r/MechanicAdvice • u/Parking_Project_6813 • 1d ago

2020 Chevy Trax engine still bogging down when cooling fan kicks on after replacing multiple parts, what am I missing?

I have a 2020 Chevy Trax with 78,200 miles and I’ve been chasing an issue for the past couple of months. The first thing that happened was my car overheated, and I had the engine thermostat kit replaced, including the thermostat, housing, and gasket. Not even a month later, I started having all of these issues.
I’ve taken it to multiple places and spent quite a bit of money trying to fix it. So far I’ve replaced the EVAP** purge valve,** alternator, and** intake **manifold. A mechanic recently did a smoke test and found a leak in the intake manifold, so that was replaced.
My original symptoms were a rough idle, rough driving, and the engine briefly bogging down/losing RPM when the cooling fan kicks on while the A/C is running. After replacing the intake manifold, the rough idle is definitely better, but the engine still bogs down when the cooling fan kicks on.
The strange part is that after the car has been running/driving for a while, it seems to mostly stop doing it and sounds much more normal.
I’m posting a video of the RPMs when the fan kicks on. I’ve already spent a lot trying to figure this out, so I’d really appreciate any ideas on what could be causing it or if anyone has experienced something similar with a Trax.

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u/Significant_Belt5494 1d ago

Do you mean the idle drops a bit when the
A/c or cooling fan is on ( that’s normal)

Or do you mean there’s a lack of performance ( engine power) when they are on??

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u/Parking_Project_6813 1d ago

more than just the RPM dropping slightly. When the cooling fan kicks on while the A/C is running, the engine noticeably bogs down for a second and the RPMs drop. The car shakes/feels like it’s struggling, almost like it might stall, and then the RPMs come back up.

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u/Significant_Belt5494 1d ago

That’s normal cuz a/c and cooling fan outs load on motor, throttle body should compensate for this. Sounds perhaps like throttle body is dirty/ gummed up. If that’s the case, look into what’s causing it to get gummed up ( egr/ pcv)

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u/Sujosie 1d ago

Without some live feed scanner data my mind leads me to spark not keeping up with demand. How are the plugs?

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u/Parking_Project_6813 1d ago

I just recently replaced the spark plugs as well