'99 V8 Won't Start

The wife's '99 V8 has been running pretty damn good since I replaced the crank sensor a few weeks back. Yesterday she wanted to go somewhere but when she turned the key the battery was flat. This has never happened before. I stuck it on the charger for a few hours but when I tried to start it the engine turns over quickly but will not fire. Check Engine light is on etc. It was ****ing down yesterday so I just left it. This morning the battery is flat again.
Given that I live in the sticks and the battery has never gone flat before I am inclined to rule out the RF receiver. I did do a check to see if some WiFi was signal was drifting in but there is nothing.
The battery was new earlier in the year and certainly looked to be holding its own when I tried to start her yesterday.

For a while the alternator has been noisey and I am now wondering if this is the cause of my problems.
I know that a faulty diode pack will flatten the battery although I don't know how long it would take. However it is unlikely that a duff alternator will stop the car from starting - or am I wrong?

My next steps are:-
1) Charge the battery again and then disconect the altenator to see if she holds the charge.
2) Check the crank sensor again - just in case.

Given that the non starting and flat battery both happened at the same time is it wrong to assume that they are linked? If not is there anything else that I should be looking at?

Many thanks.

If you have a multimeter you can easily check whether there is current drain when the BECM etc is asleep - the normal figure is around 0.05Amp (50mA). A cheap meter like this from Argos from Argos for £9 will do (it will measure up to 10A)
Buy Philex CATII Digital Test Meter 10A/600V at Argos.co.uk - Your Online Shop for Home safety and alarms.

It is then a question of tracking down what is causing any excess current drain. The alternator seems a good place to start. Just disconnect it and recheck the readings.

The failure to restart is likely to be a P38 issue - I have a Classic so i will leave that to P38 Gurus to comment on.

Good luck

Pete

Thanks Pete. I have a metre and that will be the next approach if diconnecting the altenator doesnt do the trick.
I have also ruled out the crank sensor - at least from a mechanical point of view (the one I replaced a few weeks back was phyisically damaged). I dont have a scope so I cant test for output at the moment.
Need to wait on the battery charging up before the next move.

take your plugs out if its only been doing short runs you may find them cloged up..

As you have had a flat battery issue,the BECM may well have lost sync with the engine ECU.

JohnP38 said:

As you have had a flat battery issue,the BECM may well have lost sync with the engine ECU.

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I would second this. I have had to re-sync twice after a flat battery issue.

Alternator gone, becm has lost sync.

Your engine check light comes on, your BECM has not lost sync. No need to chase wild geese. Engine turning but not firing does unfortunately point back to the crank sensor as first port of call. Once you've got the meter out and checked the battery properly that is. You may want to consider sometimes there is a drain and sometimes there is simply an inability to charge. I had a real head-scratcher of a problem once until I realised the wire from the alternator to the battery was getting pretty hot and the one down to the starter motor was slightly loose at the motor end. Changed one, tightened the other and haven't had a flat battery or starting issue since.

rasheed said:

Your engine check light comes on, your BECM has not lost sync. No need to chase wild geese. Engine turning but not firing does unfortunately point back to the crank sensor as first port of call. Once you've got the meter out and checked the battery properly that is. You may want to consider sometimes there is a drain and sometimes there is simply an inability to charge. I had a real head-scratcher of a problem once until I realised the wire from the alternator to the battery was getting pretty hot and the one down to the starter motor was slightly loose at the motor end. Changed one, tightened the other and haven't had a flat battery or starting issue since.

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Thanks Rasheed. Just checked this morning for a spark and there is none. My money is on a failed crank sensor even if it is only 1 month old. Will take it back to Rimmers when they open after the holiday. Not much point in trying fault find any more until I rule this out.

Update:
So got a new crank sensor from Rimmers this morning and despite the ****e weather I managed to get it fitted. Unfortunetly it hasn't cured the problem.
To recap -
- Engine spins well but doesn't start.
- Check engine light is on.
- No spark at plugs
- No sign of trouble before hand. Just wouldn't start one morning.

I guess next thing to test is the coil packs. Is there an easy way to do this or is it unlikely that the coils would have failed without some previous signs.

Any help greatly appriciated.

Is it a Gems or Bosch (motronic) vehicle?

JohnP38 said:

Is it a Gems or Bosch (motronic) vehicle?

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Bosch.

jt_armstrong said:

Bosch.

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Ok It may still have lost sync ,BECM to ECM,.If it was gems and the engine check light was on then it would not have lost sync.The bosch and diesel do not send a reply from the ecm to BECM to confirm the correct code has been received,where as the gems does.

JohnP38 said:

Ok It may still have lost sync ,BECM to ECM,.If it was gems and the engine check light was on then it would not have lost sync.The bosch and diesel do not send a reply from the ecm to BECM to confirm the correct code has been received,where as the gems does.

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Thanks John. Would the engine still turn over if she had lost sync?

jt_armstrong said:

Thanks John. Would the engine still turn over if she had lost sync?

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With the Bosch ECM yes.

JohnP38 said:

With the Bosch ECM yes.

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Thanks John. Done a pile of reading since your earlier post and have now ordered a Syncmate. Fingers crossed this will solve the problem.

rewmer said:

Alternator gone, becm has lost sync.

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And the truth shall set you free........

I had a similar problem with my P38 4.6 and what the garage told me I thought they were pulling my chain.
Apparently you can get interference from radio masts, mobile masts and even petrol forecourt price signs! Their radio signals interfee with your key fob frequency and the mechanic explained it to me as, although the car alarm is still armed the car constantly goes thru its pre-start diagnostic check.
There was a lug in PCB to counter this which workd well for a while but has started again and I've had to basically disable the RCL and have to manually key the door open
(Most tiresome!!)
Dunno if this is any help but its always worth sharing info

bushmanpm said:

I had a similar problem with my P38 4.6 and what the garage told me I thought they were pulling my chain.
Apparently you can get interference from radio masts, mobile masts and even petrol forecourt price signs! Their radio signals interfee with your key fob frequency and the mechanic explained it to me as, although the car alarm is still armed the car constantly goes thru its pre-start diagnostic check.
There was a lug in PCB to counter this which workd well for a while but has started again and I've had to basically disable the RCL and have to manually key the door open
(Most tiresome!!)
Dunno if this is any help but its always worth sharing info

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This a well known and documented fact.Your mechanic should have told you the solution if he is worth his salt.Buy and install the latest RF receiver from LR.
As an aside what is a Lug in the PCB.(printed circuit board)??

rewmer said:

And the truth shall set you free........

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Something tells me your original post will prove to be the most accurate 6 word diagnosis ever...