Posted: Wed Dec 18, 2013 9:30 am Post subject: 05 3.4L Runs rough/stalls @ idle/warmed up
Recently my 2005 impala has been running rough when I'm stopped at a traffic light or moving slowly through traffic. When I open up the throttle or cruise at a higher speed its fine. I took it to autozone and got 2 errors.
1 I dont remember but it was related to my traction system sensor, so obviously I'd assume this wont cause running issues. The other was p0440, evap system leak. I got a new purge valve, evap canister, and grommet for where the line goes into the engine before the purge valve. I replaced the purge valve, car didnt run any better, in fact it seems a little worse.
I guess my main question is, before I replace about every part in the system(218,000 miles on car), is it possible for vacuum leaks to cause this bad performance/stalling when idling warmed up?
**The car does run fuel rich, and after its warmed up the exhaust stinks like rotten eggs. I know my cat is bad, but its not plugged.
Lets cover the basic stuff first.
-Is the throttle body clean?
-Is the IAC free of deposits and clean?
If the cat is bad and stinks like rotten eggs, then it has enough back pressure to stall your engine. One way to check this would be to pull an 02 sensor before the catalytic converter and see if it stalls.
Most likely the lower intake gaskets are toast, which would cause your vacuum leaks ect. Have these been replaced?
If I remember correctly there are a bunch of vacuum tubes with a T on it that run to the throttle body. I would check to make sure those are in good order. They are brittle and since you just did some part replacement I would give them a once over again.
Did you try cleaning the throttle body and IAC valve?
I want to say I had a P0440 code about seven or eight years ago when I neglected to reinstall the o-ring on the PCV valve under the MAP sensor on my 3800 when I changed the valve. I remember it being a completely bizarre code that had nearly nothing to do with the MAP sensor or PCV valve. Of course, it may have been a different code and it was on a 3800, so YMMV.
_________________ 2001 Galaxy Silver 9C1 w/ L67 and 4T65E-HD...and a few other mods.
I'm well aware of a P0440. However, I show no evidence of GM actually using that exact diagnostic code in 2005. It was replaced by P0455, which basically states the same information, but is worded a little bit different since the evap system was updated in 2005.
vacuum leak off pcv valve and hose connecting to purge valve was fixed along with purge valve solonoid, however after driving it to the gas station and filling up the tank it stalled out about 3 times. took it in or a diagnostic, awaiting their results.
***short after making the post found out the fuel pressure regulator that i just replaced a year ago is already bad, so about to pick up car and test it out. ill post results
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