Dear Forum members

About six months ago, after dreaming about owning a Jaguar since I was a boy growing up in Birmingham, I bought a 2003 3.0 S Type. While it is everything I had dreamed about I do have two problems.

The first started about six weeks after I got the car and a warning light and message stated "restricted performance". This goes on and off intermittently and does affect performance. The strange thing is that it comes on and goes off at roughly the same places everyday on my way to work. My local mechanic cannot tell me what is causing this but did get a too lean code from the car.

Today I have had a second message flash up once which read "dsc not available". Can someone please tell what is going on here and how it is fixed?
Russell

 

Duplicate thread? See https://www.jaguarforums.com/forum/n...roblems-65581/

 

No, it's OK. The first post was in the New Member area and serves as a greeting and received non technical replies. We advised posting a technical question here in the S Type section.

Hope someone can help the guy.

 

Describe driving conditions when it happens - heavy/light engine load? Doing what with the throttle? etc.

Could easily be a failing battery as that affects DSC and the fuel injectors. But... too little data I feel.

 

Hi. The restricted performance light comes on usually at speeds above 60km/h and when the throttle is pressed down fast and hard. It also tends to occur about ten minutes after I set out for work or home and then will switch off about five to ten minutes later.

 

Could well be one or more bad coils. Try reading the OBD codes. If none, check fuel trims at idle and at 2500rpm.

Could also be a failing battery, as you're imposing a sudden load, but coils are common failures with age on modern cars.

 

Thanks mate.

 

Dear Forum members

I have had the air filter, fuel filter and spark plugs repolaced and as yet the restricted performance light has not come back on. Fingers crossed!

 

Problem is back again after three weeks. I was dismayed to say the least as I thought the problem had been fixed. Any ideas would be really welcome.

 

Get someone with a code scanner that works on your car. Not sure if cars in Australia use the same OBDII standard that we have in the US. Anyway, plug the scan tool in to record live data and take the car out for a drive with someone monitoring the scanner. Floor it and get it to trip the restricted performance. My guess is you either have a vacuum leak or a failing catalytic converter (or both). Also, don't clear the codes that come up, just report them at this point. With more data we may be able to at least point you and your mechanic in the right direction.

 

Many thanks Jeff. I will do this and get back on the forum.

 

Coils are still a top suspect. Your OBD is near enough same as here or USA (treat is as near enough not to matter).

If not coils could be battery (because a sudden huge demand is placed on it and it must not sag). Or cat(s).

 

Dear Guys

This is an update to my long running restricted performance thread to do with my 2002 S Type 3.0 V6.

My Launch Creader V arrived today in the post from Hong Kong. What a great buy. Three codes came up almost instantly. These are shown below:

P0171-System too lean bank 1
P0174-System too lean bank 2
P0037- HO2S heated oxygen sensor-central circuit low (Bank1 Sensor 2)

Can anyone make me a very happy man and tell me what problem these codes point to as I am desperate to sort my beloved Jag out.

 

Have a good stare at this so you have a basic idea of how modern cars work OnBoardDiagnostics.com - Engine Basics

Your car is essentially the same. All (yes, all) the sensors need to be working right.

If an O2 sensor (HO2S) is wrong then the car can't run right, but it's the upstreams (sensor 1s) that really matter. The sensor 2s are used for checking cat efficiency and fine trimming the fuelling. They need to work, however.

On the 3.0, and especially your era, an air leak (into engine vacuum) is nearly always the cause of your codes, though a dirty MAF also can be, as can a leak somewhere post-MAF.

You might try clearing those codes - mainly to see whether the P0037 comes back or not. You can be pretty sure the others will so may as well go about leak hunting. Lots of threads on here about the usual cause & fix.

You could have another cause - such as coils - but not so likely since they'd normally flag different codes, so go for the usual stuff. Probably fairly cheap & is DIY - see the FAQs I think.

hmm, looks like someone on the UK forum has "borrowed" Rick's (joycesjag) pic from the FAQs here, without attribution!!

 

My mistake! I meant to add the credit, I'll scuttle off and do it now!

Meanwhile here it is again, with thanks to Rick.

 

Can you please tell me where I would find the engine vacuum where the leak may be. I cannot see it on Rick's pic.

 

heh heh busted Norri!

Thanks for the heads up JagV8. Heck whatever I post here is up for grabs, no worries here!

Russell, could be any of the vacuum lines basically, here is the entire thread that the picture was copied from:

https://www.jaguarforums.com/forum/s...ics-faq-52720/


Another thought would be the IMT O-rings look here:

https://www.jaguarforums.com/forum/s...ck-pics-49214/


I would start with them first!

 

There is a vacume hose at the top of the engine in front which cracks look for it

 

Dear Guys, is this a MAF and if so how do I undo that strange five pointed nut?

 

The nut you are referring to is a star or "torx" screw/bolt. You will need a star bit head to remove it. The sizes range from T8 - T60

The smaller sizes like the one you are dealing with can be purchased as part of a screwdriver tool kit - the size bit you need is more than likely T10 or T15 - or you can get an assorted set that are attached to a 3/8" drive ratchet, which makes life much easier, especially re-tightening these screws to "spec" - you can get these in one of the big box stores (Home Depot/Lowes) or an auto store.

I recommend you get an assorted set if you plan on working on your vehicle. You will come across these star/torx screws quite a bit.