So I found this sweet looking XJ6 that some unappreciative guy wanted to release into the wild. Being a softie I couldn't help myself and brought the beast home. The ride was somewhat interesting but she made it as far as my driveway before passing out. Woke right up again though and I got her backed up in my shop.

So, she's got some issues. For $1500 I expected no less. Some time soon I will both have the funds and time to work on her so I figured I would try and get a bit of a head start and present some of the issues to you guys. Any help will be greatly appreciated and !

Main issue:

When I start her up she comes to life well enough but doesn't idle well. The prm goes up and down, really unstable stuff, and I usually have to keep a foot on the throttle to make sure she stays running. However, if I give her too much throttle she starts to shake badly at around 1000rpm and I can't for the life of me get her past 1500rpm. She doesn't stall. If I drive in this shape she's obviously one slow cat.

If I take the time to sit in the car and keep her running until she gets warm the symptoms usually go away and she runs just fine. Well, she does so at will more or less. If I keep the foot on the throttle she's fine, if I take it off to brake at an intersection she almost always dies out. Usually when she gets to where she would start idling (below 1000 rpm or so).

Oh, and the exhaust she puts out is super rich and smelly. Lingers in the shop forever.

Does anyone recognize these particular symptoms?

I figured it could be several things like a busted O2 sensor (the resistance with engine cold is lower than the Haynes manual recommends), a clogged catalytic converter (or two), TPS, MAF, fuel related? I guess it could be all kinds of things really.

 

Hi OldKingCole,

I had the same issues with my 3.6l. For me it was definitely the O2-sensor. I changed the plugs, cables, and distributor cap while I was at it. Runs fine after that.

But you are correct, it may also be some of the other issues you mention.

 

Hi OldKingCole,

It certainly sounds as though you have a rich-running condition, perhaps with some other issues as well. The O2 sensor is certainly a prime suspect, and you can measure it with a good digital VOM or oscilloscope for rapid switching between just above 0V and just under 5V.

Another prime suspect would be the Coolant Temperature Sensor (CTS), which is the two-conductor sensor mounted on top of the coolant thermostat housing at the front left top of the engine (the single-conductor sensor is for the dash temperature gauge). The CTS and MAF signals are used by the the Engine Control Module (ECM) to determine fuel enrichment. When the O2 sensor warms up to operating temperature the ECM then additionally refers to its signal and goes into closed-loop fuel metering. You can check the resistance across the CTS terminals with the engine cold, then again when the engine is hot, to confirm it is within spec at both temperatures. Also check the CTS wiring harness for a short or break.

Another common problem is a failed diaphragm in the Fuel Pressure Regulator (FPR), a bright metal cylinder at the front end of the fuel rail. You can do an intial test by pulling the vacuum hose from the FPR, cranking the engine, then checking for wet fuel at the vacuum line fitting. If present, the diaphragm has failed and unmetered fuel is being inhaled directly into the intake manifold contributing to rich running that the ECM may not be able to adjust for, especially if the O2 sensor is stuck or lazy and/or the CTS is out of range.

As Harald has also pointed out, it wouldn't hurt to do a basic tune-up just to rule out components such as plugs, wires, air and fuel filters, etc., and when you get the car running better, you might use a good fuel injector cleaner in your fuel tank on a regular basis for a while (or even better, remove the injectors, check them for sticking/leaking, and service them yourself or have them professionally serviced).

Let us know what you find.

Cheers,

Don

 

Thanks, that's promising and definitely gives me a good place to start. An O2 sensor is relatively cheap over here and I'd love if that turns out to be it.

Btw, are you Harald? Are you from Norway then? Just asking, cause so am I. Moved to the US a few years ago (yes, it was a woman .

Takker og bukker!

 

Thanks Don, that's a lot of awesome information. I think I'll start with the O2. Well, when I'm back home.

Oh, I did run a quick resistance test on it before I left for work. Didn't have the time to let her get warm (since I have to sit in the car for 20-30 mins to get her warm enough), also I don't have those backprobe leads. Anyway, I don't remember what the resistance of the O2 sensor was but I do remember it being approx 1-1.5 lower than the range given in the Haynes manual. Which btw must be one of the better Haynes manuals our there.

As for changing plugs and stuff, it's on the list and will be dealt with as soon as the money is available. The air filter is new though.

Speaking of, does anyone know where I can find one of those bolts that holds up the air filter house? The one with the flexible rubber on it? I jury rigged one, but not sure how long it will hold up. After she's on the road again that is.

Thanks again!

 

Hi OldKingCole,

That air cleaner mount is a common industrial item that goes by various names, such as "stud mount vibration isolator," "stud/stud vibration isolator," "cylindrical isolation mount," etc. With the various measurements (thread diameter and pitch, stud length, rubber isolator length and approximate diameter), you may be able to find a suitable replacement from one of the big industrial suppliers. For example, McMaster-Carr (mcmaster.com) carries a wide variety of sizes - they call them "vibration-damping sandwich mounts:"

McMaster-Carr

MSC Direct also carries them but their size selection seems to be more limited and their prices higher. Here's an example:

Vibration Isolators | MSCDirect.com

I bought some on eBay a couple of years ago that were the right size for some of the applications in our '93, so it might be worth searching eBay also. The one thing I haven't found is a source for new isolators with the same hex-shaped metal end plates as the original mounts. Please let us know if you find some!

Cheers,

Don

 

Thanks! Ironically, I think my jury rigged one ended up costing more than either one of those I'll see if I can get hold of a few.

After thinking about it some more, I'm going to go back on what I said earlier regarding the exhaust smell. It's definitely thick, but compared to my dad-in-law's truck, which really runs rich on fuel, mine smells a lot more catalytic to me. If there's a difference in smell from a carbureted non-catalytic vs a catalytic that runs rich, that might be why, but the Jag certainly has a different tinge and texture to it.

What's the likelihood of the catalytic converters being clogged? I'm pretty sure the exhaust, and the rest of her for that matter, is original.

Oh, and sorry for the confusion, but I'm not a Harald. I am Norwegian though

 

Might want inject a fuel system cleaner to clean the injectors. Due to the previous owner, the car probably sat unattended for some time. Clean the system, do a fuel pressure test clean or replace sensors. As Don mentioned do a maintenance tune-up.

 

Thanks. The tune-up is in the works but fuel injector cleaning is something that I definitely need to look into. Is there a recommended cleaner that can be used? I assume we're talking about a liquid poured into the fuel tank?

I've read a few articles on fuel injector cleaning and people seem to have mixed thoughts on how well it actually works, ranging from hardly any effect to pretty good. But, it's not expensive and there's not much to lose so... Someone did mention a specific kind of Lucas brand stuff that came in rather large containers, not the small regular ones normally found at Autozone or wherever. I'll see if I can find the link again.

I went ahead and invested in an O2 sensor (found a new original Bosch for $52 incl. shipping) and a new fuel filter. Any tips and tricks regarding swapping them out? Is it a good idea to warm up the car before taking the O2 sensor out for example?

 

The liquids poured into the fuel tank are probably helpful over time, and probably most of the major brands are effective and safe (Techron, BG, Lucas, STP, Redline, Gumout, etc.). I couldn't find BG for sale to home mechanics in my area, so I opted for Techron since I know several of the local new auto dealers use it and recommend it.

If your injectors are at a point where one or more are plugged, sticking and/or leaking, your best option will be to remove and clean them or have them professionally cleaned. There are a number of commercial companies that specialize in injector cleaning, and I'm sure they do a great job. I'm stubborn and cheap, so I did it myself, combining various tips and techniques I found online. I could visually watch the fuel streams from the injectors increase and become more consistent with better atomization, and the results were an improvement in fuel economy of nearly 2 mpg, which clearly answered the question for me as to whether cleaning the injectors is worthwhile. Here are links to photos showing how I did it at home for about $50.00:

Welcome to Jag-lovers - Members Photo Viewing Page
Welcome to Jag-lovers - Members Photo Viewing Page


I would definitely first try removing the old O2 sensor with the exhaust system cold, since access is limited and it is difficult to avoid touching the exhaust during the process. If you can't get the old sensor to turn, you could try running the engine for just a few minutes so the exhaust warms a little but doesn't become too hot (and the O2 sensor itself is heated to more than 500C within 20-30 seconds, so don't let it burn a hole through your hand!). Here are links photos showing how I replaced the sensor:

Welcome to Jag-lovers - Members Photo Viewing Page
Welcome to Jag-lovers - Members Photo Viewing Page


One other thought: If I recall correctly, the O2 sensor on the XJ40 is of the type that draws its reference ambient air down through the passages between the copper wires in the electrical harness, so the manner in which the electrical connector is attached to the wires is critical. If the replacement O2 sensor you purchased is of the "universal" type, with separate electrical connectors you must attach yourself, follow the directions very carefully and do not use solder. The internet is full of stories from folks who had trouble after attaching the connectors improperly or with solder, therby closing off the air passages between the copper wires. The best bet is to use an O2 sensor with the correct electrical connector attached at the factory.

Cheers,

Don

 

That's very interesting. I doubt I'm quite as stubborn (or gifted) a you but considering the state of my budget these days I think I'm going to give this one a go down the road. Excellent walkthrough, Don!

Another great walkthrough. Cheers!

Earlier today I was pretty sure I found an original Bosch for $52 but when I look closer it seems that the O2 sensor I bought is manufactured (or re-sold?) by XKS Parts, which is a Jaguar specialist based in California. I bought it based on what I figured was the original Jaguar parts code, DAC6907.

Here is the direct link to the O2 sensor on their website. As you, see no pictures. Hmm again. Hopefully it is the right type.

 

Hi OldKingCole,

A good place to confirm part numbers for your car based on your VIN is Jaguar Classic Parts (jaguarclassicparts.com), the parts service of the Jaguar Daimler Heritage Trust in the U.K. Use your VIN to check for the correct Jaguar part number for your O2 sensor:

Heated Oxygen Sensor - Parts For XJ6 (2.9, 3.2, 3.6, 4.0) from (V)500001 to (V)667828 | Jaguar Classic Parts UK

Unfortunately, the supersession function doesn't seem to be working currently (clicking on the two curved arrows that form a circle should bring up newer part numbers that superseded the older numbers).

By entering the earliest part number, AGU1870, in the search function of forum sponsor SNG Barratt's website, SNG Barratt - The Ultimate Jaguar Parts Specialist, it does appear that the earlier O2 sensors supersede to the DAC6907 number.

To find the correct Bosch part number, enter your car's details here:

Bosch Vehicle Part Finder

An intial search seems to indicate that the correct OE Bosch O2 sensor for a 1989 XJ6 is Bosch part number 13032. Searching this part number via google brings up lots of hits. The sensor seems to be available for $55 to $60 from vendors like Rock Auto, Amazon, eBay, etc.

Cheers,

Don

 

Thanks again Don.

I should have been more thorough, but there's still a fair chance that the O2 sensor I ordered is a good match for the OE one. It should be waiting for me when I get home from work and I'll definitely make sure to try and match it up to the old one before installing it.

I really should have learned my lesson from when I owned a (very very sweet) '93 Lancia Thema. Always cross-reference part numbers directly with the manufacturer's catalogs!

 

It's been a while since I've been able to work on the Jag but I finally had a few hours free and dug into it. So, here is what I have done so far:

O2 SENSOR
I replaced the O2 sensor with the universal unit. It was surprisingly easy to get the old one out, if a little cumbersome access wise. The new one fit well and I'm pretty sure I got the wires right. I didn't get a chance to test it because I decided to give the MAF and TPS a look while I had time. One question regarding the O2 sensor: do I have to drive the car a certain amount of miles or time before it registers right in the system?

MAF
Took this out in order to get the throttle body out. The filament looks clean but I gave them a dash or two of MAF cleaner since I had it apart anyway. There's a sticker on it saying it's been refurbished at some point. Anyway, I doubt this part is the one giving me trouble.

TPS SENSOR
I wanted to try and drill a couple of holes in the TPS sensor casing in order to get any gunk out so I followed DonB's excellent tutorials. I disconnected the MAF sensor without hassle. Same thing with the rubber bend connect the MAF to the throttle body but when I pulled the bend off I noticed there was a lot of oil inside it. Is that normal?

I then proceeded to undo the four 10mm bolts that connects the throttle body to the engine block. Awkward to get to but it went fairly quickly. I then disconnected the throttle linkage on top without disturbing the way it was set up (I hope). The throttle body, like the bend, also had dams of oil inside it. No surprise there. But is that normal? The oil wasn't burnt at all, looked pretty much like it does coming out of the can. Is there an oil leak in the engine?

I also noticed that there is a gasket of some kind between the throttle body and the engine block. According to DonB's tutorial it should be a metal to metal connection? Or is that just for the later model? Should I scrape the gasket off and get a clean surface?

Oh, and the TPS sensor seems much smaller on the 89 than it does on the later model. Has anyone tried to drill holes in the Lucas type TPS? If so, where is it safe to drill?

 

Hi OldKingCole,

Yes, all that oil is normal, and the cause of many TPS problems. The engine breather system delivers oil-rich vapors from the crankcase directly into the elbow in the air intake, and plenty of that oil condenses in the intake, throttle body and intake manifold instead of burning in the combustion process.


The parts diagram does show a gasket on the 3.6L engines, and the part numbers are different for engine numbers up to 180210 and from 180211:

Throttle Body-3.6 Litre - Parts For XJ6 (2.9, 3.2, 3.6, 4.0) from (V)500001 to (V)667828 | Jaguar Heritage Parts UK


Hopefully one of our early-car experts will respond, but you might look closely to see if the TPS case can be pried open to flush out the internals and drill your holes while the case is apart.

Oh, and while you have the throttle body off, you should clean your EGR port on the underside of the intake manifold:

Welcome to Jag-lovers - Members Photo Viewing Page

Cheers,

Don

 

Thanks, it's good to know that it's at least a normal situation.

Hm, yes indeed there is. I'll just add that to my cart then Hopefully I will find the time to at least get rid of the old gasket and clean the surface tomorrow.

I will try and gently pry it open tomorrow. If it should fail, how much would a new aftermarket TPS sensor be? Are there any alternatives to the Lucas one out there?

Just added it to the list . Oh, while I have been away for work my car has managed to spring a leak. I haven't been able to identify where it originates but the leak is noticeable behind the pedals and on the floor on the driver's side. Anyone have any idea what could be the culprit? I've pretty much ignored it in order to stay calm and positive

 

Hi OldKingCole,

You'll have to determine whether the liquid is oil or water. Since your car is an '89, it is possible that the brake booster is leaking Hydraulic System Mineral Oil into your driver's footwell. Many owners of the early XJ40s have converted to standard vacuum-powered brake boosters, so you might search this forum for details, as well as the archives of the XJ40 forum at Jag-Lovers.org, where I know a great deal of info is available.

If the liquid is water, my first question would whether it has been rainy where you live. If so, that might indicate a clogged duckbill in the cowl area under the windshield wiper motor, or a leaking windshield seal, sunroof drain, etc. If the weather has been dry and you've been running the air conditioning, I might suspect clogged A/C drains allowing condensation to accumulate below the evaporator and running out of the Climate Control Unit housing into the footwell. Lots of info about this problem also.

Please keep us informed.

By the way, I had to scroll up to the title of the thread to recall the model year of your car. It helps if you add that info to your signature so it appears in all of your posts. Hover your cursor over the username in the upper right of this page, and in the dropdown menu click User CP. In your Control Panel, click on Edit Signature in the left column under Settings & Options. Add any info you want, but include your car's model year, model (XJ6), engine displacement (3.6L?) and if you want, the trim level (Base, Sovereign, Vanden Plas/Daimler, Majestic).

Cheers,

Don

 

Cheers! Water is very unlikely as the car has been parked in my shop since I last was home a few months ago. No rain, no A/C so that leaves the HSMO. It's actually very likely that it is the brake booster (which I assume is the rather large contraption just in front of the windshield on the driver's side) as I noticed that the paint underneath it has been previously damaged and is either gone or peeling.

I guess I will be looking into converting it to vacuum power then. Another item added to my list

Thanks, I looked for the signature field earlier but failed to see it. I've added it now though.

 

Sooo... I went ahead and drilled two holes in the TPS, following DonB's guide. Since the 1989 has a different TPS than the later models (mine is a Lucas 215SA) I chose a small 3/32 drillbit and very carefully drilled holes on each side. As far as I could tell I didn't hit anything after penetrating the case. I then sprayed contact cleaner through both holes and yep, a fair bit of black gunk came out. I didn't have time to test if it is still working but I will do so when I am back home.

During my removal of the throttle body I once again followed one of DonB's excellent guides and I got it off without too much trouble. However, when I started looking for the EGR port underneath the manifold I almost missed it as it looks quite different from the later models. It's not red, it's not as big and it doesn't seem to be connected to a pipe but a hose. My picture is not that great, but I assume that the little grey thingamajig with the bolts sticking out of it is my EGR port?