Mechanics

CHEVY

1998 Chevrolet Corvette

Engine problem
1998 Chevy Corvette V8 Two Wheel Drive Automatic 78000 miles

hi I own a 1998 corvette when I go to start it it wont turn on motor cranks good but wont start I dont think its getting fuel or spark whys this can anybody help me on this like I said I get in car turn the key motor cranks but wont start why
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Ronald49
February 10, 2008.



Engine Cranks But Does Not Run
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 Engine Electrical for diagnosis. Make sure that there is adequate fuel in the tank(s).

Diagnostic Aids
• Check 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.

If the steps above check OK, refer to Symptoms.

Test Description
The numbers below refer to the step numbers on the diagnostic table.

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

This step is checking 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 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.

Refer to full page schematic for complete details of the ignition feed circuit.

Refer to full page schematic for complete details of the ignition feed circuit.

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 to hear the fuel pump running.

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 a test lamp 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

3
Select 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: Check the BCM for DTCs related to Vehicle Theft Deterrent (VTD) system. This indicates a problem with the Column Lock or VTD fuel enable systems. If a BCM DTC is stored, refer to Body and Accessories.

Select the Diagnostic Trouble Code (DTC) 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 engine speed while cranking the engine.

Is engine RPM indicated on the scan tool?
--
Go to Step 9
Go to Step 6

6
Disconnect the Crankshaft Position (CKP) sensor electrical connector.
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 13
Go to Step 7

7
Remove the intake Manifold. Refer to Intake Manifold Replacement in Engine Mechanical.
Disconnect the Camshaft Position (CMP) sensor electrical connector.
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 14
Go to Step 8

8
Inspect the Camshaft and Crankshaft Position sensor ignition feed circuits for a short to ground.

Did you find and correct the condition?
--
Go to Step 16
Go to Step 15

9
Check 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 10
Go to DTC P0118 Engine Coolant Temperature (ECT) Sensor Circuit High Voltage

10
Enable the fuel pump using the scan tool.

Does the fuel pump operate?
--
Go to Step 11
Go to Fuel Pump Electrical Circuit Diagnosis

11
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.
Is the fuel pressure within the specified range?
380-420 kPa (55-61 psi)
Go to Step 12
Go to Fuel System Diagnosis

12
Perform the following additional checks: • Check 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 16
Go to Symptoms for diagnosis

13
Replace the CKP sensor. Refer to Crankshaft Position Sensor Replacement.

Is the action complete?
--
Go to Step 16
--

14
Replace the CMP sensor. Refer to Camshaft Position Sensor Replacement.

Is the action complete?
--
Go to Step 16
--

15
Important: Program the replacement PCM. Refer to Powertrain Control Module/Throttle Actuator Control Module Replacement.

Replace the PCM.

Is the action complete?
--
Go to Step 16
--

16
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 17
Go to Step 2

17
Idle the engine at the normal operating temperature.
Select the Diagnostic Trouble Code (DTC) option the DTC Information option then the Failed This Ignition option using the scan tool.
Are any DTCs displayed?
--
Go to the applicable DTC table
Go to Step 18

18
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

Dennyp
Feb 18, 2008.