2000 Discovery (NAS) stalling with no error codes
Hard to restart immediately after but 'may' start fine next day
No sputtering just clean stalls
Sometimes cycling the key several times helps to restart

Replaced Crank Position Sensor (there was originally a code for this)
Replaced Fuel Pump and Relay, Voltage to Pump OK
Fuel pressure when is good, EVAP lines seem Ok

No spark! Noel Fuel Pressure, No Codes
No specific patterns tostalls

 

When installing the sensor, did you install the sensor then the spacers and nut?

 

It was a service shop that changed out the CPS. I vaugely remember a comment about a spacer. However as the problem continued the dealer worked on it and said that that would not be an issue. Still stalls!

Today I confirmed that it is a 'missing spark issue, and not fuel. I also noticed a bit of a pattern that it always stalls after about 10 minutes of idling. Takes a lot to get it going again. Somethimes when it is cooled down it starts right away. But soemtimes it is very difficult to start cold.

That being said; intially I did have a CPS error code. But I have not seen that since the sensor was removed and replced at the first shop.

And I still have no error code.

Can a CPS failure intiate a no spark without a code???

 

Yes, it can fail with no code. Here's a diagram of the parts, spacing is critical.

 

Definitely sounds related to the sensor buddy.

 

I went under and took the senor off. Last tech seems to have lost a spacer and nut so the sensor was actually loose. I refastened with proper spacers and nuts.

Still stalls during idling (almost predictable)
Seems to stall while driving on decleeration as well


This is also the third Crank Position Sensor

I think this is related to air flow after intial warmup. Stall occurs fairly regularilay when idling. Always seems to happen with in 5 minutes. I noticed that a few seconds before the stall there is some activity with revs and possibly air flow control.

I confimed it is a spark issue and not fuel

It also now seems to be too regualar to be a Crank Position fault, as far as idling show.

Today was the 5th tow turck ride in as many months due to this problem

 

Secondary Air Injection and/or Air intake

Can either of these systems negatively affect the vaccum which can get the ECM to shut off spark? (without codes?)

 

That blows man, have you done a smoke test to look for vacuum leaks? A failing mass air flow sensor can cause all kinds of problems with no light sometimes. Not having the sensor tight could have ruined it? Dies not have anything to do with sai.

Elaborate on how you determined a spark issue not fuel
could be bad wires/ plugs/ coils/ on and on i cant tell you exactly what it is without more info and be precise about maintenance performed and don't leave out the last tardo that did not put the space the crank sensor. What a dumb dip.

 

I did not do the re & re of the sensor. So on you advice I took a look
Missing one spacer and one nut. Other nut not quite tight.
I made this right but the stall was still occuring!

So now I am suspicious, took a broom handle to the sensor connector while running and it fell apart, truck stalled with no codes!

Once everything cooled down I got in there and pressed the connector together as hard as I could. It hasn't stalled since (but only the 1st day)

That said, don't always assume the dealer does it right!

 

Spark and Fuel Test:
Removed a spark plug wire , inserted an old plug and rested it on the intake manifold while cranking.

Fuel Test: Stuck a tire gauge on the Schrader valve
When the truck was not firing there was also no pressure
When I jumpered the fule pump relay there was
When the truck did fire and was running there was pressure

Conclusion: The ECM will disable grounding for the Spark Plug Modules, Fuel Pump Relay and probably the Injectors as well IFF there is no feed back from the Crank Position Sensor. And there where no codes generated either.

WARNING:
TESTNG FUEL PRESSURE AT SCHRADER VALVE CAN BE MESSY AND SHOULD NOT BE DONE WHILE TESTING SPARK