need help wife's 3.4 Impala

[03Alerosil]

Hey everyone,
thought I would come to you guys for help being everyone been so helpful with all my other questions.

My wife owns a 2005 Impala with the 3.4. Car would stall just once when really cold outside, after it died it would fire right up and run fine with a little stumble at idle. I ended up replacing the fuel pressure regulator as it was covered in fuel and leaking it back into the intake through the vacuum line.

Car was fine for a bit starting when the outside air is cold. Now the problem is back again. it only happens when it's cold outside and it only stalls once. After that it never does it again whether she is driving the car or idling at a stop light. When it's warm outside or the engine is warm it never stalls after shutting the car off. I checked the new fuel regulator and it's fine. The air cleaner is decent but could use a change. Fuel filter, spark plugs, PCV, are all new. The plug wires are original with 142k on them.

Any ideas would be appreciated. I would say it's the IAC but it only does it once when everything is cold and its cold outside. Maybe the MAF? I'm not sure. Throttle body and blade looked clean as I had it all off to change the fuel regulator.

[AleroB888]

how cold is it, and how long does it run till it stalls the first time, do you push down any on the gas pedal when trying to start it the first time cold?

I got nothing for you on it yet, but you might try key on, key off, key on again a few times (prime the pump) to make sure there is full fuel pressure.

[03Alerosil]

Thanks for responding. It does it sometimes. Usually its 10*F or so when it does it. It fires like it wants to run and just dies. She turns key off and cranks again and car fires and runs like it should. Only dies once and never does it again rest of day once engine has been warmed.

[03Alerosil]

I took out the air filter and noticed that it looks like it got wet from a big rainstorm we had. I am gonna replace the air filter and get some MAF cleaner and clean it. I may do the throttle body too but when I did the fuel pressure regulator the throttle looked pretty clean. The car hasnt stalled out at all lately so I don't know. Maybe there was a lot of gas or something in the intake.

[03Alerosil]

20 below wind chill out. Primed pump. Car started then stalled. Cranked it over again and it stayed running and ran perfect. Even after being shut off once

[Starglow]

20 below wind chill out. Primed pump. Car started then stalled. Cranked it over again and it stayed running and ran perfect. Even after being shut off once

Has the fuel filter been replaced lately?....might be time. I'd say the plug wires are due to be replaced as well. I know you replaced the FPR, but I had a new one go bad on me not long after I installed it, so don't completely rule out the FPR just because it's been replaced. You need to put a fuel pressure gauge on the fuel rail, run the engine to pressurize the system and then shut it off.

Watch the static fuel pressure over the next hour or so or even overnight to see how far it drops. If it drops down too far then either the new FPR is bad or you might have a leaky fuel injector. It probably doesn't stall for the rest of the day after being warmed up because the fuel pressure doesn't have enough time to drop down far enough before the system is re-pressurized as it might after sitting for several hours or overnight.

[03Alerosil]

Fuel filter was replaced last march with a napa gold. Fpr passed test. Doesn't stall when it's warm out. Planned on doing plug wires. Gonna wait for cold snap to end and clean the maf and iac out when I change air filter and oil.

[03Alerosil]

how cold is it, and how long does it run till it stalls the first time, do you push down any on the gas pedal when trying to start it the first time cold?

I got nothing for you on it yet, but you might try key on, key off, key on again a few times (prime the pump) to make sure there is full fuel pressure.

-13 below zero. With -30 below wind chill. Car started up then died even when I push on the gas pedal. Cycled key again and it fired right up and stayed running. It's confusing the crap outta me. The idle is perfect once it stays running.

[MilzyZ34]

any DTC's present? do you have access to a scan tool (not a code-reader), so you can scan various parameters in real time? or do we have to diagnose this old-school?

[03Alerosil]

No DTCs present. Only does it when it's really cold. Gotta diagnose old school. Was around 25 today at 5am when I started car for her. Started right up idle fluctuated then smoothed out.

[a.graham52]

Is your maf sensor been cleaned lately?

[03Alerosil]

Is your maf sensor been cleaned lately?

Cleaning it Friday on her day off along with the throttle body and idle air control motor. Changing her air filter and oil as well. Judging by the stains on the air filter I would say she got her air intake wet

[03Alerosil]

Idle surged low and high, by the sounds of it. Smoothed out at high idle after going low. Turned on defrost And high idle went straight to low but idled smoothly. Could it be a dirty maf or iac?

[a.graham52]

See if u can find an iac to borrow, I just get a new one if u can afford one. Sounds like it's sticking

[03Alerosil]

See if u can find an iac to borrow, I just get a new one if u can afford one. Sounds like it's sticking

Thanks! I was thinking along those lines but it's good to hear someone else say it. Not sure if I can afford a new one now. My alero has same engine but I don't really wanna tear it apart. ( runs too good after doing intake gaskets). Will cleaning it fix the problem? What size are the torx screws that hold it on?

[a.graham52]

Do t know the size. But there's only an oring around the iac so you shouldn't have much trouble swapping them around

[03Alerosil]

See if u can find an iac to borrow, I just get a new one if u can afford one. Sounds like it's sticking

Just got done working on my wife's car. Maf and iat looked clean but I sprayed them down with maf cleaner anyway. Throttle body was all black tummy crap. Same with the iac but it was baked onto it. Cleaned all that up and even when car warm it start faster and idles better than before. Much smoother too. Thanks for all the help.