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Oxygen sensors, Cold engine tap, LPG conversion - 2002 XJR

2930 Views 4 Replies 3 Participants Last post by  johnco

I've just picked up a 2002 Daimler Super V8 (XJR) with 145k miles on the clock.

Oxygen Sensors

It's throwing a check engine light for a P0420 code. (Bank 1, low catalyst efficiency) Thanks to Hatfields Jaguar in Sheffield for pulling the code and clearing it free of charge. It doesn't reappear immediately, but will after a long journey/when fully hot and in traffic.

Most of the miles (100k) were in the first 3 years of it's life, and it had all four oxygen sensors replaced under warranty at 69k miles (Bank 1) and 72k miles (Bank 2) due to P0420 and P0430 codes.

The catalysts don't rattle at all, idle is smooth, and the car pulls like a train so I don't think there's much mechanically wrong. Common for these sensors have reached end-of-life at about this age?

What type of sensors are they? It looks like the upstream ones are an expensive linear/wideband type. Does the car *really* need the downstream ones to run properly?

Where's best to get them? I'm UK based but Jaguar parts/support is better stateside...

I've used these guys in the past to good effect, and they're cheaper than Rock Auto for the front sensors:
Jaguar XJR 4.0i Oxygen / Lambda Sensors :: Application List :: Gendan Automotive Products
4-wire Linear Air Fuel Ratio Oxygen Sensor for some Jaguar models
4-wire Denso Oxygen Sensor for some Jaguar models

Cold Engine Tap

Other warranty engine work - new thermostat at 35k miles, conrods replaced (!) at 75k miles due to a knocking sound when cold.

There is still a tappet/lifter type sound at tappet type frequency on tickover after a cold start. It disappears after 30 secs or so, and it's only when in D/R and the revs drop, not present at regular idle speed.

It's a May 2002 car, so should have the Gen3 tensioners/be immune from timing chain issues as far as I know. Supercharged, so it isn't the variable valve timing gubbins taking time to fill with oil. I'm going to take a look at the accessory belt tensioner and an old belt, perhaps tensioner is loose/belt is stiff or similar. Any other suggestions?

LPG Conversion

Probably a question I'm better asking over on the UK forums. This thing is big and thirsty, so we're going to be converting it to run on LPG (propane; mostly) as the taxes on this fuel are substantially lower.

The experts say that "these supercharged Jaguar engines" suffer from valve seat recession when running on LPG, but all the examples I've seen are no later 4.2 engines in Range-Rovers and it's debatable whether they were caused by the LPG or by poor installations that run lean at high load and burn the exhaust valves. Has anybody ever seen exhaust valve seat recession on one of these 4.0 engines?

I'll be fitting a "flashlube" kit - doses the engine with a lead substitute to reduce valve seat recession - but don't want to go too nuts with it as it'll compromise/plate out on the oxygen sensors and catalysts if you overdose.


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Marko the O2's are like spark plugs, they're in a harsh environment and do wear out eventually, your's is a classic example, posts a code after a long run coming off gas.

Just buy a code reader (if you haven't already I'd recommend a memoscan 581, ebay £50 or so) and clear the code. If it becomes a permanent warning then buy the oem unit and replace.

Cold engine tap, first off - drop the s/c belt, see if this removes the tap - then it's look into the tensioner and idler bearings and s/c and belt. If not, then it's time to look further. The May 2002's a well clear of the plastic tensioners, indeed they have the latest and greatest 4.0s/c units with all metal timing parts and morse style silent primary chains, so it won't be a timing issue.

For the LPG - get the best you can afford, I've heard Remarno? Italian kits are the best - also talk to go-lpg these lads are the no.1 in fitting LPG to Jaguar's and always advertise them in the Jaguar Enthusiasts Club magazine, if there's anyone who can tell you about VSR it's them.

How's the de-roof car? finished?
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Cheers Sean.

Check engine is a pretty regular affair already and as the LPG fitting will rely on the oxygen sensors I was thinking of swapping them now. Best part of £400 a pair for genuine pre-cat ones from British Parts though! £350 +VAT EACH from a dealer...

Good tip on S/C belt etc. I'll inspect when I have the S/C off for the LPG install. You rebuild these, right? Anything special to look for/inspection manuals out there? Worth ordering up bearings/seals at 145k by default or should it be fine? It's been fairly well kept (FJSH to 100k in first 3 years, independents x4 thereafter) and mostly seen chauffeur use.

LPG bits are currently en-route from Poland, last seen in Germany. Stag 300 Premium ECU, (unlike the Italian AEB based stuff incl Romano, it's truly sequential and the software is open/not locked to any particular brand of sensor/injector etc) HANA injectors (unlike the Italian stuff these are purpose designed for LPG, rather than pneumatic valves with different seals thrown in and a drilled piece of pipe as a metering orifice), twin "240 kW" KME vapourisers (no single vapouriser is capable of feeding a supercharged motor; the ratings on them are nominal and you've got to supply fuel for the gross engine power excl supercharger loss, and for an extremely rich air fuel on the supercharged engines at full chat - the equivalent of 500 bhp naturally aspirated I reckon), the flashlube system, and a bunch of other top-notch goodies. Tank is a secondhand one though; 95 litre Stako multi-hole toroidal from a Range-Rover with JIC fill hose rather than 8 mm and 8 mm outlet rather than 6 mm. ~£1150 in parts, at Polish prices. £1500 at UK prices.

I was going to fit a cheapie AEB system (King), with cheapie injectors (OMVL), a single vaporiser then use petrol addition at higher loads, and no flashlube system. This could be bought for under £600 all in from Poland but the more I thought the less I liked the idea of this on a daily driven supercharged car. Ok on a naturally aspirated one but you really don't want to chop and change fuel at full chat, risk burning valves, or be replacing injectors every 20k as you need to with the cheapies.

Steve @ Go-LPG seems to be an absolute cowboy and a bully-boy that only does the right thing when forced to by a judge...

Rubbish workmanship:

To fit a totally inadequate/inappropriate front end:

A bully boy:

But can do the right thing occasionally:

If you've got a naturally aspirated car, you only ever use 150 bhp or occasionally 200 bhp, and you wouldn't know a safe/tidy install from a botch job, then you'd be perfectly happy with his services. That description probably applies to a lot of his Jaguar customers - they're generally very nice people and not too demanding. He may also have learned a thing or two (at customers' expense) over the past 6 years, but I can't bring myself to trust anything that the guy says...

One I'm convinced actually does know about the supercharged Jaguars is Simon at LPGC:

LPGC Yorkshire Autogas LPG Conversions - Home Page

Didn't waste his time by asking for a price, but I should imagine £2k for a naturally aspirated vehicle and £2.5k for a supercharged vehicle is about the going rate.

Topless 8 is still a work in progress; going to tackle again in the first two weeks of August. Requires paint and an interior before we IVA it. Will probably need a new engine to get through the IVA as the one in there is essentially toast, but we'll see what it fails on first then present for re-test.
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that's interesting, I didn't know about go-lpg.......
You could try a product called Cataclean. It is available on ebay from about £12 including p&p. You may want to run your fuel tank down as far as possible and then add some Shell V power which has extra cleaners and then add Cataclean as per instructions.

A friend's car which had the engine light coming on under the conditions you have mentioned has remained e light free for sometime. It only needs a slight decrease in efficiency of catalyst for light to come on although it would still pass emmision's test. (Although you would fail with light on)
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