You all seem to be going round the houses here. For a no start situation, follow the no start procedure from Jagrepair

Jaguar XK, XJ & S-Type No Start
This is a No Start Procedure I put together that should help. Keep in mind that not all cars are alike and procedures may be a little different.

Before we get started in looking at this you need to read the OBDII codes, document them, then clear them. DO NOT clear them until they are written down/documented. It is important to get these codes prior to your attempting your vigorous attempt to start the car. Your vigorous attempts can cause factious codes misleading you with bad information. Next is to find out what they mean. The meaning of the codes are defined by the model and model year (MY) of the car and the definition directly related to that car. Anything less is bad information.

Next - Do not use starter fluid in your attempt to start your car. You can cause serious damage to your engine and possibly you.

The first thing you need to do is be sure that you have what is necessary for the car to start.

1. Check that you have a fully charged battery and that you have power to all fuse panels.

2. Be sure that you have fuel pressure.

3. Check that you have spark.

This all seems easy until you get involved in doing it. I will suggest to you to check fuses, fuel schrader valve and all sorts of things. Because of different models and MY cars I will not be able to provide you with all that information. You will be able to find all this information by using your owner’s manual, electrical onelines and a little information on my page.

Two things to check before we go on.

Take your transmission shifter and put it in the “N” position from “P” and try to start the car. The shifter selector switch has been known to wear out or out of adjustment causing a no start situation. If the car does not start put it back in “P” and check the inertia switch.

The inertia switch is installed next to the fuse box in the LH end of the fascia. When activated, it de-energizes the ignition relays in the engine compartment, driver's side fascia and trunk fuse boxes. It also removes ground inputs from the BPM and windshield wiper stalk switch. This stops the engine and fuel pump, unlocks any locked door, and de-energizes unnecessary electrical systems. The switch is reset by pressing down on the rubber cap on the top of the switch. If your doors lock, windows, seats and the wipers work and the dash lights up then all should be good, but if it makes you feel better reset the inertia switch.

Check that you have a fully charged battery and that you have power to all fuse panels.

First check that you have 12V + a few. This is important and should not be taken lightly. For whatever reason these cars are sensitive to fluctuating and low voltage. Depending on where you are you can take your battery to AutoZone, PepBoys or Sears and have it tested. This test is performed using a tool that is not just a volt meter. It examines the integrity of the battery. In most Jaguars you have a fuse box in the trunk, the drivers and passengers section both left and right and two under the hood. You will need to check voltage at each fuse box. If voltage is not present you need to check the fuses in the High Power Protection module. Use caution in making any checks or adjustments. You should disconnect power if you need to make adjustments or replace the fuses. If they are ok then you need to check the battery connections and I am speaking of the power (+) and the negative (-) connections and the grounding point at the battery. If power is present at all locations then you need to check your fuses and relays. At times moving the fuses and relays will cause a better connection.

Power Distribution

Starter AJ27

High Power Protection Module

Be sure that you have fuel pressure.

First see if the fuses for the pump are not blown. You have two fuses to check and they would be located in the trunk. The XJ8 & XK8 has one fuel pump and the XJR & XKR have two fuel pumps, in either case they have fuses in the trunk. They also have relays related to each pump. If you think you have a bad relay you can swap that relay with a like relay. The theory is that the chances of having two bad relays at the same time is slim. Now if the fuses are ok you need to check pressure at the schrader valve with a pressure gauge. If you have a pressure gauge to do that, then do it first. If not, check the fuses. Checking the fuel pressure without a pressure gauge at the schrader valve is not a good indicator and could only delay the process of starting your car.

Check fuses & power to fuel pump

Check fuel pressure

Check that you have spark.

First see if the fuses for the ignition coils are good. This can be done by pulling one of the coil packs and inserting a spark plug, grounding it and try to start the car. Another way is to use an ignition spark checker. This process is the same but allows you to install the checker between the coil pack and the existing plug.

Also, when checking fuses under the hood check the fuses for the fuel injectors and throttle motor.

If the car has not started you need to identify if you have compression and this will require pulling the plugs and doing a compression test. At times an experienced mechanic can hear that compression is missing on all cylinders by the sound of the engine as it is attempting to start. This is not a foolproof way of checking but only an indicator. The only true way of telling is a compression test. Nikasil engine blocks have been known to have problems with cylinder washing that is often created when the car is started and run for a short period of time. The engine is not warmed up when parked causing the un-burnt fuel to wash the cylinders resulting in the no compression.

The next question is do you have a Nikasil engine block? Nikasil is not bad and it should not be identified as a problem engine block . It just needs to be finessed like a good woman. The only way to know is to check the date of manufacture of your AJ-V8. If you find that you have a Nikasil engine then you may have a case of cylinder washing. If you fall into this category you will need to get it started and that will take a little time. My procedure will spell it out in detail but what you are going to do is add a little oil to the cylinders to create compression.

Nikasil

Nikasil no start

Nilasil & Sulfur

If all attempts have failed you may want to look into the exciter ring located at the ignition lock. This ring receives a signal from your key that enables the starting process. This part of the no start process in not a common occurrence but should not be overlooked.

Please understand that this process in not a fool proof way to get your car started but is full of the most common problems. You could have other issues that prevent it from starting. I will update this process as I get other things to check.

 

 

 

The only procedure you mentioned was the throttle body procedure. I suggest you go through what I posted step by step. A scatter gun approach may come up with the fault, eventually, better to do it step by step.

 

 

Hi Gus.
I'm so sorry! I've just seen your post here.
I had someone visually inspect the ECM and re solder some connections inside
but still nothing. My next job is to test all the wires coming from the TB to the ECM with an ohms tester to see if there are any splits.
How are you getting on?

 

Thank you but i've checked twice already

 

Due to the fact that your car starts
forgot Bore Wash and all No Start-tips.
Is the ECU a LJA1410?
IMO throttle motor or ECU.

 

 

The first generation of the ECU´s is notorious.
An intermittent failure as you decribed points to the ECU,
who has inspected/repaired yours?

 

I'm thinking that toaster may be on the right track here.

When I first saw your ECM #, I thought - that's for a '97. Indeed, a member here has the same ECM in his 97 and he's in the US, where it should be different.

JEPC shows it as correct for cars up to VIN #20733, which is within the MY98 range. However, it's immaterial what I thought or what JEPC says: the VCATS label is your source of truth.

Given the issues greenforest56 had with his, I'd recommend giving the ECM a closer look; the caps don't necessarily leak when they fail, and there's no harm in replacing them as PM in any case. Cost is around Ł5.

There's a list of the Nichicon codes here:
https://www.jaguarforums.com/forum/x...6/#post1806456

HTH

 

Have you had a look at this video? Seems he was having some similar problems and it came down to an adjustment on the throttle body and ~10 drive cycles to clear the 'check engine' light.

 

Interesting post but on the 1997/1998 throttle bodies you cannot change or adjust the throttle position sensor.

 

 

 

Have you checked the throttle motor relay?
It is in the ECU-compartment.

 

From the other thread:
https://www.jaguarforums.com/forum/x...4/#post1887722
Here you go:
https://www.jaguarforums.com/forum/x...2/#post1781979