heavy cam won't idle when cold
 

Recently changed the cam to a 228R from a ZO6 factory cam. When the car is cold it won't start without a bit of gas pedal, it also requires you to keep it about 1,500 for the first 30-45 seconds before it will stay running. When warm it's fine. I have run the idle air and adjusted as necessary but I have to be missing something simple... Attached is the current HPT file. Any ideas? Pointers? Something glaringly obvious?

Mine does the same thing. My tuner says it's my throttle body. I believe he said it was due to the IAC opening being to small

Can't look at tune on my phone but general comments and questions.
did you perform ve or maf table changes based on a wideband tune?
Did you adjust the after start fuel temp enrichment? This is overly rich stock and will make a cammed car drive like crap until it's warm.
Assuming you changed the desired airflow table you also need to tweak the different proportional airflow tables for overshoot or undershoot.
How much idle timing? You need to make sure you have enough timing especially during cold start and tweak the timing idle tables.

Your tuner doesn't know what he's talking about. The idle set screw and a stock iac on a stock TB are enough to idle a huge cam without a problem from a cold start.

Mine is a 92mm TB. Not even sure on the brand. Best I can tell it might be an older Nick Williams design

There is a really good thread on how to fix this properly in the HP Tuners forum. I will see if I can find the link. It's not a fast process to find the sweet spot though.

VE and MAF are fine for the rest of the tune. it's at about 18 degrees of timing. I have not touched after start fuel temp enrichment.

Does it have a hole drilled in the throttle blade like stock? If that is what your tuner mean I will agree as that will significantly help idle.

Cool. I'd be curious to see that

Try setting the timing to 25 and see what it does. That with the other fueling changes I posted above should help stabilize the idle.

It's been a few years now, so I honestly don't remember. I wanna say it does, and that he said it's to small, which is why I have the cold start idle issue. I'll have to ask him. I've just learned to live with it lol. It fluctuates for maybe 30 seconds on a total cold start then it's all good

https://forum.hptuners.com/showthrea...de-(w-pictures)

Good deal. I'll check it out. Thanks

I gotcha.

I just tuned a c5 m6 vette with a 228 cam. After a hour tweaking it it drived great. Owner drives it daily. Sounds like your tune isnt very good.

For a good cam tune u need the correct rpm, timing, base running airflow, tb opening, and a good ve/maf fueling. Tht cam should be pretty easy to tune in tht setup.

I started tweaking it last night. I was asking it to idle around 650 because I liked the sound.... That was a bit too low. Bumped it to 750 and moved the timing to 22 degrees and it idles just fine now.

U might need to bump the rpm up higher in the colder startup rpm regions. Around 160* start getting it to where u want your base idle rpm at.

if u want the lopier sounding idle play around with the over/underspeed timing tables.

That's exactly what I did. It idles at 850 and then gradually comes down as it warmes up. The IN GEAR / AC on is also 50 RPM's higher across the board. I have not messed with the over/under tables yet I'll take a look there next time I am messing with it.