Car wont rev past 4000 RPM
 

I just took delivery of a 1986 XJ-6. Im just starting to go over it and start fixing the mechanical difficulties, and I discovered that the car will not rev over 4000 RPM's. Im told there is some sort of "intercooler" type intake that will not let it rev if there are temperature issues- Has anyone else heard of this?

RE: Car wont rev past 4000 RPM
 

hi, I'm new in this forum but I've owned a 1984 XJ-6 for the last 16 years and I never heard of that, neither have I had the problem. 1986 and 1987 models had a number of problems like that. The best XJ years are 1983, 1984, and 1985.

It sounds like an ignition, ignition module, or coil problem to me, not being entirely an 'expert' in the XK engines, I usually fix engine symptoms by trial and error and other's help. Another opinion would be the throttle butterfly adjustment at the intake, but heck it could be anything in the large array of electronic components over that engine.

Whatever it is, it can be fixed.

Jose :)

RE: Car wont rev past 4000 RPM
 

I'm just wondering why is it a problem it won't rev that high? I drive my 93 xj6 and it never needs to go over 2000 rpm really, so unless your liek racing the car, but why would u race a 24 year old jaguar?

RE: Car wont rev past 4000 RPM
 

Well, it seems that never going over 2K RPM is kinda Granny Driving(no offence). Some times you need to accelerate quickly to prevent an accident or get in to a lane, and if the car doesn't go over 4K RPM then it would be extremely difficult to pick up any speed. I have a prett heavy foot and my Jag goes to about 3K RPM normal driving and when I hit it it goes to 6500 RPM!

RE: Car wont rev past 4000 RPM
 

Simple: a 4.2 Jaguar engine should go over 4,000 rpm all the way to Redline. My 1984 4.2 engine gets to Redline (max rpm) easily, almost as if the crankshaft was on roller bearings, and I'm not neccesarily racing, but for example, from a red light or out from a ramp into the interstate, I can start in first gear and accelerate the car to the redline, then shift to 2nd gear and repeat, then shift to Drive where I can relax since I'm already at 95 mph. It is after all, a Jaguar. Luxury and Quiet Performance. My 1965 'S' type has a 3.8 Jaguar engine and it also gets to Redline easily, in fact the 'S' type is a faster car than my XJ-6, especially after 80 mph, for example while passing, it actually is faster. Understand that these cars are cruisers, their performance is not tire-screeching-red-light-acceleration-spit-fire-through-the-mufflers, these cars are designed to cruise at high speeds safely where lesser cars begin to wooble.

My suggestion would be for CurtsKitty to register at www.thejagboard.com and ask the question from Phil Prince, who is a technician at Motorcars Ltd. in Houston and who answers questions there. Phil is an expert with Jaguar engines and he will pinpoint the reason.

regards,
Jose

RE: Car wont rev past 4000 RPM
 

Dude on an old car, you don't red line the engine.

Quiete performance is how you described jagaurs, and it's true. The keyword being quiet. If you get the rpm up to the red line, it's not quiet.

If you red line the car at every shift, you will blow out your engine, if you want your car to last forever you just shift at low rpms.