2013 Chevrolet Malibu would stall after 1 hour drive time
Ok so sometimes cars can take some time to figure out or to even just duplicate the concern. Initially I had seen this car for a check engine light with a couple codes stored p0010 and p0011. So I diagnosed these codes as a bad solenoid valve and recommended both solenoids due to high failure rates of the solenoids. All was well once replaced and verified the system functioned as it should.
A couple weeks later customer calls with the concern of car stalling at stop lights. I ask some questions and take the car for a test drive and don't seem to stall on initial drive. I ask how long you have to be driving and she wasn't quite sure. So instead of saying no problem found I decided to drive it again this time a longer test drive. On the second test drive and at this point a already warmed up engine on the way back the engine stalled. Hmm alright so now I know when it happens and how it feels when it stalls.
Felt as though I was running out of fuel but according to the scanner I did not lose pressure. So maybe the low pump was dropping out intermittently or the fuel pump control module was dropping out. So I had my Vantage Pro with me and connected to the vehicle. Took for another test drive and found that the low pressure pump never lost a beat. Well now I know that is good so I pull up a diagram and find my crank sensor signal wire and hook into a coil control wire as well. Both of them appear good so I connect to a Injector control and hook up a amp clamp as well.
I get the vehicle to exhibit its problem but still no dice. I know at this point there is no problems with the spark control or injector control and they are not dropping out causing a stall. So I take the vehicle to my location so that I can hook up the pico and capture more data and zoom in and see detail. This car has not set any codes and only stalls in drive or reverse. I start thinking what would cause a stall only in gear and thought of the torque convertor. So I graph via scan tool the tcc slip speed, engine rpm, and input speed sensor. The slip speed matched the engine rpm even in stall condition so its unlikely.
So now I am really questioning what else is different in drive versus Park or neutral and this is where I finally got a chance to see a moment of the failure. I notice that in park and neutral that the oil pressure control solenoid is on but in drive it is in the off position so in park and neutral the oil pressure is higher but this isn't the cause of this fault turns out. What I did notice is when the solenoids were commanded off that the Cam Variance would increase before the stall indicating that the cams were being allowed to phase without the command. This I found very interesting and I watched this occur several times on two different scan tools.
Luckily for me I had the Exhaust Solenoid still and popped that one back in just to capture some waveforms with the Pico and to see if the new solenoid was possibly sticking and in this case it was. It would only happen when the solenoid was hot enough that the stall condition would happen. After the old solenoid was put back in just for testing purposes this condition has not happened since. So for the Fix I ordered two OEM VVT solenoids and driven hundreds of miles to confirm that it is indeed fixed. This proves the theory just cause its new don't mean its good. Also I originally wanted to buy OE but on the weekend I originally looked at this only ones I could get the same day were aftermarket solenoids and the customer needed the car for transportation. So for me this gives me a valuable lesson of only using Oem parts and not to forget the recent repair that seemed to function correctly at the time but failed in a different way when fully hot.
Very nice article. I have seen OEM parts fail, out of the box, as I'm sure you also have. I take nothing for granted. This was a good catch. Nice job!
It seems like the OE N.E.W. problem is getting worse but it might just be that so many more people are on the web talking about it. Either way, every time it happens we never forget it. I had a N.E.W. Ford PATS Transceiver once, took a lot of talking to convince the parts guy to give me another one too!