GMC Terrain 2.4 crank but no start - TerrainForum.net: GMC Terrain Forum
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post #1 of 27 (permalink) Old 11-24-2019, 02:54 PM Thread Starter
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GMC Terrain 2.4 crank but no start

I recently removed rebuilt and replaced the 2.4 DI engine on this Terrain. After completing the install the engine refused to fire and run. Verified fuel pressure to the HP pump and pressure at the rail. It does turn over with a very rare "thump/grunt" of combustion. Decided to spray carb clean through the PCV hose port on inlet air duct to see if could get more combustion events. To my surprise, not only did I get more thumps, I actually got the engine to start! Rough for about 10 seconds then smoothed out. I let run for only 30 seconds total because I didn't have adequate amount coolant in system. Next morning I topped of coolant and restarted. It was a long crank cycle but fired and ran smoothly. The long crank time caused MIL for crankshaft position sensor relearn, which I expected after an engine rebuild. I allowed the engine to run for about 40 minutes while I cleaned up garage and inspected for any leaks of coolant or oil. I found no issue. Also scanned an saw no new codes from ECM. I decided to perform the relearn procedure for sensor. When I got to the step involving turning ignition off then back on, I could not restart the engine. That has been my situation since. Fuel pressure at rail is 2300+ with fuel pressure to the HP pump at 67 PSI. Both are the desired amounts. The fuel injectors were removed, cleaned, flowed, and all seals replaced and reinstalled.

I have an OTC Evolve scan tool and used it to perform the automated systems test to all modes and sensors. All passed. I have replaced the crankshaft position sensor in case it giving false data, but no change.

I can watch RPM, fuel pressures, injector duty, ignition voltage, etc and all look strong.

I am up for any help. I'm desperate and confused. This engine ran so smoothly for 40 minutes and not since.

At this point I am willing to change headlight fluid, muffler bearings, change tire pressure. 😀😀😀🤔🤔&#x1f 60a;

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post #2 of 27 (permalink) Old 11-24-2019, 03:37 PM
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It looks like you have the fuel part covered.
Next I would check to see if you have spark at the plugs.
Almost feels like you are missing a ground somewhere.
I usually save the ECM/BCM for last.

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post #3 of 27 (permalink) Old 11-24-2019, 06:45 PM
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Just a shot in the dark. Does it try to start again with carb clean like before. try disconnecting the battery for a bit too.

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post #4 of 27 (permalink) Old 11-26-2019, 12:18 AM Thread Starter
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Okay, update for you helpers.

Verified spark at all 4 plugs.

Replaced crankshaft position sensor and MAP sensor. Both with OEM

I can "start it" with carb spray consistently but only if directly into throttle body and it will not actually run, just sputters and dies as soon as starter and or spray stops helping.

The time it actually started and ran with the carb spray it was with a short couple of bursts into the PCV port on air inlet tube. What I am experiencing now is clearly only from carb spray into TB. Despite injectors having the correct pressure to them, the ECM is not commanding them to open long enough.

Can anyone tell me what sensor may me giving the ECM bad intel to cause this?

AS I mentioned before the injectors were sent out to be flowed cleaned and balanced. No issues other than worn seals were found. The fact that it ran perfectly for 40 minutes leads me to believe they are indeed not to blame, rather not being commanded to operate likely.

If you feel I am off base or missing something, let me know please.
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post #5 of 27 (permalink) Old 11-26-2019, 07:40 AM
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Aren’t the injectors commanded via the fuel trims and the O2 sensors? But at startup, you’ve got “Open Loop” conditions, which I *believe* just uses “canned” data until the engine reaches “Closed Loop”.

Have you tried resetting the Computer by disconnecting the battery?

The other thing is Engine Timing. Could something have happened with the chain during that one “successful” run?

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post #6 of 27 (permalink) Old 11-26-2019, 07:53 AM
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Check your engine coolant temperature sensor. It will effect how much fuel the engine should get at startup.

Last edited by stopwatch; 11-26-2019 at 11:23 AM.
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post #7 of 27 (permalink) Old 11-26-2019, 10:14 AM
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What year engine? Any fuses blown?

2013 Nox 2.4L 1LT AWD from western PA.
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post #8 of 27 (permalink) Old 11-29-2019, 03:30 PM Thread Starter
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I am sorry for asking for help and not providing a full description.

2012 2.4 GMC Terrain SLT
142,500 on chassis and 40 minutes on rebuilt engine

After closer diagnosis I have determined that I have some issues to and from BCM. Despite have no engine P codes, I do have a few U and C codes from modules that have lost communication in the loop. I have no tachometer on dash and a "sabilitrak" warning light.

U0401-71
C0800-03
U0074-00
U0155-00
U0140-00

I have inspected the wiring harness and see no obvious damage unfortunately (I wish it was as simple as I pinched some wires during the installation process)

Here is a snapshot I took when it was barely running last:

DATA STREAM SNAPSHOT
MIL Lamp [Engine]
Off
Diagnostic Trouble Codes Set [Engine]
0
Fuel Sys B:Open Loop (Bank 1 Or Both) [Engine]
No
Fuel Sys B:Closed Loop - Using All O2 Sensor(s) [Engine]
No
Fuel Sys B:Closed Loop Fault With At Least One O2 Sensor [Engine]
No
Fuel Sys B:Open Loop - Due To System Fault (Bank 1 Or Both) [Engine]
No
Fuel Sys B:Open Loop Due To Driving Conditions (Bank 1 Or Both) [Engine]
No
Fuel Sys A:Open Loop (Bank 2) [Engine]
No
Fuel Sys A:Open Loop (Bank 1 Or Both) [Engine]
No
Fuel Sys A:Closed Loop - Using All O2 Sensor(s) [Engine]
Yes
Fuel Sys A:Closed Loop Fault With At Least One O2 Sensor [Engine]
No
Fuel Sys A:Open Loop - Due To System Fault (Bank 1 Or Both) [Engine]
No
Fuel Sys A:Open Loop Due To Driving Conditions (Bank 1 Or Both) [Engine]
No
Calculated Engine Load [Engine]
40.0 %
Engine Coolant Temperature [Engine]
243 F
Short Term Fuel Trim Bank 1 [Engine]
0.8 %
Long Term Fuel Trim Bank 1 [Engine]
-18.0 %
Fuel Rail Pressure Gauge [Engine]
72.7 psi
Manifold Absolute Pressure [Engine]
11.22 inHg
Engine RPM [Engine]
0 RPM
Vehicle Speed [Engine]
0 mph
Spark Advance [Engine]
16.5
Intake Air Temperature [Engine]
77 F
Mass Air Flow [Engine]
4.04 g/s
Throttle Position [Engine]
18 %
Oxygen Sensor Bank 1 Sensor 1 [Engine]
0.04 V
Short Term Fuel Trim Bank 1 Sensor 1 [Engine]
-7.8 %
Oxygen Sensor Bank 1 Sensor 2 [Engine]
0.74 V
Short Term Fuel Trim Bank 1 Sensor 2 [Engine]
Not Used %
OBD Requirements To Which Vehicle Or Engine Is Certified [Engine]
JOBD And OBD II
Time Since Eng Start [Engine]
1845 sec
MIL Lamp [ECU ID: eb]
Off
Diagnostic Trouble Codes Set [ECU ID: eb]
0
Fuel Rail Pressure Gauge [ECU ID: eb]
77.5 psi
MIL Lamp [Trans]
Off
Diagnostic Trouble Codes Set [Trans]
0
Distance MIL Active [ECU ID: eb]
0 miles
Warm-Ups Since DTC Cleared [ECU ID: eb]
NO DATA cnt
Distance Since DTC Clear [ECU ID: eb]
NO DATA miles
Distance MIL Active [Engine]
0 miles
Fuel Rail Pressure Gauge [Engine]
NO DATA psi
Commanded Evaporative Emission Vapor Purge [Engine]
NO DATA %
Fuel Level Input [Engine]
NO DATA %
Warm-Ups Since DTC Cleared [Engine]
NO DATA cnt
Distance Since DTC Clear [Engine]
NO DATA miles
Evaporative Emissions System Vapor Pressure [Engine]
NO DATA inH2O
Barometric Pressure [Engine]
NO DATA inHg
Catalyst Temperature Bank 1 Sensor 1 [Engine]
NO DATA F
Distance MIL Active [Trans]
0 miles
Warm-Ups Since DTC Cleared [Trans]
NO DATA cnt
Distance Since DTC Clear [Trans]
NO DATA miles
Control Module Voltage [Engine]
NO DATA V
Absolute Load Value [Engine]
NO DATA %
Fuel/Air Commanded Equivalence Ratio [Engine]
NO DATA :1
Relative Throttle Position [Engine]
NO DATA %
Ambient Air Temperature Degrees [Engine]
NO DATA F
Relative Throttle Position B [Engine]
NO DATA %
Accelerator Pedal Position D [Engine]
NO DATA %
Accelerator Pedal Position E [Engine]
NO DATA %
Commanded Throttle Actuator Control [Engine]
NO DATA %
Control Module Voltage [Trans]
NO DATA V
Control Module Voltage [ECU ID: eb]
NO DATA V
Intake Air Temperature Sensor Bank 1, Sensor 1 [Engine]
NO DATA F
Intake Air Temperature Sensor Bank 1, Sensor 2 [Engine]
NO DATA F


I will dig up the wiring schematics and see if I can find the failing link. If anyone recognizes the lack of communication culprit, please let me know. The obvious would be the crankshaft position sensor, however if I look specifically at it on scanner I see RPM as I should, no issue.
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post #9 of 27 (permalink) Old 11-29-2019, 03:41 PM Thread Starter
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The coolant temp sensor is also properly retrieving data.

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post #10 of 27 (permalink) Old 11-29-2019, 06:36 PM
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Just a guess here ... but according to your original post, the engine started *twice* before you performed the Relearn.

What are the steps involved with the Relearn, and how do you know it has successfully been completed?

2011 Equinox 1LT (new Jan 2011): Summit White / 3.0 L V6 / FWD / Pioneer Stereo / 18" Wheels / 138.2k miles [05-NOV-2019]

2002 Impala 1LT (new Jun 2002): Summit White / 3.4 L V6 / FWD / Cassette-CD Combo /225.5k miles [05-NOV-2019]
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