Hi Everyone,

Hoping for some helpful input.

Car got stranded in Apollo Bay on Thursday which is 215 k's from home.

I spent two hours trying to get it started then called RACV roadside assist and finally had it trayed home, so a fun day out!

The engine turned over fine, until I ran the battery flat after so many attempts to start it.

It just would not catch on or fire up.

Even sprayed the last resort 'Start Ya *******' stuff directly into the AFM box with the flap held ajar to no avail.


Other checks revealed;

Fuel pressure OK at the rail as I loosened a hose and fuel started spraying out (I was on the side of the road, so options were limited).

Spark at the coil OK, but very weak off the dissy.

Took dissy cap off, no evident arcing or wear inside, so not the problem.

Injector pulse was weak, so suspected a faulty ignition diode pack, relay or ecu.

Nothing like this on hand in country Victoria, so tray home it was.

Now the question to you all?

At the mechanics workshop back in Melbourne, the fault? was found to be that when you crank the engine over, the starter motor is drawing close to 300amps!!

Meaning sweet FA juice to send to the ignition system to actually start it.

Sounds like a possible short, but where do I start looking?

Am I on the right track?

Thanking you for your advise in advance.

Cheers,

Nigel and both a grumpy cat & wife.

 

Doesn't sound like an unreasonable amount of current given the size of engine, though I've never actually measured it on a Jaguar. But given the number of times you tried to start the engine before the battery went flat and the fact that you say the engine was turning over fine whilst cranking I suspect the problem will lie elsewhere. If it was too much then I would expect the engine too be slow on cranking.

 

I tend to agree. I don't know what the spec for starter current draw on the 4.2 is but I was gonna guess 250 amps.

300 doesn't sound all that bad to me.

What does your repair shop think it should be?

Cheers
DD

 

Hi Nigel

I that reading being considered a fault, or just a measurement? It doesnt really sound that unusual. Is the car still not running?

What occurred just sounds like a battery that has just gone beyond its useful life. Causes may be any one or a combination of age, lots of short run use, maybe being under spec, just failed, previous history of deep discharge, or some parasitic load depleting battery reserve.

 

Hi Everyone,

Thanks for the quick responses.

Battery is less than a year old and was fresh off the shelf and is 350 crank amp rating.

Disconnected and dimantled after market alarm system shortly after getting it, as it was discharging the battery.

My mechanic did his apprenticeship on these and believes that the starter is drawing way too much.

This is my every day car and does do a combination of short and longer runs on a daily basis five days a week.

Having said that, the car sat for 5 -6 days before I tried to start it on Thursday when it would not start.

As I type, the car is still at the mechanic and not running.

Cheers

 

Mmmmm, 350cca is way too low spec battery. That is more Ford Laser spec from memory.

I use, and we sell at work, the N54 for Jags etc, and they are at 650cca.

The fact teh Start Stuff did ZIP, there simply is no, or not enough, spark.

I highly suspect the HT leads, and that is based the fact you siad "good spark at the coil, but weak at the dizzy". The HT leads are the only connection here.

My favourite subject. The engine EARTH strap/s are intact and CLEAN, and doing what they should I presume??. If in doubt, use a jumper cable to supply a temp earth path.

 

300A sounds high to me, these aren't high compression engines.

It may not be the starter motor itself that's drawing big current, could also be the solenoid.

350CCA battery sounds small to me, really small in fact.

A good auto electrician will figure it out. Good luck.

 

There is a way to see if the starter draw is "using all the juice' and leaving little for ignition.


Provide 12v from another fully charged battery direct to the + post of the coil. Crank. If it fires up, you have it. If still no, more places to look and fix.


Agree, 350 CCA is a tad puny. Same, for the 300 amp draw. Marginal at best.


Caveat: if it doesn't fire in a few cranks, only rarely will continuing get a start. Just runs the battery down and cooks the starter. Starters are not set up for continious duty!!!


Suspect HT lead or leads? Check a known good one for ohms per inch as a baseline. Compare to each of yours.


Clean the HT leads at the distributor and spark plugs. Same for the coil to distributor lead.


Check the contact button in the center of the underside of the distributor cap. Badly worn or even gone!!!


Carl

 

contact Mike at Star Auto Electric to answer the draw question, he rebuilds starters, alternators, generators, etc., for British cars. Star Auto Electric Company - Home

 

Hi Nigel,

Sorry to read about your woes, hope you're having some success in the elimination process.

FWIW my calcium battery is 500cca and I've often "sensed" that it's only just big enough given the amount of work it has to do, especially since the alternators are pretty ordinary in these cars.

Given the extreme heat we've had in the last couple of months, I've seldom been using the Jag. Could be coincidental, but the battery discharged just before Christmas, zero cranking. Instead of replacing it I bought a Projecta Intelligent Charger (not cheap, best deal was $170), charged her up to full and have had no problems since. It can charge all battery types, Wet lead acid, Gel, Calcium etc. up to about 650cca. It cycles through 4 phases to recon the battery each time and cuts off when charged. Also comes with a plug-in harness permanently fitted to the battery, so no need for croc. clips. I plug it in once every 3 weeks or so, leave it overnight and the battery has never felt livelier.

Since you are driving the Jag daily maybe all you need is higher rated battery once the cause is resolved, but these chargers are brilliant if you need to keep it topped up. Shop around though, prices vary wildly.

 

Good morning all,

Thank you for all of your sage advice - I totally love this forum for exactly this reason.

In my haste to post yesterday, I mis typed my battery rating (yarpos' post about Ford Laser made me realize my mistake, thanks )

My battery is heavy duty deep cycle 650 crank amps. (Even when I flattened it the 'Good Green" indicator was still showing)

The engine earth strap is secure and clean.

The dissy cap is clean as a whistle and not worn inside (and no arcing).

When I first got the car I checked resistance through the spark / HT leads and all were ballpark OK.

After I drained the battery and called roadside assist, he attached a 1000 crank amp jumper starter pack so that we could continue diagnosis.

The engine continued to turn over freely but just would not ignite at all.

With his help and available tools we were able to observe the weak injector pulse.

Cheers,

Nigel

 

I thought we might plunge into a battery terminology debate about the meaning CA and CCA there for a while.

The new info about the roadside guy supplying an assured decent battery changes the story quit a bit. I would lean towards what Grant pointed out or at least in that area (given some start ya barstad had no effect). My car had a no start issue a while ago, and although spark was apparent (but not well tested by me at the time) it ended up being a marginal coil.

As your guy is directly experienced with the model he should know what he is on about. It will be interesting know what the outcome is.

 

Fuel injection and the Jaguar XJ6 4.2 Series 3 / AJ6 Engineering

Two things are essential to operation of the EFI system, (1) a pulse from the ignition system, and (2) a good earth from the control unit.

The pulse from the ignition system causes the system to fire the injectors all together twice per engine revolution. The ECU actually earths the injectors via power transistors. The pulse width depends on two things, (1) engine coolant temperature, and (2) mass air flow. All other inputs just supply trimming information.

With the amount of cranking you gave it, the plugs should have been soaking wet. Did you take one out to check ?

Only thing puzzling me is that you state you got stranded, thus implying the car was running perfectly OK on the run out to the breakdown location. So, anything untoward happen on the way, or did you just arrive and switch off the engine on a perfectly running car ? If a can of Easy Start won't even make it even cough, it implies there is no ignition, or the ignition is timed wrong.

 

Hi Fraser,

I did take a spark plug out at some stage and it was bone dry and so just added to the mystery.

When the roadside assist guy arrived, he queried skipped timing belt or other timing problems as well. Thankfully, none of those.

I didn't elaborate on my circumstances earlier.

We were on an extended work / holiday at the time. I had filled up one tank with petrol on the preceding Sunday and had basically driven to the carport I was using and didn't start it for a couple of days until I needed to return home on the Thursday.

Very early on in the saga, I even suspected dirty fuel as a possibility.

In regards to the running of the car previously, no drama's or signs that anything was untoward.

I do have an underlying intermittent no hot start issue where once in a while it won't start if I leave it for 15-20 mins during the day (but it isn't fuel vaporization), but this time it was definitely a cold start.

Cheers,

Nigel

 

Hi Everyone,

For anyone who read this thread, chimed in or is otherwise generally interested, this is what happened.

My battery was the problem, which was new in March last year from a specialist battery place who I will continue to use especially after this episode.

It failed a high load discharge test.

A mitigating factor were the battery terminal lead connectors. They were clean, but not clean enough.

A perfect storm of events played out when the coastal salt air in which the car was in last week, got into the terminal connections and contributed to the problem of the battery not performing as it should have.

What was happening was that when trying to start up, the battery was not delivering its full charge.
The salt air affected terminals were restricting the already reduced charge into the electrical system.

The starter motor, being starved of juice, was pulling power from wherever it could and drawing upwards of 400 amps.

This basically meant that all available electrical charge was going to the starter with nothing left to give to the ignition system.

A new battery was fitted and the problem has been solved so much so that now the key barely touches the third point as you turn it in the ignition before the engine fires into life.

The engine feels stronger and more eager as well.

This may also be the cause of my intermittent hot no start.

My mechanic also uses the same battery place as me and so a call to them had them falling over themselves to drive across town with a new battery at no cost to me what so ever.

My mechanic also modified the battery terminal connections as he believes that the existing sandwich ends are prone to the type of internal corrosion which leads to the types of problems that I had.

I have posted pictures of these.

I hope this information will assist others but I also hope that it doesn't happen to any of you as it was most frustrating and the tow home was not cheap.

Cheers,

Nigel

 

Thanks for letting us know what the final result was. Glad to hear it all running and running well after all that.

 

Well done.

 

Nigel:


Oh yeah, those "sandwich ends" are doomed to failure. Never, never, no way.
I learned the hard way!!! Usually the way I learn!!!


Another is internal corrosion on what appears to be a healthy cable. been there as welll.
I my recent no crank travails, I found a failed end on the stock Jaguar cable from the fore wall to the starter solenoid. A generic one was much beefier and with hefty ends. Cranks so much better.


Carl

 

Solved!!!


As good as it gets.


Carl

 

Great news Nigel.

I'm sure your unfortunate experience has been a great wake up call for many of us!

Battery maintenance, and more battery maintenance - time well spent since the whole starting process is obviously very demanding of power on these engines.

For peace of mind I'll be cleaning my terminals and checking cables today! Since keeping the battery charged to the max. the benefits are very evident. Yep, she fires so much more eagerly, and I've noticed the hot starts are less of an issue.