Hello all,

I'm on this forum because my dad has big problems with his ´99 3,0 S-type.

The symptoms are as follow:

At 55 mph the car jerks and starts to lose power. This upsets the automatic transmission and that one start to shift up and down.
Above 75 mph the car runs fine.

The car has been to three different shops and none of them has found solution.

The car has done about 63000 miles and is in as new condition otherwise.

The shops have so far replaced with no improvement:

5 ignition coils

All sparkplugs

One themostat sensor.

If anyone can hint towards a solution I would be most grateful.

/mikael

 

The car has a Ford 5R55N autobox. It is worth your time to search on here (see menu below logo) for:
5R55N
and see if it sounds like a problem fairly often reported.

It sounds like one of the autobox valves/springs and these are fairly cheaply replaced by any good tranny shop. (They should be as good as or better than a jag dealer and cheaper.)

I'm mildly curious as to why they replaced 5 rather than 6 coils?

 

Transplant 4.2 immediately to resolve situation.

 

Does your ford transmission need a "mercon V" transmission fluid change or a reflash of the computer controls. I HAVE THE SAME TRANSMISSION IN MY 2000 4.0 S-type. with 46,500 an had the fluid pan dropped and the filter done. If the car hasn't been push too much the fluid should be ok. A p137"maybe 139 " can't remember number," re-flash sticker is in the drivers door column if it has been done.

 

Only five coils were available at shop, so I just hope that they didn't leave a bad coil. One would think that a broken coil would show up as a fault code.

I can't see the menu below logo that you are referring to. Is it a website?

 

The car has been serviced according to Jaguars maintenance schedule. I will have to check whether they included this or not.

 

If badly broken, it would. The symptoms don't sound like a bad coil.

Top of any page here. Large logo. The menu is under it.

 

Yes Jaguar says filled for life transmission or 100,000 miles. I didn't buy that and did some checking and it seems jag may have had a slight change in theory on fluid changes. "CYA" The info on the filling hole and method is available on the WEB. A good foreign auto garage can get the mercon V fluid and filter/seal from NAPA or several other auto places. You may be feeling shutter in the transmission and the Mercon V will help even if you only change half and the other half in 30,000 miles. The re-flash was done on several models in 1999-2000. with 4.0 engines. I'm not sure about the 3.0's. you may want to Google the year and make and engine and see what problems people have.

 

I would like to update the thread with some additional information; apparently the box doesnt shift up and down.

The symptoms are worst when accelerating on the cruise control through the mentioned speed range. Then it's like the cruise control doesnt give enough throttle for the box to shift into the higher gear.

If he's accelerating with the gas pedal he doesn't notice. Probably because he's unknowingly increasing the throttle.

 

After 10+ years and 63K miles a reflash sounds like the last thing to try. Get it to a tranny specialist who knows that Ford box. Suppose there are broken parts inside, how long do you want to run it and hope nothing dire happens?

 

The driver has been in contact with a gearbox specialist in Sweden and they say it sounds like engine controller fault.

What do you guys think?

 

Do they REALLY know the Ford 5R55N?

The PCM on that year car also controls the autobox. You could try using an OBD tool but will need time and effort. If you want to do that, how much money can you afford for the tool?

Or take it to a dealer but it may be expensive.

 

The problem is now solved. It turned out to be a short in the main wiring below the hood behind the engine.
THe shop revealed the wires and parted them. Cars runs good now.

 

fantastic, thank you for updating us.

 

That's exactly the same problem I had! I'M NOT ALONE!

 

Which year, engine, and exactly which wires & where? Others cannot benefit if you don't give details

 

+1 and a picture or 2 are worth a thousand words!

 

I posted my problem on this thread: https://www.jaguarforums.com/forum/s...ad.php?t=36883

Long story short, the wire loom chaffed against the steel ring protecting the fuel connector. Top dead center at the rear of the engine. For some reason, the loom isn't well supported there, the ring is fairly sharp, and the wires are only wrapped and not clad in plastic loom. It caused an intermittent misfire, threw some weird codes (like cam position sensor), and eventually started popping the coil fuse. Some time with a meter narrowed down the offending wires, but only a diligent search found the bad spot. A little tape and replacement plastic armor and I haven't had a problem since.

Just before I found the actual problem, I replaced all six coils and plugs. The short killed one, but it was under warranty so no loss.