Since having the spark plugs replaced, we have been having the following issue:
Specifically on cold days, after staring the car and staying idle, the car RPMs will drop, the engine will shudder and the car will die.
We now sit with the car in idle and have our foot ever so lightly on the gas pedal to counter the drop in RPMs and the chugging that we notice. We do this for a few minutes before the chugging goes away and we can then drive away.
If the car sits for more than 2 hours after that, it does it again.
It definitely started happening more often now that the temperature has begun to drop. In the summer, this happened maybe twice.
No indicator lights come on, everything looks and acts as it should otherwise.
Any ideas? I have had it in to the Chevy Dealer in town with no resolution yet…
I recently ran into a bad MAP sensor that caused the same symptoms. It’s entirely possible, since they sit over all that heat and get brittle, are made of cheap crappy plastic ect, etc, etc, they could have easily have cracked it while working on it when changing your plugs. I only noticed it was cracked when I attempted to remove it to clean the upper intake. Had I not attempted to remove it, I might not have ever noticed and it still would have been stalling.
Cold temperatures make the engine – at idle – more sensitive to the air/fuel mixture and to the amount the throttle valve is open. Those would be the place to start. The throttle body check (make sure they check the throttle position sensor too) mentioned above would address the latter, and for the former a shop would start by checking the ecm memory for active or pending diagnostic codes, and a general visual check for vacuum leaks. If there’s any routine maintenance that’s behind schedule, sometimes getting all that up to date will fix a problem like this too.
George may be spot on but the MAP sensor, if cracked, will literally suck air in if you lift the top of it and separate the crack. If you’re looking for things you can check yourself and don’t have lots of tools and all that, google where the sensor is and locate it, and just gently move it around. if it’s cracked and snaps off, at least you know what your problem was. if it’s solid and moving it doesn’t change the rpm’s it wasn’t that. If it’s a bad throttle position sensor, it’ll likely throw a code pretty specific to the throttle position sensor, unless it’s just cracked and sucking air in. You may be looking at a vacuum leak and, after getting the motor cover off, will start it up and say, “hey, that’s sucking air right there…let’s find out what that part is…” If you don’t find it by “nosing” around under there, by all means take it in. These forums aren’t very good for telling people what to tell the mechanic to do, they’re good for telling people willing to get their hands greasy what to look for. A decent mechanic already knows what to look for and how to look for it. As a mechanic, my worst enemy is the internet. Customers that don’t know how to put air in their tire suddenly know “exactly how it’s done” and “exactly how much it’s supposed to cost” will literally get indignant with you if it wasn’t the same as what they googled. It’s not a bad thing to learn about stuff even if you’re not going to do it yourself but the situation I’m talking about will often result in you paying more. An unscrupulous mechanic will get really annoyed when you claim to know more than he does and will charge you more. I don’t play that, I’m just giving you fair warning about how the business works. Good luck on your problem.
Still having the issue here. We are taking it back in today for service tomorrow. Having all of the spark plugs replaced. Will let you know if that does the trick.
I’m not sure an Equinox has an IAC, but I’m gonna go look. I’ve been reading and I’m gonna try replacing the cam actuator solenoids this weekend.
So far I’ve ruled out:
Plugs
Map sensor
MAF sensor
Dirty throttle body
I keep hearing full coverage insurance, 5 gallons of gas, and a match works wonders.
It seems pretty unlikely all injectors would fail at the same time, unless perhaps the fuel system was opened up and gunk got into the fuel lines post fuel filter just prior to this occurring. Did the fuel filter get changed at the same time as the spark plugs? If not, I’m not surprised replacing the injectors didn’t help.
Have you had these tests done yet?
Diagnostic codes from ecm memory
Compression test on all cylinders, wet vs dry
Intake manifold vacuum measurement
Fuel pressure test
Measure fuel trims
Verify good quality spark
Verify base timing & timing advance is working correctly
I went to a buddy’s brothers shop instead of the dealer.
He listened to the issues I had and suggested that before I take it in anywhere, to clean the Mass Air Flow Sensor.
I paid $8 for the CRC Mass Air Flow Sensor cleaner, took 20 minutes in all from getting the sensor out and spraying it 15 times and letting it air dry for 10 minutes before popping it back in…
The car is running smoother than it has in a LONG time.