Cannot figure out why car is going into limp mode
2011 Chevy Equinox (2.4L) w/Jasper remanufactured engine. Cat converter had a hole in the flex pipe, so we changed it out for a brand new OEM cat. Once we did that, the car started going into limp mode and threw a low idle pending code. Initially it looked…
2011 Chevy Equinox (2.4L) w/Jasper remanufactured engine. Cat converter had a hole in the flex pipe, so we changed it out for a brand new OEM cat. Once we did that, the car started going into limp mode and threw a low idle pending code. Initially it looked like an O2 sensor got knocked loose, during the work on the cat. Checked everything we could, tightened everything down, cleaned everything really good and did a re-learn. Car ran fine for 2 weeks then the same symptoms came back. Diagnostics showed that the throttle body was seemingly failing. Swapped out the throttle body for a brand new one from the manufacturer & did another re-learn. Car ran fine for 3 days and then the same symptoms came back. Car has 0 issues starting. No dash lights flickering. What would you look into next? MAF sensor? Maybe a grounding issue? Any thoughts or ideas are welcome.
Collected discussion
What's the specific P-code you have? If P0506, yes the MAF would the next thing to try, but I would expect the car to be down on power and drinking fuel if it were bad enough to mess up the idle. Also worth spraying brake cleaner at all the inlet hoses to see if you have an unmetered air leak somewhere.
It finally threw an actual check engine light and yes it's the P0506 code. Will check on the MAF
If you unplug the MAF and the car behaves exactly the same as it did before, it's a fair bet. Otherwise, all you can really do is try a new one and cross fingers. As I say, an intake leak is also a strong possibility.
Since it is a P0506 and it started right after the exhaust work, I would quit throwing parts at it and watch live data first. Look at warm idle MAF g/s, short and long fuel trims, commanded throttle angle, and actual RPM. If trims are adding fuel, you still have unmetered air somewhere even if the smoke test looked clean. On those 2.4s I would also check the PCV orifice in the intake, the brake booster hose, the fresh air tube after the MAF, and the throttle body connector pins for a loose terminal or rubbed wire. A weak ground can do weird stuff, but bad air metering or a connector issue fits the reset and relearn pattern better.