Hi
Had issue with one of the Cylinder heads on my X350 XJ3.0L.
Decided to replace both with used from ebay,
Rebuilt the engine taking care to get timing right, got it running although didnt want to come off idle,
Found the exhaust manifolds were not on correct reseated them but now it wont start?
Its getting plenty fuel plugs are wet took them out and checked for spark with new plug no spark present tried at least 3 cops.
Took out crank sensor resistance shows 335 ohms which is in range, it has me stumped. checked F30 OK
No codes as it hasnt ran yet?
Any ideas is it a case of checking back to ECU or is there a quick way to find problem?
I am usually good at fault finding but this car is running me ragged even thinking of torching it lol

 

Hi joesoap,

My first thought would be low battery voltage while cranking. If the voltage falls much below 11V while cranking, the ECM will not trigger the ignition to fire.

I'm assuming you didn't disconnect the engine earth strap, but I may as well mention it since it came to mind.

Did you get the wiring to the Front Power Distribution Fuse Box all reconnected?

The engine shouldn't have to run to trigger some fault codes. Do you have SDD or another system capable of reading the proprietary Jaguar B, C and U codes?

Hopefully others will have some additional suggestions.

Cheers,

Don

 

Thanks Don
Didnt disconnect earth strap and checked it is still intact and tight.
If the front control module is under radiator yes got it reconnected.
Charged battery as the engine was offline for best part of a month.
When I had reseated the ex manifolds it felt like the flooding I got once when moving an X308 out of the drive. didnt know then that jags dont like really short runs?
I have got SDD but not great with it yet it didnt show codes but going through diagnosis it was pointing at CKP sensor thats when I took it out to check.
Could a CKP give good resistance figure and still no signal?

I have just about uncovered the ECU just not got the 5point security torx bit for connector? I can then do pinout tests from workshop manual.

 

In my experience you can't assume the battery is okay just because it's been charged. Have you measured the voltage while cranking?


On the older Jags you could watch the tachometer for 200 rpm or so while cranking to give you an idea of whether the CKPS was working, but on our X350 the tach needle actually dips below 0 while cranking, so it's of no help. You might be able to run SDD data logger to check for the engine speed signal from the CKPS, or if you have an OBDII scanner that can read live data you may be able to see the CKPS signal. Worst case, the CKPS is cheap (RockAuto has a Beck/Arnley for USD $23.79), so it would be easy to rule it out as the problem, and it's good to have a known-working spare in the boot/trunk anyway.

Thinking about your no-spark, all six coils receive 12V from the Ignition Coil Relay in the Front Power Distribution Fuse Box, which, on our V8, is in the front right corner of the engine compartment near the ABS modulator. Also, on the V6 models there is an Ignition Capacitor in the center of the bulkhead. You can download the Electrical Guide here (you didn't mention your model year or I would have linked directly to the correct manual):

http://www.jagrepair.com/JaguarXJ8%2...OBDIIcodes.htm

I bought a set of the 5-point security Torx bits on eBay for cheap. Just be sure the bits you get have the hole in the center and really have 5 lobes instead of 6.


Cheers,

Don

 

Thanks again Don,
It is a 2003 so 2004 MY is the capacitor on the engine bulkhead side or inside near ECU.
Gonna try a jump with wifes car and see if it helps after checking capacitor if I can find it.
Tried Jump and still no go?
Guess its time to call in the "experts" if i can find a good one?

 

According to the Electrical Guide, the ignition capacitor is in the Engine Compartment, at the Center of the Bulkhead. You can download the 2004 MY Electrical Guide here:

http://www.jagrepair.com/images/Elec...al%20Guide.pdf


Since yours is a U.K.-spec car, the 2003.5 MY Electrical Guide may be the correct one for your car, and you can download it here:

http://www.jagrepair.com/images/Auto...agxj2003.5.pdf


Have you checked the Ignition Coil Relay? You may be able to swap another similar relay (from a non-essential circuit) to see if a different relay makes a difference.

Something I should have mentioned earlier: I have found that when a battery goes flat in one of our Jags and I am going to try to jump start the car, I usually have to let the engine of the jumping vehicle run for 10 minutes or more with the jumper cables connected to get at least a little charge in the Jaguar's battery before the Jag will start. But note also that for the X350, I believe Jaguar states that the jumping vehicle's engine should not be running when you crank the Jaguar's engine.

Cheers,

Don

 

Already have the 2004 electrical guide but dont see the capacitor in it?

Will look through 2003.5
I pulled all the relays and reseated they all had good clean contact surfaces.
Couldnt see aguide to which realay was what.
I have done the pinout tests as per the electrical guide and it is pointing at ECU failure?

Yes the recommended jump procedure states not to run engine of other car? which is a new one on me but!!

 

Don,
do you know if an Engine ECU needs to be code to car can my SDD do it?

 

In the copy of the 2003.5 MY Electrical Guide I have, the ignition capacitor is shown in Figure 3.2 (page 34 of the pdf file), just to the right of the six ignition coils.

In the 2004 guide the capacitor is also shown in Figure 3.2, but that is page 61 of the pdf file. The capacitor location is described on page 60.


The relay numbers are shown in a diagram on page 22 of the 2004 guide, so find the relay number on a schematic, then refer back to the diagram to see where that relay is in the power distribution/fuse box. You can then try swapping in a non-essential relay for the ignition coil relay to see if the relay is the problem.

Have you checked the Electronic Control Module (ECM) connector pins for corrosion or other damage? Water accumulation around the connector due to blockage of the nearby drain is a known issue. BTW, ECM is Jaguar's terminology for the engine management ECU to distinguish it from all the other ECUs in the car (Air Suspension, Climate Control, ABS, Variable Assist Steering, Electric Park Brake and lots of others).

I do not know if a replacement ECM would have to be coded to your car, but I'm certain that at the very least it would have to be from another V6 car - the V8 ECMs wouldn't work. You can check part numbers in the Jaguar Electronic Parts Catalog (EPC), which you can download for free from this forum and install on your computer. Just follow the instructions in this thread:

https://www.jaguarforums.com/forum/x...uctions-48194/

In the EPC, you can see all of the part numbers Jaguar has used for cars within your VIN range, including older numbers that were superseded over time.

I hope you won't actually need a new ECM, but the pinout tests in the Workshop Manual are the best way of narrowing down the problem.

Not to sound like a broken record, but have you checked your battery voltage while cranking?

Please keep us informed.

Cheers,

Don

 

Don,
Couldn't get 2003.5 to download and already have the 2004; yes have seen the capacitor in guide and where its supposed to be but dont have anything that looks like a capacitor on the bulkhead?
I assume that the pinout tests at the coils check all possibilities in the wiring as it tells to repair wiring or move to next test, mine failed at last monitor circuit and said contact jag technical for possible ECM failure.
I have a new CKP on order which will try before doing anything with ECM.
Doing most of this on my own so taking crank voltages with battery in boot aint easiest that why I hooked up the boost battery with no difference.

Will keep updates coming as I work through this.

Thanks again

 

Maybe the link was corrupted - try this:

http://www.jagrepair.com/images/Auto...agxj2003.5.pdf


I don't know what it looks like (I assume it's in a plastic case of some sort), but if you can see the colors of wires that feed any components on the bulkhead you may be able to identify the capacitor that way.


What is the malfunction or DTC the pinout tests you are following designed to diagnose?


If your test leads are long enough, you can sit the meter at the backlight/rear windscreen facing the driver's seat, then feed the test leads under the boot lid to the battery. But if your meter isn't fast enough in its reaction and/or display, it may not indicate just how low the voltage falls during cranking.

For some reason, we have not found that connecting another battery or jump-starting is a surefire way to rule out a failing battery in a Jag. These cars seem to be designed to tax even the healthiest batteries, and lots of hard-to-diagnose gremlins come to be resolved by replacing an old and weakening battery. The same can be said for cleaning the battery power connections and earth points throughout the car...

Please keep us informed.

Cheers,

Don

 

If I got it right, it ran after the heads etc. Then you tweaked exhaust and it's then that it cranks but won't start.

I can't see it being a PCM (aka ECM) problem - I mean, how could it be? They don't just die like that after doing nothing to them.

Maybe you damaged some wiring or the like (or disconnected a harness?) in the last work you did - sounds a bit unlikely but I don't know just what you did and what on that model car is vaguely around where you worked.

I suppose you could have a flooded engine - more likely if the battery was going flat at any time you were cranking. The 3.0 isn't prone to this or to bore wash but any engine just about can suffer if everything goes the wrong direction, I expect. Removing a couple of plugs should reveal flooding. I think you'd need a compression test to rule bore wash in or out.

The PCM really struggles to throw a code if it's cranking but not starting. It CAN throw soome (like shorted sensors or the like), but when cranking but not starting nothing is happening to allow a bunch of others (say, lean codes - not running rules those out).

If you're not getting any PATS errors that rules a bunch of stuff out.

Oh - what does the PATS light do as you crank? It should go out and stay out I think. (Mine would flash a code over the next couple of minutes if it had a PATS-related issue. I think yours would do the same.)

BTW, if it is - almost uniquely for the 3.0 (to me, uniquely) - bore wash you'll need extended WOT cranking or to add a little oil to each bore.

hmm, somewhere there's a (jag) No-Start flowchart... PDF, I think...

 

JagV8 Thanks for Chiming in:
I am a maintenance engineer and consider a car like any piece of PLC driven equipment.
The car was flooded after the exhaust gasket tweak, took plugs out and they were wet could smell it as it cranked.
Interestingly when I put the pedal to the floor to induce no more injected fuel it seemed to pump in more petrol smell got stronger?


Like you my initial thoughts were something disturbed during the retightening of exh manifold but there isn't much attached to inner wings.
I did disconnect battery a couple of times to reset and charge.
My reason for looking at PCM/ECM was thinking I may have spiked it?
Did try new plugs and teaspoon of oil aka v8 but still didn't spark.
I have ECM out and all pins look in good condition and connector also.


Can I just plug in another ECU from an X350 V6and give it a try I am waiting for delivery of a new CKP which will try before moving to ECM.

 

I believe you can't just swap the PCM. You sure can't on S-Types and they share a lot of tech.

If PATS isn't upset you should have spark, if there are CKP signals.

If CKP is OK and no spark (be certain!) then maybe a fuse/relay/harness fault.

Stare at electrical guide to see how it all works...

E.g. my car has 8 separate circuits for spark; all 8 PCM circuits simply do not fail at once.

Usually you do have spark. WOT cranking will clear fuel but it does need to be WOT not nearly WOT.