2001 XK8 Conv 4.0 L Automatic - In the 'old days', when you stomped the gas to pass a car, the trans would drop down and the second set of butterflys would open up on the carb and you got some decent passing acceleration. With the new fuel injection and a Jaguar, is there such a thing as 'Passing Gear'. Just getting used to my 2001 and though it has good acceleration, it doesn't seem to 'kick it in the pants' when you stomp on it. From looking at other posts, I have noticed that there is a little slack in the accelerator cable (maybe about a 1/4"). Is the trans supposed to drop down, or is it just supposed to smoothly accelerate. Confused and wondering...

 

The XK8 and even the XKR are not very high on Torque and depend on downshifting to get good acceleration.

When I require power, downshifting from 5th to 3rd gear is often necessary.

Of course, too much slack in the accelerator cable could prevent proper downshifting.

 

Check the slack, but also are you aware that there is a hyperspace button underneath the accelerator pedal? I'm serious. You don't get full acceleration until you've pushed the gas pedal hard enough to depress that button. Try it with the engine off; push the gas pedal down, then push even harder. You'll feel a click as the hyperspace button gets pressed. I think some people push the pedal down until it stops, not aware than pushing it even harder will activate hyperspace and give them even better acceleration.

I know this sounds like a joke, but I'M SERIOUS! Try it!

 

This is a good name for the downshift button. When you hit it, it downshifts the tranny and the car gets into the torque curve. Acceleration is much stronger there.

 

Thanks to all. I will have to try the 'leap to hyper drive' button....

Next thing is to figure out, why the thing just went into 'fail safe mode'. Was just setting on the Rt 301 Bridge, traffic had been stopped (maybe 2-3 mintues at the most, outside air temp approx 70) for alternating traffic one way only, engine surged a little, put it in neutral, engine shut off by itself and 'fail safe' popped up. Restarted, got off the Bridge and got to the rest stop, popped the hood and it seemed like a lot of heat in the engine bay, though the Engine Temp was reading normal. Hoses didn't feel like they had any pressure on them. After it cooled down a little, pulled the cap on the reservoir and plenty of fluid. Had to limp home about 15 miles. Limiter looks like it would max the engine out at 1500. Would do 45-50 on the flat, 10-20 up the hill. Got back to the office, engine still showing normal temp/mid-scale, though the hoses now had some pressure on them and the fans (both of them) were running. The reason I mention radiator and water is, I thought that I had seen on one of the forums where the 'temp gauge' was reading OK, but in fact there was 'no water in the system' to allow the temp gauge to function/read properly. This in turn lead to the guy's engine seizing up because of the heat. Just seemed like there was an awful lot of heat in the engine bay at the 'rest stop'.

Will go out and get a scanner this evening to see what fault code popped up. Isn't life grand, Perplexed...

Just went out to see what else it was saying when the 'fail safe mode' was popping up on the speedo. Messages were like 'no trac' and 'no abs' ??). Now the 'fail safe mode' is off and not showing now, the engine is no longer on the limiter (will go up past 1500), however on the Tach , there is a 'yellow engine icon', which I am taking to mean that there is a fault code to be read. Can't tell, left all of the Manuals on the nightstand, from where I was reading them last night.

I am a little paranoid about excess heat in the engine bay, my '96 Cherokee is famous for shutting down when the temp gauge hits 210. Shut down once on Pennsylvania Ave, right next to the White House, if that didn't have the USSS shook up, nothing did. It doesn't do well in bumper to bumper even with extra fans running. It will finally start after sitting for 30-60 minutes and the eng temp has fallen. Hopefully by then the traffic has cleared out.

 

Codes? They will tell the story.

"Failsafe" and it's big brother "Restricted Performance" are common events, programmed into the ECU to keep things under control until whatever problem tripped them is addressed. That's where the codes come in.

There are many threads on the No ABS/No TRAC event. It's simple to diagnose what may be causing the problem, many people clear it up with a simple sensor cleaning.

Let us know what codes some up and you'll get good direction.

 

Scanned it and got a single fault code of P1229. No other codes indicated.
Reading Rev Sams 'list of codes', looks like a 'throttle body', reading Gus's, he kept getting this code as a sporadic/intermitent fault. Have only been running the Jag since last Friday, when I got plates on it. Total miles to date since tags approx 100. Total miles on odometer 90800. Info appreciated...

 

P1229 = Throttle motor control circuit malfunction. Possible causes are a disconnected motor, the communication between the motor and the ECU is shorting or the motor itself is bad. Start with the easy stuff - clean the throttle body electrical connectors with a proper electrical cleaner and put some dialectric grease on the connectors. There are several on the throttle body - do them all.

Next would be to check continuity within the circuit. A wiring diagram is available here on the forum I think.

Perhaps easier is to just presume the throttle motor has gone bad and have the throttle body rebuilt. There are several places that do that, with varyting degrees of expertese. Several people have said these guys are good:

Jaguar Electronic Throttle Bodies OEM Cross-Reference Guide - Jaytan Industries, Inc.

To my knowledge the motor can't be rebuilt separately, so expect to pay about $700 for the entire job.

You might get lucky and have an application that uses this throttle body:

JAGUAR XJ8 AND XK8 THROTTLE BODY NEW PART | eBay

I spoke with him and he seemed very knowledgable, it's a great deal and worth the call.

What you experienced on the road is the default actions the ECU takes in this situation:
1. Switches off the throttle motor
2. "Limp Home" activated - limits engine RPM to about 1,200 (via fuel cut off)
3. Inhibits idle speed control
4. Cuts off your cruise
5. Cuts off the ABS and TRAC

Numbers 1 and 2 explain your slow ride home and #5 explains why the ABS/TRAC notification went on.

Good luck and let us know what you decide.

 

Spurlee - thanks for the info, will try the cleaning of the elec conn's and dielectric grease first. The maint from the previous owner is a little suspect.

Maybe it's time to see if the tensioner upgrade has been performed. Though the Water Pump upgrade has been done. Then again it's a 90,000 mile vehicle and things get tired.

 

[QUOTE=Spurlee;343376]P1229 = Throttle motor control circuit malfunction.,,,, There are several places that do that, with varyting degrees of expertese. Several people have said these guys are good:

Jaguar Electronic Throttle Bodies OEM Cross-Reference Guide - Jaytan Industries, Inc.

This company is a ripoff. The sold my brother a two (2) TB and would not refund his money. He finally bought a new unit for $1400 and problem solved, so we know it was the bad TB.

I called the owner and he said he'd send the money, then he didn't. I told him I'd post the history of his tactics here on this forum and he blocked my number. All I get is a busy signal. Stay away from JayTan Industries.

 

I don't know exactly what you expect, but I can tell you that, even when running perfectly, you will not get that sudden "kick in the pants" that you got from a Detroit high hp V8 when you floored it and opened up the rear two barrels on that four barrel carburetor. I had a 340 Duster, and knew other people who had some performance cars, and those cars had a DRAMATIC effect when you floored it and went into "passing gear", which was usually 2nd in a 3 speed automatic.

This Jag engine will respond, but it won't be that dramatic effect that you may be looking for. I don't push mine very hard, very often, but I have noticed that it only starts to really seem to get going impressively when you get up to about 90 mph and you'd expect it to start tapering off a bit, but THAT is when it comes into its own.

BTW, how old do you have to be in MD, to drive a car?

(avatar)

 

You have the Right car (Jaguar) but the Wrong model.

You have: XK8.

You need: XKR.

 

It's not dramatic like the muscle cars, but the acceleration just keeps on coming. I got up to way beyond the legal limit on my private airfield the other day (>70mph) and just hadn't realised how fast she was going. Really, really smooth and she was still accelerating. What a phenomenal beast!

My last car was a Honda Prelude 2-door coupe with a tuned VTEC engine - the variable cam and timing that kicks in at 5000rpm and adds 25% to the engine power in a trice. That had a kick: a bit like an afterburner coming in at 5k revs. But the XKR is a different beast entirely: oodles of 'go' all through the rev range. I know which I prefer.

Best wishes, Colin

 

As far as the age to drive in MD (avatar), just like every where else. As far as the avatar, my youngest grandchild, whom I love dearly. Just thinking of him and my other grandkids, always keeps me thinking and feeling young. I even take him out golfing on occassion...

 

+1 to Paul's reply: You have the Right car (Jaguar) but the Wrong model.

You have: XK8.

You need: XKR.

And you might want to tighten up your throttle cable. Simple to do. Controversial. Since I tightened mine I get as good or better response OUT of sport mode than before IN sport mode.

Get those revs up around 4,000 and see what it does.
And, if that kick is important to you, GET AN XKR. Put's a grin on my face.

 

As previous posts have stated XKR will take care of the "kick in the back," however, there should still be a reasonable punch with the XK8. I have noticed that once in a while on my R if you are in between gears upshifting, sometimes it will not always downshift to passing gear. I wonder if there might be something amiss in the transmission that is preventing that passing gear from engaging. After all 285hp isn't anemic.