My car won't start mate... Do you have any great poupon...

More vehicles go into the repair shop due to a no start condition then for any other reason. A no start symptom can be fairly simple, but also quite difficult to diagnose. See it right here....



The following procedures should be used to diagnose a no start – cranks ok condition. These steps should be followed

orderly so as to make a thorough and complete diagnostics systems check.

1) Visual inspection of all engine components.

2) Scan the vehicle for any codes and out of specs PIDs on the data stream.

3) Check for fuel pressure and volume.

a) Pinch the Schrader valve. If no fuel comes out then there is no fuel pressure.

b) Take a fuel pressure reading. If pressure OK then take a fuel volume reading to verify system delivery.

c) Take a voltage reading at the wire going to the fuel pump. This will eliminate the possibility of excessive resistance in the circuit.

d) Take a current waveform using a DSO. A current waveform will reveal amperage faults as well as shorted commutator windings. The motor RPM can also be determine by this test.

4) Check for proper spark.

a) Put a neon noid-light and verify spark. If tester lights up then make sure the spark is able to jump about 1 inch between the end of the wire and ground. Do not use the negative battery post, as it may explode.

b) Take a current test of the coil’s primary winding and confirm proper ignition coil on-time (dwell). There should be between 3.5 and 8 mS of current build-up. If it is less then there will not be enough Kv reserve for the spark to last the entire ignition burn cycle and the engine will not run properly or not run at all.

c) Take an ignition primary and secondary waveform reading to determine the condition of the secondary ignition components, if the engine starts.

5) Check engine back-pressure.

a) Using an engine back-pressure or low pressure gauge determine proper exhaust back flow. Improper exhaust flow results in severe lack of power or the engine not starting at all due to dilution in the combustion chamber. It will also cause low cranking vacuum. A clogged catalytic converter is usually the problem.

6) Check ignition timing.

a) Determine distributor rotation.

b) Verify correct firing order.

c) Set engine at base timing and determine proper ignition timing using a timing light according to specification. The ECM will assume that the engine is at proper base timing when making any future timing adjustments.

7) Check valve timing. Check for correct synchronization between the CAM & CRK signals. On some engines, the ECM will cut pulsation and/or injection if the two signals are not synchronized properly. The ECM uses such strategy to prevent flooding the engine and/or damage.



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 Code Setting Criteria

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SRS Airbag DTC

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How to Get SRS Codes

Retrieving Dodge SRS   Retrieving Ford SRS     Retrieving GM SRS      Retrieving Honda SRS   Hyundai/Kia/Mitsu SRS Isuzu/Mazda/Subaru     Retrieving Toyota SRS  Nissan/Infinity SRS

SRS-Airbag Repair Guide

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