99' LHS will not start. Cranks, fuel pump runs and is delivering fuel. Shutdown relay is off but will not fire. No error codes or check engine light.
Tested cam and crank sensors. Check fuel rail for fuel.
The first thing to do is to be sure the computer is awake. Turn the key on and check reference voltage to the tps, cam and crank sensors. If there is full reference voltage, check to be sure the ASD relay is engaging when trying to start the engine and that there is power to the injectors and coil/coils when cranking. IF there is no power to the injectors or coil when cranking and the ASD relay is not engaging, then we might have a bad cam or crank sensor (or a valve timing issue).If there is no reference voltage to these sensors with the key on, then the computer might not be waking up. We will need to check all powers and grounds going into the computer with the key on. This includes, all powers through the computer fuses, fusible links and even the ignition switch.Hint: Sometimes the cam and crank sensors can short out and pull the computer down temporarily. If all powers and grounds check out and we still do not have any reference voltage to the cam, crank or the tps, then disconnect them one by one with the key on to see if the reference voltage comes back. If so, then one of the sensors is bad and will need to be replaced.
I have voltage to both cam and crank sensor with the key on both will cycle to outputs as the engine is turned. the ASD relay if off while cranking it will make on intlize key turn to run and fuel pump runs. As soon as pump stops and turn the key to start it will not rengage. I tried to jump it and it still will not fire
Ok.. the only thing the computer needs to see to ground that asd relay when cranking is the cam and crank signals in sync. Either the one of the sensors are bad, or the cam and crnak sensor signals are not in sync with each other. This would be because the valve timing is off. THis is pretty common.
Or, maybe the flex plate has cracked and is causing the crank signal to be erratic when cranking the engine over. THis will cause the computer to get confused and will cause your no start condition.
how do I resync. the sensors?
Well, you would have to verify that they are out of sync first. If they are, then chances are the timing belt broke or one of the dowel pins broke or sheared causing the cam timing to be off. IF this is the case, you would need to pull the front cover and do a timing belt job and or fix what is wrong causing them to be out of sync.
How can I confirm that the sensors are out of sync.? Timming belt timeing is good and belt is not broken
Well, you could scope the cam and crank sensor with a dual trace lab scope and compare the scope pattern with a known good one.
Short of that, its kind of guess work. You would have to check compression to make sure the engine is breathing good. But even if the timing belt is off a few teeth, the compression readings might be ok.
ASE MASTER TECHNICIAN ADVANCED LEVEL SPECIALIST