I was dawdling along at 60MPH and put my foot down (gently) to pass a slowpoke. The car lurched, for a split second the rear wheels locked (guessing when the motor cutout) and the car just coasted to a halt. I could restart it but it immediately died. I waited 5-10 mins and it restarted and ran fine the rest of 20 miles home. I tried time and time again to get it to cutout in the same manner by running at 60MPH and accelerating, but no could do.

A little history prior to this event is I haven’t used it for several months, but this was the return journey home so I had clocked about 60 miles that day. On previous outings the steering wheel positioning has not gone to the memorized setting until perhaps 10 mins into my journey. It’s a little disorientating when your steering wheel suddenly comes towards you unexpected. The windows have to be reset about once a month, then the roof wouldn’t open unless I increased the revs – i.e. more voltage output.
It has an after-market turbo-fan in the air intake pipe after the mass air flow sensor. It kicks in about mid throttle and it pulls a good few amps.

I have ordered an OBDII Bluetooth scanner to check my codes, which I should have this weekend.

My gut instinct is a volt/current problem affecting the car computer. Perhaps both battery and alternator.

Accurate, knowledgeable help greatly appreciated.

 

In these cars, stalling at speed is often caused by a dirty throttle body. A ring of carbon gunk forms around the throat of the throttle body at the butterfly valve, and under certain conditions can cause a stall.

I know...it happened to me in my 1997 coupe. Read the forum posts about it, bought some CRC Throttle Body Cleaner and followed the forum's suggestions on how to do it. Got it nice and clean and I haven't had a repeat stall in more than a year.

Pop off your air intake tube and have a look. Good luck.

 

Thx The Coupe,
Your maintenance tip certainly sounds less in depth than I was contemplating. Is it common to have such buildup on a throttle body with only 31k miles?

 

Maybe less common at those miles, but certainly possible. Pop off the intake and have a look...if you've got a black ring around the throttle body throat at the butterfly valve, I wouldn't make any other decisions until that was cleaned up properly and the car was run more. Drive that thing!

 

I’ll certainly clean the throttle body this weekend. I also read on another thread of the battery being the reason for the window resetting requirement, which I mentioned as my gut feeling because of the other issues related to the electronics.
As for driving, it is strictly a pleasuremobile, I have a Toyota Tundra for daily to and fro and the Jag only gets out to dinner, golf and the odd other trip.

 

+1 on advice given.

This may or may not be related to the stalling, but it sounds from your window behavior like you have a weak battery. If it is under 12.4 volts or so measured with a digital multimeter after sitting overnight (engine off) you should replace it.

Also check your battery cables at the clamps for corrosion. Check the two master fuses at the back of the trunk are clean and tight (do not put a wrench on these without disconnecting the battery first). Also, each fusbox has a heavy primary connection under a bolt....make sure these are clean and tight (again disconnect the battery first).

Lastly clean your throttle body connector pins with aerosol tuner cleaner from Radio Shack.

Read your codes, then clear them after you do all these things and see if any come back.

 

In addition to the advice posted already ... ditch that "turbo".

 

+2 !
At 3000 rpm you've got 6000 lpm going through the engine.
You're expecting an electric fan to compress that significantly.
Honestly it needs something very similar in size to the XKR's supercharger to do that.
Someone like Avos can tell us the exact power requirements but it is certainly a few kilowatts - several hundred amps at 12V
I'm willing to bet your fan is acting as a resistance and reducing your engine power.

 

+3!
The "turbo" is Junk!!!!

 

Thx Paul,
My OBDII bluetooth decoder showed up so this weekend I'll check the codes, the battery and connections, clean the throttle body and hopefully resolve the issue. I'll simply pull the fuse on the turbo fan and see if that fixes it too.

 

Sorry to go on but even removing the fuse won't negate the drag from your fan.
It obviously isn't the cause of this problem because you were running OK with it before but it isn't doing any good.

 

IMHO, The mere presence of the turbo fan in the intake would reduce performance, especially at high RPM.

I would remove it entirely.

 

I only meant pulling the fuse to diagnose the problem – i.e. if the fan is causing a drain on the voltage/current that is affecting the onboard computer system.

Ultimately I can remove it but do not have the replacement pipe at present.

Thx for keeping my best interests at heart.

 

Understood and perfectly valid. Let's get them codes !

 

OK, here's the deal.

The car hasn't been out for a couple of weeks so 1st I checked the battery voltage, it was 12.0V. Then started checking the connections and the ground terminal at the battery was wiggle loose - I suspect this may be the root of my evils. The positive wasn’t loose but not fully tight either and no other loose connections.

I started the car and when it warmed up it is 14.1V at idle and 13.1V with headlights, AC & fan, stereo, defogger and wipers on. I’ll check the voltage again in a week after it has been out for a run to see if the 12.0V increases.

Plugged the OBDII in but it doesn’t work and I tried it on the wife’s car but no connection with my Android – that was disappointing.

Cleaned the throttle body.

While in the trunk I checked out the convertible top hydraulics – the reservoir level is halfway – does anyone know the min and max levels?

If the rain keeps off I’ll be taking it out tomorrow for a run.

 

I believe I've discovered the answer to my question on the top hydraulic reservior - on closer examination I see the 2 lines around the 3/4 level of the tank and assume these are min and max. I need to add a few oz of fluid.

 

I would get your battery tested - I don't know the US names (? AutoZone) but any battery shop will test it for free.
These cars are terribly tetchy about voltage.

 

OK I got the OBDII codes. The scanner had 3 options and the clear codes option. Both current and history were blank and in pending codes there was P1111 and a reference to coolant over temp. I had an over heating problem earlier in the year and replaced the thermostat.