My car is a 2014 chevy cruze with a 1.4L turbo.
Right now it's throwing codes for turbocharge engine underboost (p0299) as well as catalyst system low efficiency bank 1 (p0420).
Some research says this could be a bad intake manifold. I think my manifold is holding pressure just fine though. (3/4 psi at idle up to 23 at higher rpms on highway).
What's your take? Should I vaccuum test? Is it my catalytic converter? Or the turbo itself maybe?
A test is always more useful then trying to shotgun parts haha. Pray it's not the turbo, those GM turbos seem to never hold up well lol. Do the vacuum test but also check your sensors f you haven't yet. O2 can cause issues with P0420 code.
When it comes to turbo issues, you NEED to data-log to see how the engine is operating while driving. Turbocharged engines operate completely differently at idle and under acceleration. You need to data-log how much boost your turbo is making and at what engine speed. Do some research to see how much peak boost your turbo is supposed to provide and at what engine speed. Then compare and see if the turbo is providing peak boost or lacking boost.
Things to check:
- Induction piping and Intercooler: You want to make sure all the hose clamps from the turbo all the way to the throttle body are nice and tight. Turbocharged engines operate off a pressurized system, so loose clamps WILL cause pressure loss and boost leaks. There are many ways to test for boost leaks on YouTube and Google.
- Vacuum lines: Vacuum lines are VERY important on turbos that are pneumatically operated. Your engine has a pneumatically actuated wastegate and bypass valve that uses vacuum lines to operate it.
- Wastegate: The wastegate determines how much exhaust gas is diverted to the turbo to spool it, and therefore determines how much boost the turbo makes. You want to make sure the wastegate is operating properly too. When you first start the car up, have someone rev the car while you look at the wastegate. You should see the wastegate arm move back and forth as the person revs the engine. If you don't, then that's a problem and it may be stuck.
- Turbo Bypass Valve (or "blow off valve" some call it): You want to make sure the bypass valve is working as it should. This valve controls when to relief excess boost pressure when you let off the throttle. If it is stuck open, then the system won't build any boost in the first place. Check the vacuum lines (or electrical connections if electronically controlled) associated with it.
- MAP sensor(s): You want to make sure your MAP sensor is giving correct data to the ECU on how much boost the turbo is producing. Maybe give it a cleaning as it may be super dirty.
As for the low efficiency catalyst code, I would check to see if the downstream O2 sensor is working properly (and of course check the upstream O2 sensor as well). The downstream O2 sensor is what determines whether the catalyst is working properly. Voltage should be around a steady 0.45 volts for the downstream O2 sensor.
But before trying anything, you need to data-log to see what exactly is happening with the boost and the voltages for the O2 sensors.
I have an old turbo from an engine (turbo included) with 110k miles that the previous owner overheated. This engine has 28k so hopefully it's not the turbo. {black}:pray:
@knine
You can try to see if the turbo spins freely (of course if it is easy to access). Disconnect the inlet hose from the turbo and see how it's spinning when the engine is idling. A busted or gunked up turbo won't operate well and won't build enough boost.