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Discussion Starter · #1 ·
Hello... It's been awhile since I have had to ask for help, but here we go. I recently replaced the intake manifold gaskets on 2001 Dodge Intrepid (easy job), now it won't start. Replaced Cam and Crank sensors, have checked for and have great spark, can hear the fuel pump activate. Any help here would be great. TIA
 

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Ign coils and fuel injectors get power thru same fuse and ASD, and no intermediate connectors between them and the PCM, so, if you've got spark, fuse and ASD relay should be OK. Make sure connectors to PCM are fully mated - demate and re-mate them). Is PCM not happy about something and so is not activating the fuel injectors?

Try removing battery power (at neg. jump post) for 20 minutes and then reconnect. It's a hail Mary, but sometimes resetting will solve a problem like this (even if you disconnected and re-connected the battery during the gasket job).

That's all I can think of off the top of my head.
 

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Did you have the battery disconnected when doing the upper/lower intake manifold gaskets? If not then possibly you shorted something out with your work. Did you disconnect any wiring during your work? If so then check those connections.

Have you checked for trouble codes with a code reader? If it can't communicate with the PCM then that's an issue. If you have spark then most like most of the ASD relay circuit is good along with the PCM. If the PCM doesn't detect a start after a few seconds of cranking it will shutdown the ASD circuit.

Possible crankshaft position sensor for no start condition. Where did you get the "replacement" sensors? If someplace other than the dealer then your replacement may be crap too. Aftermarket CKP/CMP sensors are known to suck donkey balls for our LH cars. A bad cam position sensor will allow the engine to start but limit RPM to around 2200.

Bill is correct in the same fuse powers both ignition coils and fuel injectors. You have spark so fuel injectors have power also. Unless you disconnected some wiring somewhere.

My money is on a CKP sensor or some wiring is disconnected.
 
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From the FSM on removing the Intake manifold..............

(4) Disconnect electrical connectors from the following
sensors and actuators:
² Short Runner Valve (SRV)(If Equipped)
² Manifold Tuning Valve (MTV)(If Equipped)
² Throttle Position Sensor (TPS)
² Idle Air Control (IAC)
² Manifold Absolute Pressure (MAP)

Did you reconnect all these? Particularly the TPS and IAC connections. Are they all secured properly?


What about these Vacuum lines? Back on and properly secured?


(5) Disconnect vacuum hoses from the following:
² Speed Control Reservoir
² Positive Crankcase Ventilation (PCV) Valve
² Proportional Purge Solenoid
² Power Brake Booster
 

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Discussion Starter · #5 ·
Hello... It's been awhile since I have had to ask for help, but here we go. I recently replaced the intake manifold gaskets on 2001 Dodge Intrepid (easy job), now it won't start. Replaced Cam and Crank sensors, have checked for and have great spark, can hear the fuel pump activate. Any help here would be great. TIA
 

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Discussion Starter · #6 ·
Thanks to all for the great input. The dirty little culprit turned out to be a bad cam sensor I bought from one of our local auto parts store! We are up and running smoothly again until next time. Thanks again for the help.
 

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🎉 Ron!

I'm curious why spark if cam sensor prevented it from starting? Ideas?
 

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Bad CMP replacement sensor pulling down the PCM +5v source voltage for CKP/CMP and other sensors?
 

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Bad CMP replacement sensor pulling down the PCM +5v source voltage for CKP/CMP and other sensors?
But without the +5 volts, there'd be no timing signals from either sensor. How does the PCM know when to fire the plugs. OP says he had spark. I'm cornfused.
 

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But without the +5 volts, there'd be no timing signals from either sensor. How does the PCM know when to fire the plugs. OP says he had spark. I'm cornfused.
But without the +5 volts, there'd be no timing signals from either sensor. How does the PCM know when to fire the plugs. OP says he had spark. I'm cornfused.
Who knows? According to Opies original post I'm assuming the following:

Disassembled and changed Intake Gaskets
Reassembled and tried starting. No Start condition but spark and most likely fuel pump and fuel injection working.

After that who knows...not enough info. I'm assuming at this point is when the CKP and CMP sensors were changed. No sure which one was changed first and with what type of sensor? Most likely aftermarket crap. After that no details on whether the CMP sensor only got changed again and again no details on the source of the part.

It's running who cares now?
 

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10-4
 

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I've seen countless minivans with camshaft crankshaft position sensors dead on arrival from the autoparts store. Every OP will wisely replace that first, cross it off their list, and then end up tearing apart half the engine and wiring harness trying to diagnose the problem when it's a defective "new" sensor. I honestly would trust junkyard sensors over new non-Mopar sensors at this point. You can always check resistance on new sensors with a multimeter to make sure the values seem logical.

SBEC engines, but I think NGC engines are the same. From a Chrysler Service Manual-


ENGINE START-UP MODE
This is an OPEN LOOP mode. The following
actions occur when the starter motor is engaged.
If the PCM receives the camshaft position sensor
and crankshaft position sensor signals, it energizes
the ASD relay and fuel pump relay. These relays supply battery voltage to the fuel pump, fuel injectors,
ignition coil, and oxygen sensor heating element. If
the PCM does not receive the camshaft position sensor and crankshaft position sensor signals within
approximately one second, it de-energizes the ASD
relay and fuel pump relay.
The PCM energizes all injectors until it determines
crankshaft position from the camshaft position sensor and crankshaft position sensor signals. The PCM
determines crankshaft position within 1 engine revolution.
After determining crankshaft position, the PCM
begins energizing the injectors in sequence. The PCM
adjusts injector pulse width and controls injector synchronization by turning the individual ground paths
to the injectors On and Off.
 
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