I have an 09 HHR SS, lately when its around freezing and below i stall at cold start. It will idle fine for literally a few seconds and then sound cammed and die out. When I hold the rev so coolant gets to 50* it will idle fine there after. One the few warm days we've had, the car would start and idle just fine. Car runs/drives great and boosts normally.. Just unsure what could cause this..

I use Shell 93 octane and have refilled a few times since this started happening.

 

Did you delete your cat warmup cycle when tuned?

 

The Cat Warmup was removed, yes. What concerns me is it was idling fine prior to a buddy putting trans mounts in. I am assuming he had to move things enough to cause a small vacuum leak maybe? My AFR is slightly funky lately but I will have my Tuner have at her.

 

Check ur second o2 sensor for moister, my startup idle is funky and af goes a bit whacky whenever the second o2 is full of condensation. Dry it out and problems goes away.

 

Interesting! i'll def take a look at that thx!

 

This is normal, i live in canada and it happens to me everyday when its cold. It may be called "cat warmup" but it is essentially there for a reason, and with u holding the gas for its absence ut is still essentially there if u think about it

 

i dont have an lnf but what you described was exactly what was happening to me. i cleaned the MAF, TB, spark plugs and air filter and the car started fine again even if it was freezing cold.

 

It's not due to the cat warm-up being deleted, I still have the cat warm-up and have the same issue.

 

I have the same issue as well but cat warm up deleted

 

When deleting the cat warm-up, there are a few things that need to be modified in the timing and cam timing tables to make the idle is perfect on startup. My startup is near perfect on hot or cold starts, sits at around 1000 until coolant is slightly warm then drops to 800.

What doesn't make sense to me is that it only does it on cold starts. Maybe its pulling timing on the IAT tables bc its seeing cold air and making it run rough.

 

So three people have cold start issues, all three people have cat warm up deleted.

What more do you need to know. You altered the proper warm up cycle, then force it to do the same thing by holding your foot on the gas?

Hmmmmmmm......?

 

I have not deleted it and have the same issue. This is nothing new, there are other threats just like this.

 

Cat warmup being disabled doesn't effect cold starting in the least. I haven't had my cat warmup enabled for years, and even with running ethanol have yet to ever have an issue with cold starts even in subzero weather. As a matter of fact, unless someone special requests it or they have the stock cats, none of my tunes have cat warmup enabled. Like stated a few posts back, as long as the appropriate tables are accounted for in the tune there are zero cold start issues....

this is of course assuming something else isn't going on with the car (mechanical issues, leaks, badly coked valves, ect ect).