Some background first:

I completed a HG job and chased a misfire about 200 miles ago. It has been running smooth since I cleared up the misfire. However on a few occasions such as sitting in the school drop-off line or idled a stop sign I noticed a sudden drop in RPM like it was almost going to stall but then it picked right back up and kept running. At the same time my UltraGauge would lose communication with the ECU and wouldn't report temp again until I had stopped and restarted. This has happened only about 3 times that I can recall, not every trip.

Then today:
I started the Rover before about 10 minutes before school and it cranked up fine. I went inside to wrangle the kids and when I went back out to leave it had died and the UltraGauge wasn't reading. I think that it encountered that sudden drop in RPM but since I wasn't sitting in it, it just died. So right now it won't start back up. The battery, oil pressure, and SES light are on, but its not reporting any DTCs on my reader.

Any ideas? I haven't tried to put a charger on it or jump it off yet, I wanted to get some opinions as to whether it may be charging system related or something else.

 

Well I got a little impatient and jumped it off. It took a few minutes hooked up before it would start up. I let it run for a few minutes, hooked up my UltraGauge and drove it around the block.

By the time I made it back the UltraGauge had stopped reading the temp from the ECU. While driving around the block I noted the UG saw the voltage at 13.8 and when I parked it it was around 13.6.

Does this sound like ECU problem or electrical?

 

Could be anything but grounding. Unless your alternator dropped from 14 + then 13.6 something got loose.

 

When did you last replace the CPS? If never (or if its been a while) that's where I would start. They normally just die but I think some can come back after cooling down a bit as you describe.

 

I replaced the CPS about 1k miles ago. Knowing my Disco I wouldn't rule it out yet, but its still relatively new. Would there be a code associated with this (I didn't have a code reader when I replaced the CPS initially). I've just never heard of them causing these drops in rpm/near stalls. I thought they just killed it all or nothing.

I kind of think the failure to crank could have been because it sat in "on" for quite a few minutes before I realized it wasn't running anymore and pulled the key. I mean prior to that and every other morning it has started right up. I even left it sitting for a weak on vacation without running and it started right up when I got back.

I'm just not sure if there could be any ECU related problems or if its something else (like the CPS)?

 

I have seen a few of these types of issues reported while getting up to speed on my Discovery and while I am new to Land Rovers, on Nissan VG33 engines that was often a symptom of a failing distributor.

Everything is fine while cool then you start misfiring or running rough warm, after a while it will not start warm. Let everything cool down and things are fine, until the final failure.

I maybe completely off base here but is it a possibility ?

 

No codes for a bad CPS you can check with a core reader and see if you have an engine RPM reading while cranking.
But if you keep loosing communication to your Scangage you may have an ECU or wiring problem?
Maybe a bad ground?

 

This is what I was thinking, I just wasn't sure if a loose ground would cause the engine to stumble? I suppose if it loosed enough to cause the ECU to reset maybe that would cause it to stumble? I'm not really sure what the relationship is there.

 

I would expect to get some codes if it were misfiring, or an SES light? Problem is previous to this morning it wouldn't have a problem restarting warm. I would actually pull over sometimes to stop and restart the truck to make sure I keep an eye on the temp.

 

These engines do not have distributors.