I have a bit of a head scratcher on my hands here with my 2008 Chevrolet HHR 2.4 L.
I’ll keep it as brief as possible, but I want to provide as many details as I can to help diagnose/fix the issue.
After the car is sitting for ~3 or more hours, it takes longer from cranking to starting. If it’s sitting less than that amount of time it seems to start fine.
The problem initially started last Fall. However, at that point the issue didn’t require as long inbetween episodes. I then discovered a rusted/leaking fuel line near the L back wheel. The bad section was replaced with rubber hosing (rated for pressure/fuel), and the problem resolved. It returned about a month ago with the same signs. I assumed that either my patch job was failing or further rusting/leaking was developing. I replaced both fuel lines, but the problem remained.
The ambient temperature impacts how long of a delay there is as well as whether and how long it idles roughly (colder = more delayed, long rough idle; warm = shorter delay, no rough idle). When it occurs, the rough idle lasts for anywhere from 3-20 seconds (longer when colder) and then smooths out. In all of the time the issue has been present, the car has only died once during the rough idle.
After getting the car started through the delay, I can immediately turn off the car and restart it with no delay or problems (doesn’t matter if car was running for 1 second or 1 hour, it will immediately start once turned off and back on).
Once the car is running, it seems to have no issues.
The check engine light came on at the end of last week and gave a P0442 code (small evap leak). I couldn’t find an obvious cause, so last weekend I swapped out the EVAP vent and purge valves/solenoids to be safe (yes, it was probably unnecessary/overkill, but they’re cheap/easy to replace; I was tired of messing around and figured it was worth trying before dropping the tank/replacing the fuel pump). I cleared the code, and it hasn’t returned so far, so we’ll see how that goes.
There is no evidence of a fuel leak along the fuel lines from what I can tell (based on visual inspection, no gas smell, and no findings when using a combustible gas detector).
Fuel pressure (measured at the rail) is within specifications as listed in the Hayne’s repair manual.
I swapped out the fuel pump assembly yesterday since HHRs are known to have fuel pump problems, and some HHR people had suggested it as a possible cause of the problem. Unfortunately it didn’t solve the problem.
Something that I recently noticed (a few days now, may have started longer ago) is a short burst of sound when I turn off the engine. It almost sounds like a small electrical motor activating. It seems to be coming from the rear half (driver’s side) of the engine on the side nearest the windshield. I couldn’t find the exact source and have no idea if it’s even relevant to the issue.
Here’s a link to a video with the sound: https://youtu.be/5DNCetYMAuU
It’s the small buzz/burst of sound shortly after the engine stops.
Also, here’s a link to a video of the delayed/slow start. It also shows the fuel pressure during one of the episodes. Sorry about the windshield wiper getting in the way of the video (didn’t realize it was on until it was too late, and, since the problem takes several hours to reoccur, I couldn’t just restart the car to re-film it). https://youtu.be/YgDfilURvsU
I did check the air filter housing, air filter, wooly worm, and spark plugs today. Everything seems fine except one of my coils (cylinder #1-furthest on the passenger side) had a very small smudge of brown gunk on the outside rubber/on the wall of the spark plug well. That spark plug appeared normal with no evidence of anything on the electrodes, threads, or ceramic insulator. The spark plug well itself also appeared otherwise normal except for the small smudge on the one side of the wall. All four spark plugs seemed normal with normal gapping and electrode appearance.
The battery voltage measures fine with my multimeter (both with the car off as well as running with the alternator).
Let me know if there are followup questions.