Hello all, I've been a viewer for a while but I'm out of ideas on a car in my autoshop class. It's a 1998 jaguar XJ8 L. Me and a buddy convinced my teacher to let us bring it in and rebuild it, as it had been brought to the school with the engine tore down to the block due to the tensioners going out and it jumped timing, bending the valves. We have used mostly new parts in rebuilding this engine from the block up, have followed all sequences and torque patterns, and all the electrical is back in place with not a plug missing. The car will not start. We of course checked all the basic things, fuel spark and compression, but can't figure it out. To further iterate what we have tried, we cleaned out the gas tank and tested the fuel pump, as well as replaced the soft lines. All good. Fuel filter is not replaced, nor are the injectors (however we did spray them out) but there are no blockages throughout the lines. I don't know how much fuel pressure we have as the Schrader on the rail is missing the actual valve part, but we do have some amount of pressure as it sprays when the cap is off. Now spark, we have tested with test lights, pulling the coil packs and testing every single one individually, and all are firing. On top of that, they seem to be firing at TDC, as the spark occurs at the same time as air shoots out of a compression testing hose we attached to each cylinder. We tested every coil pack and every plug, all functional. We did test compression, as I am somewhat familiar with the bore wash condition that these nikasil blocks are prone too, and saw we had low compression. We opted to put oil down the cylinders, and the compression came up from about 80 lbs on average to about 140 on average. We have done that a few more times since throughout testing, but I haven't tested compression since then. I've checked timing once again, and it's all fine. I am simply at a loss. It will crank and crank, but never even try to run. With ether, given enough time, it will back fire one time on the second cylinder from the front on the passenger side, but nothing else. What am I missing? I know they are finicky cars but at the most basic level of engine requirements, it should run. Fuel (or ether), spark, and air. I'm at a loss, and even my teacher has no clue either. It's very disheartening considering how much time we put into this. Thanks in advance.

 

With the starter cranking ..............

There is a specific labeled fuel injector relay and 2 fuses ( ? )

Put your finger on it and feel ( not sound ) for click on ignition key rotation , you can do this yourself by key in run and removing the relay

Fuse # 5 engine " management " fuse box

Fuse # 5 engine " compartment " fuse box

Do you have the AJ26 or 27 engine as 99 was the cross over year from my understanding

There was some wiring changes

See page 42

jagxj1998.pdf (jagrepair.com)

Researching

" Schrader on the rail is missing the actual valve part "

from my understanding the valve is not on all Jaguar V - 8s

Fuel pressure 43 psi at idle or not running engine

Change your main fuel filter and get rid of old fuel as can cause issues on starting

You may have put the cylinder into a " bore wash " condition

Hold gas pedal to the floor while cranking and the ECM know to not add fuel to reestablish oil from the bottom of the piston to recoat the cylinder walls

There is another similar condition of the early Jaguar V - 8s not having steel sleaves on the cylinder walls , the factory treatment ( nikasil ) to harden the bare aluminum bore did not hold up to real world sulfur in the fuel eating up the bore , low compression , TSB was to change whole engine to a AJ27 with steel sleaves

The fuel pump will run for 3 seconds only with key rotation , it will come back on when the CKPS sees engine rotation ( safety design )

The ignition is retarded back to 0 degrees TDC to aid starting then reverts to normal advanced angle and varies from there

There is a terminal post that gets compromised in the engine compartment that Motorcarman ( Bob ) would certainly know better about

I do not have the V - 8

 

Look to the cut off valve inside the right side foot well.

 

There is an inertia / crash switch that shuts the engine off that can be reset

This switch can trip for no reason

You can jumper the 2 white wires with a paper clip at the connector as they don't always reset

If you take apart the switch , there are spring loaded parts to fly everywhere ..................Ask me how I know

Right side foot well against the foot wall

 

Thank you for the replies, I will check inertia switch tomorrow. Does the inertia switch cut off fuel supply to the engine or does it stop it from running some other way? And on the same note, how likely could it be that my issue would be fuel pressure/filter or any other fuel related issue? Obviously not having fuel is a problem, but I'm a little baffled at the non-running state even with the use of ether.

 

Inertia switch cuts out the fuel pump from gushing fuel in a crash

Do you have a node light to test connector going into the coils ?

The coils at the coil connector have B + volts " sitting " on them at all times

The 2nd wire at the coil connector is the 8 timed ground paths provided by the ECM to only then produce a spark

There is also a dedicated ignition relay to provide this " sitting " power and it's 2 fuses

To close this and the injector relay..............................

You can jumper these relay's sockets from socket 3 to 5

3 and 5 will be the large sockets , this pic from someone in the X308 group

 

Does injectors tick when cranking? It is easier to use led voltage indicator than listen.

 

That being the case, I'm inclined to believe the inertia switch is not the problem. Fuel pump is still operable, fuel is making its way to the engine. I put a light on the injector plugs before the summer and as I remember it, they all were receiving everything they needed to. That is not to say the injectors couldn't be bad though. Again, I have to stress that I'm not super worried about fuel supply at the moment due to having spark and not firing off of engine starting fluid. Whether or not I'm getting fuel like I should be, I would think it would still fire with ether.

 

Use this

 

So let me get this straight...Your first post indicates you have spark to the
cylinders. Later posts indicate you have fuel to the cylinders. The only
thing left is compression....or timing.

 

Randy, yes that would be the case. I have both spark and fuel. Timing being done the way it is, with the locking bars and the pin in the crankshaft, I struggle to believe timing would be the case. It does seem like my first bank maybe is a tooth or two off, which I don't know how I did but regardless, it's close enough that I think it should fire, even just backfiring or chugging or sputtering or something. On the idea that my compression was low, I have tried several of the borewash cures to no avail. Was running an average of 90lbs per cylinder, but was able to bring it up to about 140 on average, although it's been a while since then. I could do another compression test but I feel like I've oiled these cylinders an awful lot to not have enough compression still. Is it possible to have done timing 180 degrees off, even with the method used? The cams rotating at half of crank speed makes me wonder if the locking pin could've been put in on exhaust stroke instead. I don't know how feasible that is.

 

Update: I redid the the timing again to verify that it was correct. Passenger side bank was off maybe a tooth, and the exhaust cam was off an additional tooth further. Probably due to me wiggling stuff around to get the chain on last time and not setting it again. I don't know if that was much of an issue or not but it's fixed anyways. Put it back together and cranked it on Friday to yield no results again. A quick compression test shows 80psi in the one cylinder I tested. Definitely low, but I don't know how low it gets as a result of the nikasil issues, and how low it would have to be for me to assume I need to redo piston rings or something. Thoughts?

 

To make sure of compression results , what was your method against a standard practice and a Jaguar factory method everyone can reference ?

Have you measured fuel pressure ? 43 PSI

You will sometimes have a test port on one of the fuel rails

Time for some relay ( s ) swapping in case they are current limited for devices like the injectors

Researching and back tomorrow

Long extension in a plug hole for cylinder X at TDC against a Y valve lobe position ?

You can certainly do the # 1 against watching the # Y valves sequence positioning to....................

There is a method looking at the # 3 valves for the inline 6 and I do not have the V - 8

AJ26 or 27 engine by ID plate serial numbers ?

 

Thinking on how to watch your valve timing......................

Before the # 1 cylinder piston gets back up from the bottom to # 1 TDC it will be drawing with the inlet valve open ( piston drawing down )

Before it comes back up in compression to the TDC the inlet will then close ( at the bottom ) and stay closed until TDC ignition

The reason they use # 3 as a reference valve on the inline 6 is a trick to see that cylinder's valve operation through the oil servicing cap without removing the valve cover to directly see # 1

To use that trick would require a determination based on your V - 8's firing order

Using the correct # 1 cylinder ?

And the correct firing order for your specific AJ26 or 27 engine ?

 

Parker, I've not test fuel pressure due to the valve itself having been taken out at some point from the screw on the rail. I can tell I have fuel pressure but I don't have a measurement for it. My method for testing compression was just using a tester on cylinder 8. What exactly are you suggesting I check? I'm not quite following

 

Some others would know the V - 8 compression test and that test minimums , but you have a fluctuation in your test at different cylinder conditions

I don't think you have a valve slightly open in the test as that would be very poor results ( incorrect valve replacement part # ? , valve seats ? , valve stem seals ? )

Maybe a coolant pressure test if you have a bad head gasket

Spend much effort on the electrical side ?

 

Head gasket was just redone, so I sure hope it isn't that. I have researched electrical problems but I couldn't find anything that would indicate the type of problems I'm having. I lacked spark but since have figured that out. Compression seems to be the only thing stopping me right now

 

Bore wash?

 

Hi Nick,

What RJ is suggesting is that the cylinders/piston rings do not have enough oil on them to produce sufficient compression. Try adding a teaspoonfull of oil to each cylinder via the spark plug hole. Remove the fuel injector relay and crank the engine several rotations. Then re-test compression. If the compression rises to, say, 150 psi, reinstall the spark plugs and injector relay and see if it will start.

To temporarily inhibit the fuel injectors while cranking, you can hold the accelerator pedal to the floor.

Cheers,

Don

 

I have put oil into each cylinder over and over again to raise compression the last few days. Some of my cylinders were as low as 55psi. Now, I'm between 135 and 175 on all of them, and so I put it back together and tried again. No dice. I am again at a loss and I am extremely frustrated at this point. Am I missing something?