2012 1LT 1.4T Auto 223,000mi. Recently had the ECU disable the turbo because of sensor failures. Codes pointed to intake tract. Replaced MAF, MAP and IAT sensors and she came back to life. During the diagnostic processes, I broke down and got the code reader because troubleshooting without them is just silly now. A few long trips after replacing all those sensors, I noticed sluggish performance and fuel economy had taken a dip from around 33-34mpg Hwy to 28-30. I hooked up the code reader and watched the data. STFT and LTFT numbers were spot on, but I noticed that the engine was pushing boost even while going down hills. O2 sensor graphing showed the typical sinusoidal waveform during steady load. I've read that the sensor can behave lazily but appear to be functioning normally which can affect economy and performance. I fear that during the few long trips I took with the wastegate being open did damage to the cat. I suspect the fuel system was running more toward the rich side as a precautionary measure to prevent engine damage due to the sensors not functioning properly and this caused the cat to load up. Once engine performance returned, I wonder if the loaded cat got too hot and damaged the honeycomb mesh inside. Cat temps during moderate load across level ground is around 1200-1300ºF which seems a little hot to me. I have new O2 sensors but I am holding off on purchasing a new cat for now as it is a much more pricey part to just replace without knowing for sure. I feel like 223,000 miles out of the original sensors in the intake and exhaust streams was good life. As it stands at this point, I have put 1400 miles on since new intake tract sensors and engine is not throwing any powertrain codes.
mk23socom
This may sound out in left field, but with that many miles, have you checked the intake PCV valve. I only ask because you mention too much boost and sluggish performance.
2011-2016 Cruze 1.4 PCV Valve Cover/Intake Manifold Issues
2011-2016 Cruze 1.4 PCV Valve Cover/Intake Manifold Issues
I'd gone through a few valve covers due to PCV issues when I discovered the absence of "the little orange dot" inside the intake manifold. I purchased the PCV bypass kit from the fella on here who builds those kits and have been happily operating with it for the last 40,000 miles. periodic checks of the PCV valve health indicate that the bypass kit is working properly.
It can be said that the performance loss is not particularly evident at low speed/lower RPM. It has decent pickup but feels like it flattens out as engine speed picks up. I genuinely feel like this is an exhaust side issue as if there is too much back pressure against the engine and it's failing to breathe properly. I may have to bite the bullet and order gaskets and just pull the cat off and inspect it. I have a low pressure gauge that I can use to check exhaust back pressure but I don't know how much faith I have in that. at a minimum, I am going to replace both O2 sensors as they are both OEM sensors and for $65 for the pair, I don't think it's unreasonable to replace them.
It can be said that the performance loss is not particularly evident at low speed/lower RPM. It has decent pickup but feels like it flattens out as engine speed picks up. I genuinely feel like this is an exhaust side issue as if there is too much back pressure against the engine and it's failing to breathe properly. I may have to bite the bullet and order gaskets and just pull the cat off and inspect it. I have a low pressure gauge that I can use to check exhaust back pressure but I don't know how much faith I have in that. at a minimum, I am going to replace both O2 sensors as they are both OEM sensors and for $65 for the pair, I don't think it's unreasonable to replace them.
So, I forgot to update this following my diagnostics and repairs I put in place.
I traced my throttle signals through range and during steady state driving and it showed that one of the throttle body channels was throwing bad data which led to increasing fuel consumption when combined with original O2 sensors having a quarter million miles on them. I also had boost leak on the connection to the intercooler which i was losing performance and likely economy to, also.
I replaced the boost hose between the turbo and the intercooler, the throttle body, O2 sensors #1 and #2, and inspected and tested flow through both the primary and secondary cats(hooked shopvac up to one end to see if flow restriction was present). while I was in the engine bay, I replaced the oil supply line to the turbo because the o-rings had gotten aged and started weeping also, although I know that was not affecting performance or economy, just a nuisance leak that was making a mess.
after repairs, I've put around 1,000miles on of my normal driving and I've lost stuttering and stumbling issues at mid-range, gained midrange boost and acceleration, improved fuel economy back to near 33-34mpg, throttle response improved and have no lights, warnings, codes or other indicators of performance issues.
All my data streams are reading favorable numbers and I anticipate many miles of trouble free driving with my batch of mods, repairs, and new sensors all over the engine systems.
This forum has been very helpful for me in diagnosing troubles based on feedback and reading about similar problems so I hope I am successful in paying it forward by providing my experiences with my recent troubles.
K
I traced my throttle signals through range and during steady state driving and it showed that one of the throttle body channels was throwing bad data which led to increasing fuel consumption when combined with original O2 sensors having a quarter million miles on them. I also had boost leak on the connection to the intercooler which i was losing performance and likely economy to, also.
I replaced the boost hose between the turbo and the intercooler, the throttle body, O2 sensors #1 and #2, and inspected and tested flow through both the primary and secondary cats(hooked shopvac up to one end to see if flow restriction was present). while I was in the engine bay, I replaced the oil supply line to the turbo because the o-rings had gotten aged and started weeping also, although I know that was not affecting performance or economy, just a nuisance leak that was making a mess.
after repairs, I've put around 1,000miles on of my normal driving and I've lost stuttering and stumbling issues at mid-range, gained midrange boost and acceleration, improved fuel economy back to near 33-34mpg, throttle response improved and have no lights, warnings, codes or other indicators of performance issues.
All my data streams are reading favorable numbers and I anticipate many miles of trouble free driving with my batch of mods, repairs, and new sensors all over the engine systems.
This forum has been very helpful for me in diagnosing troubles based on feedback and reading about similar problems so I hope I am successful in paying it forward by providing my experiences with my recent troubles.
K
I should add that the catalyst mesh looked friggin immaculate. it was clean, dry and a nice light color all around.. no loose material, rattles or other indicators of damage.
Can't say enough for this forum OR the Cruze. Easy to work on, cheap and widely available parts, and did I mention easy to work on?
Thanks for a platform to help all of us Cruze owners out.
Can't say enough for this forum OR the Cruze. Easy to work on, cheap and widely available parts, and did I mention easy to work on?
Thanks for a platform to help all of us Cruze owners out.
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