I am in a bit of a pickle with my 1999 XJR; it has had its ups and downs, but generally it will fire. Not any more though.
It will turn over on the starter but only occationally fire on the odd cylinder.
I found the battery to be dodgy; after a full recharge it took only a couple of spins before it was way down low again. I replaced it with a brand new one, expecting to get at least more willingness to fire, but it was more or less the same.
This engine hasn’t had the old “Nicasil-syndrome” although it has been a bit unwilling at times, and also (as discussed earlier on this forum) it has had a tendency to die right after it was started. Just enough to get it out of the garage and half way into the street.
I’m thinking ignition here… I also noticed that there were a little bit of exhaust coming out of the right hand side end tip, whereas on the left hand side there was only petrol fumes escaping. So, the odd ignition I’m getting is on the right hand side…
Thought I reply myself so it looks like something’s happening. . I just came to think of the fact that the Check Engine light is lit and does’t disappear after a few moments like other items do…
It isn’t the petrol pump. Why? I put a good squirt of “starting gaz” into the intake directly on the throttle body, but there was no bang! None at all… This tells me I’m facing either an ignition issue or an electronic one.
I feel I’m mostly discussing this with myself… Ah well… Thought I’d have a look at the ECU so I picked it out. Actually, it looks quite similar to the one in my XJ8 Sport (3.2); same connectors… Haven’t compared the wiring, though.
Has anyone tried to connect various ECUs to an XJ8? I’m thinking maybe I can rule out the ECU as a possible culprit that way.
Hi Bard. Very little movement on the tachometer, you mentioned that you have replaced the CPS check the wiring after the plug to make sure it isn’t frayed and shorting out. I had to swap out an ECU on a '40 that I had fried (reversed polarity, twice, don’t ask!) I had to go through a few that had been lent by a friendly wrecker, only one worked but even that was looking for an O2 sensor that the car didn’t have. I would be fairly sure that you are going to have to find a XJR ECU if you want to try swapping
Hi Robin,
My plan was merely to rule out the ECU as a possible problem; If the issue persists even with my other ECU - never mind other concerns - I know I have to direct my attention to the wiring, although it looked fine and the loom really is quite protected on its way up to the ECU…
Bard,
I’m sure that they are not interchangeable, AFAIK the Part # and all suffixes have be identical i.e. the same Edition and software revision as the original.
So take care, use an oscilloscope to trace the waveform back through the loom to the ECU if you can get your hands on one, a pin thro’ the insulation will let you probe for it.
IIRC Jim B’s write gives a value for the voltage pulses.
Hi,
We are still looking the answer to our issue… I was thinking about measuring the resistance across the Camshaft position sensor. What should the reading be…?
On your '99, each ignition coil has 4 wires. First thing, confirm that you have 12 volts between the pink/white wire and the black wire on each ignition coil connector when the ignition is in the full on position.
Hi, I’m sorry I didn’t reply to your message before. You’re right about that; AJ27SC… Actually, we got the thing running. I took it to a shop to hook it up to a Bosch diagnostic system. They concluded that one of the ignition modules was shot, and we replaced it. Luckily I could pick one from another car (3.2 Sport). Didn’t start straight away, so I ordered them to put some oil in the liners… Didn’t start, but since I was there, I said I wanted to try something; got in and cranked once: nothing, cranked again with the pedal to the metal (past the click) and it caught on right away and has started ever since.
The twist: I had a sneaking feeling they hadn’t diagnosed it correctly and tested the “defective” ignition module again. Guess what! Started right up!
My guess: it was lack of compression all the time…
Question: on a AJ26 (1998) with two leads in the coil connectors, how should the voltage be measured? Between the two or one of them plus earth?
I found out; There should be 12V between on of the terminals and vehicle ground on the AJ26 with two connectors at the coils.
Actually, I found the culprit to be a fuse in the small engine bay fuse box, marked ‘Ignition coil module’ fuse… Why didn’t I find that when I was frantically searching for an ignition fuse…???
Anyway, the engine boasted two cylinders with absolutely no compression, so I guess it’s transplant time…
. I just came to think of the fact that the Check Engine light is lit and does’t disappear after a few moments like other items do…
Bard