poor idle surge and stall when cold

[AVIDMOTION]

Do we have a Idle air control valve ? If so where is it. On cold days in am the car when in drive and I come to a stop wiLl jerk, surge then stall, starts right back up and will do this until warmed up like the first 3 min or so. I ran two tanks of fuel injection cleaner, cleaned the hsrk sensor, cleaned air filter and cleaned out the maf. All were dirty but did not stop my problem. Only happens when cold out and not warmed up. Any help appreciated.

[Napalm]

How long have you had all those mods on the car? were they all on last winter?

did you mod your tune in the last year?

have you replaced your spark plugs and/or wires recently?

finally relative temps when this occurs - IE is it in the 20's or the 50's?

I'd start by saying you either A) have a bad spark - and when the engine warms up it gets better, or B) you have something off in the tune.

outside - possibly a bad fuel injector, but that should show up.

[AVIDMOTION]

Same tune for 2 years, same mods for 2 years, new plugs 3 months old, new wires 3 months old, happens below 40 degrees, only first 3 or so mins, then once warm no problem....

[AVIDMOTION]

Update, found a 3 inch Crack in the plastic vacuum line from pvc to billet oil catch can. Temporarily I taped it up. Unfortunately it only helped but still does the stutter stall surge leap during
todays 38 degree day, it did it twice then not the rest of the day. Once 3 min goes by it becomes a nasty responsive four daily driver. It just that first am start. Do we have a IAC valve? And if so where is it, can it be cleaned or cheap to replace? Anybody?

[G8 GT V8]

No IAC valve that I'm aware of. Is your throttle body clean where the throttle blade seats? Also, is your maf and air cleaner clean? At start up, the ECM commands a rich AFR so perhaps theirs a slight air blockage and its getting "flooded".

[AVIDMOTION]

Yeah crazy paul mentioned no IAC valve since like 2005 or something it is in the tune. Did a quick maf clean and air cleaner too, probably needs a better cleaning then. Did two tanks of injection cleaner. Put same tune back in but bumped to 725 rpm for winter. With UDP with defroster and all accessories on would dim. Since finding the Crack in vacuum it much better, but still does it until 2-3 min of warming....

[STAGEUP]

Did it surge last year in cold weather, with the same tune?

[Napalm]

the IAC is not a function of the full thorttle vane. it's in the fine control of the motor that runs the throttle vane. IE why have more stuff when the computer if runing that vane all the time.

I wonder if maybe something else is just a touch loose - like the air box, air tubing, throttle body to intake. etc. might check all bolts and clamps are snug - especially since you had it all apart.

otherwise I'm stabbing in the dark. but the warm up thing almost sounds like there is a minor leak somewhere that is closing with all the parts warming up.

finally and I hate to ask - intake manifold?

[AVIDMOTION]

Hope it's not the intake, I sprayed with water looking for hesitation but found nothing. Only thing I see maybe is the throttle body flap not shut flush when car is off. I gonna clean the TB very thoroughly and tighten everything up good. Mpg is suddenly horrible also. But runs strong. Ran a plx device scan no codes in memory all parameters ok.

[STAGEUP]

Did it surge last year in cold weather, with the same tune?

[Napalm]

hmm bad mpg? like 3-4 mpgs lower or

1 or 2 - could be related to you warming up the car longer on first start - I know mine drops every fall winter but a mpg or 2 because I let mine run a bit in the driveway.


again though the clears up with warmup leads me to a airleak somewhere. how's the oil? do you have a catch can - does it collect? did you check those fittings?

otherwise I hate to shoot blind. when you cleaned the TB you didnt' move the vane did you? I found I was able to clean mine without any moving of the vane, but I did spray about a full can of carb cleaner down and around it.

[AVIDMOTION]

Tried several tunes, all had same problem.Raining today and holiday over next few days so I look at it over weekend and try to clean TB better, though it was ported last year, it was really dirty, aircleaner literally had 1/2 lb of dried bugs and some sand. Cleaned thoroughly. Catch can is good and catching some oil not like it used to before I changed valve stem seals, several were cracked, now can hardly gets anything. My HSRK sensor was full of crud, cleaned that too. Ever since I fixed the crack in the vacuum line to the can it has been better but not fixed. MPG always goes down in fall winter here in NJ, but like 1-2 this year with my current problem is horrible. Used to be 24-26 highway, 17.5+ city and 19.7 combined....this year highway best 21, city 10+, overall 15 worse ever since I had the car. Only big change is new tires. I am going to check their weights ad see if that a problem....

[AVIDMOTION]

Youch, old tires General Gmax, which I really like, 245/40\19 were 24lbs each, new tires Cooper zeon rs3-a are 29lbs ea.(255/40/19)& Michelin pilot sports A/S3 on front are 28lbs.....so since last year all 4 were Generals at 24lbs each, now I have fronts at 28 and rears at 29lb each. Pretty good difference....

[Napalm]

that's minor - tire weight will affect your mpg's when accelerating - but once at steady state, it's minimal.

if you still have your tuner/computer - check your fuel trims and then check your MAF and O2 response rates.

you might have a bad O2 sensor - do you still have O2 sensors? if no ingore that.

could also be your fuel formulation changed this year - it happens. but I'd be wary of your driving habits.

another thing could be a leaking fuel injector but you should be getting soot in the exhaust, IIRC. how many miles does your car have?

[SpeedRacerX]

For the heck of it, get a can of that spray they sell at the auto store to check for leaks. Spray it all around the motor to look for signs of obvious air escape or air draw. I hope it's something simple as a cracked hose somewhere. That's what it was recently on my son's Land Cruiser. The accordion tube after the maf cracked and it would idle very rough and stall. Once fixed, Back to normal instantly.

[AVIDMOTION]

Unfortunately(?), I am away in Naples Florida until March, so I am not around the car right now. I have cleaned and checked everything. It only does it on the first am starting and only the first two stops within the first two or three minutes of starting. Once warmed up it has no problems. There is no rough idle just a shudder stumble and the car leaps forward and stalls. Starts right back up and goes. It may do it once more in the next min then won't do it rest of day. If I auto start and warm up at least 3-5 minutes or more, it won't do it. Does not do it went above 60+ degrees.

[AVIDMOTION]

OK back from Florida and car did not do it when Temps were recently in 60's. But did it every morning when below 45 degrees.
Here's what it does: It only does it when below 45 degrees, only does it until warmed up then runs great. It will start and idle fine. But put it drive go 200 yards and when I come to a stop it will stutter and lunge forward and stall out. Start right back up and drive fine. It only does it when cold. Generally not again until next morning and first stop. Frustrating! Tried cleaning MAF, new gas, newer plugs, no vacuum line leaks, no frayed sensor wires, two tanks of FI cleaner........still lurges and stalls on first cold start. Will really clean out MAF with spray asap.

[AVIDMOTION]

Did a tighten of every connection I could see. Sprayed motor for leaks, none found. Catch can has very little ever since changing my cracked valve stem seals. Does not smoke. No black soot. What do you mean about the maf vane? Recently I was asked if it was in the original position. Not sure what that means or how it would affect anything. Check my plugs, gapped perfect still look brand new. Has no smell of gas. Started to get po455 code. Already replaced both purge valves and gas cap. Looking like a leak somewhere still. Mpg down also. Very frustrating. Car in shop getting trans rebuilt and new CircleD 3000 stall so I guess mpg will go down even more...

[-Ray-]

I already posted in your other thread. Since you are getting a TC, your tuner will need to retune. This is good for you since you can tell your tuner about the cold start problems.

[AVIDMOTION]

Not sure what a tune change could do for me. Same tune now for two years no problems. Tried other tunes including stock, all still stall when cold.

[AVIDMOTION]

It's winter and again anytime it's below 45 degrees it stalls on first drive, first stop. I finally got everything I need to scan the car and though we in a mild weather pattern when it does go down to 45 I will drive and scan the car, maybe it will have data for the tuner to catch something. Btw, after the car was retuned for the stall, there is a big difference, the car runs stupid fast for the mods it has. Since it not burning any oil etc, and I have 125,000 miles on it, I was thinking of adding a cam. But since heads have to come off for the non DOD cam I might as well throw rings in it. I just don't want a big PIA with a bunch of querks for a DD. May still attempt a mild 220 230 550 565 114 cam or so, I have the 1.85 rollers so lift will be right at my .600 springs limit. First to get rid of this stall before I add more to the plate...