainly from the overlap of the cam. You can have unburnt hydrocarbons present in lean and rich conditions and in the case of these LS engines with a bunch of overlap, you can have them present at stoich.

[bubbajohnny352]

cheers man..Appreciate the advice

[blindsquirrel]

I especially like it when someone's asked a direct question - "What injectors are in it?" - and then for the next three, four, five replies they go on talking about other stuff like the question was never asked.

[gtstorey]

I especially like it when someone's asked a direct question - "What injectors are in it?" - and then for the next three, four, five replies they go on talking about other stuff like the question was never asked.

And give of all kinds of details about the pushrods, lifters, exhaust brand etc, but gloss over most of the things that may affect the tune. And especially injectors.

[twenglish1]

Injectors are a secret, just like getting a solid answer on what the fuel pressure is.

[edcmat-l1]

But it stinks at idle so what's gonna fix it? Surely there must be some majikal numbers I can randomly punch in.

[bubbajohnny352]

very hard to check the injectors when im miles away from the car.when i pull them out ill post what they are. How am i supposed to learn unless i ask questions

[gtstorey]

How is anyone supposed to help if you don’t answer the questions?

Without good injector data you are wasting your time.