Hello all,

My 2004 Z06 will not start.

The battery (Optima) has been charged and is strong.
Engine cranks over at normal speed but will not start...is not even catching, just spinning.
I have fuel pressure (I installed a gauge at fuel rails and it's reading around 60 psi).
NO ERROR CODES AT ALL.
Cockpit gauges do their normal "sweep" and column bypass unlocks.

Only thing I can recall doing/touching that might have affected this was to insulate some wires down near the starter that were getting "crispy" from header-heat. All the wires were intact before insulation as I did a continuity test.

Maybe a disconnected a ground or something???? Can anyone suggest things I can check? Everything else seems fine and there's no indication as to what might be wrong. I figure it's something that is keeping spark from happening. Pulled a few plugs & they look good.

 

Suggest you check those "insulated" wires at the starter. Believe you'll find your problem. Good luck.

 

Thanks Jacks02. Starter is cranking just fine....nice and strong. Its just that the engine is not catching. I have fuel, compression, new sparkplugs and sparkplug wires which were installed a few weeks ago. Coils were tested then with a strobe/timing light and everything was fine. Engine always started immediately then.

Since then I replaced Bank 1's O2 sensor and also pulled Bank 1's valve cover. When I tested the continuity of the crispy wires down near the starter, I had also disconnected the two sets of DIN connectors going to the PCM so I could test the continuity of the wires that I was insulating to make sure the heat didn't fry any of them. I then buckled everything back together and the car wouldn't start. I TRIPLE-CHECKED EVERYTHING I DID BUT IT'S LIKE I FORGOT TO CONNECT SOMETHING OR BUMPED & DISCONNECTED SOMETHING BY MISTAKE. I also checked all the fuses in the engine bay compartment and they are fine (but didn't check the relays there or fuses in the passenger footwell).

Any suggestions? Do I need to do anything special if I disconnected the PCM? I'm pretty disheartened about this. Thanks everyone!

 

Have you checked for spark???...Pull a coil pack (leave the power wire attatched) and have an assistant crank the engine...You should hear and see a spark snapping from the spark plug boot....If you dont, youre not getting spark....One of the wires back by the starter goes to the crank sensor...If your crank sensor is bad, or if the wires are damaged, you wont get spark.

If youre getting spark you may have a problem with the fuel injector circuit...Just because you have fuel pressure doesnt mean fuel is getting in the combustion chamber..If the fuel injectors arent opening it wont start....Check your fuses...The injectors have their own fuse....(in the footwell fuse box)...The easiest way to test these fuses without pulling each and every one if them is to buy a simple volt tester...Ground the alligator clip to a good ground source, then touch both exposed metal tabs in each fuse with the pointed end of the tester...The tester should light up when you touch each tab...If it doesnt, you have a bad fuse.....

 

This happened to me last month. Bad fuel pump. Hopefully not what's wrong with yours as you have the newer FFS tank which is a pain i've read.

 

He said he had 60 PSI fuel pressure, so I doubt his fuel pump is bad..

 

Hopefully you disconnected the battery before you disconnected the PCM? I think I would be going back to the PCM to look and make sure the connectors are on properly with no bent pins

 

 

THANKS FOR ALL THE INPUT!!!!

I will check all of these suggestions this weekend & report back. I do remember this.....when I was reattaching the 2 DIN connectors to the PCM (yes, battery was disconnected), I had to redo one of the two connectors because it just did not feel right. I torqued to the recommended setting & figured all was alright.

I'm also curious if I screwed up the crank sensor wire (but figured I'd get an error message on the DIC if I did). I have a feeling that the problem is I'm not getting spark for one reason of another.....bent pin at the PCM, blown fuse in passenger footwell compartment, wire disconnected/broken/shorted to crank sensor/ground/etc.

 

Yeah, if the crank sensor wires aren't right, you'll not get it to run. Hopeully you didn't reverse them when you resolved the burned areas of them.

 

You wont always get a DIC error message under the conditions you describe......

 

Over the weekend, I checked the PCM connections for bent pins, dirt blocking a hole in the connectors, etc. and all seemed fine so I put it back together.

Then I undid all the thermal insulation I put on the wires that were "crispy" below the passenger side header. Just to note....these wires were burnt from the stock exhaust manifold. I had checked & redid some of the "more crispy" wires before insulating them and putting on LT headers. Wonder why GM didn't insulate better from the factory....or maybe many days at the track built up enough heat to burn these wires. Anyway, these are the wires going to Bank 2's O2 sensors, crankshaft position sensor (CPS) & oil temp sender. Once the insulation was off, I played with some of the wires by just moving them around a little and then decided to try to start her up again. WALAH...she started up right away and ran for about 30 seconds & then died immediately with no warning (no hesitation, no stumble).
I had one error code from this 30 second run...A MISFIRE P0300.

From what I deduce, some of the burnt wires are still not fully intact and I need to redo them again. I have a feeling that the wires going to the Crankshaft Position Sensor are broken somewhere under their insulation and by playing around/moving these wires, it made enough contact for me to get her started and then the heat and vibration opened the circuit again and caused the car to die immediately.

WOW....getting to the CPS is a PITA! By the way, for others who might have simialr problems, your suggestions and this post put up by another Forum member was helpful:


Engine Cranks but Does Not Run
Refer to Cell 20: CKP, CMP, KS and Traction Control System for complete circuit details.

Description
The Engine Cranks but Does Not Run diagnostic table assumes that battery condition and engine cranking speed are OK. If the battery condition and the cranking speed are not OK, refer to Starting System Check or Charging System Check in Engine Electrical for diagnosis. Make sure that there is adequate fuel in the tank(s).

Diagnostic Aids

Important
Remove any debris from the PCM\TAC module connector surfaces before servicing the PCM\TAC module. Inspect the PCM\TAC module connector gaskets when diagnosing/replacing the modules. Ensure that the gaskets are installed correctly. The gaskets prevent contaminate intrusion into the PCM\TAC modules.
For any test that requires probing the PCM or a component harness connector, use the Connector Test Adapter Kit J 35616-A . Using this kit prevents damage to the harness/component terminals. Refer to Using Connector Test Adapters in Wiring Systems.

Inspect the duct work between the Mass Air Flow (MAF) sensor and the throttle body for air leaks.
A malfunctioning MAF sensor may cause a no start or a stall after start. If you suspect this, disconnect the MAF sensor. The PCM will default to the speed density (MAP, IAT, RPM) in order to calculate the load and the air flow. If this corrects the condition and the connections are OK, replace the MAF sensor.
For an intermittent condition, refer to Symptoms .
Test Description
The numbers below refer to the step numbers on the diagnostic table.

This step verifies the IGN relay for proper operation. The IGN relay supplies voltage to the injectors and the ignition coils. When the IGN relay is not operating properly, a no start condition occurs. If the test lamp does not illuminate, this indicates the IGN relay is not suppling a voltage to the fuses.

This step is testing for a DTC that sets while the engine is cranking.

This step is testing for a grounded ignition feed circuit for the crankshaft position sensor and the camshaft position sensor. When the ignition feed circuit is shorted, a no start occurs and no DTCs are set. The ignition feed circuits are connected internally within the PCM. The PCM cannot detect that the engine is cranking with a grounded ignition feed circuit. If no engine speed is displayed on the scan tool, inspect the ignition feed circuit for a short to ground.

The scan tool may reset if the battery is at a low state of charge. The battery may need to be charged to perform this step.

This step is testing for B+ supply to the crankshaft position sensor.

The ignition feed circuits for the Camshaft and Crankshaft Position sensors is internally connected within the PCM. A short to ground on either circuit will cause a no start condition.

The fuel cap may need to be removed in order to hear if the fuel pump is operating.

Step
Action
Value(s)
Yes
No

1
Did you perform the Powertrain On-Board Diagnostic (OBD) System Check?
--
Go to Step 2
Go to Powertrain On Board Diagnostic (OBD) System Check

2
Turn ON the ignition leaving the engine OFF.
Probe both sides of the fuses (located in the Underhood Electrical Center) listed below using the test lamp J 34142-B connected to ground.
INJR1
INJR2
THROT CONT
ENG IGN 1
A/C
Does the test lamp illuminate on both sides of all the fuses?
--
Go to Step 3
Go to Ignition Relay Diagnosis for further diagnosis

3
Monitor the Diagnostic Trouble Code (DTC) option using the scan tool.

Does the scan tool display any Throttle Actuator Control (TAC) system DTCs?
--
Go to the applicable DTC table
Go to Step 4

4

Important
Monitor the BCM for DTCs related to Vehicle Theft Deterrent (VTD) system. This indicates a concern with the Column Lock or VTD fuel enable system. If a BCM DTC is stored, refer to Diagnostic System Check - Body Control System in Body Control Systems.


Select the Diagnostic Trouble Code (DTC) option, then the DTC Information option using the scan tool.

Is P0230, P0335, P0336, P0601, P0602, P0604, or P0606 displayed?
--
Go to the applicable DTC table
Go to Step 5

5
Monitor the Diagnostic Trouble Code (DTC) option using the scan tool.
Crank the engine for 15 seconds.
Did a DTC set while cranking the engine?
--
Go to the applicable DTC table
Go to Step 6

6
Monitor the engine speed while cranking the engine.

Is engine RPM indicated on the scan tool?
--
Go to Step 10
Go to Step 7

7
Turn OFF the engine.
Disconnect the Crankshaft Position (CKP) sensor electrical connector. Refer to Crankshaft Position (CKP) Sensor Replacement .
Turn ON the ignition leaving the engine OFF.
Measure the voltage at the ignition feed circuit at the CKP electrical connector using the DMM J 39200 .
Does the DMM display near the specified value?
B+
Go to Step 14
Go to Step 8

8
Disconnect the Camshaft Position (CMP) sensor electrical connector. Refer to Camshaft Position (CMP) Sensor Replacement .
Measure the voltage at the ignition feed circuit at the CMP electrical connector using the DMM J 39200 .
Does the DMM display near the specified value?
B+
Go to Step 15
Go to Step 9

9
Test the Camshaft and Crankshaft Position sensor ignition feed circuits for a short to ground. Refer to Testing for Short to Ground in Wiring Systems.

Did you find and correct the condition?
--
Go to Step 17
Go to Step 16

10
Monitor the engine coolant temperature using the scan tool.

Is the engine coolant temperature on the scan tool close to the actual engine temperature?
--
Go to Step 11
Go to DTC P0118 Engine Coolant Temperature (ECT) Sensor Circuit High Voltage

11
Enable the fuel pump using the scan tool.

Does the fuel pump operate?
--
Go to Step 12
Go to Fuel Pump Electrical Circuit Diagnosis

12
Turn OFF the ignition.
Install a fuel pressure gauge. Refer to Fuel System Diagnosis .
Turn ON the ignition leaving the engine OFF.
Observe the fuel pressure while the fuel pump is operating.
Is the fuel pressure within the specified range?
380-420 kPa (55-61 psi)
Go to Step 13
Go to Fuel System Diagnosis

13
Perform the following additional inspections:

Inspect the duct work between the Mass Air Flow (MAF) sensor and the throttle body for air leaks.
A malfunctioning MAF sensor may cause a no start or a stall after a start. If you suspect this, disconnect the MAF sensor. The PCM will default to the speed density (MAP, IAT, RPM) in order to calculate the engine load and the intake air flow. If disconnecting the MAF sensor corrects the condition and the connections are OK, replace the MAF sensor.
Inspect the spark plugs for being gas fouled. If the spark plugs are gas fouled, determine what caused the rich condition.
Inspect for an engine mechanical failure that causes an engine not to start (i.e. timing chain, low compression).
Compare MAP/BARO parameters to another vehicle. The parameter values should be close to each other.
Did you find and correct the condition?
--
Go to Step 17
Go to Symptoms for diagnosis

14
Replace the CKP sensor. Refer to Crankshaft Position (CKP) Sensor Replacement .

Is the action complete?
--
Go to Step 17
--

15
Replace the CMP sensor. Refer to Camshaft Position (CMP) Sensor Replacement .

Is the action complete?
--
Go to Step 17
--

16

Important
Program the replacement PCM. Refer to PCM/TAC Module Replacement .


Replace the PCM.

Is the action complete?
--
Go to Step 17
--

17
Select the Diagnostic Trouble Codes (DTC) option and the Clear DTC Information option using the scan tool.
Attempt to start the engine.
Does the engine start and continue to run?
--
Go to Step 18
Go to Step 2

18
Idle the engine at the normal operating temperature.
Select the Diagnostic Trouble Code (DTC) option.
Are any DTCs displayed?
--
Go to the applicable DTC table
Go to Step 19

19
Select the Capture Info option and the Review Info option using the scan tool.

Are any DTCs displayed that you have not diagnosed?
--
Go to the applicable DTC table
System OK



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Forgot to mention....now also getting a second current error code P0335 when trying to crank.

 

P0335 CKP Sensor Circuit

 

I find it very hard to believe that the factory exhaust fried your wiring ....Just another reason I dont run headers on my vehicles