Envoy stalls then does not start only while cold

[Envoy99]

I posted before about this awhile back and still have not solved it (I have been busy and the envoy has sat awhile) but I have a couple of updates and wanted to see if there are any fresh ideas. I saw another poster is currently having the exact same issue as me so having a solution would be nice for future reference.

4.2L 2006 Envoy XL

Essentially, this problem only happens in cold weather. The problem started last winter and since it had the issue daily I stopped driving it. When it got warmer I drove the envoy a bit during the summer (~6,000 miles) and it did not happen even once. Fast forward to this winter and it is a daily problem again. When you start the car, it starts up then immediately dies. If you try to restart it without waiting around 20 seconds it will not even crank, just one audible click. It acts as if it has a dead battery. After waiting 20 seconds, it will crank again and typically run a little longer, then stall and die after 1-3 minutes. It continues this behavior (waiting 20 seconds to start then stalling again) until the engine is up to temperature. Once the engine is up to temperature, it is as if the problem does not exist, the car runs fine all day. It does not stall again at all until the next time it has sat and gotten cold.

CE codes are:
P0014 - B camshaft position - timing over-advanced or system performance bank 1.
P0017 Crankshaft position - camshaft position correlation bank 1 sensor B.
P0171 System too lean bank 1.
P0601 Internal control module memory checksum error.
P0496 - Evaporation emission system high purge flow. (I suspect this one will be gone since I changed the valve)

Today I finally got around to changing the purge valve, It has had a problem with it for awhile and I crossed my fingers that may be it but no cigar, although it does seem to maybe stall less since changing it. I have a new ignition switch laying around I am going to throw on but I do not see how this could be the problem.

What are your guys thoughts? My gut is that it is not the fuel pump because I can hear it priming at accessory power and after driving ~6,000 miles this summer, if that was the issue I feel it would have shown other signs or quit all together by now.

 

[mrrsm]

Sorry about these Troubles... Let's Look things over on this Response List:

First... Watch Paul "Scanner" Danner's Brother James... performing a Proper Shop Oscilloscope Diagnosis of a P0014 and P0017 pair of issues on a 2006 Trailblazer:

...and another along the same lines of "O" Scope Diagnostics of the P0014 and P0017 Codes:

P0014

(1) Check your Oil Level. If LOW ...Ensure the volume is brought up to 7 Quarts. The Camshaft Position Actuator Solenoid (CPAS) opens and closes a Valve feeding Motor Oil at normal pressures Into and Out Of the Camshaft Phaser, so as to Retard the Exhaust Camshaft in the narrow range of 0-25 Degrees.

Ordinarily, this action behaves much like the Old EGR (Exhaust Gas Re-Circulation) Valves at Engine Idle and provides for a MUCH Stronger Engine Performance at Higher RPM and gives the Engine MORE Power and Torque in a wider RPM Range.

However... This activity cannot take place if the Oil Level in the Crankcase is TOO Low or if the CPAS Unit either has Clogged Inlet and Outlet Screens... or they are MISSING entirely. Having a Heavy Dirt Concentration and Carbon-Gas Blow By Lacquer Combustion Contaminated Oil makes this CPAS unit ...more likely to Fail. Replace the CPAS Unit and include Cleaning Out the Harness Connector with Brake-KLEEN if the connector is Saturated with Motor Oil caused by the Old CPAS Leaking Oil.

P0017

(2) On Aging Engines with High Wear... The Timing Components consisting of the Timing Chain Stretching, The Timing Chain Tensioner Over-Extending and the Timing Chain Guides Wearing Inwards, creates conditions which throw off the exquisite relationship between the Positions of the Valve Train attached to the Dual Overhead Camshafts...and the position of the Crankshaft Timing Wheel Notches meant to allow the EFIs to Spray Fuel into the Six Cylinder at Just the Right Moment... and then the Timing allowed by the PCM to Fire the Coil Over Plugs should happen to ignite the Air and Fuel at just the right moment. TIMING is EVERYTHING in Computer Controlled Modern, Fuel Injected Engines.

If their precision (Camshaft to Crankshaft Relationships) are thrown off too far, then not enough Compression will develop at just Before Top Dead Center, so when the Fuel should Spray and the Spark Plugs need to "FIRE" and POWER should develop...the proper combustion processes will be disrupted.

In aging motors...a Difference of ONLY a Few Degrees is enough to prevent the Motor from running. THIS is a BIG REPAIR JOB... and It often requires either replacing the Full Timing Chain Set and or Replacing the Cam Phaser or doing BOTH at the same time. These very involved repair jobs are very well documented here at GMT Nation.

P0171

P0601

From the GM OEM Repair Manual:

DTC Descriptors

This diagnostic procedure supports the following DTCs:

• • DTC P0601 Transmission Control Module (TCM) Read Only Memory (ROM)
  • DTC P0602 Transmission Control Module (TCM) Not Programmed
  • DTC P0603 Transmission Control Module (TCM) Long Term Memory Reset
  • DTC P0604 Transmission Control Module (TCM) Random Access Memory (RAM)
  • DTC P062F Transmission Control Module (TCM) Long Term Memory Performance
  • DTC P1621 Transmission Control Module (TCM) Long Term Memory Performance

Conditions for Running the DTC
The TCM runs the program to detect an internal fault when the engine is running. The only requirements are voltage and ground. This program runs even if the voltage is out of the valid operating range.

Conditions for Setting the DTC
The TCM has detected an internal malfunction.

Action Taken When the DTC Sets

• • The TCM requests the ECM to illuminate the malfunction indicator lamp (MIL).
  • The TCM commands second gear.
  • The TCM commands maximum line pressure.
  • The TCM inhibits torque converter clutch (TCC).
  • The TCM freezes transmission adaptive functions.
  • The ECM records the operating conditions when the Conditions for Setting the DTC are met. The ECM stores this information as Freeze Frame and Failure Records.
  • The TCM records the operating conditions when the Conditions for Setting the DTC are met. The TCM stores this information as Failure Records.
  • The TCM stores DTC P0601, P0602, P0603, P0604 or P062F, P1621 in TCM history.

P0496

 

[Mooseman]

P0601 Internal control module memory checksum error.

Your PCM is likely toast. You could try pulling the connectors and looking for green corrosion.

No crank no start

06 Chevy trailblazer 4.2 4/4 Code po601 In July 2018 went to start it nothing I tried and tried nothing then it started with check engine light on. Now no problems until this week 9/3 9/4 9/5 and to present. Start it up runs for a few seconds then stalls and no crank no start I keep trying and...

gmtnation.com

Have seen some others and a replacement PCM was the fix. At the age these are coming at now, we'll likely see this more often.

 

[budwich]

You could also try "fooling" the system to "think its warm"...
Take a hair dryer and blow hot air at the connectors that mooseman indicating.... don't disconnect them or anything... just warm them up. Do this before attempting any cold start. Does it help or change the result.... go from the result.

I had an old chrysler that wouldn't start when cool / cold. Hit it with the hair dryer and it thought it was summer and started / ran fine. The pcm connector / connections had to be cleaned / reseated to solve the problem... although the p0601 doesn't sound good but could be a "poor powering" issue maybe.

 

[Envoy99]

UPDATES:

Changing the purge valve seems to have gotten rid of every single one of the CEL codes except for the P0601. Not sure how but it did, if anybody has an explanation I am interested.

Bad news is that the envoy now stalls while at operating temperature in addition to the troubles when cold. It stalled out twice on the highway.

I would appreciate any additional thoughts but I am thinking that the PCM is to blame. I am going to try cleaning the connectors before replacing it. Do I need to disconnect negative terminal on the battery to clean the connectors?

 

[Mooseman]

You could certainly try cleaning the connections. Can't hurt but be prepared to replace the PCM. If you get one from a junker, find one with the same gearing as yours according to the sticker in the glove box. Then all you need is the security relearn.

 

[TollKeeper]

Thinking its time for a PCM...