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I'd be willing to bet its not the coils, however if you are willing to invest in a spare, people have had success with the cheap chinese coils, at least for a few months. I think an entire set of six can be had for less than $100, shipped. A failing coil or two cause rough idle and poor engine performance, but I don’t believe it would prevent the car from starting, not unless all of them failed, in which I would recommend you run out and buy some lottery tickets.
The plugs, while shiny and new looking, are old. As I mentioned, they could be original to the car, making them 22 years old. New ones run about $3 each (I typically find them for $2/ea at the local Autozone), so it would make for a wise investment on plugs that are meant to be changed every two years at the very latest! Remember you want Champion RC12YC.
Have you hooked up an OBD2 reader to see what the (a) TPS is doing or (b) MAF is doing or (c) Coolant Temp Sensor is doing? That’s where I would focus my energy at this point. Those three sensors are critical to getting the car started.
When was the last time the fuel filter was changed?
I'd be willing to bet its not the coils, however if you are willing to invest in a spare, people have had success with the cheap chinese coils, at least for a few months. I think an entire set of six can be had for less than $100, shipped.
Have you hooked up an OBD2 reader to see what the (a) TPS is doing or (b) MAF is doing or (c) Coolant Temp Sensor is doing?
When was the last time the fuel filter was changed?
No OBD2 reader will force you to throw parts at the car.
A. TPS will cost at least $200. Cheapest place I’ve come across is JDHT. It’s coming from England, start trolling now.
B. MAF - not even sure what an aftermarket new one will cost, used ones could be found for $50? Start checking eBay.
C. Coolant Temp Sensor is about $25. Easily found at many car shops. It’s not a terrible investment in time and money if it doesn’t resolve the problem.
Even if you diagnose the sensor, there’s a possibility that it’s not being read/seen by the ECU. The easiest way to ensure you’re seeing what the ECU is seeing is by plugging into the OBD2 port. It’s well worth the $15 for the reader and $20 for the application. Or you can buy a hardwired unit for a little more.
So sensors ABC haven’t been checked/diagnosed. Ok.
Im assuming the fuel filter is original to the car? Not a bad idea to change it no matter what. It’s easy to do. It’s neither a waste of time or money if it turns out not fixing the problem.
Have you put your eyes on the ECU for corrosion? It’s a free test, and a common problem. There’s no reason for you to avoid this.
Its difficult to give you a list of suggestions to respond to, but you only addressed the OBD2 Reader. What about everything else?
In addition, we haven't addressed the coolant temp sensor, the fuel filter and the MAF.
The coolant temp sensor is cheap and easy to replace. If it's original, it might be time anyways. If you want to pass on that now, unplug it and connect to two female terminals on the harness (not the sensor) with a wire, and leave it like that. Until we get the engine started we want to eliminate this pesky sensor as a problem. Keeping these two terminals shorted will tell the ECU that the car has been warmed up already. The cold engine won't get the overfuelling it's looking for, but it will turn over.
The fuel filter is cheap and easy to replace. It can cause low fuel pressure and thus lack the capacity to start. I would recommend replacing it. You will have to replace the UK passengers side front wheel to access it. (Drivers side in the US)
The MAF can be tested with a multimeter.
Pin 1 should be 12v, Pin 3 should be 0v.
Pin 2 will range between 0.8v to 4.7v
It would be interesting to see what the multimeter says. Even then, these signals might not be read by the ECU, but worth checking since you don't have an OBD2 reader.
Lastly, I would add to this list the CAMshaft position sensor. Another magnet driven sensor. When it goes bad, it causes a no-start condition.
Originally Posted by orangeblossom
Hi Vee
(1) New Crank Position Sensor
Probably not wasted money, it was probably going to go soon anyways!
(2) ECU Removed and Plugs on it Cleaned
Perfect! No corrosion to worry about! Worth checking!
(2) Spark Plugs Removed and Cleaned and put back
Unlikely to cause a no start. More of a rough running symptom. Make sure you eventually replace these inexpensive and easy to replace parts with the proper RC12YC Champion Plug.
(4) Got a Good Spark at the Spark Plugs so Coils seem OK
Agreed, coils typically wouldn't cause a no-start, just a rough run.
(5) She was trying harder to Start but Still wouldn't run
Dammit!
(6) Check every Fuse everywhere all seemed to be OK
ECM Relay could be suspect, would be worth checking, since it's easy and free.
(7) Did a Compression Test all seemed OK
OK, then you're good there.
(8) My mate who did the Compression Test couldn't hear the Injectors Clicking, so should I take the Injectors out to clean them?
That's a concern, but I think it's very unlikely they have all failed at the same time. A cleaning probably wouldn't solve your problem. A bad tank of gas could theoretically gum up all injectors, but is that plausible? However we might want to look at what would prevent the injectors from wanting to fire.
8a. Can you put a multimeter on the injector harness and see if it's getting voltage during startup?
8b.
(9) Maybe I should get myself one of those OBD2 Testers?
9a. Now I have ot doubleback. You have an OBD2 port, but I don't know if the 1995 was indeed OBD2 ready. I would think for the cost, it would be worth paying for one and seeing if it worked. Buy an ELM27 OBD2 head and then you can download some kind of app, under a trial basis and see if it works. If it does, it should shed light on what's wrong....and what's not wrong.
Thinking out loud here, if the injectors are not clicking when cranking, but it runs when fuel is added through the intake, then the ignition side works. Power to the injectors comes through the ECM controlled relay. It's a light blue relay in a blue socket, see the diagram below. I would replace that. It's on the right side underscuttle. Also look at fuse #10 (5A) on the right side fuse panel, also under the steering wheel ( UK side). Those relays are at the age and # of cycles where they do start failing.
Lots of irrelevant(even though good) and confusing info here! First of all, AJ16 is an extremely simple engine, much like AJ6 with some extra annoying things like separate coils and some good things like OBD support. It is much much easier to diagnose and work with than V12.
Some extra info not necessarily in correct order:
1. Coils can definitely cause no startup issue, especially the cheapo ones when one of them fail.
2. Cheapo coils are bad but the Lucas ones(£30 per coil on eBay) are enough to get you running and are not too bad. The QYL coils that you can get from US have very good reviews there and they are ~$80 per set.
3. Car will start even with just 4 coils plugged in, you can inspect the coils for cracks in the body, any hairline cracks and the coil is bad and will be arcing to the cam cover and you should see some damage to paint there in the well itself. You could fix the cracks by melting plastic around the cracks with a soldering iron. I got a year out of mine after repair before they started to give weak spark. When I bought my car 5 out of 6 coils had cracks in them so definitely inspect them visually.
4. RC12YCC are recommended plugs but difficult to get, sometime they show on eBay. CC stands for double copper core, whatever that means. RC12YC should be easier to source. RC9YCC are also fine. Definitely use Champions, my AJ16 doesn't like any other spark plugs indeed. Set the gap to 0.035.
5. Your completely black spark plugs mean that the car was running very rich. I'd change them as it wont be expensive.
6. Definitely get yourself an OBD scanner. Its a god send and a huuuge improvement over older engines. Go for one of these D900 scanners, they are very basic but then Jag OBD from 90s is basic too. Try eg eBay item number: 262955779685. I use one of these myself and can recommend it.
7. OBD will show you some basic info with key in position 2, like coolant temp(the one that engine use, not the dash one), MAF voltage, TPS voltage and if/when you manage to start the car, it will also show you oxygen sensor operation(closed or open mode or whether its faulty).
8. In your last pic, the one on the left is CTS, coolant temp sensor, which ECU use. It may as well be shot but OBD scanner will tell you whats going on with it.
9. The sensor next to it is the dash coolant temp sensor, which is used purely for dash reading.
10. I bet your oxygen sensors are dead and over fueling it but that wont cause a non startup as they are initially in open loop mode anyway, just all the soot on the spark plugs points to it. This can be investigated later but again OBD will easily confirm it when it runs.
11. Your video shows that the engine tries to start and it only fires up on one or two cylinders. When was the last time this car was running? Reason I ask is that I recently got 12 injectors to clean that were sitting on a bench for a year or two and out of 12, 9 were either completely stuck or leaking and I only managed to save 3 of them even with a lot of soaking in an ultrasonic bath and a lot of cleaner they just wouldn't open up.
12. If the car was sitting for a long time, consider cranking it for 2 or 3 minutes, see if that opens up injectors, I did this successfully with my AJ6 Jaguars on a couple occasions. Even my AJ6 XJS needs a minute of cranking after a year of not starting up. Usually after a minute cylinders gradually start up and after another minute the car runs fine with the throttle open.
13. Injectors are easy to remove on AJ16, you need to get the top plastic cover off, few bolts and undo the fuel rail and it can be pulled out for inspection, you could use this to test injectors individually. I can explain how if needed.
14. You could also check fuel pressure on the fuel rail if the car runs fine on easy start. Have you attempted to spray some easy start to see whether it fires up? That would further point to injectors(stuck or leaking) or low fuel pressure.
15. Its pretty much impossible to get correct adapter for a fuel gauge so you'd have to resort to an oil adapter(cant remember thread size, but can check if needed) and some PTFE tape for temporary fuel pressure reading. Alternatively you could cut the rubber line and install a gauge there permanently(which seems to be the general consensus on x300 forums).
16. If the fuel pressure is indeed an issue you could temporarily clamp the fuel return hose, just after the fuel pressure regulator. Just use one of the brake line clamps which I think you recommended me for my own XJS some time ago(or was it Daim?) My fuel pressure regulator failed and the car was barely running, when I clamped the fuel return line it worked fine.
17. I've replaced my fuel pressure regulator just to find out that the pressure dropped again after few days, only this time it was fuel filter completely clogged. You're lucky that XJS fuel filter isnt where the X300 one is. Its one of the worst jobs on x300 to do.
18. I think I covered everything, if I missed anything, let us know.
Last edited by katar83; 09-06-2018 at 05:02 PM.
Reason: typos :)
Thank you so much for sending that very detailed reply, as unlike yourself I know nothing about these Engines and you have already told me lots of useful stuff I need to know
Its quite a while since I used her, so maybe the Injectors need a clean, although I have already done what you said and Cranked her over for a couple of minutes
She is definitively trying to start, even moreso than before and so the first thing I'm planning to do in the morning, is to bridge the Coolant Temperature Sensor and in the event She doesn't start
Then I will take the Injectors out and clean them
In the V12 the Injectors are held in by a Clamp but how do you remove them from an AJ16 4.0L Engine?
Do they unscrew like Spark Plugs, or something like that?
In the V12 the Injectors are held in by a Clamp but how do you remove them from an AJ16 4.0L Engine?
The rail is held the the engine with a few bolts. Remove that and the rail and injectors should come out as a unit. The injectors are sealed to the engine basically by O rings. They will be stiff, but they will pull out.
09-05-2018, 05:51 PM
My fuel pressure regulator failed and the car was barely running, when I clamped the fuel return line it worked fine.
