Hello again all!

Thanks again for all the pointers on heater core flush on my 1996 x300 XJ6! Again, I'm a new owner and I'm concerned about how I'm going to use this car. I drove it on the highway and the thing just goes. But I also drive a lot in 25 MPH zones. So I'm in traffic at times too. I use 92- 93 Premium fuel. I find leaving the car in 3rd sport in this city traffic is fine. But I think this engine wants to run and be driven at say 3000 or even 4oooRPMs at times. My question is can I leave the car in 2cd gear and rev the engine out more as I'm cruising along at 25 MPH?

I ask because the other day, the car took 2 or 3 tries to get started. Furthermore a couple of times at a light the engine sorta burped very quickly but then continued to idle just fine. But then I drove it on the highway to a pals hours maybe for 1.5 hours. During this time I brought it to 100MPH just to see if I could get it to shift at a higher point. I found 80mph to be just a walk in the park for it and a boring one for this engine. At 90mph it finally shifted at 3- 35 RPMs.

Anyhow, I got home and the car just runs better, the idle in drive is just nicer. It fires right up too.

So can I sometimes -NOT ALL THE TIME, but sometimes just drag second gear out to hold the engine at say 3000 or 3500 rpm for a 1 minute to say 5 minutes? Will this damage the tranny? I'm not talking about abusing it, but I want to clean this motor out if all I'm doing is city driving.

 

I would NOT.

We have a blanket 50KPH suburban speed limits, heavily policed, and I simply run in D, and let the thing do what it does.

The AJ16 certainly loves to run, and open highway is the place for that.

The odd squirt, using the J GAte will do NO harm,

That is MY opinion only.
Both mine, the Mighty 3.2 Poverty Pack, and the "R" BEAST, were more than happy with my way of using them, as are the 2 later "things".

 

Thanks Grant,

Most of my driving will be around town, and that is usually just 1500 rpm. Ive been using 3rd gear but will just leave it in drive now and hope the motor doesn't get too gummed up.

Best

Basil

 

The engine ECU has a electronic speed limiter above the 5000 rpm sport mode shift point

Off the top of my head 5850 from XJRengineer ( Andy S. )

A youtube video that explains your area of interest: , this is with a Andy bracket to bias the CKPS signal

 

Thanks Parker 7,

Super video. I wish i was near those roads. I think running the motor to 3k to 3500 at times could make it run better; probably better than any fuel injector treatment. The problem with this is that on the motorway in Drive, it's quite easy to get to some high speeds! So on back roads or speed limits or 25 or 35 and where it's safe maybe an occasional hold in 2cd gear in the J-Gate to clean her out might be OK. I'm used to manual and shifting at 3k and it always seems the motor likes it in other cars. Of course don't do this on a cold motor. I baby my cars and change the oil etc regularly at 3k or many times less. But when they are warm, I think they are made to run not always poodle along at 1500 RPM. I wonder what Jaguar might say?

B

 

And then this

The Rolls Royse Merlin engine is a hemi

 

At least with the XJR, there is a TSB about clearing up poor idle with some extended highway runs, so they definitely approve of wringing out the engine from time to time to clear up carbon deposits

http://www.jagrepair.com/images/TSB/...oor%20Idle.pdf

 

Thanks Bjarnetv,

That's very helpful for me.

 

I recently picked up an X300 from a deceased estate. The car was in beautiful order but the engine had a terrible idle and ran roughly. I picked up on the XJR TSB about valve problems particularly if the car was only doing local city type driving, which is what this car had been doing

A compression check showed four cylinders at 160 psi and two closer to 100psi. a leak down check on the crook cylinders showed leakage via the exhaust valves. (you put the piston to top dead centre and insert 80psi air via the spark plug hole and listen at the exhaust, inlet, and the sump via the oil cap).

After administering a hefty dose of upper cylinder lubricant I then gave the car about 50ks (30 miles) on the highway which is speed limited to 100 ks/hr (60 mph) and a check on the crook cylinders showed improvement to 130 psi. I then took it back to the same highway and gave it a serious flogging in intermediate gears holding 3000 to 4000 rpm. Another compression check now had the two crook cylinders back up to 160 psi and the rough idle had gone.

Consequently I do recommend a good occasional flogging for the AJ16 engine.

Bill Mac
MK1
MK2
S3XJ6
X300 (x2)
15 previous Jags MK5 to X308

 

Thanks Bill!

I'm glad it worked out good for you! These cars have to be driven hard sometimes. Good luck with it. What did you use for upper cylinder treatment? Did you just dump in it where you add oil? And then did you change the oil or are you going to leave it in there?

Thanks Again,

Basil

 

Basil
The upper cylinder lubricant is added to the fuel.( petrol, gas or whatever you call it). I think any brand would do the job. I am not aware of where you live so can't recommend any "local" brands.

In this case I used double the recommended amount which can emit a little smoke but the primary objective was to get the exhaust valves working and sealing again

There is no need to change the oil as we are dealing with the upper cylinder combustion system which is (hopefully) fairly "separated" from the major engine lubrication system .
If this separation system which depends on the piston rings breaks down you will have lots of smoke!

Just remember we are dealing with the combustion part of the engine.

Cheers

BIll Mac