Jag stalling

I recently purchased a Jag XJ40, 4-litre auto (J Reg). I didn't notice any problems on the first day I got it, but twice today I've had a problem where I start the car up and it ticks over fine (though the car does judder a bit more than I would expect - timing out perhaps, or maybe sparks need replacing? it does idle at about 750 rpm - is that too low?) but as soon as I shift the box into reverse or drive it stalls. This happens 3 or 4 times and then it sets off fine, and hasn't stalled at traffic lights or anything.

The oil pressure in the car seems fine (usually just over half way on the dial - 5-ish), temps OK and there are no warnings reported by the ECU. I followed the instructions in the manual for checking the gearbox oil level, but couldn't get a very good reading.. that is, after I clean the dipstick and push it in/pull it out again, there's a thin film of oil all the way up the stick (past the "hot" marker), no matter how many times I repeat the measuring process. I'll have to have another go at this, but the gearbox seems to work fine after the initial stalling episode.

Two things I am wondering about - when I bought the car the guy at the garage said that when they got it they had to change the battery and they got standard cheap one from their regular supplier.. indeed, the central locking didn't work at first, but it had been sitting for 4-5 weeks at the garage and after I drove it the 100 miles or so home and took it around town a bit the locking suddenly started working and it's worked without fail since. However, do Jags have a heavier duty batteries fitted to them normally, given all the electrics they have in them? If that is the case, is it possible this is the cause of the stalling (OK, maybe that's daft since it starts first time and it's only when you shift it into gear that it stalls, but I have to ask as I'm no mechanic!).

The other thing is that I thought I had read somewhere in a bit of documentation that came with the car (there was loads of stuff!) that the car would take 95 ot 97 RON unleaded.. but when I was going through the manual I found a bit that said "use only premium unleaded".. isn't "premium unleaded" the 97 RON stuff? could that cause the stalling maybe?

Any ideas on this stalling issue, or for that matter - how to get a clean reading from the auto box dip stick!?

Thanks Ian

Reply to
IanW
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Just wait until winter to see if it starts ok .

IMO bite the bullet now and get a good battery .

Reply to
LP

With the stalling thing, firstly get the damn thing properly serviced and set up. The base mixture, base idle, and base timing figure is all adjustable on the pre 92 engine, although you have to put the ECU into service set mode to do so.

Do this *after* you have replaced the plugs, dissy cap and rotor arm (commonly wear out on this engine) cleaned out the throttle body- inspected the inlet bellows very carefully (they often split and cause all sorts of running problems) set the throttle butterfly base position, the TPS position, and cleaned the idle valve.

It doesnt sound like you have a fault, the engine just wants alittle TLC.

750rpm is fine when hot, though it should be ~950-1000rpm when cold.

Tim..

Reply to
Tim (Remove NOSPAM.

An I6 engine shouldn't judder - is it firing on all cylinders?

Reply to
Scott M

Thanks for the info... spoke to the mechanic I normally use and asked him to do a service plus check all the things you mentioned and so it's booked in for Thursday (£180.. not too bad since the Jag garage I spoke to wanted £382 just for a standard service!). He doesn't have an ECU thing for it though (for that matter nor do the other 3-4 garages I phoned up), but he's going to check with his m8 and if all else fails I'm waiting for a price from the Jag garage to do the ECU setup.

I like reassurance ;-) hope you're right - the engine does "sound" healthy, it's not a smoker, and the gearbox moves through the gears and kicks down pretty smoothly.

Regards Ian

Reply to
IanW

Is there an easy way of telling that? wouldn't it be reported via the ECU (I pressed that button next to the trip computer that is supposed to display any errors)?

Ian

Reply to
IanW

I don't suppose there's actually a way of telling if a cylinder fires correctly, so I wouldn't expect the computer to know. On my BM 6-cyl it's fairly obvious when its lost a cylinder of two; it's hard to explain but it won't sound "even". A properly running I6 should sound more like a turbine than an internal combustion engine.

The usual diagnosis is to pull plug leads and if you find one that doesn't make a difference then that's your culprit. Some modern engines don't take to this I believe, but if the arrangement is dizzy & single coil then I can't see it damaging anything.

Reply to
Scott M

Sounds like the throttle body needs a good clean, and also check the TPS clicks just off idle, Best done with engine off ignition on for the latter. A good run up the Motorway might help if the PO just poodled around in it.

Reply to
Stuart Gray

Yes, I see.. I think I'll leave that diagnosis to the mechanic, though, as I'm taking it in anyway :)

Regards Ian

Reply to
IanW

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