I've just picked up a 89 (and an 88) XJS and am in the process of getting the 89 running. Has been sitting for a bit and has had some parts taken off the engine. So far I've cleaned fuel surge tank (holy sh*t was it caked with rust) and replaced fuel pump and filter.

So I've been reading what to replace on the Marelli ignition, I plan on plugs, plug wires, distributor cap and rotor. While I'm ordering should I also buy?:
1.coils?
2.ignition amplifiers?
3.crank sensor?
4.speed sensors?

Related, while fuel rail is off, I'm going to replace the fuel lines and injector seals.
Should I send injectors out to be cleaned? I'd like to do this once but don't want to spend money and time on something not needed. (Will plan on several bottle of Redline and Tehran fuel system cleaner.

Thanks!
Andy

 

Good!



Opinions (and budgets) vary. Personally, I'd hold off on these items and replace only when needed. They're not cheap, and they're not too hard to replace at any time....so there's no particular advantage to doing them now.

You might wanna carefully inspect the wiring to the two crank sensors, though. Sometimes it's damaged.




While the rail is off and you're replacing hoses, I would send the injectors out for professional cleaning, yes. Doing it later means a complete duplication of labor.

IMHO, bottled add-to-the-tank cleaners are not as effective as a professional off-the-car cleaning


Cheers
DD

 

I agree with Doug here. I have sent my injectors to http://www.jaguarfuelinjectorservice.com and he did a great job. Make sure to get new ferrels for the fuel injection hose and be sure to get actual fuel injection hose and not heater hose. Be careful when touching the wiring as it is brittle and will eventually need to be replaced.

 

I agree with NOT changing what may be perfectly good parts. I feel like I beat a drum with this, but after working MANY hours on getting a dormant 89 Marelli car running, I still say that the front and rear "sensors" need to be checked for their distance from what triggers them. i.e. the fingers on the damper, and the teeth on the flywheel. In my opinion, the magnets in these "sensors gets weak with heat and age, and being too far away from their respective triggers, sends a poor signal to the ECU, resulting in poor, (if any) performance. Will gladly discuss via phone if you'd like. I am one of those odd guys that now feels pretty comfortable with the Marelli ignition system.

 

Once armed with the knowledge of how failures occur and how to prevent them there's no reason to avoid or be fearful of the Marelli cars.

'Tis only not knowing that makes the Marelli system a stinker!

Cheers
DD

 

Are the crank and flywheel sensor the same part?

 

Jaguar has them designated as different part numbers, but I can only suspect that is due to a minor difference in length of the factory lead. They appear interchangeable, but I would say the rear one has a longer lead on it.

These little things aren't sensors at all. They are little magnetic generators so to speak. A magneto. They send a AC signal to the Marelli ECU, and the Marelli ECU uses that data against programmed tables, to deliver spark. The front one controls timing signal, and the rear one is speed signal. At starting, my rear one seems to produce about .06 VAC, and then goes to about 3 after starting. They both really have to be checked using a oscilloscope, but I know you can put a volt meter across the two terminals once unplugged, and seems it should read about 680 ohms resistance. Very far out of that, and they are suspect. Yet, I know from first hand experience, mine were too far away, and once I filed the mounting boss, and got them as close to .020 away from the flywheel, and the timing fingers, my car fired right off. I feel that over time, the magnet in them gets weak, and add that to them being too far away from its trigger source, the car simply won't run. I read somewhere that at full throttle, the rear "sensor" can send up to 80 VAC to the ECU. If the wiring gets in bad shape, the signal gets scattered, hence using coax in the harness. Are we having fun yet?

 

Don't forget a New Gasket for the Distributor.