Greetings

I recently purchased an S-type R which I've driven carefully for a week without thrashing it because I wanted to take it to a garage to get the engine-warning light checked out.

The specialist plugged in the diagnostic unit and said that the engine-warning light was down to a catalytic converter giving a reading just outside of normal (he said he sees readings like this regularly and that the detection level on S-types is too sensitive so although it was reporting a fault I shouldn't consider it to be one). At any rate, he cleared the fault and I left happy that the car had no serious problem.

Having been given the all-clear, I wanted to feel the V8's power so booted it in sport mode. This resulted in wonderfully rapid acceleration for about 2 seconds then sudden dying, lurching and spluttering of the engine with accompanying message "Restricted Performance" on the dash display. When I took my foot off the accelerator for a couple of seconds the "Restricted Performance" message cleared itself and I was then able to accelerate hard with full power available once again...until it the same thing happened a few seconds later. I was on a nice dry road and the wheels were not slipping i.e. it was not being limited by traction-control (unless malfunctioning!).

The engine-warning light has come back on again but the car drives fine provided I don't accelerate hard or rev high.

If anyone has any suggestions where to start I would be grateful to hear them!

If this was a carburetor-model I would have immediately suspected a blocked fuel-filter, but with the complexity of modern cars (about which I am not knowledgeable) I wonder whether the catalytic converter giving a known out-of-range reading (which was just recently been confirmed by the specialist as the reason the engine-warning light was on) could be contributory? The only other relevant piece of information is that the vehicle had just had a new throttle-body fitted before I bought it.

Hoping someone can steer me in the right direction - I'm hesitant to take it to a Jaguar garage and have them rack up a huge bill without knowing what's wrong.

Thanks and regards

Gordon

 

Gordon, to get any useful advice you will need to provide the actual code that the garage found, did they give you that?
If not you will need to have it checked again preferably elsewhere.
Where are you in the UK? Maybe some of the UK members can suggest a garage.

 

hmmmmm, my best guess its soemthing to do with the catalyst converter. When your accelerating hard the overly sensitive sensor is throwing you the restricted performance code and cutting power. If the mechanic cleared the check engine light it will probably go back on shortly if it hasent already done so. Either way i would drive it conservatively untill you can get that sensor checked out.

 

Buy yourself an OBD code reader (there's a huge thread on them here https://www.jaguarforums.com/forum/g...-%2A%2A-33347/ )
It's the only way you'll sort this out.

 

First thing is to change mechanics. The S-Types do NOT have overly sensitive sensors.

And buy your own OBD tool as suggested. One that does "live data" (so you can read sensors and fuel trims).

Try hard to find out what maintenance has actually been done on the car. By all means change the fuel filter as they're cheap and easy to do, but it's unlikely to be the cause - this is what OBD is for, to give info to rule out/in possible causes.

Grab JTIS and do some "light" reading so you get a feel for the car.

Have a browse and read of this forum, again to get a feel. Yes they have some commonish problems but hardly any are too scary. (STR valley pipe being an exception.)

It's kinda odd that the TB was changed. Any idea why?

 

First of all your mechanic is an idiot!! Please never go back to him again.

Can you find a independent garage that works on Jaguars? Here in the states I find the dealer to be the best but I always back it up with my knowledge.

The check engine light is on for a reason. You did the right thing and that is to always clear the code and then see if it comes back. Yours did so the car has a problem. Guaranteed!! No overly sensitive BS!! Now we need to remember that sometimes the code flags a certain item when the underlying problem is something else.

Have the spark plus and/or coils been changed or inspected?

The throttle body might have been replaced because the S Type has a known problem with water getting in thru the cowl which then drips on an exposed electrical plug that goes to the TB. So what I am saying is throttle bodies have been replaced when the underlying problem was water intrusion. The symptoms are often exactly what you posted. Was it raining or had it been raining when the RP happened?

We are in the dark as the other posters have mentioned. We must have codes to work with.

Finally not to criticize but why buy an STR and not enjoy the power? I have people ask me why I need a 400 HP car. The answer is I don't need anything but a POS car but I want something better. I use all 400 HP everyday and plan on my next car to be even stronger!!

Of course I wish the rear tires would last more than 15K miles but it's part of the game!!

You have a very early STR. What are the last 6 digits of the VIN? You might have one of the very first STR's.
.
.
.

 

Virtualgordon, ditto to all who posted. Let's get the scanner, etc.

Open the hood and check around for a vaccume leak. At 100k, cracked hose(s) or even one that's not connected will put her in restricted performance mode.

Go to the air filter box. Be sure that the lid is affirmatively set and clipped to the lower portion.

Check that the air intake tube leaving the airbox is secured to the airbox and aluminum tube running ontop the engine to the throttle body.

You can unscrew the Mass Air Flow sensor from the air intake tube and clean it. The EGR valve is located on the passenger rear side of engine and has a steel pipe connecting it to the passenger exhaust manifold.

This can rot out causing an exhaust leak which can lean her out. The brake booster has a hose coming off the rear of intake manifold to feed it vaccume.

The connection of the hose to the intake manifold can leak and will require a new hose (has an integrated connector at each end to connect it to manifold and booster).
Finally, jack her up and with engine cold, start her up, listening for rattling sounds eminating from the catalytic converters.

If rattling, then they need replacement. Aftermarket versions are much more affordable than OEM Jaguar. So whilst ordering an OBDII scanner, snoop around. Often times it's a situation that can be "self remedied".

If you're not the ratchet churning type, write down or print this post and give it to a competent mechanic.

Good luck chap.

 

I would also verify that your intercooler aux. coolant pump is running---check the fuse which should be identified in your owners manual.

 

Agree - that's exactly what has happened to my STR. Within 2-3 seconds of pedal to metal, poof, "Restricted performance".
The fuse (F36 in the engine compartment, right by the coolant reservoir) was OK, it was the pump that was gone. Mucho pricey from Jaguar (around $600), so I am about to test (a high-output) pump from Eurotoys at $280, but I hear that a Bosch model for about $120 is available.

 

Folks,

I'm truly humbled by your generosity with time and advice - thank you so much!

I shall need a bit of time to make the checks suggested and will post back asap. A Jaguar main-dealer will do a free report on the vehicle tomorrow morning which I think I am going to take advantage of to know where I stand regarding knowing what amount of money it is worth spending before I get drawn into buying parts and kit.

Norri - I didn't think to ask for the code from the garage; because the mechanic said there was no actual problem I didn't think to ask for it. (This was before the engine started dying when I only wanted to understand why the engine-warning light was on).

Ingo - Yep, sure enough the engine warning light is back on just as you said.

Steve - thanks for the link buddy!

JagV8 - no idea why the TB was changed I'm afraid (clubairth1 has explained why this is significant).

clubairth1 - Thanks for all the info. The last 8 digits of the VIN are: 21M54857. The car has full Jaguar service history (which does not list details!) and is in beautiful condition so I would not initially suspect plugs or regular-maintenance items. Re the 400bhp: Believe me when I tell you that the fact I have been driving the car gently is only due to that engine-warning light being on! My restraint is proof that I have finally grown up! I shall certainly be transformed into a teenager again as soon as I'm confident that booting it won't wreck the engine!

bfsgross - Thank you I shall check everything on that list.

Mountaincat and Robinb - I see where you are going with that suggestion and why it would cause a problem of that nature; fingers-crossed all this is just a fuse that would be a great result!



Your posts have made me realise that after being a very competent mechanic until the late 90's (maybe even a bit smug with my ability), technology has moved on and I'm a complete ignoramus again! ...I needed a good kick-in-the-pants; I've been behind a desk far too long! :-)


Cheers for now

Gordon

 

It is a bewildering leap to get involved with these complex beasts - I went from mending tractors to an XKR. For a tractor the only decision is what size of lump hammer....
The guys here will try to lead you through a logical sequence of diagnosis (unless it is a known 'standard' problem for this model like he s/c coolant pump)
Most diagnoses start with the OBD codes (that's what they're for after all).

 

Sometimes the Throttle position sensor on the pedal assembly causes that, but you're saying it goes away if you're lighter on the throttle. I bet everyone is right on with the pump reservoir.

 

Small (well, not so small!) point but the TPS (*) is not there (you apear to mean the APP sensors). And you'd expect a code to identify the culprit - others have had them.

(*) OK, there are 2 but let's not get too picky...

 

LOL, right right. I've had all kinds of strangeness happen. Like O2 Sensors throwing codes after the TPS code is thrown, and then both going away for no reason.

Right now I have a christmas tree dash caused by O2 sensors & the park brake actuator.

I still love this car though, just dropped $3k USD to have the transmission rebuilt.

Now if I can ever get to swapping out the timing chain tensioners on the XKR I'd be happy man. Just never seem to have the time to do it.

 

Lots of lights... are you sure the trans was faulty? Could easily be some underlying thing making all manner of others seem faulty when really they aren't.

If (that's IF) it's not power (connections, battery etc) then the next likely culprits are aftermarket work (now possibly semi-removed) or a harness fault - the latter is detailed in other lengthy threads and is a real PAIN if you're an unlucky owner.

 

Yeah, the trans was def shot, it was slipping horribly. When I got under it the cooling lines were cracked and the fluid leaked/sprayed out. Once they pulled it apart, 4th/5th/6th steels were pretty much shot, thankfully the hard parts were good! I had them go through it, replaced everything, even got the upgrade kit for the valve body.

As far as the park brake actuator, it sounds awful when it engages, sounds like the motor itself, the pads & caliper seem to be OK. Just shows up park brake fault when it engages. Once I get it apart, maybe I can fix the actuator, we'll see!

The fact that I have a Xmas tree for a dash is probably due to the fact that I have o2 sensors and the park brake failure occurring at the same time. You do bring up an interesting idea, I should probably check the loom around the wheel well and make sure its not rubbing anywhere. I really need to put some more time into this thing, I need to fix the drooping headlights too!

 

Update:

It's the driver's side cat... I took it to a main dealer who pretty much tried to get me to commit to a full car rebuild without even diagnosing the fault...I declined! :-)

I got the car up on a ramp and pulled the sensors out to get a viewing scope in to check the physical condition and the cat is a mess - the mesh is in pieces and all collapsed obstructing the outlet.

So I'm on the lookout for a replacement catalytic converter - but glad that I know what the fault was!

Grateful thanks for all your help and suggestions - very much appreciated!!!

Regards

Gordon

 

Let us know if this clears up your problem - always good to close a thread and helps others.

 

That's a very interesting way of checking out the cats ... beats tapping on them and listening for rattles any day of the week.

 

Had a feeling it was a cat.