Greetings from the Seattle, Washington area.

I’m looking at buying a ‘94 XJS 4.0 liter convertible. It’s an early ‘94 and has the AJ6 engine. Jaguar later in MY ‘94 switched to the AJ16 engine. Can anyone please share their thoughts on the AJ6 vs. AJ16? Is the AJ16 a better engine? I’ve read since the AJ6 was in production longer, parts are easier to get than the AJ16.

I would appreciate any of your thoughts. Thank you!

 

I've never heard anything negative about the AJ6.

I don't know that the AJ16 offers any huge benefit over the AJ6.

I think I'd prefer the AJ6 just to avoid the coil problems and driveability issues which plagued my AJ16 ownership experience.

Others with chime in

Cheers
DD

 

The AJ6 is the most robust and reliable engine Jaguar ever made.

 

In response to Doug, I am wondering that if you had a distributor, Coil, Rotor, cap and ignition lead set for a AJ6 motor if it would be possible to make it work in a AJ16 motor? The ECM portion of the Coil would have to be reworked somehow. You then could maybe adjust the ignition timing at the distributor?

Larry Louton

 

One of the main issues with the AJ16 is a high idle that can only be corrected with an almost extinct dealer diagostic unit. Thankfully I have not yet had that problem with my AJ16 and some here on the forum have devised ways to correct the idle. I believe the AJ6 idle is easily adjustible.

 

Thank you, everyone, for your responses. I haven’t read any advantages of the AJ16 yet. Only disadvantages. I’m feeling glad the car I’m planning to buy has the AJ6 engine.

Why did Jaguar change to the AJ16? They must have felt they were improving the car at the time.

 

I have two Jaguars with an AJ16 4.0 engine. I have one for 18 years and which has driven 330,000 km. Never had a problem with the engine. The other I bought in the USA and had some overdue maintenance. It now runs without any problems. I sometimes buy the ignition coils from the scrapper, original without cracks. Yes, I have a Jaguar expert in my area with the right dealer diagostic units. Proper maintenance is important for any car of this age if you want to drive smoothly.

 

Unfortunately the timing CANNOT be adjusted with the distributor. The CKPS and ECM parameters set the timing and the distributor simply decides which cylinder gets the spark. (the dist has no internal electronics)

I guess you could use an AJ16 engine with AJ6 electronics/ECM by replacing the CMPS with a Distributor, Cap, Coil and Wires?(never tried it)