Hello

2012 Chevy Equinox with 80,000 miles on chassis and 5,000 on rebuilt engine from a reputable, national builder. Engine was replaced due to excessive oil consumption.

About 8 months after engine replacement, the 2.4 started to idle terribly when cold started and shifted into reverse.

Relevant facts:

1. Does NOT set a code
2. Does NOT set a mis-fire
3. LT Fuel Trim at -3 after running
4. ST Fuel Trim oscillates between -5 to +2
   1. Seldomly to Plus side
   2. Does seem to be quite active and all over the board
5. Throttle Position responsive and in spec
6. Cylinder Balance in spec
7. Injector pulse in spec
8. Engine Mounts good
9. Battery replaced
10. MAF sensor replaced
11. Traced each connection wire status through the loom
12. Checked pins of each connector
13. Vacuum leak checks down to the intake manifold with NO vacuum leak
14. Nothing from the Fuel Trim indicates a rich condition
15. Ran system without EVAP to test for symptom - with EVAP blocked off, symptom persisted
16. Tests and system monitor through Snap On Solus Scan Tool
17. Replaced O2 Sensor
18. .
19. When removing the Air Box, noticed what appeared to be excessive blow-by liquid remnants as the air box was removed. High Pressure fuel pump could be internally leaking causing excessive buildup in the crankcase and pushed into air box

New Parts installed during Engine replacement

1. Plugs
2. Cam Phasers
3. VVT sensor
4. Coolant Sensor
5. Thermostat

I have never seen an ECM replacement solve a situation like this, but we are at wits end here....

General Thoughts on Progression:

1. Potentially replace High Pressure Fuel Pump
2. Could swap out Cam solenoids; but they are active and within spec
3. Potentially replace ECM
4. Thought about a torque converter issue, but if the engine is not running correctly, the tranny will not function properly....and vice versa

At this point, we are leaning towards replacement of the High Pressure Fuel Pump. Any thoughts? Running out of money and patience

Condition seems to go away after the vehicle has warmed up.

Thanks in advance

 

I have a 2015 equinox with the exact same issue. New remanufactured engine. On cold start if shifted directly into reverse I get a very noticeable shake/vibration in the driveline. Goes away completely if I wait for high idle to complete before shifting into reverse. Was wondering if you were able to resolve this?

 

To Cole5894...we dug pretty deeply into the issue to find internal mis-fires under #2 and heavily on #3. Combined with excessive blowby, we determined a badly scored piston on #3...remanufactured unit was toast.